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UBC Theses and Dissertations

Effects of single-dose and short-term oral captopril on hepatic blood flow and haemodynamics in mild… Orbay, Judit 1992

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EFFECTS OF SINGLE-DOSE AND SHORT-TERM ORAL CAPTOPRIL ON HEPATIC BLOOD FLOW AND HAEMODYNAMICS IN MILD TO MODERATE HYPERTENSIVE PATIENTS by J U D I T ORBAY B.Sc. ( P h a r m ) , Semmelweis U n i v e r s i t y o f M e d i c i n e , 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES ( F a c u l t y o f P h a r m a c e u t i c a l S c i e n c e s ) ( D i v i s i o n o f P h a r m a c e u t i c s and B i o p h a r m a c e u t i c s ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF B R I T I S H COLUMBIA MAY, 1992 © J u d i t O r b a y , 1992 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives, it is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver, Canada Date i^, DE-6 (2/88) i i ABSTRACT The a n g i o t e n s i n c o n v e r t i n g enzyme i n h i b i t o r , c a p t o p r i l has been e x t e n s i v e l y u s e d i n t h e t r e a t m e n t o f m i l d t o m o d e r a t e h y p e r t e n s i o n and c o n g e s t i v e h e a r t f a i l u r e . A l t h o u g h t h e haemodynamic c h a n g e s a s s o c i a t e d w i t h a c u t e a n d / o r c h r o n i c c a p t o p r i l t h e r a p y have been e x t e n s i v e l y s t u d i e d , t h e r e i s c o n f l i c t i n g i n f o r m a t i o n o f i t s i n f l u e n c e on h e p a t i c b l o o d f l o w (QH). M o s t o f t h e human s t u d i e s have been i n v e s t i g a t e d t h e i n f l u e n c e o f c a p t o p r i l on a f t e r s i n g l e - d o s e a d m i n i s t r a t i o n and v e r y f e w d a t a a r e a v a i l a b l e on i t s e f f e c t s a f t e r c h r o n i c t h e r a p y . The most f r e q u e n t l y u s e d method t o e s t i m a t e i s b a s e d on t h e h e p a t i c c l e a r a n c e o f i n d o c y a n i n e g r e e n ( I C G ) f r o m t h e b l o o d . T h i s t h e s i s r e p o r t s i ) t h e e f f e c t s o f s i n g l e - d o s e (100 mg) and two-weeks (1 0 0 mg/day) c a p t o p r i l t r e a t m e n t on QH, a s s e s s e d by ICG c l e a r a n c e , i n s i x m i l d t o m o d e r a t e h y p e r t e n s i v e m a l e s u b j e c t s , i i ) t h e c h a n g e s i n t h e a r e a u n d e r t h e serum c o n c e n t r a t i o n - t i m e c u r v e (AUC) and p l a s m a c l e a r a n c e ( C l p I C G ) o f ICG, i i i ) t h e c h a n g e s i n b l o o d p r e s s u r e , h e a r t r a t e and s p l a n c h n i c v a s c u l a r r e s i s t a n c e (SVR) b e f o r e and a f t e r a c u t e and s h o r t - t e r m c a p t o p r i l t h e r a p y , i v ) t h e e f f e c t s o f p o s t u r a l c h a n g e f r o m s i t t i n g t o u p r i g h t on ClpICG and Q H b l o o d p r e s s u r e , h e a r t r a t e and SVR b e f o r e and a f t e r two-weeks c a p t o p r i l t h e r a p y , v) t h e e f f e c t s o f a c u t e and two-weeks c a p t o p r i l t r e a t m e n t on some i m p o r t a n t p h a r m a c o k i n e t i c p a r a m e t e r s o f u n c h a n g e d c a p t o p r i l . T h e r e w e r e two s t u d y d a y s two-weeks a p a r t ( d a y 1 and d a y 1 4 ) . was e s t i m a t e d a t b a s e l i n e s e a t e d , u p r i g h t , r e s e a t e d and 1 h o u r a f t e r c a p t o p r i l d o s i n g on t h e f i r s t s t u d y d a y . The same p r o c e d u r e s were r e p e a t e d i n t h e same p a t i e n t s f o l l o w i n g 14 d a y s c a p t o p r i l t h e r a p y . The serum c o n c e n t r a t i o n o f ICG was i i i d e t e r m i n e d by s p e c t r o p h o t o m e t r i c a n a l y s i s f o l l o w i n g i n t r a v e n o u s ICG d o s e o f 0.45 mg/kg. T h e r e was a s l i g h t ~ 5% and ~ 6% d e c r e a s e , b u t , no s i g n i f i c a n t c h a n g e i n C l p I C G and Q^, r e s p e c t i v e l y , w h e t h e r e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a , f o l l o w i n g t h e i n i t i a l and t e r m i n a l d o s e s o f c a p t o p r i l . A s i g n i f i c a n t 2 5 % - 2 9 % (p = 0.04) i n c r e a s e i n ICG p l a s m a c l e a r a n c e a f t e r two-weeks c a p t o p r i l t r e a t m e n t was o b s e r v e d i n a l l o f t h e f o u r s t u d y p h a s e s ( s e a t e d , u p r i g h t , r e s e a t e d and p o s t - c a p t o p r i l ) as c ompared t o c o n t r o l v a l u e s . L i v e r b l o o d f l o w i n c r e a s e d s u b s t a n t i a l l y , i n t h e f o u r s t u d y p h a s e s , i n t h e r a n g e f r o m 2 1 % t o 2 5 % (p = 0.06) a f t e r 14 d a y s t r e a t m e n t w i t h c a p t o p r i l . S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were r e d u c e d s i g n i f i c a n t l y a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l f r o m 160.5 ± 5.3 and 103.3 ± 1 mm Hg t o 132.4 ± 9.3 mm Hg (p < 0.005) and 86.6 ± 6.3 mm Hg ( p < 0 . 0 5 ) , r e s p e c t i v e l y , w i t h p e a k r e d u c t i o n 3 h o u r s a f t e r c a p t o p r i l d o s i n g . T r e a t e d b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s on d a y 14 were « 15 and ~ 11 mm Hg l o w e r t h a n t h e p r e t r e a t m e n t v a l u e s (p < 0.005 and p < 0.05, r e s p e c t i v e l y ) . The r e d u c t i o n i n b l o o d p r e s s u r e a f t e r two-weeks c a p t o p r i l t r e a t m e n t was s u s t a i n e d f o r 20 h o u r s p o s t - d o s e . The a b s o l u t e d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , 3 h o u r s a f t e r t h e t e r m i n a l c a p t o p r i l d o s e , was 31.7 ± 6.6 mm Hg ( 1 9 . 7 % ) and 20.4 ± 8.0 mm Hg ( 1 9 . 8 % ) , r e s p e c t i v e l y (p < 0 . 0 0 5 ) , as c o m p a r e d t o p r e t r e a t m e n t v a l u e s . H e a r t r a t e r e m a i n e d u n a l t e r e d a f t e r t h e a c u t e d o s e s o f c a p t o p r i l and d e c r e a s e d s l i g h t l y = 3 b e a t s / min a f t e r two-weeks c a p t o p r i l t h e r a p y . D e s p i t e t h e s i g n i f i c a n t r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , SVR was u n a f f e c t e d by t h e a c u t e d o s e s o f c a p t o p r i l . In c o n t r a s t , a f t e r t wo-weeks c a p t o p r i l t h e r a p y SVR d e c r e a s e d as an a v e r a g e by 19% ± 3% (p i V = 0 . 1 2 5 ) . P o s t u r a l c h a n g e f r o m s i t t i n g t o u p r i g h t s i g n i f i c a n t l y d e c r e a s e d C l p I C G by ~ 2 5 % (p = 0.005) and 2 7 % (p = 0.001) on d a y 1 and 14, r e s p e c t i v e l y . S i m i l a r l y , s i g n i f i c a n t l y d e c r e a s e d by ~ 2 3 % (p = 0.008) and = 2 5 % (p = 0.003) d u r i n g u p r i g h t p o s t u r e b e f o r e and a f t e r two-weeks c a p t o p r i l t h e r a p y , r e s p e c t i v e l y . T h e r e was a s l i g h t i n c r e a s e i n d i a s t o l i c b l o o d p r e s s u r e (= 5-7 mm Hg) i n u p r i g h t p o s i t i o n on b o t h s t u d y d a y s . A s i g n i f i c a n t i n c r e a s e i n h e a r t r a t e o f 4 and 6 b e a t s / m i n (p < 0.025) was o b s e r v e d on s t a n d i n g b e f o r e and a f t e r c a p t o p r i l . The SVR i n c r e a s e d i n u p r i g h t p o s i t i o n by 3 1 . 0 % (p < 0.05) and 3 3 . 3 % ( n o n - s i g n i f i c a n t ) , b e f o r e and a f t e r two-weeks c a p t o p r i l t r e a t m e n t , r e s p e c t i v e l y , as c ompared t o s e a t e d v a l u e s . I n a g r e e m e n t w i t h p r e v i o u s s t u d i e s , t h e s erum c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l i n c r e a s e d r a p i d l y a f t e r c a p t o p r i l a d m i n i s t r a t i o n . Peak serum c o n c e n t r a t i o n (Cmax) u n c h a n g e d c a p t o p r i l was 697.2 ± 192.8 ng/ml (mean ± SEM) and t h e t i m e r e q u i r e d t o r e a c h Cmax (tmax^ ~ 76 m i n u t e s a f t e r a s i n g l e c a p t o p r i l d o s e . The Cmax a f t e r t h e t e r m i n a l d o s e o f two-weeks c a p t o p r i l t r e a t m e n t was 870.5 ± 85.9 ng/ml w h i c h i s ~ 2 5 % ( n o n - s i g n i f i c a n t ) l a r g e r t h a n t h a t a f t e r t h e i n i t i a l d o s e and was r e a c h e d ~ 52 m i n u t e s f o l l o w i n g d r u g a d m i n i s t r a t i o n . I n c o n c l u s i o n , d e s p i t e t h e f a c t t h a t c a p t o p r i l has no a p p a r e n t a c u t e e f f e c t on as m e a s u r e d I h o u r p o s t - d o s e , t h e r e i s a s u b s t a n t i a l c h r o n i c i n c r e a s e i n on c o n t i n u e d c a p t o p r i l a d m i n i s t r a t i o n i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n . A c u t e and s h o r t - t e r m a d m i n i s t r a t i o n o f c a p t o p r i l d o e s n o t i n t e r f e r e w i t h t h e h o m e o s t a t i c r e s p o n s e s t o p o s t u r a l c h a n g e . The d e c r e a s e i n SVR on c o n t i n u e d t h e r a p y may s u g g e s t an i m p o r t a n t a n t i h y p e r t e n s i v e m e c h a n i s m o f c a p t o p r i l . The c a p t o p r i l i n d u c e d i n c r e a s e i n a f t e r p r o l o n g e d t h e r a p y s h o u l d be c o n s i d e r e d when c a p t o p r i l i s c o a d m i n i s t e r e d w i t h h i g h - c l e a r a n c e d r u g s , h e n c e , t h e r a p e u t i c e f f e c t may be a l t e r e d . b e c a u s e s y s t e m i c a v a i l a b i l i t y . T a b l e o f C o n t e n t s A b s t r a c t i i T a b l e o f C o n t e n t s v i L i s t o f F i g u r e s x L i s t o f T a b l e s x i v L i s t o f A p p e n d i c e s x v i A b b r e v i a t i o n s x v i i A c k n o w l e d g e m e n t x x i D e d i c a t i o n x x i i 1. INTRODUCTION 1 1.1. G e n e r a l B a c k g r o u n d 1 1.2. R e n i n - A n g i o t e n s i n S y s t e m 1 1.3. C a p t o p r i l 4 1.3.1. M e c h a n i s m and S i t e s o f A c t i o n 5 1.3.2. Haemodynamic E f f e c t s i n H y p e r t e n s i o n 8 1.3.3. E f f e c t s on L i v e r B l o o d F l o w 9 1.3.4. C a p t o p r i l P h a r m a c o k i n e t i c s i n H y p e r t e n s i o n 11 1.4. E s t i m a t i o n o f L i v e r B l o o d F l o w 13 1.4.1. I n d o c y a n i n e G r e e n C l e a r a n c e M e t h o d 14 1.4.2. H e p a t i c C l e a r a n c e 15 1.4.3. E f f e c t s o f L i v e r B l o o d F l o w on H e p a t i c C l e a r a n c e 16 1.4.4. I n d o c y a n i n e G r e e n 18 1.4.4.1. P h a r m a c o k i n e t i c s o f ICG 18 1.4.4.2. A n a l y s i s o f ICG i n Human Serum 19 1.5. U p r i g h t P o s t u r e : A P h y s i o l o g i c a l S t i m u l u s t o A l t e r L i v e r B l o o d F l o w 20 1.6. R a t i o n a l e and O b j e c t i v e s 21 1.6.1. R a t i o n a l e 21 1.6.2. O b j e c t i v e s 22 2. EXPERIMENTAL 24 2.1 M a t e r i a l s and S u p p l i e s 24 2.1.1. D r u g s 24 2.1.2. C h e m i c a l s and R e a g e n t s 24 2.1.3. S o l v e n t s 25 2.1.4. S u p p l i e s f o r Human E x p e r i m e n t s 25 2.1.5. O t h e r S u p p l i e s 26 2.2 E q u i p m e n t 26 2.2.1. S p e c t r o p h o t o m e t e r 26 2.2.2. H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h 26 2.2.3. M i s c e l l a n e o u s 27 2.3. P r e p a r a t i o n o f S t o c k and R e a g e n t S o l u t i o n s 27 2.3.1. I n d o c y a n i n e G r e e n 27 2.3.2. C a p t o p r i l 28 2.3.3. R e a g e n t S o l u t i o n s 28 2.4. UV S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n ( I C G ) i n Human Serum 29 2.4.1. P r e l i m i n a r y E x p e r i m e n t s 29 2.4.1.1. S t a b i l i t y o f ICG i n D e i o n i z e d W a t e r 29 2.4.1.2. S t a b i l i t y o f ICG i n Human Serum 29 2.4.2. Q u a n t i t a t i v e S p e c t r o p h o t o m e t r i c A n a l y s i s o f ICG i n P a t i e n t Serum 30 2.4.2.1. P r e p a r a t i o n o f S a m p l e s f o r S t a n d a r d C u r v e 30 2.4.2.2. S p e c t r o p h o t o m e t r i c A n a l y s i s 31 2.4.3. I n t e r - d a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c A s s a y 31 2.4.4. I n t r a - d a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c Method 32 2.5. H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h i c A n a l y s i s o f Unchanged C a p t o p r i l i n Serum 32 2.6. Human S u b j e c t s 33 2.7. S t u d y P r o t o c o l 34 2.7.1. Dye and Drug A d m i n i s t r a t i o n , B l o o d Sample C o l l e c t i o n 3 4 2.7.2. B l o o d P r e s s u r e and H e a r t R a t e Measurement 38 2.8. D a t a A n a l y s i s 38 2.8.1. K i n e t i c P a r a m e t e r s o f ICG and L i v e r B l o o d F l o w 38 2.8.2. P h y s i o l o g i c a l C a l c u l a t i o n s 39 2.8.3. S t a t i s t i c a l A n a l y s e s 41 RESULTS 42 3.1. S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n ( I C G ) 42 3.1.1. S t a b i l i t y o f ICG i n D i s t i l l e d W a t e r 42 3.1.2. S t a b i l i t y o f ICG i n Human Serum 42 3.1.3. R e p r o d u c i b i l i t y o f S t a n d a r d C u r v e s 44 3.1.4. S t a n d a r d C u r v e s f o r t h e Q u a n t i t a t i o n o f ICG i n P a t i e n t S a m p l e s 44 3.1.5. I n t e r - D a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c Method 49 3.2. Human S u b j e c t s 49 3.3. Changes i n t h e K i n e t i c P a r a m e t e r s o f ICG 53 3.3.1. Serum C o n c e n t r a t i o n D a t a o f I n d o c y a n i n e G r e e n 53 3.3.2. K i n e t i c P a r a m e t e r s o f ICG ( t w o , AUCQ" and C l „ T p p ) 53 3.3.2.1. E f f e c t s o f P o s t u r a l Change on AUC and ^ C l p T p Q B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t 55 3.3.2.2. A d u t e E f f e c t s o f C a p t o p r i l on AUC and C l p T ^ g 64 3.3.2.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on AUC and C l p I C G 68 v i i i 3.4. Changes i n L i v e r B l o o d F l o w (Qu) 71 3 . 4 . 1 . H e m a t o c r i t D a t a 71 3 . 4 . 2 . Qy D a t a 72 3 . 4 . Z . 1 . E f f e c t s o f P o s t u r a l Change on B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t 7 5 3 . 4 . 2 . 2 . A c u t e E f f e c t s o f C a p t o p r i l on 79 3 . 4 . 2 . 3 . S h o r t - T e r m E f f e c t s o f C a p t o p r i l on 81 3 . 5 . Changes i n B l o o d P r e s s u r e and H e a r t R a t e 8 5 3 . 5 . 1 . E f f e c t s o f P o s t u r a l Change on B l o o d P r e s s u r e and H e a r t R a t e 8 6 3 . 5 . 2 . A c u t e E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e and H e a r t R a t e 8 6 3 . 5 . 3 . S h o r t - T e r m E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e and H e a r t R a t e 102 3.6. Changes i n S p l a n c h n i c V a s c u l a r R e s i s t a n c e 1 08 3 . 6 . 1 . E f f e c t s o f U p r i g h t P o s t u r e 108 3 . 6 . 2 . A c u t e E f f e c t s o f C a p t o p r i l on SVR 111 3 . 6 . 3 . S h o r t - t e r m E f f e c t s o f C a p t o p r i l on SVR 111 3.7. Serum C o n c e n t r a t i o n D a t a o f C a p t o p r i l 1 13 4. DISCUSSION 1 1 8 4.1 . S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n i n Human Serum 1 1 8 4 . 1 . 1 . V a l i d a t i o n o f t h e S p e c t r o p h o t o m e t r i c Method 119 4.2. E s t i m a t i o n o f QH by ICG C l e a r a n c e 121 4.3. Serum C o n c e n t r a t i o n D a t a o f ICG 122 4.4. Changes i n C l p j Q g and 124 4 . 4 . 1 . E f f e c t s o f P o s t u r a l Change on C l „ T r g and Qu B e f o r e and A f t e r C a p t o p r i l ^ 124 4 . 4 . 2 . A c u t e E f f e c t s o f C a p t o p r i l on CI J(^Q and Q^ ^ 128 4 . 4 . 3 . S h o r t - t e r m E f f e c t s o f C a p t o p r i l on C l p j ^ g and Q^ 135 4.5. Changes i n S p l a n c h n i c V a s c u l a r R e s i s t a n c e 138 4 . 5 . 1 . C a l c u l a t i o n o f S p l a n c h n i c V a s c u l a r R e s i s t a n c e 138 4 . 5 . 2 . E f f e c t s o f P o s t u r a l Change on SVR B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t 139 4 . 5 . 3 . A c u t e E f f e c t s o f C a p t o p r i l on SVR 140 4 .5.4. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on SVR 140 4.6. Changes i n B l o o d P r e s s u r e 142 4 . 6 . 1 . E f f e c t s o f P o s t u r a l Change on B l o o d P r e s s u r e B e f o r e and A f t e r C a p t o p r i l 142 4 . 6 . 2 . A c u t e E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e 143 4 . 6 . 3 . S h o r t - T e r m E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e 147 4.7. Changes i n H e a r t R a t e 149 4.7.1. E f f e c t s o f P o s t u r a l Change on H e a r t R a t e B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t 149 4.7.2. E f f e c t s o f A c u t e and S h o r t - T e r m C a p t o p r i l T r e a t m e n t on H e a r t R a t e 150 4.8. Changes i n H e m a t o c r i t 151 4.8.1. E f f e c t s o f P o s t u r a l Change on H e m a t o c r i t B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t 151 4.8.2. A c u t e E f f e c t s o f C a p t o p r i l on H e m a t o c r i t 153 4.8.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on H e m a t o c r i t 153 4.9. Serum C o n c e n t r a t i o n D a t a o f C a p t o p r i l 154 5. SUMMARY AND CONCLUSIONS 156 5.1. UV S p e c t r o p h o t o m e t r i c A n a l y s i s o f ICG i n Human Serum 156 5.2. E f f e c t s o f P o s t u r a l Change 156 5.2.1. ClpjçG and Qu 156 5.2.2. H e m a t o c r i t , S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e , H e a r t R a t e 157 5.2.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e 157 5.3. A c u t e E f f e c t s o f C a p t o p r i l 158 5.3.1. ClpTQg and Q,^  158 5.3.2. S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e and H e a r t R a t e 158 5.3.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e 159 5.4. S h o r t - t e r m E f f e c t s o f C a p t o p r i l 160 5.4.1. ClpjçG and Qu 160 5.4.2. H e m a t o c r i t , S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e and H e a r t R a t e 161 5.4.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e 162 5.5. Serum C o n c e n t r a t i o n D a t a o f Unchanged C a p t o p r i l 162 5.6. C o n c l u s i o n s 163 6. REFERENCES 165 APPENDIX 175 L i s t o f F i g u r e s F i g u r e 1. F i g u r e 2. F i g u r e 3. F i g u r e 4. F i g u r e 5. F i g u r e 6. F i g u r e 7. F i g u r e 8. F i g u r e 9. F i g u r e 10. F i g u r e 11 S i t e s o f a c t i o n o f c a p t o p r i l ( m o d i f i e d f r o m B e n o w i t z and B o u r n e , 1 9 8 9 ) . C h e m i c a l s t r u c t u r e o f c a p t o p r i l S t a b i l i t y t e s t o f ICG i n human s e r u m a t h i g h ( 6 . 0 Mg/ml) and l o w ( 0 . 2 ng/ml) c o n c e n t r a t i o n s . V a r i a b i l i t y i n t h e s l o p e s o f t h e r e g r e s s i o n l i n e s o f s t a n d a r d c u r v e s u s e d i n t h e s t a b i l i t y t e s t o f ICG i n human serum. S p e c t r o p h o t o m e t r i c s c a n s o f ICG s t a n d a r d s a m p l e s i n human serum. C o n c e n t r a t i o n r a n g e f r o m 0.2 t o 5.0 /zg/ml. R e p r e s e n t a t i v e s t a n d a r d c u r v e i n t h e c o n c e n t r a t i o n r a n g e f r o m 0.2 t o 5.0 /ig/ml ( n = 4 ) . R e l a t i o n s h i p b e t w e e n t h e a c t u a l and f o u n d ICG c o n c e n t r a t i o n s . D a t a a r e p r e s e n t e d as mean ± SD, n=4. R e p r e s e n t a t i v e s erum c o n c e n t r a t i o n versus t i m e c u r v e o f ICG o b t a i n e d i n a p a t i e n t on d a y 1 and d a y 14 i n s e a t e d (open c i r c l e ) , u p r i g h t ( c l o s e d c i r c l e ) , r e s e a t e d ( o p e n t r i a n g l e ) p o s i t i o n s and 1 h o u r a f t e r c a p t o p r i l ( c l o s e d t r i a n g l e s ) . C l p j Q Q ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) i n t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) p h a s e s o b t a i n e d i n s i x p a t i e n t s on d a y 1 and d a y 14. E f f e c t s o f p o s t u r a l c h a n g e and t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) ^o§e o f c a p t o p r i l on C l p j r g (mean ± SEM, n=6) i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , MANOVA, p < 0.005. C o m p a r i s o n o f C K J ^ Q ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) ( m e a n ± SEM, n=6) b e f o r e ^nd a f t e r two-weeks c a p t o p r i l . i n d i c a t e s s i g n i f i c a n t l y 3 5 43 45 45 48 50 54 60 d i f f e r e n t f r o m day 1, MANOVA, p < 0.05. 70 F i g u r e 12. Q^ ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i 1 (CA) p h a s e s o b t a i n e d i n s i x p a t i e n t s on d a y 1 and d a y 14. 74 F i g u r e 13. E f f e c t s o f p o s t u r a l c h a n g e and t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e g f c a p j o g r i l on (mean ± SEM, n=6). and i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , MANOVA, p < 0.05 and p < 0.005, r e s p e c t i v e l y . 78 F i g u r e 14. C o m p a r i s o n o f ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) ( m e a n ± SEM, n=6) b e f o r e and a f t e r two-weeks c a p t o p r i l . 83 F i g u r e 15. I n c r e a s e i n Qjj (mean ± SEM, n=6) f r o m d a y 1 (o p e n c i r c l e s ) t o d a y 14 ( c l o s e d c i r c l e s ) . 84 F i g u r e 15. S y s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c a p t o p r i l (CA) on d a y 1 and d a y 14. 87 F i g u r e 17. D i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c a p t o p r i l (CA) on d a y 1 and d a y 14, 88 F i g u r e 18. H e a r t r a t e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c g p t o p r i l (CA) on day 1 and d a y 14. i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , p a i r e d s a m p l e t - t e s t , p < 0.05. 89 F i g u r e 19. Changes i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l ( d a y 1) i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 91 F i g u r e 20. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6), as compared t o p r e t r e a t m e n t v a l u e s , 1 and 3 h o u r s | f t e r Jhg i n i t i a l d o s e o f c a p t o p r i l . and i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . 94 F i g u r e 2 1 . Changes i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l ( d a y 14) i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . F i g u r e 22. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6), as compared t o t h e t r e a t e d b a s e l i n e o f d a y 14, 1 and 3 h o u r ^ a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l . i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05. F i g u r e 2 3 . Changes i n mean a r t e r i a l p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e o f c a p t o p r i l i n s m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . F i g u r e 24. Changes i n h e a r t r a t e 1 and 3 h o u r s a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . F i g u r e 2 5. D e c r e a s e i n s y s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) f r o m p r e t r e a t m e n t v a l u e s a f t e r two-weeks c a p t o p r i l i n m i l d / m o d g r a t e J j y g e r t e n s i v e p a t i e n t s . and i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . F i g u r e 26. D e c r e a s e i n d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) f r o m p r e t r e a t m e n t v a l u e s a f t e r two-weeks c a p t o p r i l i n ^ i l d / m g d g r a t e h y p e r t e n s i v e p a t i e n t s . and i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . F i g u r e 27. A c u t e e f f e c t s o f c a p t o p r i l on h e a r t r a t e (mean ± SEM, n=6), 1 and 3 h o u r s a f t e r c a p t o p r i l on d a y 1 and d a y 14. F i g u r e 28. S p l a n c h n i c v a s c u l a r r e s i s t a n c e (SVR) (mean + SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and p o s t - c a p t o p r i l (CA) on day 1 and d a y 14. i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , MANOVA, p < 0.05. x i i i F i g u r e 29. Serum c o n c e n t r a t i o n versus t i m e p r o f i l e o f u n c h a n g e d c a p t o p r i l f r o m s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n a f t e r t h e i n i t i a l ( d o t t e d l i n e ) and t e r m i n a l d o s e ( s o l i d l i n e ) o f c a p t o p r i l . 114 F i g u r e 3 0 . Serum c o n c e n t r a t i o n versus t i m e p r o f i l e o f u n c h a n g e d c a p t o p r i l (mean ± SEM, n=6) a f t e r a s i n g l e d o s e ( o p e n c i r c l e ) and t h e l a s t d o s e ( c l o s e d c i r c l e ) o f two-weeks c a p t o p r i l t r e a t m e n t . 116 F i g u r e 3 1 . Changes i n Qu d u r i n g t h e c o u r s e o f d a y 1 (op e n t r i a n g l e s ) and d a y 14 ( o p e n c i r c l e s ) , as c o m p a r e d t o t h e c h a n g e s i n Q^ due t o c i r c a d i a n v a r i a t i o n ( b a s e d on Lemmer and N o l d , 1 9 9 1 ) . 134 L I S T OF TABLES S t a n d a r d c u r v e d a t a o f ICG f o r p a t i e n t s erum s a m p l e s . R e s u l t s o f t h e i n t e r - d a y r e p r o d u c i b i l i t y t e s t o f t h e s p e c t r o p h o t o m e t r i c method f o r m e a s u r i n g ICG i n human s e r u m . C h a r a c t e r i s t i c s o f Human S u b j e c t s . C h anges i n AUCQ"' o f ICG b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t i n s i x m i l d t o m o d e r a t e h y p e r t e n s i v e p a t i e n t s . C h a n g e s i n C l p j j ^ Q b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t i n s i x p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n . C h anges i n t h e mean AUCQ® and ClpjQo b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t on d a y 1 and d a y 14. C o m p a r i s o n o f t h e mean AUCQ" and C I p J P G d a t a ( n o r m a l i z e d t o body w e i g h t ana body s u r f a c e a r e a ) o b t a i n e d i n t h e f o u r s t u d y p h a s e s o f d a y 14 w i t h t h o s e o f d a y 1. Changes i n h e m a t o c r i t i n s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n d u r i n g p o s t u r a l c h a n g e and b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . C h anges i n Q^  and Qu n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a (mean ± SEM, n=6) b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . C o m p a r i s o n o f Q^  d a t a ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) o b t a i n e d i n t h e f o u r s t u d y p h a s e s o f day 14 w i t h t h o s e o f d a y 1. Change i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . C h anges i n mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n . T a b l e 13. Change i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 95 T a b l e 14. Changes i n mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n . 98 T a b l e 15. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as com p a r e d t o t h e p r e t r e a t m e n t b a s e l i n e i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 103 T a b l e 16. C o m p a r i s o n o f mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e o b t a i n e d a f t e r two-weeks c a p t o p r i l t r e a t m e n t w i t h t h e u n t r e a t e d v a l u e o f d a y 1. 104 T a b l e 17. Changes i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e f r o m s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n d u r i n g p o s t u r a l c h a n g e and b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . 110 T a b l e 18. The d a t a o f AUCn*, C^.^' ^max serum c o n c e n t r a t i o n a f t e r 180 m i n u t e s o f d o s i n g (Cp3h) o f u n c h a n g e d c a p t o p r i l f o r s i x p a t i e n t s on d a y 1 and d a y 14. 114 L I S T OF APPENDICES A p p e n d i x 1. S e m i - l o g a r i t h m i c p l o t s o f ICG serum c o n c e n t r a t i o n versus t i m e c u r v e s f r o m f i v e p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n o b t a i n e d on d a y 1 and d a y 14 i n s e a t e d ( s i , open c i r c l e s ) , u p r i g h t ( u p , c l o s e d c i r c l e s ) , r e s e a t e d ( s 2 , open t r i a n g l e s ) and 1 h o u r a f t e r c a p t o p r i l d o s i n g . A p p e n d i x 2. C l p ( n o r m a l i z e d t o body w e i g h t and b ody s u r f a c e a r e a ) d a t a o f ICG b e f o r e and a f t e r t h e i n i t i a l d o s e ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f c a p t o p r i l . A p p e n d i x 3. Qu d a t a b e f o r e and a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f c a p t o p r i l . 176 178 179 X V I 1 A B B R E V I A T I O N S ACE ANOVA AUC AUCQ" AUCQ* AUTOAN B BP BSA BW °C Ca CA CHF CI C1 CI CI H i n t pICG -max ^ p 3 Hr a n g i o t e n s i n - c o n v e r t i n g enzyme a n a l y s i s o f v a r i a n c e a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e f r o m t i m e z e r o t o i n f i n i t y a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e f r o m t i m e z e r o t o t i m e t d e c i s i o n m a k i n g p h a r m a c o k i n e t i c m o d e l l i n g p r o g r a m b a s e l i n e b l o o d p r e s s u r e body s u r f a c e a r e a body w e i g h t d e g r e e s C e l s i u s h e p a t i c a r t e r i a l p l u s p o r t a l v e n o u s d r u g c o n c e n t r a t i o n p o s t - c a p t o p r i l p h a s e o f t h e s t u d y c o n g e s t i v e h e a r t f a i l u r e c l e a r a n c e h e p a t i c c l e a r a n c e h e p a t i c i n t r i n s i c c l e a r a n c e p l a s m a c l e a r a n c e o f i n d o c y a n i n e g r e e n Peak serum c o n c e n t r a t i o n o f d r u g serum c o n c e n t r a t i o n o f d r u g 3 h o u r s a f t e r a d m i n i s t r a t i o n s e rum c o n c e n t r a t i o n a t t i m e t serum c o n c e n t r a t i o n a t t i m e z e r o m i c r o - c a p i l l a r y r e a d e r h e p a t i c v e n o u s c o n c e n t r a t i o n c o e f f i c i e n t o f v a r i a t i o n e l e c t r o c a r d i o g r a m e t h y l e n e d i a m i n - t e t r a a c e t i c a c i d d i h y d r a t e h e p a t i c e x t r a c t i o n r a t i o et alii and o t h e r p e o p l e f r e e f r a c t i o n i n b l o o d gram g a s t r o i n t e s t i n a l h o u r h o u r h e i g h t h e m a t o c r i t H e w l e t t - P a c k a r d h i g h - p e r f o r m a n c e l i q u i d c h r o m a t o g r a p h h e p a t i c v e n o u s p r e s s u r e i n d o c y a n i n e g r e e n i n t r a v e n o u s a p p a r e n t e l i m i n a t i o n r a t e c o n s t a n t k i l o g r a m m o n o p o t a s s i u m p h o s p h a t e m o l a r m u l t i v a r i a t e a n a l y s i s o f v a r i a n c e mean a r t e r i a l p r e s s u r e m i c r o g r a m m i c r o l i t e r Hm m i c r o m e t e r mg m i l l i g r a m m i n m i n u t e ml m i l l i l i t e r m^ s q u a r e m e t e r mm m i l l i m e t e r mM m i l l i m o l a r mm Hg m i l l i m e t e r s o f m e r c u r y n s a m p l e s i z e Na2HP04 d i s o d i u m p h o s p h a t e ng nanogram nm n a n o m e t e r NPM N - ( 3 - P y r e n y l ) m a l e i m i d e NS s t a t i s t i c a l l y n o t s i g n i f i c a n t pH n e g a t i v e l o g a r i t h m ( b a s e 10) o f t h e h y d r o g e n i o n c o n c e n t r a t i o n PTFE p o l y t e t r a f l u o r o e t h y l e n e h e p a t i c b l o o d f l o w r ^ r - s q u a r e ( a n d r i s t h e P e a r s o n p r o d u c t - m o m e n t c o r r e l a t i o n c o e f f i c i e n t ) RAS r e n i n - a n g i o t e n s i n s y s t e m rpm r e v o l u t i o n s p e r m i n u t e s i f i r s t s e a t e d phase o f t h e s t u d y s2 s e c o n d s e a t e d ( r e s e a t e d ) p h a s e o f t h e s t u d y SD s t a n d a r d d e v i a t i o n s e c s e c o n d SEM s t a n d a r d e r r o r o f t h e mean SH s p o n t a n e o u s l y h y p e r t e n s i v e SVR s p l a n c h n i c v a s c u l a r r e s i s t a n c e SPSS S t a t i s t i c a l P a c k a g e f o r S o c i a l S c i e n c e s t - t e s t t e s t o f a s t a t i s t i c a l h y p o t h e s i s c o n c e r n i n g t h e S t u d e n t -t d i s t r i b u t i o n t j / 2 e l i m i n a t i o n h a l f - l i f e t ^ g ^ t i m e t o r e a c h maximum serum c o n c e n t r a t i o n T t r e a t e d v a l u e U.B.C. U n i v e r s i t y o f B r i r t i s h C o l u m b i a U u n i t up u p r i g h t p h a s e o f t h e s t u d y USP U n i t e d S t a t e s P h a r m a c o p e i a UV u l t r a v i o l e t vs versus W body w e i g h t ACKNOWLEDGEMENT I w o u l d l i k e t o s i n c e r e l y t h a n k my s u p e r v i s o r D r . James E. A x e l s o n f o r h i s s u p e r v i s i o n , f r i e n d s h i p , g u i d a n c e and f i n a n c i a l s u p p o r t . S p e c i a l t h a n k s f o r h i s u n c e a s i n g e n c o u r a g e m e n t and u n f a i l i n g s u p p o r t t h r o u g h o u t t h e s t u d y . S i n c e r e t h a n k s a l s o t o D r . R o b e r t E. Rangno f o r h i s v a l u a b l e a d v i c e , g u i d a n c e , e n t h u s i a s m and c o n s t r u c t i v e c r i t i c i s m d u r i n g t h i s p r o j e c t . I w o u l d a l s o l i k e t o t h a n k my c o m m i t t e e members D r . F r a n k A b b o t t , D r . James O r r and D r . Ron R e i d f o r t h e i r g u i d a n c e and s u p p o r t d u r i n g t h e c o u r s e o f t h i s w o r k . Many t h a n k s t o D r . K. Wayne R i g g s f o r h i s s u p p o r t , e c o u r a g e m e n t and f r i e n d s h i p t h r o u g h o u t my p r o j e c t . T h a n k s go t o Dr. T i m o t h y P. S t r a t t o n f o r h i s h e l p t o s o l v e many s t a t i s t i c a l p r o b l e m s i n t h e s e e x p e r i m e n t s . S i n c e r e t h a n k s t o Mr. R o l a n d W. B u r t o n f o r h i s h e l p and p a t i e n c e i n s o l v i n g many i n s t r u m e n t a l p r o b l e m s d u r i n g my s t u d i e s . My a p p r e c i a t i o n t o S h e l l e y Dean and R u t h Graham f o r t h e i r a s s i s t a n c e i n c o l l e c t i n g b l o o d s a m p l e s . S p e c i a l t h a n k s go t o D r . M a t t h e w R. W r i g h t f o r h i s v a l u a b l e a d v i c e t h r o u g h o u t t h i s p r o j e c t and f o r h i s c o n s t r u c t i v e c r i t i c i s m w r i t i n g t h i s t h e s i s . The a s s i s t a n c e o f Ms. J i n g Wang d u r i n g t h e human e x p e r i m e n t s and h e r f r i e n d s h i p i s g r e a t l y a p p r e c i a t e d . S i n c e r e t h a n k s t o my c o l l e a g u e s i n t h e l a b o r a t o r y Mr. G e o r g e Tonn, Mr. K r i s h n a s w a m y Y e l e s w a r a m , and D r . A n d r a s S z e i t z f o r t h e i r f r i e n d s h i p , p a t i e n c e , e n c o u r a g e m e n t and c o u n t l e s s v a l u a b l e a d v i c e . Many t h a n k s t o D r . G r a c e Lap-Yu Chan f o r h e r f r i e n d s h i p and h e l p d u r i n g t h e p r e p a r a t i o n f o r t h e human e x p e r i m e n t s and t o M a r i o n Wong, M a r g u e r i t e Yee and Sue P a n e s a r f o r t h e i r f r i e n d s h i p and i n s p i r a t i o n . S p e c i a l t h a n k s go t o D r . Kâroly N i k o l i c s , P r e s i d e n t o f t h e H u n g a r i a n P h a r m a c e u t i c a l A s s o c i a t i o n , f o r h i s e n c o u r a g e m e n t and s u p p o r t d u r i n g my s t u d i e s . S i n c e r e t h a n k s t o D r . G y o r g y Szatmàri, D i r e c t o r o f t h e S t a t e S a n a t o r i u m o f S o p r o n , f o r p r o v i d i n g me t h e t i m e t o c o m p l e t e t h i s p r o j e c t . x x i i T h i s t h e s i s i s d e d i c a t e d t o L a s z l o , my h u s b a n d who l i v e d t h r o u g h a l l t h e h a r d s h i p w i t h me and t o my p a r e n t s whose l o v e c a r r i e d me t h r o u g h t h i s p r o j e c t . 1. INTRODUCTION 1.1. G e n e r a l B a c k g r o u n d H y p e r t e n s i o n i s a m a j o r r i s k f a c t o r i n t h e d e v e l o p m e n t o f c a r d i o v a s c u l a r d i s e a s e s s u c h a s c o r o n a r y a r t e r y d i s e a s e , c e r e b r o v a s c u l a r d i s o r d e r and r e n a l d i s e a s e ( D z a u , 1 9 8 9 ) . H y p e r t e n s i o n i s g e n e r a l l y d e f i n e d as s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s p e r s i s t e n t l y e x c e e d i n g 160 and 95 mm Hg, r e s p e c t i v e l y ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . P r i m a r y o r e s s e n t i a l h y p e r t e n s i o n , i s t h e most common f o r m o f s y s t e m i c h y p e r t e n s i o n . A l t h o u g h i t s c a u s e i s unknown, t h e e l e v a t e d b l o o d p r e s s u r e i s g e n e r a l l y assumed t o be c a u s e d by an i n c r e a s e i n p e r i p h e r a l r e s i s t a n c e t o b l o o d f l o w ( W a l t e r , 1 9 8 2 ) . The l i n e a r r e l a t i o n s h i p b e t w e e n e l e v a t e d b l o o d p r e s s u r e and d e v e l o p m e n t o f c a r d i o v a s c u l a r d i s o r d e r s b e g i n s a t t h e l e v e l c l a s s i f i e d as m i l d h y p e r t e n s i o n ( d i a s t o l i c p r e s s u r e 90-104 mm Hg) (McMahon, 1 9 8 4 ) . A n g i o t e n s i n - c o n v e r t i n g enzyme (ACE) i n h i b i t o r s r e p r e s e n t a r e l a t i v e l y new t y p e o f a n t i h y p e r t e n s i v e d r u g s w h i c h h a v e been recommended as f i r s t - l i n e d r u g s i n t h e U n i t e d S t a t e s ( D z a u , 1 9 8 9 ) . A l t h o u g h , ACE i n h i b i t o r s a r e w i d e l y u s e d i n E u r o p e t h e i r a c c e p t a n c e a s f i r s t - l i n e d r u g s has n o t been u n i f o r m ( Z a n n a d and G i l g e n k r a n t z , 1 9 8 9 ) . 1.2. R e n i n - A n g i o t e n s i n S y s t e m The r e n i n - a n g i o t e n s i n s y s t e m (RAS) p l a y s an i m p o r t a n t r o l e i n t h e m a i n t e n a n c e o f c a r d i o v a s c u l a r h o m e o s t a s i s i n b o t h , h e a l t h y and h y p e r t e n s i v e s u b j e c t s ( B r o g d e n et al., 1 9 8 8 ) . The s c h e m a t i c r e p r e s e n t a t i o n o f t h e RAS i s shown on F i g u r e 1. A c c o r d i n g t o t h e c l a s s i c a l c o n c e p t , t h e enzyme r e n i n i s r e l e a s e d f r o m t h e k i d n e y c i r c u l a t e s i n t h e p l a s m a where i t c o n v e r t s a n g i o t e n s i n o g e n ( p r o d u c e d i n t h e l i v e r ) t o t h e i n a c t i v e d e c a p e p t i d e a n g i o t e n s i n I ( D z a u , 1 9 8 8 ) . S u b s e q u e n t l y , ACE c l e a v e s a n g i o t e n s i n I t o f o r m t h e o c t a p e p t i d e a n g i o t e n s i n I I , a p o t e n t v a s o c o n s t r i c t o r , w h i c h i s t h e m a i n a c t i v e compound i n t h e s y s t e m . A n g i o t e n s i n I I i s t r a n s p o r t e d by a r t e r i a l b l o o d t o p e r i p h e r a l t i s s u e s ( b l o o d v e s s e l , k i d n e y , h e a r t , b r a i n e t c . ) and e x e r t s i t s a c t i o n on a n g i o t e n s i n I I r e c e p t o r s ( C a m p b e l l , 1 9 8 7 ) . R e c e n t l y , t h i s c l a s s i c a l c o n c e p t o f t h e c i r c u l a t i n g RAS has been r e v i s e d b a s e d on e v i d e n c e w h i c h s u g g e s t t h a t a n g i o t e n s i n I I i s p r o d u c e d m a i n l y i n t i s s u e s by t h e a c t i o n o f l o c a l ACE t o c o n v e r t t h e l o c a l l y p r o d u c e d a n g i o t e n s i n I t o a n g i o t e n s i n I I ( C a m p b e l l , 1 9 8 7 ) . T h e r e f o r e , t h e RAS c a n n o t be c o n s i d e r e d s i m p l y as a c i r c u l a t i n g e n d o c r i n e hormone s y s t e m , b u t a l s o as a t i s s u e g e n e r a t e d r e g u l a t o r o f v a s c u l a r r e s i s t a n c e and t i s s u e f u n c t i o n ( D z a u , 1 9 8 8 ) . T h e s e l o c a l RASs may f u n c t i o n , p a r t l y o r c o m p l e t e l y , i n d e p e n d e n t l y o f t h e c i r c u l a t i n g RAS ( C a m p b e l l , 1 9 8 7 ) . The e x i s t a n c e o f l o c a l l y p r o d u c e d a n g i o t e n s i n has been d e m o n s t r a t e d i n a number o f t i s s u e s w h i c h a r e i n v o l v e d i n t h e r e g u l a t i o n o f c a r d i o v a s c u l a r h o m e o s t a s i s s u c h as t h e b l o o d v e s s e l w a l l , k i d n e y , h e a r t , b r a i n , a d r e n a l g l a n d s and i n t e s t i n e ( U n g e r et al., 1989; D z a u et al., 1 9 8 8 ) . M o s t r e c e n t l y , t h e c o n t r i b u t i o n o f p e r i p h e r a l and s p l a n c h n i c v a s c u l a r t i s s u e s t o t h e s y s t e m i c a n g i o t e n s i n I I d i s p o s i t i o n and t h e r e g u l a t o r y f u n c t i o n o f t h e s p l a n c h n i c v a s c u l a r bed has been d e m o n s t r a t e d i n humans ( G a s i c et al., 1 9 9 1 ) . The v a s o c o n s t r i c t o r e f f e c t s o f a n g i o t e n s i n I I a r e p r i m a r i l y e x h i b i t e d on t h e s m o oth m u s c l e o f a r t e r i o l e s , h e n c e , l e a d s t o an i n c r e a s e i n s y s t e m i c v a s c u l a r r e s i s t a n c e . A n g i o t e n s i n I I a l s o s t i m u l a t e s t h e s e c r e t i o n o f a l d o s t e r o n e by t h e a d r e n a l c o r t e x , w h i c h f a c i l i t a t e s s o d i u m and w a t e r A n g i o t e n s i n o g e n K i n i n o g e n Ren in A n g i o t e n s i n 1 7^  A C E ( k i n i n a s e II) A n g i o t e n s i n II V a s o c o n s t r i c t i o n A l d o s t e r o n e s e c r e t i o n I n c r e a s e d p e r i p h e r a l v a s c u l a r r e s i s t a n c e I n c r e a s e d s o d i u m a n d water r e t e n t i o n I n c r e a s e d b l o o d p r e s s u r e K a l l i k r e i n B r a d y k i n i n Inac t ive I n c r e a s e d p r o s t a g l a n d i n s y n t h e s i s V a s o d i l a t a t i o n D e c r e a s e d p e r i p h e r a l v a s c u l a r r e s i s t a n c e D e c r e a s e d b l o o d p r e s s u r e F i g u r e 1. S i t e s o f a c t i o n o f c a p t o p r i l ( m o d i f i e d f r o m B e n o w i t z and B o u r n e , 1 9 8 9 ) . r e t e n t i o n and p o t a s s i u m e x c r e t i o n ( B r o g d e n et al., 1988; R a i a et al., 1 9 9 0 ) . T h e r e f o r e , a n g i o t e n s i n I I f o r m a t i o n p r o d u c e s v a s o c o n s t r i c t i o n and i n c r e a s e d b l o o d v o l u m e w h i c h , i n t u r n , r e s u l t i n an i n c r e a s e d s y s t e m i c b l o o d p r e s s u r e . U n d e r p h y s i o l o g i c a l c o n d i t i o n s t h e i n c r e a s e i n b l o o d p r e s s u r e , b l o o d v o l u m e and a n g i o t e n s i n I I l e v e l c a u s e an i n h i b i t o r y a c t i o n on t h e r e l e a s e o f r e n i n by n e g a t i v e f e e d b a c k m e c h a n i s m s t o m a i n t a i n h o m e o s t a s i s ( B r o g d e n et al., 1 9 8 8 ) . S i n c e ACE i s i d e n t i c a l t o k i n i n a s e I I i t a l s o i n a c t i v a t e s t h e p o t e n t v a s o d i l a t o r b r a d y k i n i n , w h i c h has been shown t o e n h a n c e t h e f o r m a t i o n o f v a s o d i l a t o r y p r o s t a g l a n d i n s ( F i g u r e 1) ( R a i a e t al., 1 9 9 0 ) . 1.3. C a p t o p r i l C a p t o p r i l , ( D - 3 - m e r c a p t o - 2 - m e t h y l - 1 - o x o p r o p y l - L - p r o l i n e ) ( C a p o t e n * ^ ) , i s an o r a l l y a c t i v e a n g i o t e n s i n - c o n v e r t i n g enzyme (ACE) i n h i b i t o r f r e q u e n t l y u s e d i n t h e t r e a t m e n t o f m i l d t o m o d e r a t e h y p e r t e n s i o n and c o n g e s t i v e h e a r t f a i l u r e ( K a d i n , 1982; B r o g d e n e t al. 1 9 8 8 ) . C h e m i c a l l y , c a p t o p r i l i s a d i p e p t i d e t h i o l ( F i g u r e 2 ) , c o n t a i n i n g a s u l f h y d r y l m o i e t y and two o p t i c a l l y a c t i v e c e n t e r s . I n p l a s m a c a p t o p r i l u n d e r g o e s o x i d a t i o n a t t h e t h i o l g r o u p t o y i e l d c a p t o p r i l d i s u l f i d e ( K a d i n , 1 9 8 2 ) , T h e r e f o r e , t h e i m m e d i a t e p r o t e c t i o n o f t h e t h i o l g r o u p by t h e d e r i v a t i z a t i o n w i t h N - e t h y l m a l e i m i d e i s e s s e n t i a l t o p r e v e n t l o s s o f c a p t o p r i l a f t e r b l o o d s a m p l i n g ( F u n k e , 1 9 8 0 ) . F i g u r e 2. C h e m i c a l s t r u c t u r e o f c a p t o p r i l 1.3.1. M e c h a n i s m and S i t e s o f A c t i o n The i n h i b i t o r y e f f e c t s o f c a p t o p r i l on t h e RAS i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n have been d e m o n s t r a t e d i n a number o f s t u d i e s ( A t l a s et al., 1979; M u i e s a n e t al., 1982; W e n t i n g e t al., 1 9 8 2 ) . The s u l f h y d r y l g r o u p e n a b l e s t h e c a p t o p r i l m o l e c u l e t o r e v e r s i b l y i n t e r a c t w i t h t h e z i n c i o n a t t h e a c t i v e s i t e o f ACE ( O n d e t t i , 1 9 8 8 ) . I t i s t h i s i n h i b i t o r y a c t i o n on ACE t h a t d e t e r m i n e s , p a r t l y , t h e p h a r m a c o l o g i c a l e f f e c t s o f c a p t o p r i l . The p r e c i s e m echanism by w h i c h c a p t o p r i l r e d u c e s b l o o d p r e s s u r e and p e r i p h e r a l r e s i s t a n c e has n o t , y e t , been f u l l y e l u c i d a t e d ( B r o g d e n et al., 1 9 8 8 ) . A c u t e i n h i b i t i o n o f ACE by c a p t o p r i l r e s u l t i n a d e c r e a s e i n a n g i o t e n s i n I I and p l a s m a a l d o s t e r o n e ( A t l a s e t al., 1979; T a r a z i et al., 1 9 8 0 ) , an i n c r e a s e i n p l a s m a r e n i n a c t i v i t y and a n g i o t e n s i n I ( T a r a z i et al., 1 9 8 0 ) . The i n c r e a s e d p r o d u c t i o n o f r e n i n i s a r e s u l t o f f e e d b a c k m echanisms i n r e s p o n s e t o t h e d e c r e a s e d l e v e l o f a n g i o t e n s i n I I ( B r o g d e n et al., 1 9 8 8 ) . C a p t o p r i l has been shown t o i n c r e a s e t h e p l a s m a l e v e l s o f b r a d y k i n i n s i n h y p e r t e n s i v e p a t i e n t s a f t e r a c u t e d o s i n g ( M o o k h e r j e e et al., 1 9 8 3 ) , b u t , t h e s e l e v e l s have r e m a i n e d u n c h a n g e d i n o t h e r s t u d i e s ( J o h n s t o n e t al., 1 9 7 9 ) . An i n c r e a s e i n t i s s u e l e v e l s o f b r a d y k i n i n a f t e r c a p t o p r i l t r e a t m e n t has been d e m o n s t r a t e d i n t h e d o g ; f u r t h e r , s u c h c h a n g e s have been p o s t u l a t e d t o c o n t r i b u t e t o t h e h y p o t e n s i v e e f f e c t s o f c a p t o p r i l ( J o h n s t o n e t al., 1 9 8 2 ) . S w a r t z and W i l l i a m s ( 1 9 8 2 ) have d e m o n s t r a t e d t h e i n c r e a s e d p r o d u c t i o n o f v a s o d i l a t o r y p r o s t a g l a n d i n s a f t e r a c u t e and c h r o n i c a d m i n i s t r a t i o n o f c a p t o p r i l i n h y p e r t e n s i v e s u b j e c t s . The h y p o t e n s i v e e f f e c t s o f c a p t o p r i l , i n p a r t , may be r e l a t e d t o t h e i n c r e a s e d r e l e a s e o f p r o s t a g l a n d i n s ( S w a r t z and W i l l i a m s , 1 9 8 2 ) . I n a d d i t i o n t o t h e i n h i b i t o r y e f f e c t s on c i r c u l a t i n g ACE, c a p t o p r i l has been shown t o i n t e r f e r e w i t h l o c a l ACE a c t i v i t y ( U n g e r e t al., 1 9 8 9 ) . I t h a s been d e m o n s t r a t e d , t h a t c a p t o p r i l e f f e c t i v e l y i n h i b i t e d ACE a c t i v i t y i n s e v e r a l t i s s u e s o f s p o n t a n e o u s l y h y p e r t e n s i v e (SH) r a t s ( l u n g , k i d n e y , a o r t a , b r a i n , h e a r t ) 15 m i n u t e s a f t e r a d m i n i s t r a t i o n (Cohen and K u r t z , 1 9 8 2 ) . The e x t e n t and d u r a t i o n o f b l o o d p r e s s u r e r e d u c t i o n seemed t o c o r r e l a t e b e t t e r w i t h t h e i n h i b i t i o n o f ACE i n c e r t a i n t i s s u e s , f o r e x a m p l e , k i d n e y o r a r t e r i a l w a l l , t h a n w i t h t h e p l a s m a ACE a c t i v i t y (Cohen and K u r t z , 1982; D z a u , 1 9 8 8 ) . T h e r e i s c l i n i c a l e v i d e n c e w h i c h shows t h a t , f o l l o w i n g c h r o n i c t h e r a p y w i t h c a p t o p r i l , b l o o d p r e s s u r e r e m a i n e d d e c r e a s e d l o n g a f t e r t h e d i s c o n t i n u a t i o n o f t h e d r u g e v e n t h o u g h p l a s m a ACE a c t i v i t y was f o u n d t o be a t p r e t r e a t m e n t l e v e l s (Waeber e t al., 1 9 8 9 ) . W h e t h e r t h i s m echanism o f a c t i o n c a n be r e l a t e d t o t h e l o c a l RAS has n o t y e t been e s t a b l i s h e d (Waeber et al., 1 9 8 9 ) . I n a d d i t i o n t o t h e h o r m o n a l e f f e c t s o f c a p t o p r i l , t h e r e a r e o t h e r m e c h a n i s m s w h i c h may c o n t r i b u t e t o t h e o v e r a l l e f f e c t s o f t h e d r u g . L a r g e d o s e s o f c a p t o p r i l c a u s e d smooth m u s c l e r e l a x a t i o n i n t h e p o r t a l v e i n s o f SH r a t s ( L j u n g et al., 1 9 8 1 ) . I n humans e v i d e n c e o f smooth m u s c l e r e l a x a t i o n i n t h e a r t e r i a l w a l l may be t h e o b s e r v e d d i l a t i o n and i m p r o v e d d i s t e n s i b i l i t y o f l a r g e a r t e r i e s a f t e r a c u t e and c h r o n i c t r e a t m e n t w i t h c a p t o p r i l i n h y p e r t e n s i v e p a t i e n t s ( S i m o n et al., 1 9 8 5 ) . F u r t h e r , c a p t o p r i l may i n t e r a c t w i t h t h e s y m p a t h e t i c n e r v o u s s y s t e m as d e m o n s t r a t e d by t h e d e c r e a s e i n p l a s m a n o r a d r e n a l i n e c o n c e n t r a t i o n s i n h y p e r t e n s i v e p a t i e n t s ( W e n t i n g et al., 1 9 8 3 ) . I t has been d e m o n s t r a t e d t h a t a t h i g h c o n c e n t r a t i o n s c a p t o p r i l may d e p r e s s t h e r e s p o n s i v e n e s s o f v a s c u l a r smooth m u s c l e t o s y m p a t h e t i c n e r v e s t i m u l a t i o n ( V a n h o u t t e et al., 1 9 8 9 ) . I n a n o t h e r s t u d y , no d i r e c t e v i d e n c e t h a t ACE i n h i b i t o r s d e c r e a s e t h e a c t i v i t y o f s y m p a t h e t i c n e r v o u s s y s t e m has been r e p o r t e d , i n p a t i e n t s w i t h h y p e r t e n s i o n o r c a r d i a c f a i l u r e ( B a l l , 1 9 8 9 ) . L a s t l y , t h e s u l f h y d r y l g r o u p o f c a p t o p r i l c a n s e r v e as an a n t i o x i d a n t and c a n p r o t e c t t h e p o t e n t v a s o d i l a t o r s u b s t a n c e , t h e e n d o t h e l i u m - d e r i v e d r e l a x i n g f a c t o r , f r o m s u p e r o x i d e m e d i a t e d i n a c t i v a t i o n i n t h e b l o o d v e s s e l w a l l o f t h e r a b b i t ( G o l d s h m i d t et a l . 1 9 9 1 ) . I n summary, c a p t o p r i l e x e r t s p h a r m a c o l o g i c a l e f f e c t s on b o t h p l a s m a and t i s s u e l e v e l . The a c u t e a d m i n i s t r a t i o n o f c a p t o p r i l l e a d s t o t h e i n h i b i t i o n o f ACE a c t i v i t y , t h e r e d u c t i o n and i n c r e a s e o f s y s t e m i c a n g i o t e n s i n I I and a n g i o t e n s i n I , r e s p e c t i v e l y , t h e i n c r e a s e and d e c r e a s e o f p l a s m a r e n i n and a l d o s t e r o n e c o n c e n t r a t i o n . I n a d d i t i o n , i t c o u l d f a c i l i t a t e t h e r e l e a s e o r a c t i o n o f v a s o d i l a t o r s u b s t a n c e s s u c h as b r a d y k i n i n and p r o s t a g l a n d i n b o t h i n p l a s m a and i n t i s s u e s . I t may c a u s e d i r e c t r e l a x a t i o n o f t h e v a s c u l a r smooth m u s c l e and r e d u c e t h e r e s p o n s i v e n e s s o f v a s c u l a r smooth m u s c l e t o v a s o c o n s t r i c t o r s t i m u l i . C a p t o p r i l may i n t e r a c t w i t h t h e s y m p a t h e t i c n e r v o u s s y s t e m and r e d u c e t h e r e l e a s e o f n o r a d r e n a l i n e . F i n a l l y , c a p t o p r i l may s e r v e as an a n t i o x i d a n t and p r o t e c t t h e v a s o d i l a t o r e n d o t h e l i u m - d e r i v e d r e l a x i n g f a c t o r f r o m d e g r a d a t i o n . 1.3.2. Haemodynamic E f f e c t s i n H y p e r t e n s i o n Numerous t r i a l s have d e m o n s t r a t e d t h e b l o o d p r e s s u r e r e d u c i n g e f f e c t s o f c a p t o p r i l i n m i l d t o m o d e r a t e l y h y p e r t e n s i v e p a t i e n t s ( V e t e r a n s A d m i n i s t r a t i o n C o o p e r a t i v e S t u d y G roup on A n t i h y p e r t e n s i v e A g e n t s , 1 9 8 4 ) . Many s t u d i e s have r e p o r t e d a d e q u a t e c o n t r o l o f m i l d t o m o d e r a t e h y p e r t e n s i o n w i t h o n c e d a i l y a d m i n i s t r a t i o n o f c a p t o p r i l ( P a r a t i et al., 1 9 8 9 ) . The b l o o d p r e s s u r e r e d u c t i o n i s a l w a y s a s s o c i a t e d w i t h t h e l o w e r i n g o f t o t a l p e r i p h e r a l r e s i s t a n c e a f t e r a c u t e o r c h r o n i c t r e a t m e n t ( T a r a z i et al., 1 9 8 0 ) . Maximum b l o o d p r e s s u r e r e d u c t i o n (10 t o 20%) o c c u r s a b o u t 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f a s i n g l e o r a l d o s e o f c a p t o p r i l ; h i g h e r d o s e s may i n c r e a s e t h e d u r a t i o n o f i t s a n t i h y p e r t e n s i v e a c t i o n ( B r o g d e n e t al., 1 9 8 8 ) . D e s p i t e t h e s i g n i f i c a n t d e c r e a s e i n b l o o d p r e s s u r e and t o t a l p e r i p h e r a l r e s i s t a n c e , c a p t o p r i l t r e a t m e n t i s u s u a l l y n o t a s s o c i a t e d w i t h c h a n g e s i n c a r d i a c o u t p u t and h e a r t r a t e ( T a r a z i e t al., 1980; W e n t i n g e t al., 1 9 8 2 ) . However, a s l i g h t i n c r e a s e i n c a r d i a c o u t p u t and h e a r t r a t e a f t e r a s i n g l e o r a l d o s e o f c a p t o p r i l has a l s o been r e p o r t e d ( F a g a r d e t al., 1 9 8 2 ) . The f a c t , t h a t b l o o d p r e s s u r e r e d u c t i o n by c a p t o p r i l d o e s n o t c a u s e a r e f l e x i n c r e a s e i n h e a r t r a t e s u g g e s t s t h a t t h e b a r o r e c e p t o r r e f l e x e s may be b l u n t e d by c a p t o p r i l ( T a r a z i e t al., 1 9 8 0 ) . However, no a l t e r a t i o n s i n b a r o r e c e p t o r r e s p o n s e has been r e p o r t e d due t o p o s t u r a l c h a n g e ( V a n d e n b u r g e t al., 1983) o r t o c a r o t i d b a r o r e c e p t o r s t i m u l a t i o n ( M a n c i a et al., 1 9 8 2 ) . 1.3.3. E f f e c t s on L i v e r B l o o d F l o w L i v e r b l o o d f l o w i s an i m p o r t a n t d e t e r m i n a n t o f d r u g m e t a b o l i s m p a r t i c u l a r l y o f d r u g s t h a t a r e c h a r a c t e r i z e d w i t h a h i g h h e p a t i c c l e a r a n c e ( N i e s et al., 1 9 7 6 ) . I t has been d e m o n s t r a t e d t h a t a n g i o t e n s i n I I , t h e p o t e n t v a s o c o n s t r i c t o r i n t h e RAS, a l t e r s l i v e r b l o o d f l o w and s p l a n c h n i c v a s c u l a r r e s i s t a n c e ( M e s s e r l i et al., 1 9 7 7 ) . F u r t h e r , t h e s p l a n c h n i c v e s s e l s h a v e been shown t o be more s e n s i t i v e t o a n g i o t e n s i n t h a n o t h e r v e s s e l s i n t h e c i r c u l a t i o n ( M e s s e r l i e t al., 1 9 7 5 ) . In h e a l t h y s u b j e c t s , a n g i o t e n s i n i n f u s i o n p r o d u c e d v a s o c o n s t r i c t i o n i n t h e s p l a n c h n i c v a s c u l a r bed and r e d u c e d l i v e r b l o o d f l o w by a b o u t 1 8 % and 3 3 % w i t h s u b p r e s s o r and p r e s s o r d o s e s , r e s p e c t i v e l y ( M e s s e r l i et al., 1 9 7 7 ) . In a d d i t i o n , a n g i o t e n s i n I I , i n d o s e s w h i c h d e c r e a s e d h e p a t i c b l o o d f l o w by 18%, d e c r e a s e d t h e m e t a b o l i c c l e a r a n c e r a t e s o f t h o s e s t e r o i d s , t h a t a r e h i g h l y c l e a r e d i n t h e l i v e r , by 1 4 - 3 3 % ( M e s s e r l i e t al., 1 9 7 7 ) . G a s i c e t al., ( 1 9 8 9 ) h a s r e p o r t e d t h a t a n g i o t e n s i n I d o s e - d e p e n d e n t l y d e c r e a s e d s p l a n c h n i c b l o o d f l o w and i n c r e a s e d s p l a n c h n i c v a s c u l a r r e s i s t a n c e i n n o r m o t e n s i v e s u b j e c t s . T h e s e e f f e c t s o f a n g i o t e n s i n I on s p l a n c h n i c b l o o d f l o w w e r e a t t e n u a t e d by t h e a d m i n i s t r a t i o n o f an ACE i n h i b i t o r , c i l a z a p r i l ( G a s i c e t al., 1 9 8 9 ) . T h e s e d a t a s u g g e s t t h a t t h e RAS may p l a y an i m p o r t a n t r o l e i n t h e r e g u l a t i o n o f b l o o d f l o w i n t h e s p l a n c h n i c v a s c u l a r b e d . I n a number o f s t u d i e s , i n v o l v i n g a n i m a l s and human s u b j e c t s , t h e e f f e c t o f ACE i n h i b i t o r s on h e p a t i c b l o o d f l o w , h o w e v e r , r e m a i n s r a t h e r c o n t r o v e r s i a l ( G a v r a s et al., 1978; E chtenkamp e t al., 1983; S t a d e a g e r e t al., 1 9 8 9 ) . S t u d i e s i n s o d i u m - d e p l e t e d n o r m o t e n s i v e , c o n s c i o u s dogs have shown a d e c r e a s e i n l i v e r b l o o d f l o w m e a s u r e d by r a d i o a c t i v e m i c r o s p h e r e s f o l l o w i n g t h e i n h i b i t i o n o f ACE w i t h t e p r o t i d e ( G a v r a s et al., 1 9 7 8 ) . In c o n t r a s t , E c h t e n k a m p et al., ( 1 9 8 3 ) d e m o n s t r a t e d a p r o n o u n c e d ( 1 8 % ) i n c r e a s e i n h e p a t i c b l o o d f l o w a s s e s s e d by t h e b r o m s u l p h a l e i n (BSP) c l e a r a n c e method i n c o n s c i o u s , s o d i u m - d e p l e t e d d o g s a f t e r t h e i n h i b i t i o n o f a n g i o t e n s i n I I w i t h i n t r a v e n o u s l y a d m i n i s t e r e d s a r a l a s i n . I n t h e same s t u d y , a f t e r s a r a l a s i n a d m i n i s t r a t i o n s p l a n c h n i c v a s c u l a r r e s i s t a n c e d e c r e a s e d by 3 5 % c o m p a r e d t o c o n t r o l v a l u e s . R i c h e r e t al., ( 1 9 8 3 ) have n o t e d a s i g n i f i c a n t , 2 f o l d i n c r e a s e i n l i v e r b l o o d f l o w and 5 6 % d e c r e a s e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e a f t e r 8 d a y s t r e a t m e n t w i t h 100 mg/kg o r a l d o s e s o f c a p t o p r i l i n SH r a t s . M o s t r e c e n t l y , R o z s a e t al., ( 1 9 9 1 ) r e p o r t e d a s i g n i f i c a n t ( 3 3 . 5 % ) i n c r e a s e i n t h e m e s e n t e r i c b l o o d f l o w a f t e r 6 weeks o r a l t r e a t m e n t w i t h 100 mg c a p t o p r i l i n n o r m o t e n s i v e and SH r a t s . I t has been s u g g e s t e d , t h a t t h i s i n c r e a s e i n l i v e r b l o o d f l o w was due t o t h e i n h i b i t i o n o f ACE i n t h e s p l a n c h n i c v a s c u l a r t i s s u e ( R o z s a e t al., 1 9 9 1 ) . S t a d e a g e r e t al., (1989) have r e p o r t e d a s i g n i f i c a n t i n c r e a s e i n s p l a n c h n i c b l o o d f l o w and d e c r e a s e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e a f t e r t h e i . v . i n j e c t i o n o f 10 mg e n a l a p r i l (ACE i n h i b i t o r ) i n 19 h e a l t h y human s u b j e c t s . M o s t o f t h e human s t u d i e s u s i n g c a p t o p r i l as t h e ACE i n h i b i t o r have been d e s i g n e d t o i n v e s t i g a t e i t s i n f l u e n c e o f c a p t o p r i l on t h e r e d i s t r i b u t i o n o f r e g i o n a l b l o o d f l o w i n p a t i e n t s w i t h e i t h e r c o n g e s t i v e h e a r t f a i l u r e ( F a x o n e t al., 1984, L e v i n e e t al., 1984, C r a e g e r e t al., 1981) o r e s s e n t i a l h y p e r t e n s i o n ( V e n t u r a e t al., 1 9 8 5 ) . A l t h o u g h i t has been o b s e r v e d i n t h e s e s t u d i e s t h a t r e d i s t r i b u t i o n o f r e g i o n a l b l o o d may o c c u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n and t h a t c a p t o p r i l has h e t e r o g e n e o u s e f f e c t s i n d i f f e r e n t v a s c u l a r b e d s , t h e r e a r e c o n f l i c t i n g r e p o r t s o f t h e e f f e c t s o f c a p t o p r i l on l i v e r b l o o d f l o w . L e v i n e e t al., ( 1 9 8 4 ) and C r a e g e r e t al., ( 1 9 8 1 ) have o b s e r v e d a n o n - s i g n i f i c a n t ( 3 0 % ) and a s i g n i f i c a n t ( 1 8 % ) d e c r e a s e i n s p l a n c h n i c b l o o d f l o w , r e s p e c t i v e l y , a f t e r a s i n g l e o r a l d o s e o f c a p t o p r i l ( 2 5 - 1 5 0 mg) i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e . O t h e r s t u d i e s i n v e s t i g a t e d t h e e f f e c t s o f c a p t o p r i l on l i v e r b l o o d f l o w i n p a t i e n t s w i t h l i v e r c i r r h o s i s ( E r i k s s o n et al., 1984) and h e a l t h y s u b j e c t s ( S h e p h e r d et al., 1985) t o e s t a b l i s h i t s p o t e n t i a l c o n t r i b u t i o n i n t h e t r e a t m e n t o f p o r t a l h y p e r t e n s i o n . I n t h e s e p a t i e n t s , mean h e p a t i c b l o o d f l o w r e m a i n e d u n a l t e r e d by 12.5-25 mg s i n g l e o r a l d o s e s o f c a p t o p r i l . I n s p i t e o f t h e r e l a t i v e l y l a r g e number o f s t u d i e s c o n d u c t e d i n o r d e r t o i n v e s t i g a t e t h e haemodynamic c h a n g e s a s s o c i a t e d w i t h c a p t o p r i l t r e a t m e n t i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n , o n l y a f e w e x a m i n e d i t s e f f e c t s on l i v e r b l o o d f l o w . C r o s s l e y e t al., ( 1 9 8 4 ) r e p o r t e d a u n i f o r m , s i g n i f i c a n t 2 5 % r e d u c t i o n i n h e p a t i c b l o o d f l o w a b o u t 60 m i n u t e s a f t e r a s i n g l e 50 t o 100 mg o r a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . I n c o n t r a s t , V e n t u r a e t al., ( 1 9 8 5 ) , who i n v e s t i g a t e d t h e r e g i o n a l b l o o d f l o w d i s t r i b u t i o n a f t e r c a p t o p r i l t r e a t m e n t (25 m g / day), n o t e d no c h a n g e i n s p l a n c h n i c b l o o d f l o w 90 m i n u t e s and 12 weeks a f t e r c a p t o p r i l d o s i n g , d e s p i t e a r e d u c t i o n i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . 1.3.4. C a p t o p r i l P h a r m a c o k i n e t i c s i n H y p e r t e n s i o n The p h a r m a c o k i n e t i c s o f c a p t o p r i l i n h e a l t h y s u b j e c t s and i n h y p e r t e n s i v e p a t i e n t s h a v e been r e v i e w e d by Kubo and Cody ( 1 9 8 5 ) . M o s t r e c e n t l y , t h e p h a r m a c o k i n e t i c s o f c a p t o p r i l has been r e v i e w e d i n r e l a t i o n t o o t h e r ACE i n h i b i t o r s ( B u r n i e r , 1 9 8 9 ) . The p h a r m a c o k i n e t i c p r o p e r t i e s o f c a p t o p r i l i n h y p e r t e n s i v e p a t i e n t s a r e s i m i l a r t o t h o s e o f h e a l t h y s u b j e c t s , e x c e p t i n t h o s e c a s e s , when h y p e r t e n s i o n i s a s s o c i a t e d w i t h s e c o n d a r y r e n a l d y s f u n c t i o n (Kubo and Cody, 1 9 8 5 ) . C a p t o p r i l i s c h a r a c t e r i z e d by r a p i d a b s o r p t i o n f r o m t h e GI t r a c t a f t e r o r a l a d m i n i s t r a t i o n w i t h 6 0 - 7 5 % o f t h e a d m i n i s t e r e d d o s e b e i n g a b s o r b e d ( K r i p a l a n i e t al., 1980; D u c h i n e t al., 1 9 8 2 ) . The t i m e t o r e a c h maximum p l a s m a c o n c e n t r a t i o n ( t ^ g ^ ) a f t e r a s i n g l e - d o s e i s b e t w e e n 30-80 m i n u t e s i n h y p e r t e n s i v e s u b j e c t s and somewhat l e s s , 3 0 - 50 m i n u t e s a f t e r c h r o n i c (6 month) a d m i n i s t r a t i o n ( J a r r o t t e t al., 1 9 8 2 ) . T h e r e a r e c o n t r o v e r s i a l r e p o r t s on t h e e f f e c t s o f f o o d on t h e b i o a v a i l a b i l i t y o f c a p t o p r i l ( R a i a e t al., 1 9 9 0 ) . E a r l i e r r e p o r t s s u g g e s t e d t h a t c o n c u r r e n t c o n s u m p t i o n o f f o o d has r e d u c e d t h e b i o a v a i l a b i l i t y o f c a p t o p r i l a b o u t 3 0 - 5 0 % ( S h i n g v i e t al., 1 9 8 2 ) . Ôhman e t al., ( 1 9 8 5 ) n o t e d o n l y a s l i g h t d e c r e a s e i n t h e AUG o f c a p t o p r i l and no a l t e r a t i o n i n b l o o d p r e s s u r e r e s p o n s e when c a p t o p r i l was t a k e n w i t h f o o d f o r 5-weeks i n p a t i e n t s w i t h h y p e r t e n s i o n . Maximum p l a s m a c o n c e n t r a t i o n ( C ^ ^ x ) a f t e r a s i n g l e 100 mg o r a l c a p t o p r i l d o s e have been n o t e d t o be 361 ± 11 ng/ml i n h y p e r t e n s i v e s u b j e c t s ( J a r r o t t et al., 1 9 8 2 ) . In a n o t h e r s t u d y i n v o l v i n g p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n , C^^^ o f u n c h a n g e d c a p t o p r i l has been f o u n d t o be 1310 ± 20 ng/ml a f t e r a s i n g l e 1 mg/kg o r a l c a p t o p r i l d o s e ( R i c h e r 1 9 8 4 ) . I n one s t u d y ( J a r r o t t e t al., 1982) c h r o n i c c a p t o p r i l a d m i n i s t r a t i o n i n h y p e r t e n s i v e s u b j e c t s (100 mg 3 t i m e s a d a y f o r 6 month) i n c r e a s e d C^g^ ° f u n c h a n g e d c a p t o p r i l a b o u t 3 f o l d (361 vs 1080 n g / m l ) , as c ompared t o t h e a c u t e d o s i n g . I n a n o t h e r s t u d y , 0^,^^ o f u n c h a n g e d c a p t o p r i l r e m a i n e d t h e same a f t e r 2-weeks c a p t o p r i l t r e a t m e n t (Ôhman e t al., 1 9 8 5 ) . In most o f t h e s t u d i e s , t h e AUG o f t o t a l c a p t o p r i l p l a s m a c o n c e n t r a t i o n , w h i c h r e p r e s e n t s a p o o l o f c a p t o p r i l and m i x e d d i s u l f i d e s ( P e r e i r a e t al., 1 9 8 8 ) , has been f o u n d t o be a b o u t 2 0 % h i g h e r a f t e r m u l t i p l e d r u g a d m i n i s t r a t i o n t h a n a f t e r a s i n g l e - d o s e ( B r o g d e n et al., 1 9 8 8 ) . C a p t o p r i l p l a s m a c o n c e n t r a t i o n d e c l i n e s r a p i d l y a f t e r a c u t e a d m i n i s t r a t i o n w i t h an e l i m i n a t i o n h a l f - l i f e ( t 2 / 2 ^ 0.7 ( R i c h e r e t al., 1984) t o 1.7 h o u r s ( J a r r o t t et al., 1 9 8 2 ) . The t i / 2 o f c a p t o p r i l r e m a i n e d u n c h a n g e d a f t e r c h r o n i c t r e a t m e n t w i t h t h e d r u g ( J a r r o t t et al., 1 9 8 2 ) . Due t o i t s s h o r t t j ^ 2 ' ^ h o u r s a f t e r d o s i n g c a p t o p r i l was n o t d e t e c t a b l e i n p l a s m a ( R i c h e r et al., 1 9 8 4 ) . I t has been shown ( R i c h e r et al., 1984) t h a t d e s p i t e t h e r a p i d d e c l i n e i n c a p t o p r i l p l a s m a c o n c e n t r a t i o n , t h e b l o o d p r e s s u r e l o w e r i n g e f f e c t s o f t h e d r u g p e r s i s t much l o n g e r . Once a b s o r b e d , c a p t o p r i l i s p a r t i a l l y o x i d i z e d a t t h e t h i o l g r o u p and u n d e r g o e s r e v e r s i b l e m o d i f i c a t i o n s by i n t e r a c t i n g w i t h e ndogenous s u l f h y d r y l - c o n t a i n i n g s u b s t a n c e s f o r m i n g v a r i o u s d i s u l f i d e s s u c h as d i s u l f i d e d i m e r o f c a p t o p r i l , c y s t e i n e c a p t o p r i l d i s u l f i d e s and S - m e t h y l -d i s u l f i d e s ( O n d e t t i , 1988; Drummer et al., 1 9 8 4 ) . T h e s e d i s u l f i d e m e t a b o l i t e s c a n be r e c o n v e r t e d t o c a p t o p r i l ( O n d e t t i , 1988) and may c o n t r i b u t e t o t h e p r o l o n g e d a n t i h y p e r t e n s i v e a c t i v i t y o f t h e d r u g ( J a r r o t t et al., 1 9 8 2 ) . F u r t h e r , Drummer et al., ( 1 9 8 4 ) r e p o r t e d t h a t some o f t h e d i s u l f i d e m e t a b o l i t e s o f c a p t o p r i l e f f e c t i v e l y i n h i b i t ACE w h i c h may e x p l a i n t h e l o n g b l o o d p r e s s u r e l o w e r i n g e f f e c t o f t h e d r u g . C a p t o p r i l and i t s m e t a b o l i t e s a r e e x c r e t e d m a i n l y i n t h e k i d n e y s (Kubo and Cody 1 9 8 5 ) . I m p a i r e d r e n a l f u n c t i o n i n c r e a s e d t h e a n t i h y p e r t e n s i v e e f f e c t o f c a p t o p r i l and t h i s has been shown t o be t h e c o n s e q u e n c e o f t h e a c c u m u l a t i o n o f c a p t o p r i l m e t a b o l i t e s (Drummer et al., 1 9 8 7 ) . 1.4. E s t i m a t i o n o f L i v e r B l o o d F l o w S e v e r a l a t t e m p t s have been made i n t h e p a s t y e a r s t o d e v e l o p a r e l a t i v e l y n o n - i n v a s i v e method t o e s t i m a t e l i v e r b l o o d f l o w i n man ( B r a d l e y , 1 9 7 4 ) . D i f f i c u l t y a r i s e s f r o m t h e d o u b l e b l o o d s u p p l y o f t h e l i v e r , one by t h e h e p a t i c a r t e r y and one by t h e p o r t a l v e i n ( O h n haus, 1 9 7 9 ) . The p o r t a l v e i n i s t h e c o n f l u e n c e o f v e i n s f r o m t h e s p l a n c h n i c o r g a n s ( s p l e e n . i n t e s t i n e , p a n c r e a s and s t o m a c h ) ( G r e e n w a y and L a u t t , 1 9 8 9 ) . In a d d i t i o n , c a p i l l a r y c o n n e c t i o n s between t h e h e p a t i c a r t e r y and p o r t a l v e i n e x i s t w h i c h p r o v i d e f u n c t i o n a l i n t e r r e l a t i o n s h i p s b e t w e e n t h e two s y s t e m s ( R i c h a r d s o n and W i t h r i n g t o n , 1 9 8 1 ) . T h e r e f o r e , s h u n t s o f t h e b l o o d f l o w between t h e two s y s t e m s may o c c u r (Ohnhaus, 1 9 7 9 ) . U n d e r t h e s e p h y s i o l o g i c a l c i r c u m s t a n c e s t h e a c c u r a t e measurement o f l i v e r b l o o d f l o w i s d i f f i c u l t i n man and none o f t h e c u r r e n t l y a v a i l a b l e methods p r o v i d e c o m p l e t e l y s a t i s f a c t o r y measurement o f l i v e r b l o o d f l o w u n d e r a l l c i r c u m s t a n c e s ( H u e t , 1 9 8 1 ) . D i r e c t m e a s u r e m e n t o f l i v e r b l o o d f l o w r e q u i r e s s u r g i c a l i n t e r v e n t i o n and a n a e s t h e s i a w h i c h , b e s i d e s b e i n g an i n v a s i v e t e c h n i q u e , a l s o may i n f l u e n c e h e p a t i c b l o o d f l o w ( H u e t , 1 9 8 1 ) . 1.4.1. I n d o c y a n i n e G r e e n C l e a r a n c e M e t h o d The most w i d e l y u s e d t e c h n i q u e s t o e s t i m a t e l i v e r b l o o d f l o w i n man a r e b a s e d on t h e h e p a t i c c l e a r a n c e o f s u b s t a n c e s s u c h as b r o m s u l p h a l e i n ( B r a d l e y et a / . , 1 9 4 5 ) , i n d o c y a n i n e g r e e n ( C a e s a r e t a / . , 1 9 6 1 ) , g a l a c t o s e ( T y g s t r u p and W i n k l e r , 1958) t h a t a r e h i g h l y c l e a r e d f r o m t h e b l o o d when p e r f u s e d t h r o u g h t h e l i v e r . T h i s method has been d e v e l o p e d by B r a d l e y e t al., ( 1 9 4 5 ) and i n v o l v e s t h e c o n s t a n t i n t r a v e n o u s i n f u s i o n o f b r o m s u l p h a l e i n and t h e s i m u l t a n e o u s m e a s u r e m e n t s o f i t s c o n c e n t r a t i o n i n t h e a r t e r i a l b l o o d ( p o r t a l v e i n ) e n t e r i n g t h e l i v e r and i n t h e v e n o u s b l o o d ( h e p a t i c v e i n ) l e a v i n g t h e l i v e r , b a s e d on t h e P i c k p r i n c i p l e ( B r a d l e y et.al., ( 1 9 4 5 ) . U s i n g i n d o c y a n i n e g r e e n ( I C G ) as a t e s t s u b s t a n c e , t h i s method has been f r e q u e n t l y u s e d t o e s t a b l i s h h e p a t i c b l o o d f l o w r a t e s i n man (Wynne e t al., 1990; C r o s s l e y et al., 1984; G r a i n g e r e t al., 1983; C a e s a r e t al., 1 9 6 1 ) . H e p a t i c e x t r a c t i o n r a t i o o f ICG was i n t h e r a n g e f r o m 0.63-0.85 (mean 0.78) (Wynne et al., 1 9 9 0 ) , 0.68-0.89 (mean 0.78) ( G r a i n g e r e t al., 1 9 8 3 ) . C r o s s l e y e t al., ( 1 9 8 4 ) r e p o r t e d t h a t t h e h e p a t i c e x t r a c t i o n r a t i o o f ICG was 0.68 ± 0.08 i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n and t h i s r a t i o d i d n o t c h ange s i g n i f i c a n t l y 1 h o u r a f t e r c a p t o p r i l (0.71 ± 0 . 0 7 ) . T h i s method, h o w e v e r , i s a h i g h l y i n v a s i v e t e c h n i q u e s i n c e i t r e q u i r e s h e p a t i c v e n o u s b l o o d s a m p l i n g w h i c h c a n o n l y be p e r f o r m e d by t h e c a t h e t e r i z a t i o n o f t h e h e p a t i c v e i n . T h e r e f o r e , t h e o r i g i n a l t e c h n i q u e has been m o d i f i e d t o a s i n g l e i . v . i n j e c t i o n o f ICG and p e r i p h e r a l v e n o u s b l o o d s a m p l i n g w i t h t h e p u r p o s e t o a v o i d v e n o u s c a t h e t e r i z a t i o n and make t h e method l e s s i n v a s i v e and e a s i e r t o p e r f o r m i n c l i n i c a l p r a c t i c e (Wynne e t al., 1989; S h e p h e r d e t al., 1985; Geneve e t al., 1990; Robson e t al., 1 9 9 0 ) . In t h i s s i m p l i f i e d method t h e p l a s m a c l e a r a n c e o f ICG i s e q u a l t o l i v e r p l a s m a f l o w , b a s e d on t h e a s s u m p t i o n s t h a t ICG i s c l e a r e d o n l y by t h e l i v e r and h e p a t i c e x t r a c t i o n o f ICG i s c o m p l e t e ( B u r c z y n s k i e t al., 1 9 8 7 ) . S i n c e i n t h i s s i m p l i f i e d method h e p a t i c e x t r a c t i o n r a t i o o f ICG i s n o t m e a s u r e d , an h e p a t i c e x t r a c t i o n o f 1 0 0 % i s u s u a l l y assumed ( S o o n s e t al., 1 9 9 0 ) . The c l e a r a n c e methods were r e c e n t l y r e v i e w e d ( G r e e n w a y and L a u t t , 1987; B r a d l e y , 1974; Huet e t al., 1 9 8 1 ) . The p r i n c i p l e s o f t h e s e c l e a r a n c e t e c h n i q u e s a r e d i s c u s s e d as f o l l o w s . 1.4.2. H e p a t i c C l e a r a n c e I n t h e c a s e o f a s u b s t a n c e e l i m i n a t e d p r i m a r i l y by t h e l i v e r , t h a t i s by m e t a b o l i s m a n d / o r b i l i a r y e x c r e t i o n , t h e h e p a t i c c l e a r a n c e e s t i m a t e s t o t a l b ody c l e a r a n c e (Morgan and S m a l l w o o d , 1 9 9 0 ) . T h u s , h e p a t i c c l e a r a n c e ( C l ^ ) r e f e r s t o t h e e f f i c i e n c y o f t h e l i v e r t o e l i m i n a t e a s u b s t a n c e f r o m t h e body by t h e l i v e r and i s e q u a l t o t h e p r o d u c t o f l i v e r b l o o d f l o w (Q^) and e x t r a c t i o n r a t i o ( E ^ ) : C I H = QH EH E^ o f a s u b s t a n c e c a n be c a l c u l a t e d as ( C ^ - Z\)/Z^, t h e h e p a t i c a r t e r i a l p l u s p o r t a l v e n o u s (C^) and h e p a t i c v e n o u s ( C y ) c o n c e n t r a t i o n d i f f e r e n c e a c r o s s t h e l i v e r ( W i l k i n s o n and S h a n d , 1 9 7 5 ) . S i n c e E^ i s d e p e n d e n t on t h e b l o o d f l o w t o t h e l i v e r ( Q ^ ) , t h e unbound f r a c t i o n o f s u b s t a n c e i n t h e b l o o d {f^) and t h e h e p a t i c i n t r i n s i c c l e a r a n c e o f t h e s u b s t a n c e ( C l ^ j ^ j - ) t h e p r e v i o u s e q u a t i o n 1 has been e x t e n d e d as f o l l o w s ( R o w l a n d e t al., 1 9 7 6 ) : 1H + f b C l i n t T h i s i s t h e most f r e q u e n t l y a p p l i e d model o f h e p a t i c d r u g c l e a r a n c e w h i c h c o n s i d e r s t h e l i v e r as a " w e l l - s t i r r e d " c o m p a r t m e n t a s s u m i n g t h a t t h e d r u g i n t h e l i v e r c o m p a r t m e n t i s i n e q u i l i b r i u m w i t h b l o o d l e a v i n g t h e l i v e r ( N i e s e t al., 1 9 7 6 ) . T h i s model d e s c r i b e s q u a n t i t a t i v e l y t h e i n f l u e n c e o f p h y s i o l o g i c a l f a c t o r s s u c h as l i v e r b l o o d f l o w , enzyme a c t i v i t y and p r o t e i n b i n d i n g on t h e h e p a t i c c l e a r a n c e o f d r u g s ( W i l k i n s o n and S h a n d , 1 9 7 5 ) . 1.4.3. E f f e c t s o f L i v e r B l o o d F l o w on H e p a t i c C l e a r a n c e B a s e d on t h e p r e v i o u s l y m e n t i o n e d model o f h e p a t i c c l e a r a n c e , when t h e l i v e r e x h i b i t s v e r y i n e f f i c i e n t e l i m i n a t i o n o f t h e d r u g {i.e. e x t r a c t i o n r a t i o i s l o w and no c h a n g e i n t h e p r o t e i n b i n d i n g o f t h e d r u g assumed ( C l ^ ^ ^ « QH^^' h e p a t i c c l e a r a n c e o f t h e d r u g d e p e n d s on t h e i n t r i n s i c a b i l i t y o f t h e l i v e r t o e l i m i n a t e t h e d r u g ( C l ^ ~ C l ^ ^ ^ ) ( R o w l a n d et al., 1 9 7 6 ) . C o n v e r s e l y , when t h e l i v e r e f f i c i e n t l y e l i m i n a t e s d r u g s {i.e. e x t r a c t i o n r a t i o i s h i g h ) and p l a s m a p r o t e i n b i n d i n g o f t h e d r u g r e m a i n s unchanged ( C l ^ ^ ^ » Q^), t h e n h e p a t i c c l e a r a n c e o f t h e d r u g d e p e n d s e n t i r e l y on l i v e r b l o o d f l o w ( C l | ^ =K Q^) ( R o w l a n d et al., 1 9 7 6 ) . F o r t h e s e d r u g s , an i n c r e a s e i n h e p a t i c b l o o d f l o w w i l l c a u s e a p r o p o r t i o n a l i n c r e a s e i n h e p a t i c c l e a r a n c e s ( W i l k i n s o n and S h a n d , 1 9 7 5 ) . E x p e r i m e n t a l e v i d e n c e has been p r o v i d e d i n t h e dog t o s u b s t a n t i a t e t h i s r e l a t i o n s h i p between h e p a t i c b l o o d f l o w and d r u g c l e a r a n c e u s i n g t h e h i g h - c l e a r a n c e d r u g p r o p r a n o l o l ( N i e s et al., 1 9 7 6 ) . S e v e r a l d r u g s , a c t i n g on t h e c a r d i o v a s c u l a r s y s t e m , have been shown t o e x h i b i t h e p a t i c b l o o d f l o w d e p e n d e n t k i n e t i c s i n man, f o r e x a m p l e , t h e a n t i a r r h y t h m i c d r u g l i d o c a i n e and t h e l i p o p h i l i c ) 8 - a d r e n o r e c e p t o r a n t a g o n i s t s viz. m e t o p r o l o l , l a b e t o l o l and p r o p r a n o l o l ( G e o r g e , 1 9 7 9 ) . P r o p r a n o l o l has been d e m o n s t r a t e d t o u n d e r g o e x t e n s i v e p r e s y s t e m i c ( f i r s t -p a s s ) m e t a b o l i s m a f t e r o r a l a d m i n i s t r a t i o n , as a r e s u l t o f t h e h i g h h e p a t i c e x t r a c t i o n p a s s i n g t h r o u g h t h e l i v e r ( R o u t l e d g e and S h a n d , 1 9 7 9 ) . A l s o , t h e b i o a v a i l a b i l i t y o f p r o p r a n o l o l has been shown t o i n c r e a s e by 6 1 % i n h e a l t h y s u b j e c t s when a d m i n i s t e r e d t o g e t h e r w i t h t h e v a s o d i l a t o r y a g e n t h y d r a l a z i n e (McLean e t al., 1980; S c h n e c k and V a r y , 1 9 8 4 ) . The i n c r e a s e i n t h e o r a l b i o a v a i l a b i l i t y o f p r o p r a n o l o l by h y d r a l a z i n e has been a t t r i b u t e d t o t h e t r a n s i e n t i n c r e a s e i n l i v e r b l o o d f l o w c a u s e d by t h e v a s o d i l a t o r y a c t i o n o f h y d r a l a z i n e (McLean e t al., 1980; S c h n e c k and V a r y , 1 9 8 4 ) . 1.4.4. I n d o c y a n i n e G r e e n 1.4.4.1. P h a r m a c o k i n e t i c s o f ICG I n d o c y a n i n e g r e e n ( I C G ) , i s a s u l f o n i c a c i d d y e , w h i c h has been e x t e n s i v e l y u s e d t o e v a l u a t e h e p a t i c f u n c t i o n and e s t i m a t e l i v e r b l o o d f l o w i n man and a n i m a l s ( C e a s a r e t al., 1961; S v e n s s o n e t al., 1982; H e i n t z e t al., 1986; Modi e t al., 1988; B u r n s e t al., 1989; D o r r e t al., 1989; Wynne e t al., 1 9 9 0 ) . A r e v i e w o f ICG i n r e l a t i o n t o t h e l i v e r has been made by P a u m g a r t n e r ( 1 9 7 5 ) . ICG has a h i g h m o l e c u l a r w e i g h t o f 775 and i s r a p i d l y and c o m p l e t e l y bound t o p l a s m a p r o t e i n s and d i s t r i b u t e d i n t o t h e v a s c u l a r s y s t e m ( P a u m g a r t n e r 1 9 7 5 ) . M e i j e r e t a 7 . ( 1 9 8 8 ) r e p o r t e d a l m o s t c o m p l e t e ( 8 5 % ) r e c o v e r y o f u n c h a n g e d ICG i n t h e b i l e o f humans. ICG i s removed f r o m t h e c i r c u l a t i o n s p e c i f i c a l l y by t h e l i v e r and t h e r e d o e s n o t a p p e a r t o be any s i g n i f i c a n t e n t e r o h e p a t i c r e c i r c u l a t i o n o r e x t r a h e p a t i c e l i m i n a t i o n o f t h e d y e ( C a e s a r e t al., 1961; P a u m g a r t n e r , 1 9 7 5 ) . The h e p a t i c e x t r a c t i o n r a t i o o f ICG i s o v e r 0.70 o b t a i n e d by d i r e c t measurement i n h e a l t h y man ( C a e s a r e t al., 1 9 6 1 ; Wynne e t al., 1990; G r a i n g e r e t al., 1 9 8 3 ) . I n a d d i t i o n , ICG i s r e l a t i v e l y s a f e ( H u e t e t al., 1981) and s e n s i t i v e a n a l y t i c a l methods a r e a v a i l a b l e t o measure i t s c o n c e n t r a t i o n i n p l a s m a o r serum ( C a e s a r e t al., 1961; R a p p a p o r t and T h i e s s e n 1982; S v e n s s o n e t al., 1 9 8 2 ) . T h e s e c h a r a c t e r i s t i c s make ICG a s u i t a b l e t e s t s u b s t a n c e t o e s t i m a t e l i v e r b l o o d f l o w i n man, p a r t i c u l a r l y , t o a s s e s s r e l a t i v e c h a n g e s i n l i v e r b l o o d f l o w i n p a t i e n t s w i t h no l i v e r d i s e a s e ( S o o n s et al., 1 9 9 0 ) . 1.4.4.2. A n a l y s i s o f ICG i n Human Serum T r a d i t i o n a l l y , ICG has been m e a s u r e d i n human p l a s m a by a b s o r b a n c e s p e c t r o p h o t o m e t r y a t 800-805 nm ( C a e s a r e t a / . , 1 9 5 1 ; G r a i n g e r e t al., 1 9 8 3 ; H o l l i n s e t al., 1 9 8 7 ) . T h i s method has been w i d e l y a c c e p t e d due t o t h e f a c t t h a t i t i s s i m p l e , f a s t and r e l a t i v e l y s e n s i t i v e . R e c e n t l y , t h e s p e c i f i c i t y o f t h e s p e c t r o p h o t o m e t r i c a s s a y has been q u e s t i o n e d due t o an i n t e r f e r i n g compound w h i c h a b s o r b s l i g h t a t t h e same w a v e l e n g t h as t h e p a r e n t compound ( R a p p a p o r t and T h i e s s e n , 1 9 8 2 ) . T h i s i m p u r i t y a n d / o r d e g r a d a t i o n p r o d u c t f o r m e d t h e b a s i s t o d e v e l o p s e v e r a l h i g h - p e r f o r m a n c e l i q u i d c h r o m a t o g r a p h i c (HPLC) a s s a y s w h i c h c i r c u m v e n t t h e p o s s i b l e n o n s p e c i f i c i t y o f t h e s p e c t r o p h o t o m e t r i c a s s a y . T h e s e HPLC methods e m p l o y e i t h e r f l u o r e s e n c e d e t e c t i o n ( D o r r e t al., 1989; H o l l i n s e t al., 1987;) o r UV d e t e c t i o n ( R a p p a p o r t and T h i e s s e n , 1982; H e i n t z e t al., 1986) and t h e i r s p e c i f i c i t y f o r p a r e n t ICG has been d e m o n s t r a t e d . S e v e r a l s t u d i e s were c o n d u c t e d t o compare t h e s p e c t r o p h o t o m e t r i c and HPLC a n a l y s i s o f ICG i n p l a s m a ( S v e n s s o n e t al., 1982; O ' R e i l l y e t al., 1987; G r a s e l a e t al., 1 9 8 7 ) . T h e s e c o m p a r i s o n s r e v e a l e d t h a t t h e d i f f e r e n c e s i n ICG p l a s m a c o n c e n t r a t i o n s d e t e r m i n e d by HPLC and s p e c t r o p h o t o m e t r y a r e a p p a r e n t o n l y a t l a t e t i m e p o i n t s (>20 m i n ) and t h e two methods h a v e been shown t o g i v e s i m i l a r r e s u l t s i f b l o o d s a m p l i n g f o r ICG were r e s t r i c t e d b e t w e e n 2 and 15 m i n u t e s ( H e i n t z e t al., 1 9 8 6 ) . G r a s e l a e t al., ( 1 9 8 7 ) f o u n d t h a t t h e s p e c t r o p h o t o m e t r i c method o v e r e s t i m a t e d ICG p l a s m a c o n c e n t r a t i o n c ompared t o t h e HPLC m e t h o d , h o w e v e r , t h e s t a t i s t i c a l i n f e r e n c e s made f r o m t h e c l i n i c a l s t u d y w e r e i d e n t i c a l r e g a r d l e s s w h i c h method was u s e d f o r ICG a n a l y s i s . S v e n s s o n e t al., ( 1 9 8 2 ) r e p o r t e d no d e t e c t a b l e l e v e l s o f ICG i n human p l a s m a 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f m u l t i p l e i . v . d o s e s o f 0.5 mg/kg ICG i n two h e a l t h y s u b j e c t s . 1.5. U p r i g h t P o s t u r e : A P h y s i o l o g i c a l S t i m u l u s t o A l t e r L i v e r B l o o d F l o w S e v e r a l f a c t o r s , i n c l u d i n g e x e r c i s e , h e a t , f o o d , age and u p r i g h t p o s t u r e a r e known t o a l t e r h e p a t i c b l o o d f l o w ( N i e s et al., 1976; G e o r g e , 1 9 7 9 ) . In a d d i t i o n , many d i s e a s e s t a t e s s u c h as c o n g e s t i v e h e a r t f a i l u r e , l i v e r and t h y r o i d d i s e a s e and h a e m o r r h a g i c s h o c k may c a u s e c h a n g e s i n l i v e r b l o o d f l o w ( N i e s et al., 1976; G e o r g e , 1 9 7 9 ) . S p l a n c h n i c b l o o d f l o w has been r e p o r t e d t o be s i g n i f i c a n t l y r e d u c e d ( 1 5 % ) i n p a t i e n t s w i t h h y p e r t e n s i o n , p a r t i c u l a r l y i n t h o s e w i t h r e n a l s t e n o s i s ( M e s s e r l i e t al., 1 9 7 5 ) . A c h a n g e i n p o s t u r e t o s t a n d i n g i s a w e l l known p h y s i o l o g i c a l f a c t o r a l t e r i n g l i v e r b l o o d f l o w ( W i l k i n s o n , 1 9 7 6 ) . Due t o t h e r e d i s t r i b u t i o n o f b l o o d f r o m t h e u p p e r p o r t i o n o f t h e body ( h e a r t and l u n g s ) t o t h e l e g s , r e f l e x v a s o c o n s t r i c t i o n o c c u r i n t h e s p l a n c h n i c v a s c u l a r bed t o c o m p e n s a t e f o r t h e d e c r e a s e i n c a r d i a c o u t p u t and t o m a i n t a i n b l o o d p r e s s u r e ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . T h e s e r e f l e x c h a n g e s c a u s e a s i g n i f i c a n t d e c r e a s e i n l i v e r b l o o d f l o w and an i n c r e a s e i n h e a r t r a t e ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . The v a s o c o n s t r i c t i o n i s m e d i a t e d t h r o u g h t h e s y m p a t h e t i c n e r v o u s s y s t e m , s i n c e t h e r e s p o n s e i s a b o l i s h e d by s p l a n c h n i c s y m p a t h e c t o m y i n h y p e r t e n s i v e s u b j e c t s ( W i l k i n s e t al., 1 9 5 1 ) . The i n c r e a s e d h y d r o s t a t i c p r e s s u r e i n t h e l e g s f a c i l i t a t e s t h e u l t r a f i l t r a t i o n o f p l a s m a t o t h e i n t e r s t i t i a l s p a c e , hence d e c r e a s e s p l a s m a v o l u m e and i n c r e a s e s t h e c o n c e n t r a t i o n s o f b l o o d c o n s t i t u e n t s s u c h as h e m a t o c r i t , h a e m o g l o b i n and p r o t e i n s (Hagan e t al., 1978; D i x o n and P a t e r s o n 1 9 7 8 ) . The s t a b i l i z a t i o n o f p l a s m a v o l u m e r e q u i r e s a b o u t 40-60 m i n u t e s i n t h e assumed p o s t u r e (Hagan e t al., 1 9 7 8 ) . The d e c r e a s e i n l i v e r b l o o d f l o w upon s t a n d i n g has been d e m o n s t r a t e d i n a number o f s t u d i e s i n v o l v i n g h e a l t h y s u b j e c t s (Daneshmend e t al., 1 9 8 1 ; Modi e t al., 1988) and p a t i e n t s w i t h h y p e r t e n s i o n ( C u l b e r t s o n e t al., 1 9 5 1 ) . The m a g n i t u d e o f c h a n g e i n l i v e r b l o o d f l o w due t o u p r i g h t p o s t u r e i n h e a l t h y s u b j e c t s has been f o u n d t o be 30 t o 4 0 % (Daneshmend e t al., 1 9 8 1 ; Modi e t al., 1988; C u l b e r t s o n e t al., 1951) and 3 0 % i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n ( C u l b e r t s o n e t al., 1 9 5 1 ) . P o s s i b l e i n t e r f e r e n c e o f t h e i n h i b i t i o n o f ACE w i t h t h e r e f l e x c a r d i o v a s c u l a r r e s p o n s e s t o u p r i g h t p o s t u r e h ave been i n v e s t i g a t e d i n a number o f s t u d i e s ( S t a d e a g e r e t al., 1989; V a n d e n b u r g e t al., 1983; M u i e s a n e t al., 1982; T a r a z i e t al., 1 9 8 0 ) . M o s t o f t h e s t u d i e s c o n d u c t e d i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n and u s i n g c a p t o p r i l an ACE i n h i b i t o r a g r e e d t h a t c a p t o p r i l d o es n o t seem t o i n t e r f e r e w i t h t h e c i r c u l a t o r y r e f l e x e s i n d u c e d by s t a n d i n g and m e d i a t e d t h r o u g h t h e s y m p a t h e t i c n e r v o u s s y s t e m ( V a n d e n b u r g e t al., 1983; M u i e s a n e t al., 1 9 8 2 ) . 1.6. R a t i o n a l e and O b j e c t i v e s 1.6.1. R a t i o n a l e T h e r e a r e a number o f s t u d i e s w h i c h e x a m i n e d t h e p h a r m a c o l o g i c a l e f f e c t s o f c a p t o p r i l i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . However, v e r y few s t u d i e s m e a s u r e d t h e c h a n g e s i n l i v e r b l o o d f l o w a f t e r c a p t o p r i l a d m i n i s t r a t i o n i n p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n . In t h e s e s t u d i e s , most o f t e n t h e a c u t e e f f e c t s o f c a p t o p r i l on l i v e r b l o o d f l o w have been i n v e s t i g a t e d and o n l y a few s t u d i e s w e r e c o n d u c t e d t o e x a m i n e i t s e f f e c t s a f t e r p r o l o n g e d t h e r a p y . S i n c e h y p e r t e n s i o n i s a c h r o n i c d i s e a s e and t h e c o n t r o l o f m i l d / m o d e r a t e h y p e r t e n s i o n r e q u i r e s l o n g - t e r m t h e r a p y , t o s t u d y t h e e f f e c t s o f c a p t o p r i l on l i v e r b l o o d f l o w a f t e r r e p e a t e d a d m i n i s t r a t i o n may be more i m p o r t a n t t h a n a f t e r a c u t e d o s i n g . C a p t o p r i l has been f r e q u e n t l y u s e d i n c o m b i n a t i o n w i t h o t h e r d r u g s , f o r e x a m p l e , t h e -^a d r e n o r e c e p t o r b l o c k e r p r o p r a n o l o l ( M c A r e a v e y and R o b e r t s o n , 1990) i n w h i c h h e p a t i c and s y s t e m i c c l e a r a n c e i s l a r g e l y d e p e n d e n t on t h e r a t e o f d r u g d e l i v e r y t o t h e l i v e r ( R o u t l e d g e and Sh a n d , 1 9 7 9 ) . A c l e a n u n d e r s t a n d i n g o f c a p t o p r i l i n d u c e d a l t e r a t i o n s i n l i v e r b l o o d f l o w w o u l d be e x p e c t e d t o c l a r i f y t h e p o t e n t i a l f o r d r u g / d r u g i n t e r a c t i o n s when f l o w d e p e n d e n t d r u g s a r e c o a d m i n i s t e r e d w i t h c a p t o p r i l . C l i n i c a l l y , c a p t o p r i l i n d u c e d c h a n g e s i n h e p a t i c b l o o d f l o w may l e a d t o a c h a n g e i n h e p a t i c c l e a r a n c e n e c e s s i t a t i n g a c h a n g e i n d r u g d o s a g e i n o r d e r t o m a i n t a i n s t e a d y - s t a t e b l o o d c o n c e n t r a t i o n . The a s s e s s m e n t o f ICG c l e a r a n c e a f t e r an i n t r a v e n o u s b o l u s o f 0,5 mg/kg has been w i d e l y u s e d t o e s t i m a t e r e l a t i v e c h a n g e s i n l i v e r b l o o d f l o w i n man ( O h n h a u s , 1 9 7 9 ) , I t has been d e m o n s t r a t e d t h a t r e p e a t e d measurement o f ICG c l e a r a n c e i n t h e same s u b j e c t u n d e r t h e same c o n d i t i o n s has been r e p r o d u c i b l e w i t h a c o e f f i c i e n t o f v a r i a t i o n 5% (Daneshmend et al., 1 9 8 1 ) , The s p e c t r o p h o t o m e t r i c method u s e d f o r t h e a n a l y s i s o f ICG i n human serum has b e en p r o v e d t o p r o v i d e s i m i l a r r e s u l t s t o t h a t o f t h e HPLC method, i f b l o o d s a m p l i n g was r e s t r i c t e d t o 2 t o 15 m i n u t e s ( S v e n s s o n et al., 1982; G r a s e l a e t al., 1 9 8 7 ) , 1,6,2, O b j e c t i v e s 1, To e x a m i n e t h e a c u t e e f f e c t s o f c a p t o p r i l on ICG c l e a r a n c e and l i v e r b l o o d f l o w i n m i l d t o m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 2. To i n v e s t i g a t e t h e p r o l o n g e d e f f e c t s o f c a p t o p r i l on ICG c l e a r a n c e and l i v e r b l o o d f l o w i n m i l d t o m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 3. To r e p r o d u c e t h e w e l l e s t a b l i s h e d d e c r e a s e i n l i v e r b l o o d f l o w d u r i n g p o s t u r a l c h a n g e f r o m s i t t i n g t o s t a n d i n g and use t h i s as g u i d e i n i n t e r p r e t i n g any c h a n g e s i n ICG c l e a r a n c e o r l i v e r b l o o d f l o w s e e n w i t h c a p t o p r i l t r e a t m e n t . 4. To e x a m i n e t h e e f f e c t s o f two-weeks c a p t o p r i l t r e a t m e n t on l i v e r b l o o d f l o w d u r i n g p o s t u r a l c h a n g e . 5. To s t u d y t h e c h a n g e s i n t h e haemodynamic p a r a m e t e r s ( b l o o d p r e s s u r e , h e a r t r a t e , s p l a n c h n i c v a s c u l a r r e s i s t a n c e ) o f p a t i e n t s a f t e r a c u t e and s h o r t - t e r m a d m i n i s t r a t i o n o f c a p t o p r i l . 2. EXPERIMENTAL 2.1 M a t e r i a l s and S u p p l i e s 2.1.1. D r u g s C a p t o p r i l t a b l e t s (CAPOTEN'^) (50 mg) were p u r c h a s e d f r o m B r i s t o l - M y e r s S q u i b b C a n a d a I n c . , M o n t r e a l , C a n a d a . S t e r i l e I n d o c y a n i n e G r e e n , USP (CARDIO-GREEN"^ ( C G ) ) (50 mg v i a l ) was p u r c h a s e d f r o m B e c t o n D i c k i n s o n M i c r o b i o l o g y S y s t e m s , C o c k e y s v i l l e , M a r y l a n d , U.S.A. S o d i u m C h l o r i d e I n j e c t i o n USP (30 m l , 0.9%) was p u r c h a s e d f r o m A b b o t t L a b o r a t o r i e s L t d . , M o n t r e a l , C a n a d a . H e p a r i n S o d i u m I n j e c t i o n USP (10 m l , 1000 U/ml) was o b t a i n e d f r o m A l l a n and H a n b u r y , G l a x o Canada L t d . , T o r o n t o , O n t a r i o , C a n a d a . 2.1.2. C h e m i c a l s and R e a g e n t s C a p t o p r i l was d o n a t e d by B r i s t o l - M y e r s S q u i b b Canada I n c . , M o n t r e a l , Quebec, C a n a d a . ACS r e a g e n t g r a d e d i s o d i u m e t h y l e n e d i a m i n e t e t r a a c e t i c a c i d d i h y d r a t e (EDTA) and L - A s c o r b i c A c i d ( V i t a m i n C) were o b t a i n e d f r o m S i g m a C h e m i c a l Company, S t . L o u i s , M o n t a n a , U.S.A.; N - ( 3 - P y r e n y l ) m a l e i m i d e (NPM) was p u r c h a s e d f r o m F l u k a , Hauppauge, New Y o r k , U.S.A. and was p u r i f i e d i n t h e l a b o r a t o r y o f Dr. Y.K.Tam ( U n i v e r s i t y o f A l b e r t a , F a c u l t y o f Pharmacy and P h a r m a c e u t i c a l S c i e n c e s , Edmonton, A l b e r t a , C a n a d a ) . ACS r e a g e n t g r a d e m o n o p o t a s s i u m p h o s p h a t e , d i s o d i u m p h o s p h a t e were p u r c h a s e d f r o m BDH C h e m i c a l s , T o r o n t o , O n t a r i o , C a n a d a . 2.1.3. S o l v e n t s ACS r e a g e n t g r a d e m e t h a n o l was o b t a i n e d f r o m BOH C h e m i c a l s , T o r o n t o , O n t a r i o , C a n a d a . E t h a n o l ( 9 5 % ) was s u p p l i e d by StanChem, V a n c o u v e r , B.C., Ca n a d a . D e i o n i z e d w a t e r was p r o d u c e d on s i t e via a M i l l i - R o ' ^ s y s t e m , M i l l i p o r e C o r p . , B e d f o r d , MA., U.S.A. HPLC g r a d e a c e t o n i t r i l e ( u l t r a v i o l e t (UV) c u t o f f 190 nm) was p u r c h a s e d f r o m C a l e d o n L a b o r a t o r i e s L t d . , G e o r g e t o w n , O n t a r i o , C a n a d a . 2.1.4. S u p p l i e s f o r Human E x p e r i m e n t s I n d o c y a n i n e g r e e n was a d m i n i s t e r e d i n t r a v e n o u s l y ( i . v . ) t h r o u g h a s t e r i l e t h r e e way s t o p c o c k o b t a i n e d f r o m Medex I n c . , H i l l i a r d , O h i o , U.S.A. The s t e r i l e J e l c o S t r i p e d i . v . c a t h e t e r n e e d l e s (20 g, 32 mm) were o b t a i n e d f r o m C r i t i c o n , Canada I n c . , Markham, O n t a r i o , C a n a d a . P l a s t i c 5 ml s y r i n g e s , 22 and 19 gauge n e e d l e s and V a c u t a i n e r * ^ b l o o d c o l l e c t i o n t u b e s ( w i t h o u t a d d i t i v e ) were o b t a i n e d f r o m B e c t o n D i c k i n s o n Canada I n c . , M i s s i s s a u g a , O n t a r i o , Canada. F o l l o w i n g c e n t r i f u g a t i o n t h e serum was s t o r e d f r o z e n i n amber v i a l s (4 ml) w i t h p o l y t e t r a f l u o r o e t h y l e n e (PTFE) l i n e d s c r e w c a p s ( K i m b l e , D i v i s i o n o f O w e n s - I l l i n o i s , U.S.A. C a p t o p r i l serum s a m p l e s were s t o r e d f r o z e n i n c o n i c a l t i p p e d p o l y p r o p y l e n e t u b e s (15 ml) w i t h s c r e w c a p s w h i c h were p u r c h a s e d f r o m S a r s t e d t C a n a d a , S t . L a u r e n t , Quebec, Canada. 2.1.5. O t h e r S u p p l i e s S l i c k S e a l ' ^ m i c r o - c e n t r i f u g e p o l y p r o p y l e n e t u b e s w i t h f l a t , p e r m e a b l e c a p s ( 1 . 7 m l ) were o b t a i n e d f r o m I s l a n d S c i e n t i f i c , B a i n b r i d g e I s l a n d , W a s h i n g t o n , U.S.A. M a p l e Leaf'^ d i s p o s a b l e g l a s s c u l t u r e t u b e s (3 m l ) , were o b t a i n e d f r o m J o h n s S c i e n t i f i c I n c . , T o r o n t o , O n t a r i o , C a n a d a . 2.2 E q u i p m e n t 2.2.1. S p e c t r o p h o t o m e t e r A H e w l e t t P a c k a r d (HP) 8452 A d i o d e - a r r a y u l t r a v i o l e t / v i s i b l e (UV) s p e c t r o p h o t o m e t e r e q u i p p e d w i t h a HP V e c t r a ' ^ c o m p u t e r i n t e r f a c e was u s e d t o m e a s u r e i n d o c y a n i n e g r e e n i n human serum. 2.2.2. H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h The l i q u i d c h r o m a t o g r a p h i c a n a l y s i s o f u n c h a n g e d c a p t o p r i l was c a r r i e d o u t i n t h e l a b o r a t o r y o f D r . Y.K. Tarn, D i v i s i o n o f P h a r m a c e u t i c s , F a c u l t y o f Pharmacy and P h a r m a c e u t i c a l S c i e n c e s , U n i v e r s i t y o f A l b e r t a , Edmonton, A l b e r t a . A h i g h - p e r f o r m a n c e l i q u i d c h r o m a t o g r a p h e q u i p p e d w i t h P a r t i s i l ' ^ 5 ODS-3 C j g col u m n (5 nm, 100 mm x 4.6 mm I.D., Whatman, C l i f t o n , N J , U.S.A.), a Model U6K s a m p l e i n j e c t o r and an FS 970 f l u o r o m e t e r ( S c h o e f f e l , O a k v i l l e , C anada) w i t h e x c i t a t i o n and emission w a v e l e n g t h o f 340 and 389 nm, r e s p e c t i v e l y , was u s e d . 2.2.3. M i s c e l l a n e o u s O t h e r e q u i p m e n t u s e d i n c l u d e d : V o r t e x - G e n i e ' ^ m i x e r ( F i s h e r S c i e n t i f i c Co., S p r i n g f i e l d , MA, U.S.A).; F i s h e r Accumet'^ Model 912 pH m e t e r and e l e c t r o d e ( F i s h e r S c i e n t i f i c Co., S p r i n g f i e l d , MA, U . S . A . ) ; a W r i s t A c t i o n ' ^ l a b o r a t o r y s h a k e r a t a b o u t 1400 rpm ( B u r r e l C o r p . , P i t t s b u r g , PA, U.S.A.); a F i s h e r * ^ Model 235C m i c r o - c e n t r i f u g e a t 13,000 x g, ( F i s h e r S c i e n t i f i c Co., S p r i n g f i e l d , MA, U . S .A.); a S i l e n c e r ' ^ t a b l e t o p g e n e r a l p u r p o s e c e n t r i f u g e w i t h t e m p e r a t u r e c o n t r o l s e t a t 4''C ( W e s t e r n S c i e n t i f i c L t d . , L ondon, O n t a r i o , C a n a d a ) ; a C r i t i c o n ' ^ 1900 Dinamap 845 x T v i t a l s i g n s m o n i t o r w i t h h e a r t r a t e , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e ( B P ) , mean a r t e r i a l p r e s s u r e measurement c a p a b i l i t y ; a C a n l a b lEc'^ Model CR m i c r o - c a p i l l a r y r e a d e r and lEC MB c e n t r i f u g e , (Damon/IEC D i v i s i o n , I n t e r n a t i o n a l E q u i p m e n t C o r p . , Needham, H e i g h t s , MA., U.S.A.) f o r h e m a t o c r i t m e a s u r e m e n t ; SpeedVac'^ a u t o m a t i c s a m p l e c o n c e n t r a t o r and d r y e r . Model A 2 9 0, ( S a v a n t I n s t r u m e n t s , I n c . , F a r m i n g d a l e , NY., U.S.A.). 2.3. P r e p a r a t i o n o f S t o c k and R e a g e n t S o l u t i o n s 2.3.1. I n d o c y a n i n e G r e e n I n d o c y a n i n e g r e e n was a c c u r a t e l y w e i g h e d and d i s s o l v e d i n m e t h a n o l t o o b t a i n a f i n a l c o n c e n t r a t i o n o f « 10 /zg/ml. T h i s s o l u t i o n was p r o t e c t e d f r o m l i g h t by w r a p p i n g t h e v o l u m e t r i c f l a s k i n a l u m i n i u m f o i l and s t o r a g e a t 4°C f o r up t o 48 h o u r s . 2.3.2. C a p t o p r i l A p p r o x i m a t e l y 5 mg o f c a p t o p r i l was a c c u r a t e l y w e i g h e d and t r a n s f e r r e d t o a 50 ml v o l u m e t r i c f l a s k and d i s s o l v e d i n an aque o u s 1 mM s o l u t i o n o f d i s o d i u m EDTA. A 2.5 ml a l i q u o t o f t h i s s o l u t i o n was d i l u t e d t o 50 ml i n a v o l u m e t r i c f l a s k w i t h a q u e o u s 1 mM d i s o d i u m EDTA s o l u t i o n ( f i n a l c o n c e n t r a t i o n 5 /xg/ml), C a p t o p r i l s t o c k s o l u t i o n was p r e p a r e d d a i l y f o r a n a l y s i s . 2.3.3. R e a g e n t S o l u t i o n s D i s o d i u m EDTA s o l u t i o n (1 mM) was p r e p a r e d by d i s s o l v i n g ~ 37.22 mg d i s o d i u m EDTA i n d e i o n i z e d w a t e r i n a 100 ml v o l u m e t r i c f l a s k . D i s o d i u m EDTA ( 3 7 . 2 2 mg/ml) and a s c o r b i c a c i d ( 1 9 . 8 0 mg/ml) s o l u t i o n was p r e p a r e d by d i s s o l v i n g 186.12 mg and 99.05 mg d i s o d i u m EDTA and a s c o r b i c a c i d , r e s p e c t i v e l y , i n d e i o n i z e d w a t e r i n a 5 ml v o l u m e t r i c f l a s k . T h i s s o l u t i o n was f r e s h l y p r e p a r e d on t h e d a y o f a n a l y s i s . S o r e n s e n p h o s p h a t e b u f f e r (pH 7.0) was p r e p a r e d u s i n g t h e f o l l o w i n g p r o c e d u r e s . M o n o p o t a s s i u m p h o s p h a t e (KH2PO4, 1.81 g) was a c c u r a t e l y w e i g h e d and d i s s o l v e d i n d e i o n i z e d w a t e r t o a f i n a l v o l u m e o f 200 ml ( s o l u t i o n 1 ) . D i s o d i u m p h o s p h a t e (Na2HP04, 1.90 g) was a c c u r a t e l y w e i g h e d and d i s s o l v e d i n d e i o n i z e d w a t e r t o a f i n a l v olume o f 200 ml ( s o l u t i o n 2 ) . An a c c u r a t e v o l u m e ( 4 1 . 3 0 m l ) o f s o l u t i o n 1 was t r a n s f e r r e d t o a 100 ml v o l u m e t r i c f l a s k and was a d j u s t e d t o t h e f i n a l volume w i t h s o l u t i o n 2 t o y i e l d a b u f f e r s o l u t i o n o f 0.067 M. The pH o f t h e f i n a l s o l u t i o n was m e a s u r e d and a d j u s t e d , i f n e c e s s a r y , t o 7.0 w i t h a l i q u o t s o f s o l u t i o n 1 o r 2. N - ( 3 - P y r e n y l ) m a l e i m i d e (NPM) s o l u t i o n was p r e p a r e d by d i s s o l v i n g 7.5 mg p u r i f i e d NPM i n HPLC g r a d e a c e t o n i t r i l e . T h i s s o l u t i o n was s t o r e d a t 4°C a f t e r p r e p a r a t i o n f o r up t o 24 h o u r s . 2.4. UV S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n ( I C G ) i n Human Serum 2.4.1. P r e l i m i n a r y E x p e r i m e n t s 2 .4.1.1. S t a b i l i t y o f ICG i n D e i o n i z e d W a t e r The d e g r a d a t i o n o f ICG i n d e i o n i z e d w a t e r was d e t e r m i n e d as f o l l o w s : ICG was d i s s o l v e d i n d e i o n i z e d w a t e r t o p r o d u c e a c o n c e n t r a t i o n o f 10 / i g / m l . The a b s o r b a n c e o f t h e ICG s o l u t i o n was r e p e a t e d l y m e a s u r e d a t t h e w a v e l e n g t h o f 778 nm o v e r 24 h o u r s f o l l o w i n g p r e p a r a t i o n . ICG s a m p l e s were s t o r e d a t 4°C i n a g l a s s c o n t a i n e r w r a p p e d i n a l u m i n i u m f o i l t o p r o t e c t f r o m l i g h t c a t a l y z e d d e g r a d a t i o n . 2.4.1.2. S t a b i l i t y o f ICG i n Human Serum A m e t h a n o l i c s o l u t i o n o f ICG was p r e p a r e d t o o b t a i n a c o n c e n t r a t i o n o f 0.01 mg/ml. Volumes ( 0 . 0 2 and 0.6 ml) o f t h i s s o l u t i o n , w i t h c o n c e n t r a t i o n s o f 0.2 and 6 /ig/ml were e v a p o r a t e d t o d r y n e s s a t 40°C u n d e r a g e n t l e s t r e a m o f n i t r o g e n (N=7 f o r e a c h c o n c e n t r a t i o n ) . The ICG r e s i d u e was r e c o n s t i t u t e d by a d d i n g 0.4 ml b l a n k human serum t o t h e s a m p l e s and by a l l o w i n g them t o s t a n d 30 m i n u t e s w i t h i n t e r m i t t e n t v o r t e x m i x i n g . A l l s a m p l e s were s t o r e d a t - S T and w e r e p r o t e c t e d f r o m l i g h t . I m m e d i a t e l y p r i o r t o a n a l y s i s , 0.6 ml v o l u m e o f d o u b l e d i s t i l l e d w a t e r was added t o t h e s a m p l e s t o o b t a i n ICG c o n c e n t r a t i o n s o f 0.2 and 6.0 ^ig/m^. T h e s e s a m p l e s w e r e a n a l y z e d s p e c t r o p h o t o m e t r i c a l l y a t 0, 4, 8, 14, 24, 36 and 48 h o u r s f o l l o w i n g p r e p a r a t i o n as f o l l o w s . S a m p l e s were s t o r e d a t -5°C u n t i l a n a l y s i s and were p r o t e c t e d f r o m l i g h t . A l l s a m p l e s w e r e a n a l y z e d a g a i n s t b l a n k serum a t t h e w a v e l e n g t h o f 800 nm. S t a n d a r d s a m p l e s were p r e p a r e d a t t h e t i m e o f t h e a n a l y s i s , i d e n t i c a l t o t h e ICG s a m p l e s , t o p r o v i d e a c o n c e n t r a t i o n r a n g e f r o m 0.2 t o 6.0 /ig/ml o f ICG. The t i m e d e p e n d e n t c h a n g e o f ICG i n human se r u m was e s t i m a t e d by p l o t t i n g t h e m e a s u r e d c o n c e n t r a t i o n s o f t h e two s a m p l e s a g a i n s t t i m e and by c a l c u l a t i n g t h e c o e f f i c i e n t o f v a r i a t i o n f o r e a c h c o n c e n t r a t i o n . 2.4.2. Q u a n t i t a t i v e S p e c t r o p h o t o m e t r i c A n a l y s i s o f ICG i n P a t i e n t Serum 2.4.2.1. P r e p a r a t i o n o f S a m p l e s f o r S t a n d a r d C u r v e F o r t h e p r e p a r a t i o n o f s t a n d a r d s a m p l e s t h e m o d i f i e d methods o f R a p p a p o r t T h i e s s e n ( 1 9 8 2 ) and D o r r e t . al. ( 1 9 8 9 ) were u s e d as f o l l o w s . A l i q u o t s o f 0.02, 0.06, 0.1, 0.2, 0.3 and 0.5 ml o f m e t h a n o l i c ICG s t o c k s o l u t i o n ( 0 .01 Mg/ml) were p i p e t t e d i n t o c l e a n amber v i a l s . Each v i a l was made up t o a volume o f 0.5 ml w i t h m e t h a n o l . Each s a m p l e was e v a p o r a t e d t o d r y n e s s u s i n g t h e Savant*^ (40°C x 15 m i n ) . V i a l s were c a p p e d w i t h t e f l o n l i n e d s c r e w c a p s and were s t o r e d i n a vacuum d e s i c c a t o r a t -20°C u n t i l a n a l y s i s f o r up t o 48 h o u r s . I m m e d i a t e l y p r i o r t o a n a l y s i s , a s e t o f s t a n d a r d s a m p l e s was s e l e c t e d and t h e ICG r e s i d u e s were r e c o n s t i t u t e d w i t h 50 n^ e t h a n o l ( 9 5 % ) and w e r e g e n t l y v o r t e x m i x e d f o r 5 s e c o n d s t o e n s u r e c o m p l e t e d i s s o l u t i o n o f ICG. To e a c h v i a l , 0.95 ml b l a n k human serum was p i p e t t e d t o o b t a i n c o n c e n t r a t i o n s o f 0.2, 0.6, 1.0, 2.0, 3.0 and 5.0 Mg/ml. S a m p l e s w e r e g e n t l y v o r t e x m i x e d f o r 15 s e c o n d s . A s i m i l a r l y p r e p a r e d serum b l a n k was u s e d as r e f e r e n c e . A l l s t a n d a r d s were p r o t e c t e d f r o m l i g h t . A s t a n d a r d c u r v e was c o n s t r u c t e d by p l o t t i n g t h e a b s o r b a n c e a g a i n s t t h e c o n c e n t r a t i o n o f ICG u s i n g l i n e a r r e g r e s s i o n . F o r e a c h a n a l y s i s a new s t a n d a r d c u r v e was p r e p a r e d . 2.4.2.2. S p e c t r o p h o t o m e t r i c A n a l y s i s ICG i n s e r u m was a n a l y z e d by t h e m o d i f i e d UV s p e c t r o p h o t o m e t r i c method d e s c r i b e d by C a e s a r e t al. ( 1 9 6 1 ) . The a b s o r b a n c e o f ICG i n p a t i e n t s a m p l e s was m e a s u r e d a t t h e w a v e l e n g t h o f maximum a b s o r b a n c e ( 8 06 nm). The t e m p e r a t u r e o f t h e s a m p l e s was c o n t r o l l e d by u s i n g t e m p e r a t u r e c o n t r o l l e d s a m p l e c e l l h o l d e r . P a t i e n t s a m p l e s w e r e p r e p a r e d i m m e d i a t e l y p r i o r t o a n a l y s i s i n a s i m i l a r manner t o t h e b l a n k and s t a n d a r d s a m p l e s . The a n a l y s i s o f t h e s a m p l e s was c a r r i e d o u t w i t h i n 30 m i n u t e s f o l l o w i n g p r e p a r a t i o n . A l l s t a n d a r d s and p a t i e n t s a m p l e s were m e a s u r e d i n d u p l i c a t e . The unknown c o n c e n t r a t i o n s o f ICG i n p a t i e n t s a m p l e s were d e t e r m i n e d by f i t t i n g t h e a b s o r b a n c e s t o t h e r e g r e s s i o n l i n e o f t h e s t a n d a r d c u r v e . 2.4.3 I n t e r - d a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c A s s a y The i n t e r - d a y r e p r o d u c i b i l i t y o f t h e s p e c t r o p h o t o m e t r i c method was e s t i m a t e d by p r e p a r i n g f o u r s e t s o f ICG s o l u t i o n i n human serum w i t h d i f f e r e n t c o n c e n t r a t i o n s ( 0 . 2 , 0.6, 1.0, 2.0, 3.0 and 5.0 ng/m]) on f o u r c o n s e c u t i v e d a y s . P r e p a r a t i o n o f t h e s a m p l e s was as was o u t l i n e d i n s e c t i o n 2.4.1.2. On t h e d a y o f a n a l y s i s t h e a b s o r b a n c e o f one s e t o f t h e s a m p l e s was m e a s u r e d a g a i n s t a s i m i l a r l y p r e p a r e d s erum b l a n k and t h e c o n c e n t r a t i o n o f ICG d e t e r m i n e d . The p r e c i s i o n o f t h e s p e c t r o p h o t o m e t r i c method was e s t i m a t e d a s t h e r e l a t i v e s t a n d a r d d e v i a t i o n ( c o e f f i c i e n t o f v a r i a t i o n ) . The r e l a t i o n s h i p b e t w e e n t h e a c t u a l and c a l c u l a t e d ICG serum c o n c e n t r a t i o n s was e s t a b l i s h e d by p l o t t i n g t h e mean c a l c u l a t e d ICG c o n c e n t r a t i o n s versus t h e mean a c t u a l ICG c o n c e n t r a t i o n s . 2.4.4. I n t r a - d a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c M e t h o d The i n t r a - d a y p r e c i s i o n o f t h e s p e c t r o p h o t o m e t r i c a s s a y was d e t e r m i n e d by p r e p a r i n g ICG s o l u t i o n s i n human serum w i t h c o n c e n t r a t i o n s o f 0.2, 1.0 and 5.0 fig/m]. P r e p a r a t i o n o f t h e s a m p l e s was t h e same as o u t l i n e d i n S e c t i o n 2 . 4 .2.1. F o u r r e p l i c a t e m e a s u r e m e n t s w e r e p e r f o r m e d f o r e a c h ICG c o n c e n t r a t i o n u s i n g s t a n d a r d s a m p l e s and serum b l a n k as r e f e r e n c e . The c o e f f i c i e n t o f v a r i a t i o n f o r e a c h o f t h e t h r e e ICG c o n c e n t r a t i o n s u s e d was c a l c u l a t e d . 2.5. H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h i c A n a l y s i s o f Unchanged C a p t o p r i l i n Serum B l o o d s a m p l e s (3 ml) w i t h d r a w n f o r t h e measurement o f unchanged c a p t o p r i l w e r e i m m e d i a t e l y m i x e d w i t h 50 //I o f a s o l u t i o n o f EDTA (0.1 M) and a s c o r b i c a c i d (0.1 M) ( J a r r o t t et al. 1 9 8 1 ) . A f t e r c e n t r i f u g a t i o n a t 13000 X g f o r 2 min a 0.5 ml a l i q u o t o f t h e s u p e r n a t a n t was m i x e d w i t h 2 ml o f 0.1 M p h o s p h a t e b u f f e r (pH 7) and 0.2 ml o f t h e d e r i v a t i z i n g a g e n t , NPM. T h i s m i x t u r e was s h a k e n a t room t e m p e r a t u r e f o r 15 min a t !=1400 rpm on a l a b o r a t o r y s h a k e r . S a m p l e s w e r e k e p t f r o z e n a t -20°C and t h e n s e n t p a c k e d i n d r y i c e t o Dr.Y. K. Tam, ( U n i v e r s i t y o f A l b e r t a ) f o r e x t r a c t i o n and a n a l y s i s by a method d e v e l o p e d i n t h e i r l a b o r a t o r y ( P e r e i r a et al. 1 9 8 8 ) . A l l s a m p l e s w e r e p r e p a r e d i n d u p l i c a t e . B l a n k s a m p l e s w e r e w i t h d r a w n p r i o r t o c a p t o p r i l a d m i n i s t r a t i o n and were p r e p a r e d s i m i l a r l y t o t h e s a m p l e s f o l l o w i n g c a p t o p r i l t r e a t m e n t . 2.6. Human S u b j e c t s S e v e n n o n - s m o k i n g m a l e p a t i e n t s ( a g e 42-58 y e a r s , w e i g h t 84-118 kg) w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n ( d i a s t o l i c b l o o d p r e s s u r e >90 mm Hg) gave t h e i r w r i t t e n c o n s e n t p r i o r t o t h e i n i t i a t i o n o f t h e s t u d y . The r e c r u i t m e n t o f t h e p a t i e n t s was made by t h e c o l l a b o r a t i n g p h y s i c i a n ( D r . R.E. R a n g n o ) . The p r o t o c o l and p r o c e d u r e s o f t h e p r e s e n t s t u d y w e r e a p p r o v e d by t h e U n i v e r s i t y Human E t h i c s C o m m i t t e e , U.B.C. and by t h e Human E t h i c s C o m m i t t e e o f S t . P a u l ' s H o s p i t a l . A l l p a t i e n t s were i n s t r u c t e d n o t t o t a k e c a p t o p r i l f o r 1 month o r any o t h e r m e d i c a t i o n f o r a t l e a s t 2 weeks p r i o r t o t h e s t u d y . T h i s was v a l i d a t e d t h r o u g h measurement o f t h e b l a n k s a m p l e . A l l p a t i e n t s w e r e r e q u i r e d t o a b s t a i n f r o m a l c o h o l o r c a f f e i n e f o r a t l e a s t 48 h o u r s p r i o r t o t h e s t u d y . None o f t h e p a t i e n t s had a h i s t o r y o f h e p a t i c o r r e n a l d i s e a s e , o r c a r d i a c d y s f u n c t i o n ( e . g . CHF) and a l l p a t i e n t s had norm a l ECG and b i o c h e m i c a l / h a e m a t o l o g i c a l l a b o r a t o r y r e s u l t s a t t h e t i m e o f t h e s t u d y . P a t i e n t s w e r e p r o h i b i t e d f r o m c o n s u m p t i o n o f f o o d f o r 12 h o u r s p r i o r t o t h e s t u d y and d u r i n g e a c h s t u d y d a y , b u t were a l l o w e d t o d r i n k w a t e r ( S p r i n g Water'^) a n d / o r a p p l e j u i c e ( u n s w e e t e n e d and w i t h o u t p r e s e r v a t i v e s ) ad libitum. Room t e m p e r a t u r e was m a i n t a i n e d a t 24°C and body t e m p e r a t u r e s were r e c o r d e d t w i c e a f t e r a r r i v a l t o t h e h o s p i t a l and 1 h o u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n d u r i n g e a c h s t u d y d a y . 2.7. S t u d y P r o t o c o l Scheme 1 shows a s y n o p s i s o f t h e s t u d y p r o t o c o l . T h e r e were two s t u d y d a y s two-weeks a p a r t . D u r i n g b o t h s t u d y d a y s ( d a y 1 and d a y 14) t h e p a t i e n t was g i v e n i n d o c y a n i n e g r e e n (CARDIO-GREEN'^, 0.45 mg/kg i . v . b o l u s ) f o u r t i m e s i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and a f t e r t h e 100 mg o r a l d o s e o f c a p t o p r i l ( C A ) . D u r i n g t h e two-weeks c a p t o p r i l t r e a t m e n t p e r i o d b e t w e e n t h e s t u d y d a y s , t h e p a t i e n t s r e c e i v e d 100 mg c a p t o p r i l ( 2 CAPOTEN'^ 50 mg t a b l e t s ) once d a i l y . The s e c o n d l a s t d o s e was t a k e n a b o u t 20 h o u r s b e f o r e t h e b a s e l i n e m e a s u r e m e n t s o f t h e s e c o n d s t u d y d a y were p e r f o r m e d . B l o o d p r e s s u r e s and h e a r t r a t e were r e c o r d e d p r i o r t o and f o l l o w i n g t h e i n j e c t i o n o f ICG and a f t e r c a p t o p r i l d o s i n g . The p r o c e d u r e s and s t u d y c o n d i t i o n s o f day 1 were r e p e a t e d on d a y 14. D u r i n g t h e e n t i r e s t u d y p e r i o d a l l p a t i e n t s were u n d e r t h e s u p e r v i s i o n o f Dr. R. E. Rangno ( D i v i s i o n o f C l i n i c a l P h a r m a c o l o g y , S t . P a u l ' s H o s p i t a l ) . 2.7.1. Dye and Drug A d m i n i s t r a t i o n , B l o o d Sample C o l l e c t i o n Scheme 2 shows t h e d e t a i l e d s t u d y p r o t o c o l o f d a y s 1 and 14. On e a c h s t u d y d a y an i n d w e l l i n g t e f l o n c a t h e t e r was p l a c e d i n a l a r g e f o r e a r m v e i n o f t h e p a t i e n t . A t h r e e - w a y s t o p c o c k was a t t a c h e d t o f a c i l i t a t e b l o o d s a m p l i n g and d r u g a d m i n i s t r a t i o n . B l a n k b l o o d s a m p l e s were c o l l e c t e d p r i o r t o t h e f i r s t i . v . i n j e c t i o n o f ICG. The p a t e n c y o f t h e c a t h e t e r and b l o o d s i up s2 ICG ICG ICG ICG CA s i ICG X Î, Î, up s2 CA ICG ICG ICG ca ca DAY1 Blank DAY2 .... DAY13 CA TREATMENT 100 mg P.O. daily DAY14 Blood samples collected for ICG and CA analysis Blood samples collected for ICG and CA analysis Abbreviations: ca captopril ICG indocyanine green s i first seated up upright s2 reseated CA post-CA Scheme 1. S t u d y p r o t o c o l . ICG 0.4 5 m g/kg i . v . d o s e A r r i v a l to h o s p i t a l - 6 0 m i n -ICG 0 . 4 5 mg/kg i . v . d o s e ICG 0 . 4 5 m g/kg i . v . d o s e P a t i e n t s t a n d s up 62 66 70 - 6 0 m i n -P a t i e n t s i t s d o w n 136 140 144 I I I I 1 I - 6 0 m i n -C A lOOmg o r a l d o s e P a t i e n t M i l l I C G 0 . 4 5mg/kg i . v . d o s e r e m a i n s s i t t i n g , ^ 1 0 214 218 22 2, ,298, ,3 30 334 338 342 388 448 1 I I I 1 I I I 1 0 m i n u t e s 60 64 68 7 2 7 4 134 138 142 1 4 6 1 4 8 208 212 2 1 6 2 2 0 268 3 2 8 3 3 2 3 3 6 3 4 0 358 411 A A T T o , . J h e m a t o c r i t B l a n k b l o o d s a m p l i n g B l o o d p r e s s u r e H e a r t ra te h e m a t o c r i t h e m a t o c r i t 0 t i m e b l o o d s a m p l i n g for CA L e g e n d : I b l o o d s a m p l i n g for I C G , 0 t i m e b l o o d s a m p l i n g for I C G , ^ b l o o d s a m p l i n g for CA Scheme 2. D e t a i l e d s t u d y p r o t o c o l . s a m p l i n g d e v i c e was m a i n t a i n e d d u r i n g t h e e x p e r i m e n t by u s i n g h e p a r i n i z e d s a l i n e ( 5 0 U/ml) t o f l u s h t h e c a t h e t e r . To m i n i m i z e a l t e r a t i o n s i n h e p a t i c b l o o d f l o w c a u s e d by p o s t u r a l c h a n g e s a l l p a t i e n t s were r e q u i r e d t o r e m a i n s e a t e d f o r a minimum o f 6 0 m i n u t e s p r i o r t o t h e i n j e c t i o n o f ICG e x c e p t when ICG was i n j e c t e d t o e s t i m a t e h e p a t i c b l o o d f l o w d u r i n g t h e u p r i g h t p o s i t i o n . The s t e r i l e ICG s o l u t i o n (CARDIO-GREEN'^) f o r i n t r a v e n o u s i n j e c t i o n was p r e p a r e d i m m e d i a t e l y p r i o r t o i n j e c t i o n by a d d i n g t h e s u p p l i e d aqueous s o l v e n t ( 1 0 m l ) t o t h e s t e r i l e ICG powder. Each p a t i e n t r e c e i v e d t h e same ICG d o s e on day 1 and d a y 14. The 0.45 mg/kg ICG d o s e was g i v e n as an i . v . b o l u s o v e r 1 5 s e c o n d s . B l o o d s a m p l e s ( 7 ml) were drawn f r o m t h e c a t h e t e r , a f t e r t h e r e m o v a l o f h e p a r i n i z e d s a l i n e , i n t o V a c u t a i n e r * ^ t u b e s a t - 2 , 2, 4, 6, 8, 10 , 1 2 , 14 m i n u t e s f o l l o w i n g t h e i n j e c t i o n o f ICG . A f t e r t h e i . v . i n j e c t i o n o f ICG t h e s t o p - c o c k was t h o r o u g h l y r i n s e d w i t h a b o u t 20 ml o f norm a l s a l i n e o r g l u c o s e ( 2 0 % ) . B l o o d s a m p l e s were a l l o w e d t o c l o t a t room t e m p e r a t u r e and serum was s e p a r a t e d by c e n t r i f u g a t i o n a t 3 0 0 0 rpm f o r 30 m i n u t e s a t 4''C. The serum was t r a n s f e r r e d i n t o amber g l a s s v i a l s w i t h t e f l o n l i n e d s c r e w c a p s and k e p t f r o z e n a t - 2 0 ° C u n t i l a n a l y s i s (maximum o f 36 h o u r s ) . The 100 mg c a p t o p r i l d o s e was t a k e n w i t h a b o u t 2 0 0 ml w a t e r . B l o o d s a m p l e s ( 3 m l ) f o r t h e c a p t o p r i l a n a l y s i s w e r e drawn f r o m t h e c a t h e t e r , f o l l o w i n g t h e r e m o v a l o f h e p a r i n i z e d s a l i n e , i n t o s t e r i l e , d i s p o s a b l e s y r i n g e s a t - 5 , 3 0 , 6 0 , 9 0 , 1 2 0 , 1 5 0 , 180 m i n u t e s f o l l o w i n g t h e a d m i n i s t r a t i o n o f c a p t o p r i l . B l o o d s a m p l e s (~ 1.5 m l ) wer e i m m e d i a t e l y t r a n s f e r r e d i n t o two 1.5 ml Eppendorf'^ v i a l s c o n t a i n i n g t h e 5 0 / i l m i x t u r e o f EDTA ( 0 . 1 M) and a s c o r b i c a c i d ( 0 . 1 M). A f t e r c e n t r i f u g a t i o n a t 1 3 0 0 0 g f o r 2 m i n u t e s t h e s u p e r n a t a n t was p r o c e s s e d as o u t l i n e d i n S e c t i o n 2.5. Serum s a m p l e s f o r c a p t o p r i l measurement were k e p t f r o z e n (-20°C) i n p o l y p r o p y l e n e t u b e s u n t i l a n a l y s i s . In a d d i t i o n , b l o o d s a m p l e s ( 2 ml) were drawn i n t o V a c u t a i n e r ' ^ t u b e s c o n t a i n i n g l i t h i u m h e p a r i n and t h e h e m a t o c r i t was me a s u r e d a t t h e t i m e i n d i c a t e d i n Scheme 2. 2.7.2. B l o o d P r e s s u r e and H e a r t R a t e M e a s u r e m e n t B a s e l i n e b l o o d p r e s s u r e s and h e a r t r a t e w e r e m e a s u r e d a t t h e b e g i n n i n g o f e a c h s t u d y d a y a f t e r t h e p a t i e n t s w e r e s e a t e d p o s i t i o n f o r ~ 60 m i n u t e s . F o u r t o s i x b l o o d p r e s s u r e and h e a r t r a t e r e c o r d i n g s were p e r f o r m e d a t 2 m i n u t e i n t e r v a l s b e f o r e and f o l l o w i n g t h e i n j e c t i o n s o f ICG. S u b s e q u e n t t o t h e a d m i n i s t r a t i o n o f c a p t o p r i l , b l o o d p r e s s u r e and h e a r t r a t e m e a surements w e r e made a t 10 m i n u t e i n t e r v a l s u n t i l t h e end o f t h e s t u d y d a y . E x c e p t d u r i n g t h e u p r i g h t p o s i t i o n , b l o o d p r e s s u r e and h e a r t r a t e w e r e m e a s u r e d i n t h e s e a t e d p o s i t i o n . 2.8. D a t a A n a l y s i s 2.8.1. K i n e t i c P a r a m e t e r s o f ICG and L i v e r B l o o d F l o w The serum c o n c e n t r a t i o n versus t i m e d a t a o f ICG we r e f i t t o a c o m p a r t m e n t a l p h a r m a c o k i n e t i c model u s i n g t h e c o m p u t e r programme AUTOAN (Sedman and Wagner, 1 9 7 8 ) . The e s t i m a t e d e l i m i n a t i o n r a t e c o n s t a n t (K^) and t h e e s t i m a t e d z e r o t i m e serum c o n c e n t r a t i o n o f ICG were u s e d f o r t h e c a l c u l a t i o n o f t h e k i n e t i c p a r a m e t e r s o f ICG. F o r m u l a e u s e d i n t h e p h a r m a c o k i n e t i c p a r a m e t e r c a l c u l a t i o n were o b t a i n e d f r o m G i b a l d i and P e r r i e r ( 1 9 7 5 ) . The a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e f r o m t i m e z e r o t o i n f i n i t y (AUCQ") was c a l c u l a t e d by u s i n g t h e t r a p e z o i d a l a p p r o x i m a t i o n and t h e f o l l o w i n g e q u a t i o n : AUCQ" = AUCQ^ + AUC^* ( 1 ) w h e r e AUCQ* i s t h e a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e f r o m z e r o t o t h e l a s t drawn s a m p l e . AUC^" was c a l c u l a t e d by d i v i d i n g t h e l a s t ICG s e r u m c o n c e n t r a t i o n (Cp) d a t a by K^. The a p p a r e n t e l i m i n a t i o n h a l f - l i f e ( t i / 2 ) ^ ^ s c a l c u l a t e d by d i v i d i n g 0.693 by K^. The p l a s m a c l e a r a n c e ( C l p j Q g ) was o b t a i n e d by t h e f o l l o w i n g e q u a t i o n : DOSE AUCQ L i v e r b l o o d f l o w (Qy) was e s t i m a t e d a s : ^ ^ I C G QH = ( 3 ) EH ( 1 - H c t ) w h e r e Ey i s t h e h e p a t i c e x t r a c t i o n r a t i o ( a s s u m e d t o be 1) and H c t i s t h e m e a s u r e d h e m a t o c r i t . P e a k u n c h a n g e d c a p t o p r i l s erum c o n c e n t r a t i o n ( C ^ ^ ^ ) and t h e t i m e o f maximum c a p t o p r i l c o n c e n t r a t i o n ( t j ^ ^ ^ j were o b t a i n e d f r o m e a c h p a t i e n t ' s s erum d a t a . 2.8.2. P h y s i o l o g i c a l C a l c u l a t i o n s Mean a r t e r i a l p r e s s u r e (MAP) was c a l c u l a t e d by t h e a u t o m a t e d d e v i c e a s : S y s t o l i c BP + 2 ( D i a s t o l i c BP) MAP = (4) Body s u r f a c e a r e a (BSA) o f e a c h p a t i e n t was c a l c u l a t e d f r o m t h e f o r m u l a o f D u b o i s and D u b o i s ( 1 9 1 5 ) : BSA = W °-425 * H 0.725 * 71^4 c o n s t a n t ) (5) w h e r e BSA i s t h e body s u r f a c e a r e a i n cm^, W i s t h e body w e i g h t i n k i l o g r a m s , and H i s t h e h e i g h t i n cm. S p l a n c h n i c v a s c u l a r r e s i s t a n c e (SVR) was c a l c u l a t e d as f o l l o w s : MAP SVR = (6) QH w h e r e MAP i s t h e mean a r t e r i a l p r e s s u r e i n mm Hg, i s t h e e s t i m a t e d l i v e r b l o o d f l o w i n m l / s e c . The s t u d y p r o t o c o l was d e s i g n e d so t h a t e a c h p a t i e n t s e r v e d as h i s own c o n t r o l . The p e r c e n t c h a n g e (% c h a n g e ) i n t r e a t e d v a l u e (T) f r o m t h e a p p r o p r i a t e b a s e l i n e (B) was c a l c u l a t e d as f o l l o w s : T - B % change= x 100 (7) B The p e r c e n t c h a n g e (% c h a n g e ) i n t h e a b s o l u t e d e c r e a s e i n t r e a t e d v a l u e (T) f r o m b a s e l i n e (B) on d a y 1 and d a y 14 was c a l c u l a t e d by t h e f o l l o w i n g e q u a t i o n : (Day 14 B - Day 14 T) - (Day 1 B - Day 1 T) % change= x 100 (8) (Day 1 B - Day 1 T) 2.8.3. S t a t i s t i c a l A n a l y s e s S t a t i s t i c a l c o m p a r i s o n s w e r e made by m u l t i v a r i a t e a n a l y s i s o f v a r i a n c e (MANOVA) w i t h r e p e a t e d m e a s u r e s u s i n g t h e S o f t w a r e P a c k a g e f o r S o c i a l S c i e n c e s c o m p u t e r p r o g r a m (SPSS-X, SPSS I n c . , C h i c a g o , I l l i n o i s , U.S.A.), a n a l y s i s o f v a r i a n c e (ANOVA) and t w o - t a i l e d o r o n e - t a i l e d p a i r e d s a m p l e t-t e s t , w h e r e a p p r o p r i a t e . The l e v e l o f s i g n i f i c a n c e c h o s e n f o r a l l s t a t i s t i c a l a n a l y s e s was a = 0.05. 3. RESULTS 3.1. S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n ( I C G ) 3.1.1. S t a b i l i t y o f ICG i n D i s t i l l e d W a t e r In vitro s t u d i e s p r e v i o u s l y d e m o n s t r a t e d t h e i n s t a b i l i t y o f ICG i n d i s t i l l e d w a t e r ( G a t h j e et. al. 1 9 7 0 ) . I n o u r e x p e r i m e n t s t h e UV a b s o r p t i o n o f ICG, m e a s u r e d a t 778 nm d e c r e a s e d by 23 % d u r i n g t h e f i r s t 7 h o u r s a f t e r p r e p a r a t i o n and by 63 % by t h e end o f 24 h o u r s , i n d i c a t i n g s i g n i f i c a n t i n s t a b i l i t y i n w a t e r . The r a t e o f d e c l i n e was a p p a r e n t l y f a s t e r d u r i n g t h e f i r s t 7 h o u r s t h a n b e t w e e n 7-24 h o u r s . 3.1.2. S t a b i l i t y o f ICG i n Human Serum The s t a b i l i t y o f ICG i n human serum i n l o w ( 0 . 2 /zg/ml ) and h i g h (6.0 /ig/ml) c o n c e n t r a t i o n s was d e t e r m i n e d by m e a s u r i n g t h e c h a n g e i n c o n c e n t r a t i o n as a f u n c t i o n o f t i m e . The a b s o r b a n c e was m e a s u r e d a t 806 nm. The r e s u l t s a r e shown i n F i g u r e 3. The b e s t f i t t h r o u g h t h e d a t a p o i n t s was o b t a i n e d by l i n e a r r e g r e s s i o n and was d e s c r i b e d by Y = 0.00003X + 0.197 f o r t h e 0.2 /ig/ml and Y = - 0.0005X + 5.772 f o r t h e 6.0 /tg/ml ICG c o n c e n t r a t i o n . The p v a l u e s o f t h e two r e g r e s s i o n l i n e s w ere l a r g e r t h a n 0.25 s u g g e s t i n g t h a t t h e s l o p e s were n o t s i g n i f i c a n t l y d i f f e r e n t f r o m z e r o and t h e ICG c o n c e n t r a t i o n s were s t a b l e w i t h t i m e i n serum (ANOVA) u n l i k e i n d i s t i l l e d w a t e r . The mean (± SD, n=7) ICG c o n c e n t r a t i o n s were f o u n d t o be 0.197 ± 0.025 and 5.762 ± 0.225 /ig/ml f o r t h e 0.2 and 6.0 /ig/ml ICG s e r u m s o l u t i o n s , r e s p e c t i v e l y . The c o e f f i c i e n t s o f v a r i a t i o n w e r e 1 2 . 8 % and 3.8% f o r t h e l o w 8 T Y = - 0 . 0 0 0 5 X + 5 . 7 7 2 6.0 / i , g / m l 6 i 4 + 2 + Y = 0 . 0 0 0 0 3 X + 0 . 1 9 7 0.2 y u g / m l 0 ^ o •o- o-- 2 0 8 1 6 2 4 3 2 T i m e ( h o u r s ) 4 0 4 8 5 6 F i g u r e 3. S t a b i l i t y t e s t o f ICG i n human serum a t h i g h ( 6.0 liq/m^) and l o w (0.2 /xg/ml) c o n c e n t r a t i o n s . and h i g h ICG c o n c e n t r a t i o n s , r e s p e c t i v e l y . The s l o p e s o f t h e two r e g r e s s i o n l i n e s w ere 0.00003 and - 0.0005 (/ig/ml/hour) f o r ICG c o n c e n t r a t i o n s 0.2 and 6.0 / i g / m l , r e s p e c t i v e l y . T h e s e r e s u l t s i n d i c a t e t h a t ICG s a m p l e s p r e p a r e d i n human serum were s t a b l e f o r 48 h o u r s w i t h o u t any s i g n i f i c a n t d e c l i n e i n ICG c o n c e n t r a t i o n when s t o r e d a t -20''C. 3.1.3. R e p r o d u c i b i l i t y o f S t a n d a r d C u r v e s The d a y t o d a y r e p r o d u c i b i l i t y o f t h e s t a n d a r d c u r v e s u s e d f o r t h e q u a n t i t a t i o n o f ICG i n serum d u r i n g t h e s t a b i l i t y t e s t i s i l l u s t r a t e d i n F i g u r e 4. I n t h i s f i g u r e , t h e s l o p e s o f t h e s e v e n s t a n d a r d c u r v e s (0.2 -6.0 /ig/ml) w e r e p l o t t e d a g a i n s t t h e t i m e o f t h e i r p r e p a r a t i o n . The l i n e a r r e g r e s s i o n l i n e f i t t e d t h r o u g h t h e d a t a p o i n t s i s d e s c r i b e d by Y = -0.0002 + 1.007. The s i g n i f i c a n c e o f r e g r e s s i o n was t e s t e d by ANOVA and t h e p v a l u e was f o u n d t o be l a r g e r t h a n 0.25 s u g g e s t i n g t h a t t h e s l o p e s do n o t change w i t h t i m e . The c o e f f i c i e n t s o f v a r i a t i o n f o r t h e s l o p e s was f o u n d t o be 1.6%. The a b s o r b a n c e s p e c t r a o f t h e s t a n d a r d c u r v e s a m p l e s o f ICG i n serum, i n t h e c o n c e n t r a t i o n r a n g e f r o m 0.2-6.0 /zg/ml a r e shown i n F i g u r e 5. 3.1.4. S t a n d a r d C u r v e s f o r t h e Q u a n t i t a t i o n o f ICG i n P a t i e n t S a m p l e s T a b l e 1 p r e s e n t s t h e d a t a o f a r e p r e s e n t a t i v e s t a n d a r d c u r v e u s e d f o r t h e q u a n t i t a t i o n o f ICG i n p a t i e n t s a m p l e s . The r e l a t i o n s h i p between a b s o r b a n c e and c o n c e n t r a t i o n o f ICG was l i n e a r i n t h e r a n g e o f 0.2-5.0 /ig/ml w i t h a c o r r e l a t i o n c o e f f i c i e n t o f r ^ = 0.999 ( F i g u r e 6 ) . C o e f f i c i e n t s o f v a r i a t i o n w e r e l e s s t h a n 10% f o r a l l c o n c e n t r a t i o n s . The Y - i n t e r c e p t was l e s s t h a n 1 0 % o f t h e h i g h e s t a b s o r b a n c e . 1 . 1 0 0 r 1 . 0 5 0 in 1 . 0 0 0 - e - o o s l o p e = - 0 . 0 0 0 2 O O O 0 . 9 5 0 0 . 9 0 0 0 8 - j I - - - I -1 6 2 4 3 2 4 0 4 8 T i m e ( h o u r s ) F i g u r e 4. V a r i a b i l i t y i n t h e s l o p e s o f t h e r e g r e s s i o n l i n e s o f s t a n d a r d c u r v e s u s e d i n t h e s t a b i l i t y t e s t o f ICG i n human serum. 1.8681 -1.3128-Overlay spectrun of ICG standards / >^  LU 3= ex ÛD c:-0.95757-rj.2-*706- / — " • • -.10319 -too 500 600 U p V E L E H G T H 700 800 F i g u r e 5. S p e c t r o p h o t o m e t r i c s c a n s o f ICG s t a n d a r d s a m p l e s i n human serum. C o n c e n t r a t i o n r a n g e f r o m 0.2 t o 5.0 / i g / m l . T a b l e 1. S t a n d a r d c u r v e d a t a o f ICG f o r p a t i e n t serum s a m p l e s Number o f s a m p l e s , n = 4 C o n c e n t r a t i o n A b s o r b a n c e C o e f f i c i e n t o f o f ICG (Mg/ml) (mean ± SD) v a r i a t i o n % 0.2 0.0592 ± 0.002 3.6 0.6 0.1660 ± 0.003 1.8 1.0 0.2820 ± 0.007 2.6 2.0 0.5823 ± 0.011 1.9 3.0 0.8910 ± 0.016 1.8 5.0 1.4873 ± 0.009 0.6 L i n e a r r e g r e s s i o n : Y = 0.300X - 0.013 r ^ = 0.999 1.600T 0 1 2 3 4 5 ICG concentration (//.g/ml) F i g u r e 6. R e p r e s e n t a t i v e s t a n d a r d c u r v e i n t h e c o n c e n t r a t i o n r a n g e f r o m t o 5.0 /ig/ml ( n=4). 3.1.5. I n t e r - D a y and I n t r a - D a y R e p r o d u c i b i l i t y o f t h e S p e c t r o p h o t o m e t r i c M e t h o d F i g u r e 7 shows t h a t t h e r e i s a l i n e a r r e l a t i o n s h i p b e t w e e n t h e mean (± SD, n=4) f o u n d and a c t u a l ICG c o n c e n t r a t i o n s w i t h a c o r r e l a t i o n c o e f f i c i e n t r ^ = 0.999. T a b l e 2 p r e s e n t s t h e r e s u l t s o f t h e i n t e r - d a y r e c o v e r y o f ICG and t h e c o e f f i c i e n t s o f v a r i a t i o n i n ICG c o n c e n t r a t i o n s . The r e c o v e r y o f ICG was f o u n d t o be b e t w e e n 93.3 and 102.7%. The h i g h e s t c o e f f i c i e n t o f v a r i a t i o n ( 9 . 8 %) was f o u n d f o r t h e ICG c o n c e n t r a t i o n o f 0.2 /zg/ml. S i m i l a r l y , t h e i n t r a - d a y c o e f f i c i e n t s o f v a r i a t i o n f o r ICG c o n c e n t r a t i o n s 0.2, 1.0 and 5.0 jiig/ml w e r e 8.4%, 4.9% and 2.1%, r e s p e c t i v e l y . 3.2. Human S u b j e c t s T a b l e 3 shows t h e c h a r a c t e r i s t i c s o f human s u b j e c t s who p a r t i c i p a t e d i n t h e s t u d y . The c o e f f i c i e n t s o f v a r i a t i o n f o r t h e age, body w e i g h t and body s u r f a c e a r e a w e r e 13.6%, 1 2 . 6 % and 4.5%, r e s p e c t i v e l y . The c o e f f i c i e n t s o f v a r i a t i o n f o r t h e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e 8.4 and 2.2 mm Hg, r e s p e c t i v e l y . One p a t i e n t (R.S.) was w i t h d r a w n a f t e r t h e f i r s t s t u d y d a y due t o h i s l o w h e m a t o c r i t , C a p t o p r i l was w e l l t o l e r a t e d i n t h e p a t i e n t s s t u d i e d . A m i l d i r r i t a t i n g s e n s a t i o n i n t h e t h r o a t d e v e l o p e d i n one p a t i e n t a f t e r 7 d a y s o f t r e a t m e n t w i t h c a p t o p r i l , b u t i t d i d n o t r e q u i r e a s t o p p a g e i n t h e r a p y . H y p o t e n s i o n w i t h o u t any symptoms was o b s e r v e d i n one p a t i e n t a f t e r t h e f i r s t d o s e o f c a p t o p r i l , b u t r e s o l v e d w i t h o u t d i s c o n t i n u a t i o n o f t h e d r u g . Body t e m p e r a t u r e s were i n t h e r a n g e f r o m 35.8 t o 36.7°C. Linear regression: Y = 1.01 IX - 0.041 ACTUAL ICG CONCENTRATION /^g/ml F i g u r e 7. R e l a t i o n s h i p between t h e a c t u a l and f o u n d ICG c o n c e n t r a t i o n s . D a t a a r e p r e s e n t e d as mean ± SD, n=4. T a b l e 2. R e s u l t s o f t h e i n t e r - d a y r e p r o d u c i b i l i t y t e s t o f t h e s p e c t r o p h o t o m e t r i c method f o r m e a s u r i n g ICG i n human serum. A c t u a l Found R e c o v e r y ^ C o e f f i c i e n t s o f ICG c o n e . ICG c o n e . v a r i a t i o n /ig/ml /ig/ml ( % ) ( % ) (mean ± SD, n = 4) 0.2 0.205 ± 0.020 102.7 + 10.1 9.8 0.6 0.592 + 0.017 98.6 ± 2.8 2.9 1.0 1.002 ± 0.031 100.2 ± 3.1 3.1 2.0 1.866 + 0.088 93.3 + 4.4 4.7 3.0 2.952 + 0.087 98.4 + 2.9 3.0 5.0 5.074 + 0.082 101.5 + 1.6 1.6 L i n e a r r e g r e s s i o n : Y = l . O l l X - 0.041 r"^ = 0.999 SD s t a n d a r d d e v i a t i o n ^ C a l c u l a t e d f r o m t h e r a t i o o f f o u n d and a c t u a l ICG c o n c e n t r a t i o n m u l t i p l y i n g by 100 T a b l e 3. C h a r a c t e r i s t i c s o f Human S u b j e c t s . P a t i e n t Age BW H e i g h t BSA BP B a s e l i n e ( y e a r s ) ( k g ) (cm) (m2) (mm Hg) H e m a t o c r i t OW 52 93 179 2.1 182 / 103 0.43 MO 44 119 188 2.4 162 / 102 0.44 MS 42 96 185 2.2 145 / 104 0.46 BH 58 92 173 2.1 152 / 104 0.50 DA 55 85 188 2.1 155 / 107 0.47 CB 58 84 173 2.0 168 / 100 0.41 RS^ 44 101 180 2.1 143 / 102 0.38 Mean 51.5 95 181 2.2 160 / 103 ± SD: ± 7.0 + 12 ± 7 ± 0.1 ± 13.5 / ± 2.3 C.V.% 13.6 12.6 3.9 4.5 8.4 / 2.2 BW body w e i g h t BSA body s u r f a c e a r e a BP p r e t r e a t m e n t b l o o d p r e s s u r e SD s t a n d a r d d e v i a t i o n C.V. c o e f f i c i e n t o f v a r i a t i o n P a t i e n t was w i t h d r a w n a f t e r d a y 1; d a t a a r e e x c l u d e d f r o m t h e c a l c u l a t i o n o f mean v a l u e s 3.3. Changes i n t h e K i n e t i c P a r a m e t e r s o f ICG 3.3.1. Serum C o n c e n t r a t i o n D a t a o f I n d o c y a n i n e G r e e n R e p r e s e n t a t i v e s e m i - l o g a r i t h m i c p l o t s o f t h e serum c o n c e n t r a t i o n versus t i m e c u r v e s o f ICG o b t a i n e d f r o m a p a t i e n t on d a y 1 and d a y 14 a r e shown i n F i g u r e 8. The s e m i - l o g a r i t h m i c p l o t s o f t h e serum c o n c e n t r a t i o n versus t i m e c u r v e s f r o m f i v e p a t i e n t s a r e shown i n A p p e n d i x 1. The f o u r c u r v e s o f e a c h g r a p h r e p r e s e n t t h e f o u r p h a s e s o f d a y 1 and 14, s u c h as s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and a f t e r c a p t o p r i l d o s i n g ( C A ) . F o r d e s c r i b i n g t h e c h a n g e s i n ICG serum c o n c e n t r a t i o n s w i t h t i m e a f t e r i . v . d o s e s o f 0.45 mg/kg o f ICG a one co m p a r t m e n t model was u s e d as d e t e r m i n e d by AUTOAN. The m o n o e x p o n e n t i a l e q u a t i o n w h i c h d e s c r i b e s t h e d i s p o s i t i o n o f ICG i n s e r u m was as f o l l o w s : C p ( t ) = C p ( 0 ) e - V w h e r e C p ( t ) and C p ( 0 ) a r e t h e serum c o n c e n t r a t i o n s o f ICG a t t i m e t and t i m e z e r o , r e s p e c t i v e l y and K^ i s t h e e l i m i n a t i o n r a t e c o n s t a n t . In some i n s t a n c e s , t h e d e c a y o f ICG serum l e v e l s was b e t t e r f i t t o a two- c o m p a r t m e n t model s u g g e s t i n g an i n i t i a l d i s t r i b u t i o n p h a s e o f ICG a f t e r i . v . a d m i n i s t r a t i o n . 3.3.2. K i n e t i c P a r a m e t e r s o f ICG (ti/2» AUCg" and C l p j ^ Q ) The e l i m i n a t i o n h a l f - l i f e ( t 2 / 2 ) o f ICG has been f o u n d t o be 4.03 ± 0.68 F i g u r e 8. R e p r e s e n t a t i v e serum c o n c e n t r a t i o n versus t i m e c u r v e o f ICG o b t a i n e d i n a p a t i e n t on day I and d a y 14 i n s e a t e d ( o p e n c i r c l e ) , u p r i g h t ( c l o s e d c i r c l e ) , r e s e a t e d (open t r i a n g l e ) p o s i t i o n s and 1 h o u r a f t e r c a p t o p r i l ( c l o s e d t r i a n g l e s ) . m i n u t e s (mean ± SD, n = 2 4 ) , on day 1 and 3.98 ± 0.52 m i n u t e s (mean ± SD, n = 2 4 ) , on d a y 14. The t o t a l a r e a u n d e r t h e serum c o n c e n t r a t i o n vs t i m e c u r v e (AUCQ°°, r e f e r r e d t o as AUC i n t h e t e x t ) and p l a s m a c l e a r a n c e ( C l p j ^ g ) d a t a o f ICG f o r t h e s i x p a t i e n t s b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t on d a y 1 and 14 a r e shown i n T a b l e 4 and T a b l e 5, r e s p e c t i v e l y . I n t h e s e t a b l e s , t h e a b s o l u t e and p e r c e n t a g e d i f f e r e n c e s f r o m b a s e l i n e ( s i ) v a l u e s d u r i n g u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and 1 h o u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n (CA) f o r t h e s i x p a t i e n t s , on day 1 and 14 a r e a l s o p r e s e n t e d . The a b s o l u t e and p e r c e n t a g e d i f f e r e n c e s f r o m r e s e a t e d ( s 2 ) v a l u e s a f t e r c a p t o p r i l d o s i n g (CA) a r e shown i n t h e l a s t c o l u m n s o f t h e t a b l e s . I n a d d i t i o n , t h e l a s t p a r t s o f T a b l e 4 and T a b l e 5 show t h e s h o r t - t e r m e f f e c t s o f c a p t o p r i l on AUC and C l p j Q Q , r e s p e c t i v e l y , f o r t h e s i x p a t i e n t s , c a l c u l a t e d as t h e a b s o l u t e and p e r c e n t a g e d i f f e r e n c e s f r o m da y 1 d a t a . F i g u r e 9 i l l u s t r a t e s t h e c h a n g e s i n C l p j Q g , e x p r e s s e d i n a b s o l u t e t e r m s and p e r u n i t body w e i g h t and body s u r f a c e a r e a , f o r t h e s i x p a t i e n t s d u r i n g t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) s t u d y p h a s e s , on d a y 1 and 14. D a t a o f C l p j Q Q n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a a r e p r e s e n t e d i n A p p e n d i x 2. 3 . 3.2.1. E f f e c t s o f P o s t u r a l Change on AUC and C l p j Q g B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t The r e s u l t s o f t h e c o m p a r i s o n s o f mean (± SEM, n=6) AUC and C l p j Q Q d a t a d u r i n g p o s t u r a l c h a n g e f r o m s e a t e d ( s i ) t o u p r i g h t (up) and r e s e a t e d ( s 2 ) p o s i t i o n s b e f o r e and a f t e r t h e a d m i n i s t r a t i o n o f c a p t o p r i l on d a y 1 and 14 a r e shown on T a b l e 6. S t a t i s t i c a l c o m p a r i s o n s were n o t p e r f o r m e d f o r t h e T a b l e 4. Changes i n AUCg" o f ICG b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s D A Y 1 AUCQ" ( m i n - / i g / m l ) D i f f e r e n c e f r o m s i D i f f e r e n c e P a t i e n t f r o m s2 s i up s2 CA up s2 CA CA MO 65.9 92.1 68.2 57.3 26.2 . 39.8%1 2.3 3.5% -8.6 - 1 3 . 0 % -10.9 - 1 6 . 0 % OW 71.3 85.3 74.3 78.7 14.0 1 9 . 6 % 3.0 4.2% 7.4 1 0 . 4 % 4.4 5.9% MS 57.3 77.2 74.8 73.5 19.9 3 4 . 7 % 17.5 3 0 . 6 % 16.2 2 8 . 3 % -1.3 - 1 . 8 % BH 84.7 119.2 100.2 106.9 34.5 4 0 . 7 % 15.5 1 8 . 3 % 22.2 2 6 . 2 % 6.7 6.7% DA 67.4 98.6 64.3 80.4 31.2 4 6 . 2 % -3.1 - 4 . 6 % 13.0 1 9 . 2 % 16.1 2 5 . 0 % CB 65.6 79.5 55.7 72.5 13.9 2 1 . 2 % -9.9 - 1 5 . 1 % 6.9 1 0 . 5 % 16.8 3 0 . 3 % D A Y 1 4 AUCQ" ( m i n - / i g / m l ) D i f f e r e n c e f r o m s i D i f f e r e n c e P a t i e n t f r o m s2 s i up s2 CA up s2 CA CA MO 48.5 59.5 57.6 54.7 11.1 9.2 6.2 -2.9 2 2 . 9 % 1 8 . 9 % 1 2 . 9 % - 5 . 1 % OW 42.6 65.0 47.5 55.3 22.3 4.8 12.7 7.8 5 2 . 3 % 1 1 . 4 % 2 9 . 7 % 1 6 . 5 % MS 45.4 58.5 49.1 61.3 13.1 3.7 15.9 12.1 2 8 . 8 % 8.2% 3 5 . 0 % 2 4 . 7 % BH 68.7 104.4 94.6 80.6 35.7 25.9 11.9 -14.0 5 1 . 9 % 3 7 . 7 % 1 7 . 3 % - 1 4 . 8 % DA 61.1 69.3 45.2 46.0 8.2 -15.9 -15.2 0.7 1 3 . 4 % - 2 6 . 0 % - 2 4 . 8 % 1.6% CB 62.6 102.3 77.5 81.8 39.8 14.9 19.3 4.3 6 3 . 6 % 2 3 . 9 % 3 0 . 8 % 5.6% T a b l e 4. C o n t ' d D A Y 1 4 D I F F E R E N C E F R O M D A Y 1 P a t i e n t AUCQ"" (min •/zg/ml) s i up s2 CA MO -17.4 -32.5 -10.5 -2.6 - 2 6 . 4 % - 3 5 . 3 % - 1 5 . 5 % - 4 . 5 % OW -28.7 -20.4 -26.8 -23.4 - 4 0 . 2 % - 2 3 . 9 % - 3 6 . 1 % - 2 9 . 7 % MS -11.9 -18.7 -25.7 -12.2 - 2 0 . 8 % - 2 4 . 3 % - 3 4 . 3 % - 1 6 . 7 % BH -16.0 -14.8 -5.6 -26.3 - 1 8 . 9 % - 1 2 . 4 % - 5 . 6 % - 2 4 . 6 % DA -6.3 -29.3 -19.1 -34.5 - 9 . 4 % - 2 9 . 7 % - 2 9 . 7 % - 4 2 . 9 % CB -3.1 22.8 21.8 9.3 - 4 . 6 % 2 8 . 7 % 3 9 . 2 % 1 2 . 8 % ^ % c h a n g e i n AUC s i d a t a o b t a i n e d i n s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean T a b l e 5. C h a n g e s i n Clpjçg b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t i n s i x p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n . 1 P a t i e n t C l p I C G ( m l / m i n ) s i up s2 CA D i f f e r e n c e f r o m s i up s2 CA D i f f e r e n c e f r o m s2 CA MO 683.4 488.8 660.1 785 .6 -194.5 . -28.5%^ -23.2 - 3 . 4 % 102.3 1 5 . 0 % 125.5 '19.0% OW 649.0 542.7 586.5 553 .8 -106.3 - 1 6 . 4 % -62.4 - 9 . 6 % -95.2 - 1 4 . 7 % -32.7 - 5 . 6 % MS 785.3 583.1 601.3 612, .1 -202.2 - 2 5 . 8 % -184.0 - 2 3 . 4 % -173.2 - 2 2 . 1 % 10.7 1.8% BH 531.1 377.5 449.1 421, .0 -153.6 - 2 8 . 9 % -82.0 - 1 5 . 4 % -110.1 - 2 0 . 7 % -28.1 - 6 . 3 % DA 519.1 355.0 544.1 435. .3 -164.1 - 3 1 . 6 % 25.0 4.8% -83.8 - 1 6 . 1 % -108.8 - 2 0 . 0 % CB 533.5 440.3 628.7 482, ,7 -93.2 - 1 7 . 5 % 95.2 1 7 . 9 % -50.8 - 9 . 5 % -146.1 - 2 3 . 2 % 1 4 D i f f e r e n c e f r o m s i up s2 CA P a t i e n t ^"•pICG ( m l / m i n ) s i up s2 CA D i f f e r e n c e f r o m s2 CA MO 928 .6 755 .9 780 .8 822.6 -172.7 - 1 8 . 6 % -147.9 - 1 5 . 9 % -106.1 - 1 1 . 4 % 41.8 5.4% OW 1055 .2 692 .8 947 .5 813.4 -362.3 - 3 4 . 3 % -107.6 - 1 0 . 2 % -241.8 - 2 2 . 9 % -134.2 - 1 4 . 2 % MS 991 .3 769 .9 915 .8 734.3 -221.4 - 2 2 . 3 % -75.5 - 7 . 6 % -257.0 - 2 5 . 9 % -181.5 - 1 9 . 8 % BH 654, .9 431 .2 475, .6 558.3 -223.7 - 3 4 . 2 % -179.3 - 2 7 . 4 % -96.6 - 1 4 . 8 % 82.7 1 7 . 4 % DA 572, .8 505 .1 773, .7 761.7 -67.7 - 1 1 . 8 % 200.9 3 5 . 1 % 188.9 3 3 . 0 % -12.0 - 1 . 6 % CB 559. ,5 342, .0 451. ,7 427.8 -217.5 - 3 8 . 9 % -107.8 - 1 9 . 3 % -131.7 - 2 3 . 5 % -23.9 - 5 . 3 % T a b l e 5. C o n t ' d D A Y 1 4 D I F F E R E N C E F R O M D A Y 1 P a t i e n t C^pICG ( m l / m i n ) s i up s2 CA MO 245.3 3 5 . 9 % 267.1 5 4 . 6 % 120.7 1 8 . 3 % 36.9 4.7% OW 406.2 6 2 . 6 % 150.1 2 7 . 7 % 361.0 6 1 . 6 % 259.5 4 6 . 9 % MS 206.0 2 6 . 2 % 186.8 3 2 . 0 % 314.5 5 2 . 3 % 122.2 2 0 . 0 % BH 123.8 2 3 . 3 % 53.7 1 4 . 2 % 26.5 5.9% 137.3 3 2 . 6 % DA 53.7 1 0 . 3 % 150.1 4 2 . 3 % 229.6 4 2 . 2 % 326.4 7 5 . 0 % CB 26.0 4.9% -98.3 - 2 2 . 3 % -177.0 - 2 8 . 2 % -54.9 - 1 1 . 4 % % c h a n g e i n C l p j Q g s i d a t a o b t a i n e d i n s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean 1 100,0 ç 900.0 E o o 700.0 _Q- 500.0-o 300.0 s i up s2 CA DAY I s i up s2 CA DAY 14 13.0 11.0 £ 9.0 7.0-m a ô 5.0 3.0 s i -H 1— up s2 DAY 1 -+-CA s i up s2 CA DAY U - o O.W. M.O. M.S. - a B.H. - • D.A. - o C . B . F i g u r e 9. C l pTCG ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) i n t h e . j & t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) p h a s e s o b t a i n e d i n s i x p a t i e n t s on d a y 1 and d a y 14. T a b l e 6. Changes i n t h e mean AUCQ" and C K J ^ Q b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t on d a y 1 and day 14. Mean ± SEM, n = 6 s i up s2 CA D i f f e r e n c e f r o m s i up s2 CA D i f f e -r e n c e f r o m s2 CA DAY 1 , AUCQ" 68.7 92.0 72.9 78.2 2 3 . 3 ^ 4.2 9.5 5.3 min.Mg/ml ±3.7 ±6.3 ±6.2 ±6.6 ±3.6 ±4.3 ±4.3 ±4.3 33 . 9 % 6.1% 1 3 . 8 % 7.3% DAY 14 AUCQ" 54.8 76.5 61.9 63.3 21.7^ 7.1 8.5 1.3 min.Mg/ml ±4.4 ±8.6 ±8.1 ±6.0 ±5.5 ±5.7 ±5.0 ±3.8 3 9 . 5 % 1 3 . 0 % 1 5 . 4 % 2.2% DAY 1 — -- — -C l p 616.9 464.6 578.3 548.4 -152.3 -38.6 -68.5 -29.9 ml / m i n ±43.9 ±36.9 ±30.4 55.9 ±18.3 ±39.1 ±37.9 ±39.0 - 2 4 . 7 % - 6 . 3 % - 1 1 . 1 % - 5 . 2 % DAY 14 C l p 793.7 582.8 724.2 686.3 -210.9 -69.5 -107.4 -37.8 ml/ m i n ±91.0 ±74.0 ±87.2 ±64.8 ±38.8 ±56.1 ±65.6 ±41.5 -2 6 . 6 % - 8 . 8 % - 1 3 . 5 % - 5 . 2 % DAY 1 Clp/BW 6.5 4.9 6.2 5.7 -1.6 -0.4 -0.8 -0.4 ml/mi n/kg ±0.4 ±0.4 ±0.4 ±0.3 ±0.2 ±0.4 ±0.4 ±0.4 -2 4 . 5 % - 5 . 7 % - 1 2 . 2 % - 6 . 5 % DAY 14 Clp/BW 8.3 6.1 7.7 7.2 -2.2 -0.7 -1.1 -0.4 ml / m i n / k g ±0.8 ±0.6 ±0.9 ±0.6 ±0.4 ±0.6 ±0.7 ±0.4 -2 7 . 0 % - 8 . 1 % - 1 3 . 1 % - 5 . 5 % DAY 1 C l p / B S A 286.4 216.3 269.7 253.2 -70.4 -17.1 -33.5 -16.4 ml/min/m^ ±16.3 ±15.8 ±13.0 ±18.2 ±7.3 ±18.5 ±16.7 ±17.9 -2 4 . 6 % - 6 . 0 % - 1 1 . 7 % - 6 . 1 % DAY 14 C l p / B S A - 367.6 268.6 335.7 318.0 -99.0 -31.9 -49.6 -17.7 ml/min/m^ ±37.7 ±29.0 ±37.8 ±25.6 ±18.8 ±26.6 ±30.9 ±19.2 -2 6 . 9 % - 8 . 7 % - 1 3 . 5 % - 5 . 3 % ^ no s t a t i s t i c a l c o m p a r i s o n s were made f o r AUC d a t a s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean BW body w e i g h t BSA body s u r f a c e a r e a S t a t i s t i c a l l y s i g n i f i c a n t (p < 0.005) c o m p a r e d t o s i , MANOVA AUC d a t a . T a b l e 6 shows t h a t p o s t u r a l c hange f r o m s i t t i n g t o u p r i g h t i n c r e a s e d AUC (mean ± SEM, n=6) f r o m 68.7 ± 3.7 t o 92.0 ± 6.3 min'/xg/ml on day 1 and f r o m 54.8 ± 4.4 t o 76.5 ± 8.6 min-jug/ml on day 14. The a b s o l u t e i n c r e a s e i n AUC upon s t a n d i n g was 23.3 ± 3.6 min-/ig/ml o r 3 3 . 9 % o f c o n t r o l v a l u e b e f o r e c a p t o p r i l t r e a t m e n t on d a y 1 and 21.7 ± 5.5 min'/ig/ml o r 3 9 . 5 % o f c o n t r o l v a l ue on d a y 14. S i m i l a r l y , C l p j ^ Q (mean ± SEM, n-6) d e c r e a s e d i n u p r i g h t p o s i t i o n f r o m 616.9 ± 43.9 t o 464.6 ± 36.9 m l / m i n ( 2 4 . 7 % ) on day 1 and f r o m 793.7 ± 91.0 t o 582.8 ± 74.0 m l / m i n ( 2 6 . 6 % ) on d a y 14. T h i s d e c r e a s e i n C l p j f ^ Q i n u p r i g h t p o s i t i o n was s t a t i s t i c a l l y s i g n i f i c a n t (p = 0 . 0 0 1 ) , as c o m p a r e d t o s e a t e d v a l u e and d e t e r m i n e d by MANOVA. When t h e d a t a o f C l p j Q Q n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a w e r e u s e d t o a s s e s s t h e e f f e c t s o f p o s t u r a l s h i f t f r o m s i t t i n g t o u p r i g h t , C l p j ^ g (mean ± SEM, n=6) n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a d e c r e a s e d f r o m 6.5 ± 0.4 t o 4.9 ± 0.4 m l / m i n / k g ( 2 4 . 5 % , p = 0.002, MANOVA) and 286.7 ± 16.3 t o 216.3 ± 15.8 ml/min/m^ ( 2 4 . 6 % , p = 0.003, MANOVA), r e s p e c t i v e l y , on day 1 and f r o m 8.3 ± 0.8 t o 6.1 ± 0.6 m l / m i n / k g ( 2 7 . 0 % , p = 0.002, MANOVA) and 367.6 ± 37.7 t o 268.6 ± 29.0 ml/min/m^ ( 2 6 . 9 % , p = 0.002, MANOVA), r e s p e c t i v e l y , on d a y 14. T h e s e r e s u l t s show, t h a t t h e p e r c e n t d e c r e a s e s f r o m s e a t e d v a l u e s i n C l p j Q g (mean ± SEM, n=6) n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a d u r i n g u p r i g h t p o s t u r e on d a y 1 and 14 we r e a l m o s t i d e n t i c a l t o t h o s e o f t h e a b s o l u t e C l p j ^ g v a l u e s . F u r t h e r , t h e r e was no s i g n i f i c a n t d i f f e r e n c e b e t w e e n t h e AUC v a l u e s (mean ± SEM, n=6) o b t a i n e d i n t h e f i r s t s e a t e d ( s i ) and r e s e a t e d ( s 2 ) p e r i o d s o f t h e s t u d y e i t h e r on day 1 o r d a y 14. The d i f f e r e n c e s i n AUC (± SEM, n=6) f r o m s e a t e d ( s i ) v a l u e s when p a t i e n t s were r e s e a t e d were f o u n d t o be 4.2 ± 4.3 min'/^g/ml ( 6 . 1 % ) on d a y 1 and 7.1 ± 5.7 ( 1 3 . 0 % ) min-/ig/ml on d a y 14. However, t h e r e was a t e n d e n c y f o r an i n c r e a s e i n AUC i n r e s e a t e d p o s i t i o n s on b o t h s t u d y d a y s . S i m i l a r l y , C^pICG ^^pICG n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a o b t a i n e d d u r i n g t h e r e s e a t e d ( s 2 ) p e r i o d were n o t s t a t i s t i c a l l y d i f f e r e n t f r o m t h e f i r s t s e a t e d ( s i ) v a l u e s e i t h e r on day 1 o r day 14, as d e t e r m i n e d by MANOVA (p = 0.904, p = 0.964 and p = 0.985, r e s p e c t i v e l y , on d a y 1 and p = 0.685, p = 0.759 and p = 0.698, r e s p e c t i v e l y , on d a y 1 4 ) . T h e r e was, however, a s l i g h t d e c r e a s e i n mean C l p j Q Q (± SEM, n=6) f r o m 616.9 ± 43.9 t o 578.3 ± 30.4 m l / m i n ( 6 . 3 % ) on d a y 1 and f r o m 793.7 ± 91.0 t o 724.2 ± 87.2 ml/min ( 8 . 8 % ) on d a y 14. The p e r c e n t d e c r e a s e i n C l p j Q Q i n r e s e a t e d p o s i t i o n s were s i m i l a r i n m a g n i t u d e when C l p j ^ g n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a w e r e u s e d f o r t h e c o m p a r i s o n ( 5 . 7 % and 6.0%, r e s p e c t i v e l y , on day 1 and 8 . 1 % and 8.7%, r e s p e c t i v e l y , on d a y 1 4 ) . F i g u r e 9 shows t h e i n d i v i d u a l d a t a o f C l p j Q Q , e x p r e s s e d i n a b s o l u t e t e r m s and p e r u n i t body w e i g h t and body s u r f a c e a r e a , d u r i n g t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and a f t e r c a p t o p r i l d o s i n g (CA) on d a y 1 and 14. D a t a , f o r F i g u r e 9 a r e p r e s e n t e d i n T a b l e 5. The a b s o l u t e d e c r e a s e s i n C l p j Q Q f r o m s e a t e d ( s i ) v a l u e s upon s t a n d i n g w e r e i n t h e r a n g e f r o m -93.2 t o -202.2 m l / m i n ( 2 . 1 f o l d d i f f e r e n c e ) on d a y 1 and f r o m -67.7 t o -362.3 m l / m i n ( 5 . 3 f o l d d i f f e r e n c e ) on d a y 14. The d e c r e a s e s i n C l p j Q Q i n u p r i g h t p o s t u r e f r o m s e a t e d ( s i ) v a l u e s , e x p r e s s e d i n p e r c e n t a g e , were i n t h e r a n g e f r o m 1 6 . 4 % t o 3 1 . 6 % ( 1 . 9 f o l d d i f f e r e n c e ) on d a y 1 and 1 1 . 8 % t o 3 8 . 9 % ( 3 . 3 f o l d d i f f e r e n c e ) on d a y 14. A l l s i x p a t i e n t s r e s p o n d e d t o u p r i g h t p o s t u r e w i t h a d e c r e a s e i n C l p j Q Q , w h e t h e r i t e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a . I n e x a m i n i n g t h e i n d i v i d u a l d a t a o f t h e s i x p a t i e n t s on d a y 1, a d e c r e a s e i n C l p j Q Q d u r i n g t h e r e s e a t e d ( s 2 ) p e r i o d w e r e o b s e r v e d i n 4 o f t h e 6 p a t i e n t s s t u d i e d ( r a n g e f r o m 3.4% t o 2 3 . 4 % ) , when co m p a r e d t o t h e s e a t e d ( s i ) v a l u e s and an i n c r e a s e i n 2 p a t i e n t s ( 4 . 8 % and 1 7 . 9 % ) . On d a y 14, C l p j Q Q d e c r e a s e d i n 5 o f t h e 6 p a t i e n t s d u r i n g t h e r e s e a t e d ( s 2 ) p e r i o d ( r a n g e f r o m 7.6 t o 2 7 . 4 % ) , as c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e s . In one p a t i e n t a 3 5 . 1 % i n c r e a s e i n C l p j Q Q was n o t e d when p a t i e n t r e a s s u m e d s e a t e d p o s i t i o n a f t e r s t a n d i n g . T h e s e r e s u l t s show l a r g e i n t e r p a t i e n t v a r i a t i o n i n C l p j ^ Q d u r i n g t h e r e s e a t e d ( s 2 ) p e r i o d as compared t o s e a t e d ( s i ) v a l u e . F i g u r e 10 ( u p r i g h t , n a r r o w c r o s s h a t c h e d b a r s ) shows t h e a b s o l u t e d e c r e a s e f r o m s e a t e d ( s i ) v a l u e s i n C l p j Q Q and C l p j ^ g n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a (± SEM, n = 6) i n u p r i g h t p o s i t i o n on day 1 and 14. The a b s o l u t e d e c r e a s e i n C l p j Q g was -152.3 ± 18.3 o r 2 4 . 7 % on d a y 1 and -210.9 ± 38.8 o r 2 6 . 6 % on d a y 14, as compared t o t h e s e a t e d ( s i ) v a l u e s . T h e s e d a t a s u g g e s t a 3 8 . 5 % g r e a t e r a b s o l u t e d e c r e a s e i n C l p j ^ g d u r i n g u p r i g h t p o s i t i o n a f t e r two-weeks c a p t o p r i l t r e a t m e n t , when compared t o t h e s e a t e d ( s i ) v a l u e and c a l c u l a t e d by e q u a t i o n ( 8 ) ( S e c t i o n 2 . 8 . 2 . ) . However, t h e a p p a r e n t l y g r e a t e r r e s p o n s e t o u p r i g h t p o s t u r e on day 14 i s due t o t h e h i g h e r c o n t r o l ( s i ) C l p j Q g v a l u e s a f t e r two-weeks t r e a t m e n t w i t h c a p t o p r i l . T h i s c a n be shown by t h e a l m o s t s i m i l a r r e s u l t s when t h e d e c r e a s e i n C l p j ^ g upon s t a n d i n g on d a y 1 and 14 were e x p r e s s e d by t h e p e r c e n t d e c r e a s e f r o m c o n t r o l ( s i ) v a l u e s ( 2 4 . 7 % vs 2 6 . 6 % , r e s p e c t i v e l y ) . F u r t h e r , t h e mean (± SEM, n=6) a b s o l u t e d e c r e a s e i n C l p j Q Q i n r e s e a t e d ( s 2 ) p o s i t i o n ( w i d e l e f t d i a g o n a l b a r s ) was -38.6 ± 39.1 m l / m i n o r 6.3% on d a y 1 and -69.5 ± 56.1 ml/min o r 8.8% on d a y 14, as c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e . 3.3.2.2. A c u t e E f f e c t s o f C a p t o p r i l on AUC and C l p j ^ g To e v a l u a t e t h e a c u t e e f f e c t s o f c a p t o p r i l on AUC and C l p j Q Q , t h e d a t a o b t a i n e d 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e o f c a p t o p r i l on day 1 and 14 were c o m p a r e d t o t h o s e o f t h e r e s e a t e d ( s 2 ) m e a s u r e m e n t s . T a b l e 6 shows ( l a s t c o l u m n , CA) t h a t t h e r e was 0.00 - 5 0 . 0 0 - -Ë -100 .00 ô'^ -150 .00 c -200 .00 o -250.00- ' -D A Y 1 upright reseated p o s t - C A 0.00 g - 5 0 . 0 0 - 1 0 0 . 0 0 - -o s - 150 .00 - 2 0 0 . 0 0 - -- 2 5 0 . 0 0 D A Y 1 4 upright reseated p o s t - C A - s i o SI o 0,00 - 0 . 5 0 - 1 . 0 0 - 1 . 5 0 - 2 . 0 0 - 2 . 5 0 - 3 . 0 0 D A Y 1 upright reseated p o s t - C A E E m \ o 0.00 - 0 . 5 0 - 1 . 0 0 - 1 . 5 0 - 2 . 0 0 - 2 . 5 0 - 3 . 0 0 D A Y 1 4 upright reseated p o s t - C A -s1 0.00 \ - 2 0 . 0 0 - -£ ^ - 40 .00 M -60 .00 ô - 8 0 . 0 0 - -D) -100 .00 c -120.00- ' -D A Y I upright reseated p o s t - C A 0.00 N E > - 2 0 . 0 0 1 ^ - 4 0 . 0 0 - -< m -60.00 -80.00 ra - 100 .00 CL o JC o -120.00- ' -0 A Y 1 4 upright reseated p o s t - C A - s i F i g u r e 10. E f f e c t s o f p o s t u r a l change and t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e o f c a p t o p r i l on C l p j ^ g (mean ± SEM, n=6). * * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , MANOVA, p < 0.005. no s i g n i f i c a n t c h ange i n AUC (mean ± SEM, n=6) o f ICG 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l on day 1 and 14, when com p a r e d t o t h e r e s e a t e d ( s 2 ) v a l u e s . The mean AUC (± SEM, n = 6) i n c r e a s e d s l i g h t l y f r o m 72.9 ± 6.2 t o 78.2 ± 6.6 min-/zg/ml ( 7 . 3 % ) and f r o m 61.9 ± 8.1 t o 63.3 ± 6.0 min'/ig/ml ( 2 . 2 % ) on d a y 1 and 14, r e s p e c t i v e l y . S i m i l a r l y , t h e r e was no s i g n i f i c a n t c h a n g e i n C l p j ^ Q (± SEM, n=6) 60 m i n u t e s a f t e r c a p t o p r i l d o s i n g e i t h e r on d a y 1 o r 14, as compared t o r e s e a t e d v a l u e s . However, C l p j Q Q (mean ± SEM, n=6) d e c r e a s e d s l i g h t l y f r o m 578.3 ± 30.4 t o 548.4 ± 55.9 m l / m i n ( 5 . 2 % ) a f t e r t h e i n i t i a l d o s e and f r o m 724.2 ± 87.2 t o 686.3 ± 64.8 m l / m i n ( 5 . 2 % ) a f t e r t h e t e r m i n a l c a p t o p r i l d o s e on day 1 and 14, r e s p e c t i v e l y , as com p a r e d t o t h e r e s e a t e d ( s 2 ) v a l u e s . The a b s o l u t e d e c r e a s e s f r o m s2 i n C l p j ^ g (mean ± SEM, n=6) were f o u n d t o be -29.9 ± 39.0 m l / m i n and -37,8 ± 41.5 m l / m i n on d a y 1 and 14, r e s p e c t i v e l y . The p e r c e n t c h a n g e s f r o m s 2 i n C l p j Q g w e r e s i m i l a r w h e t h e r e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t and body s u r f a c e a r e a ( 6 . 5 % and 5.5 % on d a y 1 and 6.1 % and 5.3 % on d a y 14, r e s p e c t i v e l y ) . In e x a m i n i n g t h e i n d i v i d u a l C l p j Q Q d a t a , l a r g e i n t e r i n d i v i d u a ! v a r i a t i o n s w e r e o b s e r v e d i n t h e r e s p o n s e s t o t h e a c u t e d o s e s o f c a p t o p r i l ( p o s t - C A ) , when d a t a were compared t o t h e r e s e a t e d ( s 2 ) v a l u e s ( F i g u r e 9 ) . In two p a t i e n t s C l p j Q Q i n c r e a s e d by 1 9 . 0 % and 1.8% and 5.4% and 1 7 . 4 % on day 1 and d a y 14, r e s p e c t i v e l y , and d e c r e a s e d i n f o u r o t h e r s i n t h e r a n g e f r o m 5.6% t o 2 3 . 2 % and f r o m 1.6% t o 1 9 . 8 % on d a y 1 and 14, r e s p e c t i v e l y , when d a t a were co m p a r e d t o r e s e a t e d ( s 2 ) v a l u e s . In o r d e r t o d e t e r m i n e how t h e t i m e d i f f e r e n c e b e t w e e n t h e s e a t e d ( s i ) and 1 h o u r p o s t - c a p t o p r i l m e a s u r e m e n t s a f f e c t e d t h e k i n e t i c p a r a m e t e r s o f ICG, c o m p a r i s o n s between t h e s e two m e a s u r e m e n t s were made. T a b l e 6 shows t h a t , when AUC d a t a o b t a i n e d 1 h o u r a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l (CA, d a y 1) w e r e compared w i t h t h o s e o f t h e s e a t e d ( s i ) v a l u e s , an i n c r e a s e i n AUC (mean ± SEM, n=6) o c c u r r e d f r o m 68.7 ± 3.7 t o 78.2 ± 6.6 min - j U g/ml ( 1 3 . 8 % ) . A s i m i l a r i n c r e a s e i n AUC f r o m 54.8 ± 4.4 t o 63.3 ± 6.0 min'/ig/ml ( 1 5 . 5 % ) was o b s e r v e d 1 h o u r a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l (CA, day 14) when d a t a were compared t o t h e f i r s t s e a t e d ( s i ) measurement o f day 14. L i k e w i s e , C l p j Q g d e c l i n e d f r o m 616.9 ± 43.9 t o 548.4 ± 55.9 m l / m i n (11.1 %) and f r o m 793.7 ± 91.0 t o 686.3 ± 64.8 m l / m i n ( 1 3 . 5 % ) , 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l on d a y 1 and d a y 14, r e s p e c t i v e l y , as c o m p a r e d t o t h e C l p j ^ ^ g v a l u e o b t a i n e d i n t h e s e a t e d ( s i ) p e r i o d o f t h e s t u d y . The d e c r e a s e i n C l p j Q Q a f t e r t h e i n i t i a l and t e r m i n a l d o s e s o f c a p t o r i l w ere s t a t i s t i c a l l y n o t s i g n i f i c a n t , as compared t o s e a t e d ( s i ) (p = 0.131 and p = 0.162, MANOVA). S i m i l a r d e c r e a s e s i n C l p j Q Q were n o t e d when d a t a o f C l p j f ^ g n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a were u s e d f o r t h e c o m p a r i s o n ( 6 . 5 ± 0.4 vs. 5.7 ± 0.3 m l / m i n / k g , 12.2 % and 286.7 ± 16.3 vs. 253.2 ± 18.2 ml/min/m^, 11.7 %, r e s p e c t i v e l y ) . The d i f f e r e n c e f r o m f i r s t s e a t e d ( s i ) i n C l p j ^ Q n o r m a l i z e d t o b ody w e i g h t and body s u r f a c e a r e a i s c l o s e t o , b u t d o e s n o t r e a c h t h e e s t a b l i s h e d p < 0.05 l e v e l o f s i g n i f i c a n c e (p = 0.083 and p = 0.101, r e s p e c t i v e l y ) . F i g u r e 10 i l l u s t r a t e s t h e a b s o l u t e d e c r e a s e i n C l p j ^ g a f t e r t h e i n i t i a l c a p t o p r i l d o s e ( p o s t - C A , day 1, w i d e c r o s s h a t c h e d b a r s ) and a f t e r t h e t e r m i n a l d o s e o f two-weeks t r e a t m e n t w i t h c a p t o p r i l ( p o s t - C A , d a y 14) as c o m p a r e d t o s e a t e d s i v a l u e s . The a b s o l u t e d e c r e a s e (± SEM, n=6) i n Clpj(^Q was -68.5 ± 37.9 m l / m i n o r 1 1 . 1 % on d a y 1 and -107.4 ± 65.6 m l / m i n o r 1 3 . 5 % on d a y 14 as compared t o t h e s e a t e d ( s i ) v a l u e s . T h i s s u g g e s t s a 5 5 . 8 % g r e a t e r a b s o l u t e d e c r e a s e i n C K J ^ Q on d a y 14 as c o m p a r e d t o day 1. However, t h i s a p p a r e n t l y g r e a t e r d e c r e a s e i n C l p j Q Q a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l c o r r e s p o n d s t o t h e h i g h e r b a s e l i n e v a l u e on d a y 14. The d e c r e a s e s i n C l p j Q Q 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l and t e r m i n a l d o s e o f CA t r e a t m e n t (CA d a y 1 and d a y 14) as compared t o s e a t e d ( s i ) v a l u e s were c o n s i s t e n t i n 5 o f t h e 6 p a t i e n t s s t u d i e d ( F i g u r e 9 ) . I n t h e 5 p a t i e n t s who r e s p o n d e d s i m i l a r l y t h e r a n g e was f o u n d t o be f r o m 9.5% and 2 2 . 1 % on d a y 1 and 1 1 . 4 % and 2 5 . 9 % on d a y 14 ( T a b l e 5 ) . 3.3.2.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on AUC and C l p j Q Q The e f f e c t s o f two-weeks c a p t o p r i l t r e a t m e n t on AUC and C l p j Q Q were e s t i m a t e d by c o m p a r i n g t h e AUC and C l p j Q Q v a l u e s o b t a i n e d d u r i n g t h e f o u r p h a s e s o f d a y 14 ( s e a t e d , u p r i g h t , r e s e a t e d and p o s t - C A ) w i t h t h e a p p r o p r i a t e p h a s e s o f d a y 1. T a b l e 7 shows t h e c o m p a r i s o n s o f mean (± SEM, n=6) AUC, C l p j Q Q , e x p r e s s e d i n a b s o l u t e t e r m s and n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a o f d a y 14 w i t h t h e same d a t a o f d a y 1. As compared t o day 1, AUC d e c r e a s e d by 13.9 ± 3.7 min . / z g/ml ( 2 0 . 2 % ) i n s e a t e d ( s i ) , 15.5 ± 8.1 min - j L t g/ml ( 1 6 . 8 % ) i n u p r i g h t ( u p ) , 11.1 ± 7.4 min-/ig/ml ( 1 5 . 1 % ) i n r e s e a t e d ( s 2 ) p o s i t i o n s and 14.9 ± 6.7 min-jug/ml ( 1 9 . 1 % ) 1 h o u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n ( C A ) . S i m i l a r l y , C l p j Q Q i n c r e a s e d i n a l l f o u r p h a s e s o f d a y 14, as compared t o d a y 1. The a b s o l u t e i n c r e a s e s (± SEM, n=6) i n C l p j Q Q f r o m d a y 1 i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and p o s t - c a p t o p r i l (CA) were 176.8 ± 57.4 m l / m i n ( 2 8 . 7 % ) , 118.2 + 51.6 m l / m i n ( 2 5 . 5 % ) , 145.9 ± 81.8 m l / m i n ( 2 5 . 2 % ) and 137.9 ± 57.1 m l / m i n ( 2 5 . 2 % ) , r e s p e c t i v e l y . F i g u r e I I i l l u s t r a t e s t h e c h a n g e s i n C l p j Q Q , e x p r e s s e d i n a b s o l u t e t e r m s and n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a . The o v e r a l l i n c r e a s e T a b l e 7. C o m p a r i s o n o f t h e mean AUCQ" and C l p j Q Q d a t a ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) o b t a i h e d i n t h e f o u r s t u d y p h a s e s o f d a y 14 w i t h t h o s e o f d a y 1. D A Y 1 4 D I F F E R E N C E F R O M D A Y 1 Mean ± SEM, n = 6 s i up s2 CA AUCQ"^ min./ig/ml -13.9 ±3.7 -15.5 ±8.1 -11.0 ±7.4 -14.9 ±6.7 % c h a n g e i n AUCQ*" -20.2 -16.8 -15.1 -19.1 m l / m i n 176.8 ±57.4 118.2 ±51.6 145.9 ±81.8 137.9 ±57.1 % c h a n g e i n C l p 28.7 25.5 25.2 25.2 CI /BW* m l / m i n / k g 1.8 ±0.6 1.2 ±0.5 1.5 ±0.9 1.5 ±0.7 % c h a n g e i n Clp/BW 27.8 23.7 24.6 26.3 C l p / B S A * ml/min/m*^ 80.9 ±26.4 52.3 ±23.2 66.0 ±39.2 64.8 ±27.6 % c h a n g e i n C l p / B S A 28.2 24.2 24.5 25.6 no s t a t i s t i c a l c o m p a r i s o n s were made f o r AUC d a t a s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean BW body w e i g h t BSA body s u r f a c e a r e a * s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.05) compared t o c o m b i n e d d a y 1, MANOVA 3: m o o 10.0 8.0 6.0-4.0-2.0 0.0 C Z I s I E 3 u p K S a s 2 C D C A Dayl Day 14 500.0 C D s l K a s 2 CZDCA Dayl Dayl 4 F i g u r e 11. C o m p a r i s o n o f C l p j Q g ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) ( m e a n + SEM, n=6) b e f o r e and a f t e r two-weeks c a p t o p r i l . * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m d a y 1, MANOVA, p < 0.05. i n C l p j Q Q a f t e r two-weeks c a p t o p r i l t r e a t m e n t was s t a t i s t i c a l l y s i g n i f i c a n t , w h e t h e r e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t and body s u r f a c e a r e a (p=0.039, p=0.048, p=0.044, MANOVA). In e x a m i n i n g t h e i n d i v i d u a l d a t a o f t h e s i x p a t i e n t s t h e i n c r e a s e i n C l p j Q Q was c o n s i s t e n t i n f i v e o f t h e s i x p a t i e n t s s t u d i e d ( T a b l e 5, F i g u r e 9 ) . The m a g n i t u d e o f i n c r e a s e , h o w e v e r , showed l a r g e i n t e r i n d i v i d u a l v a r i a b i l i t y . The p e r c e n t i n c r e a s e i n C l p j Q Q a f t e r two-weeks c a p t o p r i l t r e a t m e n t was i n t h e r a n g e f r o m 1 0 . 3 % t o 6 2 . 6 % ( 6 . 1 f o l d d i f f e r e n c e ) i n s e a t e d ( s i ) , f r o m 1 4 . 2 % t o 5 4 . 6 % ( 3 . 8 f o l d d i f f e r e n c e ) i n u p r i g h t ( u p ) , f r o m 5.9% t o 6 1 . 6 % ( 1 0 . 4 f o l d d i f f e r e n c e ) i n r e s e a t e d ( s 2 ) and f r o m 4.7% t o 7 5 . 0 % ( 1 5 . 9 f o l d d i f f e r e n c e ) a f t e r CA a d m i n i s t r a t i o n ( C A ) . One p a t i e n t (C.B.) e x h i b i t e d a d e c r e a s e r a t h e r t h a n i n c r e a s e i n C l p j Q Q i n 3 o f t h e f o u r p h a s e s o f t h e s t u d y ( u p r i g h t , r e s e a t e d and p o s t - C A ) , as c o m p a r e d t o t h e d a y 1 v a l u e s . 3.4. Changes i n L i v e r B l o o d F l o w (Qy) 3 . 4.1. H e m a t o c r i t D a t a As i t i s shown by e q u a t i o n ( 8 ) i n S e c t i o n 2.8.1., i n o r d e r t o e s t i m a t e Qy f r o m C l p j Q Q d a t a t h e h e p a t i c e x t r a c t i o n r a t i o ( E y ) o f ICG and v a l u e s o f t h e h e m a t o c r i t a r e r e q u i r e d . I n t h e p r e s e n t s t u d y , Ey was c o n s i d e r e d t o be 1 a s s u m i n g 1 0 0 % h e p a t i c e x t r a c t i o n f o r ICG. T h u s , - u n l e s s l a r g e c h a n g e s i n p a t i e n t s ' h e m a t o c r i t o c c u r d u r i n g t h e s t u d y - t h e c h a n g e s i n C l p j Q Q r e f l e c t s t h e c h a n g e s a l s o i n Qy In t h e p r e s e n t s t u d y , t h e h e m a t o c r i t was m e a s u r e d i n s e a t e d p o s i t i o n b e f o r e t h e f i r s t ICG i n j e c t i o n ( s i ) , d u r i n g t h e s a m p l i n g p e r i o d s o f u p r i g h t p o s i t i o n s ( u p ) and c a p t o p r i l d o s i n g ( C A ) . T a b l e 8 shows t h e h e m a t o c r i t v a l u e s o f t h e s i x p a t i e n t s o b t a i n e d d u r i n g t h e two s t u d y d a y s . P o s t u r a l s h i f t f r o m s i t t i n g t o u p r i g h t r e s u l t e d i n an i n c r e a s e i n h e m a t o c r i t by 3.8% and 5.2% d a y 1 and 14, r e s p e c t i v e l y . A l t h o u g h t h i s i n c r e a s e i n h e m a t o c r i t upon s t a n d i n g i s r e l a t i v e l y s m a l l i t was s t a t i s t i c a l l y s i g n i f i c a n t on b o t h s t u d y d a y s , d a y 1 and 14 (p < 0.005 and p < 0.05, r e s p e c t i v e l y , p a i r e d s a m p l e t - t e s t ) . T h e r e was no s i g n i f i c a n t c h a n g e i n h e m a t o c r i t (mean ± SD, n=6) d u r i n g t h e p o s t - c a p t o p r i l (CA) p e r i o d , as c o m p a r e d t o t h e b a s e l i n e v a l u e ( s i ) e i t h e r on d a y 1 o r d a y 14. However, a s t a t i s t i c a l l y s i g n i f i c a n t d e c r e a s e i n mean h e m a t o c r i t was o b s e r v e d a f t e r two-weeks t r e a t m e n t w i t h c a p t o p r i l when b a s e l i n e ( s i ) and u p r i g h t (up) v a l u e s o f d a y 14 w e r e compared t o t h a t o f d a y 1 (- 5.4%, p < 0.05 and - 4.3%, p < 0.01, r e s p e c t i v e l y , p a i r e d s a m p l e t - t e s t ) . A l t h o u g h , h e m a t o c r i t v a l u e s were s i g n i f i c a n t l y h i g h e r d u r i n g s t a n d i n g and l o w e r on d a y 14 as c o m p a r e d t o t h a t o f day 1, t h e y a p p a r e n t l y d i d n o t a f f e c t t h e e s t i m a t e d c h a n g e s i n Qy. 3.4.2. Qy D a t a A p p e n d i x 3 p r e s e n t s t h e i n d i v i d u a l Qy d a t a , e x p r e s s e d i n a b s o l u t e t e r m s and n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a f o r s i x p a t i e n t s d u r i n g t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l p e r i o d s o f t h e s t u d y on d a y 1 and 14. B a s e d on t h e s e d a t a , t h e c h a n g e s i n Qy and Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a d u r i n g t h e f o u r s t u d y p h a s e s ( s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l ( C A ) ) o f day 1 and d a y 14 a r e shown i n F i g u r e 12. T a b l e 8. Changes i n h e m a t o c r i t i n s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n d u r i n g p o s t u r a l c h a n g e and b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . D A Y 1 D A Y 14 P a t i e n t s i up CA s i up CA OW 0.430 0.453 0.452 0.400 0.430 0.400 MO 0.436 0.450 0.428 0.420 0.430 0.430 MS 0.440 0.460 0.430 0.440 0.458 0.440 BH 0.500 0.510 0.490 0.440 0.470 0.443 DA 0.465 0.480 0.455 0.449 0.458 0.420 CB 0.405 0.425 0.395 0.380 0.410 0.380 Mean ± SD: 0.446 ±0.03 0.463 ±0.03 0.442 ±0.03 0.421 ±0.03 0.443 ±0.02 0.419 ±0.03 % c h a n g e u p r i g h t ^ 3 . 8 1 * * 5.0** % c h a n g e p o s t - C A ^ -O.9NS -0.6NS 7o c h a n g e d a y 14^ - 5 . 5 * - 4 . 4 * -5.1NS s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM S t a n d a r d e r r o r o f t h e mean 7c c h a n g e d u r i n g u p r i g h t p o s i t i o n , as compared t o t h e s e a t e d ( s i ) v a l u e s o f d a y 1 and 14 % c h a n g e a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as c o m p a r e d t o d a y 1 s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.005) co m p a r e d t o s i , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.05) compared t o s i , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y n o t s i g n i f i c a n t (p > 0 . 0 5 ) , compared t o s i , p a i r e d s a m p l e t - t e s t 2000 F i g u r e 12. Qy ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) p h a s e s o b t a i n e d i n s i x p a t i e n t s on day 1 and d a y 14. 3.4.2.1. E f f e c t s o f P o s t u r a l Change on B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t A summary o f c h a n g e s i n and Q^, n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a (mean ± SEM, n=6) d u r i n g t h e f o u r s t u d y p h a s e s on d a y 1 and day 14 a r e shown i n T a b l e 9. Mean (± SEM, n=6) d e c r e a s e d f r o m 1114 ± 74 t o 863 ± 62 m l / m i n ( 2 2 . 5 % ) and f r o m 1389 ± 164 t o 1045 ± 132 m l / m i n ( 2 4 . 7 % ) , r e s p e c t i v e l y , upon s t a n d i n g on d a y 1 and 14, as compared t o t h e s e a t e d ( s i ) v a l u e s . When Q^ d a t a were n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a t h e m a g n i t u d e o f d e c r e a s e s i n u p r i g h t p o s i t i o n were s i m i l a r t o t h o s e o f t h e a b s o l u t e v a l u e s ( 2 2 . 3 % and 2 5 . 2 % on d a y 1 and 2 2 . 3 % and 2 3 . 9 % on day 14, r e s p e c t i v e l y ) . The o b s e r v e d d e c r e a s e i n and i n Q^ n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a d u r i n g p o s t u r a l c h a n g e f r o m s i t t i n g t o u p r i g h t was s t a t i s t i c a l l y s i g n i f i c a n t , as d e t e r m i n e d by MANOVA (p = 0.008, p = 0.004 p = 0.005, r e s p e c t i v e l y , on d a y 1 and p = 0.003, p = 0.005 and p = 0.004, r e s p e c t i v e l y , on d a y 1 4 ) . F u r t h e r , mean (± SEM, n=6) i n c r e a s e d f r o m 863 ± 62 t o 1043 ± 34 m l / m i n on d a y 1 and f r o m 1045 ± 132 t o 1271 ± 160 ml/min on d a y 14 when p a t i e n t s r e a s s u m e d s e a t e d ( s 2 ) p o s i t i o n , as c o m p a r e d t o t h o s e o f t h e u p r i g h t ( u p ) v a l u e s . When r e s e a t e d ( s 2 ) Q^ v a l u e s w e r e compared t o t h o s e o f s e a t e d ( s i ) v a l u e s , t h e r e s e a t e d ( s 2 ) v a l u e s (mean ± SEM, n=6) were l o w e r t h a n s e a t e d ( s i ) v a l u e s by -71 ± 69 ( 6 . 3 % ) and -118 ± 100 ml/min ( 8 . 5 % ) on d a y 1 and d a y 14, r e s p e c t i v e l y ( F i g u r e 13, w i d e l e f t d i a g o n a l b a r s ) . T h e s e d i f f e r e n c e s f r o m s i v a l u e s , w h e t h e r Q^ was e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a , were s t a t i s t i c a l l y n o t s i g n i f i c a n t (p = 0.949, p = 0.910, and p = 0.968, r e s p e c t i v e l y , on day 1 and p = 0.860, p = 0.862 and p = 0.921, r e s p e c t i v e l y , T a b l e 9. Changes i n Qy and Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a (mean ± SEM, n=6) b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . D i f f e r e n c e D i f f e -Mean ± SEM, n=6 f r o m s i r e n c e fyom s2 s i up s2 CA up s2 CA CA _ _ Qy 1114 863 1043 980 -250 -71 -134 -63 mT/min ±74 ±62 ±34 ±92 ±36 ±69 ±68 ±70 - 2 2 . 5 % - 6 . 3 % - 1 2 . 0 % - 6 . 0 % DAY 14 Qy 1389 1045 1271 1193 -344 -118 -196 -78 mT/min ±164 ±132 ±160 ±119 ±68 ±100 ±107 ±73 - 2 4 . 7 % - 8 . 5 % - 1 4 . 1 % - 6 . 1 % DAY 1 Qy/BW 11.8 9.2 11.1 10.3 -2.6 -0.7 -1.5 -0.8 m l / m i n / k g ±0.6 ±0.6 ±0.5 ±0.4 ±0.3 ±0.8 ±0.7 ±0,7 - 2 2 . 3 % - 5 . 8 % - 1 3 . 0 % - 7 . 6 % DAY 14 Qy/BW 14.6 10.9 13.4 12.6 -3.7 -1.1 -2.0 -0.9 mT/min/kg ±1.5 ±1.2 ±1.7 ±1.1 ±0.8 ±1.1 ±1.2 ±0.8 - 2 5 . 2 % - 7 . 8 % - 1 3 . 8 % - 6 . 5 % DAY 1 Qy/BSA - 517.8 402.1 486.4 452.7 -115.7 -31.3 -65.1 -33.7 mT/min/m^ ±27.2 ±26.1 ±13.0 ±28.4 ±15.3 ±32.6 ±30.2 ±32.2 - 2 2 . 3 % - 6 . 0 % - 1 2 . 6 % - 6 . 9 % DAY 14 Qy/BSA - 632.8 481.9 588.7 552.2 -150.9 -44.1 -80.5 -36.5 ml/min/m'^ ±72.7 ±52.6 ±70.1 ±47.7 ±40.2 ±57.2 ±59.1 ±33.8 - 2 3 . 9 % - 7 . 0 % - 1 2 . 7 % - 6 . 2 % s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean BW body w e i g h t BSA body s u r f a c e a r e a * s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 5 ) , c o m p a r e d t o s i , MANOVA. ** s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 0 5 ) , c o m p a r e d t o s i , MANOVA. on d a y 14, MANOVA). T h e r e was, h o w e v e r , a t e n d e n c y f o r r e d u c t i o n i n d u r i n g t h e r e s e a t e d ( s 2 ) p o s i t i o n , as co m p a r e d t o t h e s e a t e d ( s i ) m e a s u r e m e n t s . F i g u r e 12 shows t h a t t h e d e c r e a s e i n d u r i n g p o s t u r a l c h a n g e f r o m s i t t i n g t o s t a n d i n g (up) was c o n s i s t e n t i n t h e s i x p a t i e n t , w h e t h e r Q^ was e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a . The p e r c e n t d e c r e a s e i n Q^ upon s t a n d i n g was i n t h e r a n g e f r o m 1 2 . 9 % t o 2 9 . 7 % ( 2 . 3 f o l d d i f f e r e n c e ) on d a y 1 and 1 0 . 4 % t o 3 5 . 8 % (3.4 f o l d d i f f e r e n c e ) on d a y 14. As c o n t r a s t , l a r g e i n t e r i n d i v i d u a l v a r i a b i l i t y i n Q^ we r e o b s e r v e d on d a y 1 and 14, when d i f f e r e n c e s ( e x p r e s s e d i n p e r c e n t a g e ) b e t w e e n t h e r e s e a t e d ( s 2 ) and s e a t e d ( s i ) v a l u e s were c a l c u l a t e d . R e s e a t e d ( s 2 ) Q|,| v a l u e s w e r e l o w e r i n f o u r p a t i e n t s i n t h e r a n g e f r o m - 4 . 8 % t o 2 3 . 4 % ( 4 . 9 f o l d d i f f e r e n c e ) and were h i g h e r i n two p a t i e n t s by 4.8% and 1 7 . 9 % (3.7 f o l d d i f f e r e n c e ) on d a y 1, as compared t o t h e f i r s t s e a t e d ( s i ) measurement. A f t e r two-weeks c a p t o p r i l t r e a t m e n t t h e Q^ v a l u e s w e r e s m a l l e r i n f i v e o f t h e s i x p a t i e n t s s t u d i e d by 7.6% t o 27.4 % and Qj.^  was h i g h e r i n one p a t i e n t by 3 5 . 1 % , as co m p a r e d t o s e a t e d ( s i ) v a l u e s . F i g u r e 13 shows t h a t t h e a b s o l u t e d e c r e a s e (mean ± SEM, n = 6) i n upon s t a n d i n g was -250 ± 36 m l / m i n o r on d a y 1 and -344 ± 68 m l / m i n on day 14, as co m p a r e d t o t h e s e a t e d v a l u e . T h i s s u g g e s t s a 3 7 . 3 % g r e a t e r a b s o l u t e d e c r e a s e i n a f t e r two-weeks c a p t o p r i l t r e a t m e n t i n u p r i g h t p o s i t i o n as c o m p a r e d t o d a y 1. However, t h e a p p a r e n t l y g r e a t e r r e s p o n s e t o u p r i g h t p o s t u r e i s due t o t h e h i g h e r c o n t r o l v a l u e ( s e a t e d s i ) v a l u e on day 14. When t h e d e c r e a s e i n Q^ f r o m c o n t r o l v a l u e upon s t a n d i n g was e x p r e s s e d i n p e r c e n t a g e , t h e d e c r e a s e i n were s i m i l a r on b o t h s t u d y d a y s ( 2 2 . 5 % vs 2 4 . 7 % ) . X o -50 .00 -150 .00 •- - 250 .00 ^ - 350 .00 - 4 5 0 . 0 0 D A Y 1 upright rcseotcd p o s t - C A - 5 0 . 0 0 -150.00 - 250 .00 + -350.00 - 4 5 0 . 0 0 D A Y 1 4 upright reseated p o s t - C A - s i X o 0.00 -1 .00 - f - 2 .00 - 3 . 0 0 -4 .00 -5 .00 D A Y 1 upright resected post—CA 0.00 -1 .00-f -2.00 4-- 3 . 0 0 + - 4 . 0 0 + - 5 . 0 0 D A Y 1 4 upright reseated post—CA s i E 0.00 E - 5 0 . 0 0 E 5) - 100 .00 m X a •£ - 150 .00 -200.00-1-D A Y 1 upright reseated p o s t - C A 0.00 - 5 0 . 0 0 - 1 0 0 . 0 0 -150 .00 - 2 0 0 . 0 0 D A Y 1 4 upright reseoted p o s t - C A 1 * * . s i F i g u r e 13. E f f e c t s o f p o s t u r a l change and t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e o f c a p t o p r i l on (mean ± SEM, n=6). * and * * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , MANOVA, p < 0.05 and p < 0.005, r e s p e c t i v e l y . 3.4.2.2. A c u t e E f f e c t s o f C a p t o p r i l on The p u r p o s e o f i n c l u d i n g t h e r e s e a t e d ( s 2 ) measurement i n t h e s t u d y p r o t o c o l was t o s t a b i l i z e a f t e r s t a n d i n g and b e f o r e t h e a d m i n i s t r a t i o n o f c a p t o p r i l . T h e r e f o r e , t h e a c u t e e f f e c t s o f c a p t o p r i l on w e r e e s t i m a t e d by c o m p a r i n g t h e c h a n g e s 1 h o u r a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l t o t h o s e o b t a i n e d i n t h e r e s e a t e d ( s 2 ) p o s i t i o n . T a b l e 9 ( l a s t c o l u m n , CA) d e p i c t s t h e c h a n g e s i n and n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a (mean ± SEM, n=6) when v a l u e s , o b t a i n e d 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l c a p t o p r i l d o s e ( d a y 1, CA) and t h e t e r m i n a l c a p t o p r i l d o s e ( d a y 14, C A ) , were compared t o t h o s e o f t h e r e s e a t e d ( s 2 ) m e a s u r e m e n t s . Mean (± SEM, n=6) s l i g h t l y d e c r e a s e d f r o m 1043 ± 34 t o 980 ± 92 m l / m i n ( 6 . 0 % ) and f r o m 1271 ± 160 t o 1193 ± 119 m l / m i n ( 6 . 1 % ) a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l . The a b s o l u t e d e c r e a s e i n Q^ (mean ± SEM, n=6) a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l were f o u n d t o be -63 ± 70 ( 6 . 0 % ) and -78 ± 73 ( 6 . 1 % ) m l / m i n , r e s p e c t i v e l y . T h i s c h a n g e i n a f t e r t h e a c u t e d o s e s o f c a p t o p r i l was s t a t i s t i c a l l y n o t s i g n i f i c a n t . T h e r e was, however a t e n d e n c y f o r d e c r e a s e i n Q^, a f t e r t h e a c u t e d o s e s o f c a p t o p r i l , as compared t o t h e r e s e a t e d ( s 2 ) v a l u e s on b o t h s t u d y d a y s , w h e t h e r Q^ d a t a were e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t b ody w e i g h t and body s u r f a c e a r e a . The m a g n i t u d e o f d e c r e a s e i n was, h o w e v e r , s i m i l a r t o t h a t o b s e r v e d when t h e two s e a t e d ( s i and s 2 ) v a l u e s w e r e c o m p a r e d . By c o m p a r i n g t h e i n d i v i d u a l r e s p o n s e s o f Q^ ^ i n t h e r e s e a t e d ( s 2 ) p e r i o d s t o t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l (CA) i t i s a p p a r e n t t h a t i n two p a t i e n t s t h e r e was no c h a n g e (O.W.and M.S.), i n one p a t i e n t (M.O.) t h e r e was an i n c r e a s e and i n two p a t i e n t s (D.A. and C.B.) t h e r e was a d e c r e a s e i n QH ( F i g u r e 1 2 ) . T h e s e r e s u l t s s u g g e s t l a r g e i n t e r p a t i e n t v a r i a b i l i t y i n t h e r e s p o n s e s t o t h e a c u t e d o s e s o f c a p t o p r i l . T h e r e was a b o u t a 5 h o u r t i m e d i f f e r e n c e b e t w e e n t h e m e a s u r e m e n t s o f Q|^  i n t h e f i r s t s e a t e d ( s i ) p o s i t i o n and a f t e r c a p t o p r i l a d m i n i s t r a t i o n . In o r d e r t o e v a l u a t e how t h i s t i m e d i f f e r e n c e a f f e c t e d e s t i m a t e d Q^, d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g were c o m p a r e d t o t h e Q^ d a t a m easured d u r i n g t h e f i r s t s e a t e d ( s i ) p h a s e o f t h e s t u d y ( T a b l e 9, C A ) . As a r e s u l t o f t h i s c o m p a r i s o n , a r e d u c t i o n i n Q^ (mean ± SEM, n=6) f r o m 1114 ± 74 t o 980 ± 92 m l / m i n and f r o m 1389 ± 164 t o 1193 ± 119 m l / m i n was n o t e d on b o t h s t u d y d a y s , d a y 1 and 14, r e s p e c t i v e l y . F i g u r e 13 shows t h a t t h e a b s o l u t e d e c r e a s e i n Q^ (mean ± SEM, n=6) 1 h o u r a f t e r c a p t o p r i l d o s i n g was -134 ± 68 o r 1 2 . 0 % on d a y 1 and -196 ± 107 o r 1 4 . 1 % on d a y 14, as c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e s ( w i d e c r o s s h a t c h e d b a r s ) . T h e s e d a t a s u g g e s t a 4 6 . 6 % g r e a t e r a b s o l u t e d e c r e a s e i n Q^ on day 14 t h a n on day 1. However, t h e a p p a r e n t l y g r e a t e r d e c r e a s e i n Q[^ a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l on d a y 14, as c o m p a r e d t o t h e d a y 1 v a l u e s i s a t t r i b u t e d t o t h e h i g h e r b a s e l i n e v a l u e ( s i ) o f d a y 14. T h i s i s shown by t h e f a c t t h a t t h e m a g n i t u d e o f r e d u c t i o n i n Q^ e x p r e s s e d i n p e r c e n t a g e were a l m o s t s i m i l a r on d a y 1 and 14 ( 1 2 . 0 % vs 1 4 . 1 % , r e s p e c t i v e l y ) . The r e d u c t i o n i n Q^ a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l , as c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e was s t a t i s t i c a l l y n o t s i g n i f i c a n t , w h e t h e r Q^ was e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a (p=0.107, p= 0.070 and p=0.084, r e s p e c t i v e l y on d a y 1 and p=0.126, p=0.150 and p=0.231, r e s p e c t i v e l y on d a y 14, MANOVA). 3.4.2.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on Qy The r e s u l t s o f t h e c o m p a r i s o n s o f mean Qy and Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a o b t a i n e d d u r i n g t h e f o u r p h a s e s ( s i , up, s2 and CA) o f d a y 14 t o t h a t o f t h e same p h a s e s o f d a y 1 a r e p r e s e n t e d i n T a b l e 10. The Qy v a l u e s a f t e r two-weeks t h e r a p y w i t h c a p t o p r i l w e r e g r e a t e r i n a l l f o u r p h a s e s o f d a y 14, as c ompared t o t h e same p h a s e s o f d a y 1. The a b s o l u t e i n c r e a s e (± SEM, n=6) i n Qy was 275.0 ± 107.3 m l / m i n ( 2 4 . 7 % ) i n s e a t e d ( s i ) , 182.0 ± 90.6 m l / m i n ( 2 1 . 1 % ) i n u p r i g h t ( u p ) , 227.8 ± 147.8 m l / m i n ( 2 1 . 8 % ) i n r e s e a t e d ( s 2 ) p o s i t i o n s and 212.8 ± 92.5 m l / m i n ( 2 1 . 7 % ) a f t e r c a p t o p r i l d o s i n g ( C A ) . F i g u r e 14 shows t h e c h a n g e s i n mean Qy and Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a on d a y 1 and a f t e r s h o r t -t e r m t r e a t m e n t w i t h c a p t o p r i l , on day 14. The s t a t i s t i c a l t e s t (MANOVA) j u s t f a i l e d t h e l e v e l o f s i g n i f i c a n c e , w i t h p v a l u e s o f 0.062, 0.075 and 0.074 f o r t h e a b s o l u t e v a l u e s o f Qy and Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a , r e s p e c t i v e l y . The m a g n i t u d e o f t h e a b s o l u t e i n c r e a s e i n Qy, e x p r e s s e d i n p e r c e n t a g e were s i m i l a r i n a l l p h a s e s o f t h e s t u d y ( r a n g e f r o m 1 9 . 8 % t o 2 4 . 7 % ) . T h i s i s i l l u s t r a t e d on F i g u r e 15 w h i c h shows t h a t t h e i n c r e a s e i n Qy a f t e r two-weeks c a p t o p r i l t r e a t m e n t f o l l o w s an a l m o s t p a r a l l e l p a t t e r n w i t h t h e d a y 1 d a t a . The m a g n i t u d e o f t h e c h a n g e i n Qy n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a were s l i g h t l y s m a l l e r , b u t s i m i l a r t o t h o s e o f t h e a b s o l u t e Qy v a l u e s . I n e x a m i n i n g t h e d a t a o f i n d i v i d u a l s u b j e c t s ( F i g u r e 12) i t i s a p p a r e n t t h a t t h e i n c r e a s e i n Qy a f t e r two-weeks c a p t o p r i l t r e a t m e n t was o b s e r v e d i n f i v e o f t h e s i x p a t i e n t s s t u d i e d . One p a t i e n t (C.B.) e x h i b i t e d a d e c r e a s e i n Qy a f t e r p r o l o n g e d a d m i n i s t r a t i o n o f c a p t o p r i l . When t h e r e s u l t s o f t h i s T a b l e 10. C o m p a r i s o n o f d a t a ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) o b t a i n e d i n t h e f o u r s t u d y p h a s e s o f d a y 14 w i t h t h o s e o f d a y 1. D A Y 1 4 D I F F E R Mean E N C E F R O M ± SEM, n = 6 D A Y 1 s i up s2 CA ml/mm 275.0 ±107.3 182.0 ±90.6 227.8 ±147.8 212.8 ±92.5 % c h a n g e i n QH 24.7 21.1 21.8 21.7 QH/BW NS m l / m i n / k g 2.8 ±1.1 1.8 ±0.9 2.3 ±1.6 2.3 ±1.1 % c h a n g e i n QH/BW 23.8 19.4 21.1 22.7 Qu/BSA ml/min/m^ 115.0 ±54.1 79.8 ±41.1 102.3 ±70.6 99.5 ±44.6 % c h a n g e i n QH/BSA 22.2 19.8 21.0 22.0 s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM S t a n d a r d e r r o r o f t h e mean BW body w e i g h t BSA body s u r f a c e a r e a s t a t i s t i c a l l y n o t s i g n i f i c a n t ( 0 . 0 5 < p < 0 . 1 ) , co m p a r e d t o c o m b i n e d day 1, MANOVA p = 0.06 p = 0.07 0.0 Day 1 Day 14 F i g u r e 14. C o m p a r i s o n o f Qy ( n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ) ( m e a n ± SEM, n=5) b e f o r e and a f t e r two-weeks c a p t o p r i l . 1800 J 1500--1200--1 900 4-600--300--0 O T i O O First seated (si) Upright (up) Reseated (32) T O Post-CA (CA) F i g u r e 15. I n c r e a s e i n (mean + SEM, n=6) f r o m d a y 1 (open c i r c l e s ) d a y 14 ( c l o s e d c i r c l e s ) . p a t i e n t w e r e e x c l u d e d f r o m t h e s t a t i s t i c a l c o m p a r i s o n , a s t a t i s t i c a l l y s i g n i f i c a n t i n c r e a s e i n ( e x p r e s s e d i n a b s o l u t e t e r m s and p e r u n i t body w e i g h t o r body s u r f a c e a r e a ) was o b t a i n e d a f t e r two-weeks c a p t o p r i l t h e r a p y , as c o m p a r e d t o t h e d a y 1 v a l u e s (p=0.011, p=0.014 and p=0.014, r e s p e c t i v e l y ) . 3.5. C h a n g e s i n B l o o d P r e s s u r e and H e a r t R a t e B a s e l i n e ( p r e t r e a t m e n t ) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e (MAP) and h e a r t r a t e were r e c o r d e d on b o t h s t u d y d a y s a f t e r t h e p a t i e n t a r r i v a l t o t h e h o s p i t a l ( a v e r a g e t i m e ± SD, n=12 8:20 am ± 25 m i n u t e s ) i n s e a t e d p o s i t i o n (mean t i m e o f s i t t i n g ± SD, n=12 66.9 ± 22.5 m i n u t e s ) b e f o r e any t r e a t m e n t was a p p l i e d . The mean (± SEM, n=6) b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , MAP and h e a r t r a t e o b t a i n e d on day 1 were f o u n d t o be 160.5 ± 5.3, 103.3 ± SEM, 118.0 ± 3.0 and 72.6 ± 4.1 mm Hg, r e s p e c t i v e l y ( T a b l e 3 ) . I n o r d e r t o e v a l u a t e t h e a c u t e e f f e c t s o f t h e i n i t i a l ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f two-weeks c a p t o p r i l t h e r a p y on b l o o d p r e s s u r e and h e a r t r a t e c o m p a r i s o n s were made between t h e b a s e l i n e m e a s u r e m e n t s ( p r e t r e a t m e n t , d a y 1 and t r e a t e d , d a y 14) and t h o s e r e c o r d e d 1 and 3 h o u r s f o l l o w i n g t h e a d m i n i s t r a t i o n o f c a p t o p r i l . The e f f e c t s o f s h o r t - t e r m c a p t o p r i l t h e r a p y on b l o o d p r e s s u r e and h e a r t r a t e w e r e e v a l u a t e d by c o m p a r i n g t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e v a l u e s o b t a i n e d on d a y 14 t o t h e p r e - t r e a t m e n t b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e d a t a o f d a y 1. 3.5.1. E f f e c t s o f P o s t u r a l Change on B l o o d P r e s s u r e and H e a r t R a t e F i g u r e 16 and F i g u r e 17 show t h e c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , r e s p e c t i v e l y , d u r i n g d a y 1 and 14. T h e r e was no s i g n i f i c a n t c h a n g e i n mean s y s t o l i c b l o o d p r e s s u r e b e f o r e c a p t o p r i l t r e a t m e n t . A s l i g h t b u t n o t s i g n i f i c a n t i n c r e a s e i n mean d i a s t o l i c b l o o d p r e s s u r e (~ 5-7 mm Hg) was o b s e r v e d d u r i n g s t a n d i n g , as compared t o t h e s e a t e d v a l u e s . F i g u r e 18 shows t h a t mean (± SEM, n=6) h e a r t r a t e i n c r e a s e d b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t f r o m 73 ± 4 t o 77 ± 5 b e a t s / m i n u t e s and f r o m 71 ± 4 t o 77 ± 4 b e a t s / m i n u t e s upon s t a n d i n g . The i n c r e a s e i n h e a r t r a t e d u r i n g t h e u p r i g h t p o s i t i o n was s t a t i s t i c a l l y s i g n i f i c a n t on b o t h s t u d y d a y s (p < 0.025 and p < 0.025 f o r d a y 1 and day 14, r e s p e c t i v e l y , p a i r e d t t e s t ) . 3.5.2. A c u t e E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e and H e a r t R a t e The c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l c a p t o p r i l d o s e ( d a y 1) o f t h e s i x p a t i e n t s a r e shown i n T a b l e 11, F i g u r e 19, r e s p e c t i v e l y . I n e x a m i n i n g t h e i n d i v i d u a l b l o o d p r e s s u r e c h a n g e s i n t h e s i x p a t i e n t s i t i s a p p a r e n t t h a t s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e d e c r e a s e d i n t h e r a n g e f r o m -7.0 t o -53 mm Hg and f r o m -9.5 t o -28.8 mm Hg, r e s p e c t i v e l y , 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l c a p t o p r i l d o s e i n f i v e o f t h e s i x p a t i e n t s s t u d i e d . In one p a t i e n t (B.H.) an e x t e n s i v e f a l l i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s was n o t e d 1 h o u r a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l ( 53.0 and 28.8 mm Hg, r e s p e c t i v e l y ) . Mean s y s t o l i c , as w e l l as d i a s t o l i c b l o o d p r e s s u r e s were f u r t h e r d e c r e a s e d 3 h o u r s a f t e r c a p t o p r i l d o s i n g , h o w e v e r , t h e a b s o l u t e d e c r e a s e f r o m b a s e l i n e F i g u r e 16. S y s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c a p t o p r i l (CA) day 1 and d a y 14. T i m e ( h o u r s ) F i g u r e 17. D i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c a p t o p r i l (CA) on day 1 and d a y 14. 90.00 n -s 80.00-70.00-60.00-50.00 s i + up s2 DAY 1 CA s i -1 1— up s2 DAY 14 CA F i g u r e 18. H e a r t r a t e (mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n and p o s t - c a p t o p r i l (CA) on d a y 1 and day 14. * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , p a i r e d s a m p l e t - t e s t , p < 0.05. T a b l e 11. Change i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s I N I T I A L DGSE EFFECT ( DAY 1 ) P a t i e n t P r e -t r e a t m e n t b a s e l i n e A f t e 1 Hr r CA 3 Hr D i f f e r e n c e f r o m b a s e l i n e 1 Hr 3 Hr % change f r o m b a s e l i n e 1 Hr 3 Hr ( mm Hg ) MO S D 162.3 102.3 146.0 82.0 129.0 78.0 -16.3 -20.3 -33.3 -24.3 - 1 0 . 1 % - 1 9 . 9 % - 2 0 . 5 % -23.8% OW S D 181.5 103.0 174.5 105.5 165.0 107.5 -7.0 2.5 -16.5 4.5 - 3 . 9 % 2.4% - 9 . 1 % 4.4% MS S D 145.0 104.0 128.0 90.5 129.5 85.0 -17.0 -13.5 -15.5 -19.0 - 1 1 . 7 % - 1 3 . 0 % -10.7% - 1 8 . 3 % BH S D 151.5 104.3 98.5 75.5 94.3 63.0 -53.0 -28.8 -57.2 -41.3 - 3 5 . 0 % - 2 7 . 6 % -37.7 -39.6% DA S D 154.6 106.5 139.0 97.0 140.0 97.0 -15.7 -9.5 -14.7 -9.5 - 1 0 . 1 % - 8 . 9 % - 9 . 5 % - 8 . 9 % CB S D 167.8 99.5 147.5 88.5 136.3 89.3 -20.3 -11.0 -31.4 -11.1 - 1 2 . 1 % - 1 1 . 1 % - 1 8 . 7 % -10.2% CA c a p t o p r i l S s y s t o l i c b l o o d p r e s s u r e D d i a s t o l i c b l o o d p r e s s u r e F i g u r e 19. Changes i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l ( d a y 1) i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . was n o t g r e a t e r t h a n a f t e r 1 h o u r o f c a p t o p r i l d o s i n g i n two p a t i e n t s (D.A. and M.S.). The a b s o l u t e d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 3 h o u r s a f t e r t h e i n i t i a l c a p t o p r i l d o s e were i n t h e r a n g e f r o m 14.7 t o 57.2 mm Hg and f r o m 9.5 t o 41.3 mm Hg, r e s p e c t i v e l y , f o r t h e s i x p a t i e n t s . In t h e c a s e o f (O.W.) no d e c r e a s e i n d i a s t o l i c b l o o d p r e s s u r e was n o t e d 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o r i l . The r e s u l t s o f t h e c h a n g e s i n mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , mean a r t e r i a l p r e s s u r e and h e a r t r a t e a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l a r e s u m m a r i z e d i n T a b l e 12. S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s d e c r e a s e d f r o m 160.5 ± 5.3 t o 138.9 ± 10.2 mm Hg and f r o m 103.3 ± 1.0 t o 89.8 ± 6.3 mm Hg, r e s p e c t i v e l y , 1 h o u r a f t e r t h e f i r s t d o s e o f c a p t o p r i l . S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were f u r t h e r d e c r e a s e d w i t h a n a d i r 3 h o u r s a f t e r c a p t o p r i l (132.4 ± 9.3 and 86.6 ± 6.3 mm Hg, r e s p e c t i v e l y ) . F i g u r e 20 shows t h a t 1 and 3 h o u r s a f t e r t h e i n i t i a l c a p t o p r i l d o s e t h e a b s o l u t e d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s (mean ± SEM, n=6) was -21.5 ± 6.5 mm Hg o r 13.4% (p < 0.025, p a i r e d s a m p l e t - t e s t ) and -28.1 ± 6.7 mm Hg o r 1 7 . 5 % (p < 0.005, p a i r e d s a m p l e t - t e s t ) f o r s y s t o l i c and -13.4 ± 4.3 mm Hg o r 1 3 . 0 % (p < 0.025, p a i r e d s a m p l e t - t e s t ) and -16.6 ± 6.4 mm Hg o r 1 6 . 1 % (p < 0.025, p a i r e d s a m p l e t - t e s t , f o r d i a s t o l i c b l o o d p r e s s u r e , r e s p e c t i v e l y , as compared t o b a s e l i n e v a l u e . The c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 1 and 3 h o u r s a f t e r t h e t e r m i n a l c a p t o p r i l d o s e ( d a y 14) o f t h e s i x p a t i e n t s a r e shown i n T a b l e 13, F i g u r e 2 1 , r e s p e c t i v e l y . In one p a t i e n t (O.W.) t h e r e was no d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 1 h o u r a f t e r t h e t e r m i n a l c a p t o p r i l d o s e . The a b s o l u t e r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s f o r t h e s i x p a t i e n t were i n t h e r a n g e f r o m -2.2 t o -13.5 mm Hg T a b l e 12. C h a n g e s i n mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n . I N I T I A L DOSE EFFECT ( DAY 1) A f t e r CA D i f f e r e n c e f r o m b a s e l i n e B a s e l i n e ^ 1 Hr 3 Hr 1 Hr 3 Hr S y s t o l i c BP (mm Hg) 160.5±5. .3 138, .9±10.2 132 .4±9 .3 - 2 1 . 5 ± 6 - 1 3 . 4 % . 5 * - 2 8 . 1 ± 6 . 7 * * - 1 7 . 5 % D i a s t o l i c BP (mm Hg) 1 0 3 . 3 ± 1 . .0 89, .8±4.3 8 6 .6±6 .3 - 1 3 . 4 ± 4 - 1 3 . 0 % . 3 * - 1 6 . 6 ± 6 . 4 * - 1 6 . 1 % MAP^ (mm Hg) 118.0±3. .0 104. .9±5.4 101 .0±6 .6 - 1 3 . 1 ± 4 - 1 1 . 1 % .3 - 1 7 . 0 ± 4 . 9 - 1 4 . 4 % H e a r t r a t e ( b e a t s / m i n ) 72.6±4. .1 72, .2±4.5 73 .6±3 .5 - 0 . 4 ± 1 - 0 . 5 % QNS 1.011.3^5 1.4% CA c a p t o p r i l SEM s t a n d a r d e r r o r o f t h e mean U n t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e w e r e o b t a i n e d i n s i t t i n g p o s i t i o n on day 1 a f t e r t h e p a t i e n t s ' a r r i v a l a t t h e h o s p i t a l . T r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e were o b t a i n e d i n s i t t i n g p o s i t i o n on day 14 a f t e r t h e p a t i e n t s ' r e t u r n t o t h e h o s p i t a l . no s t a t i s t i c a l c o m p a r i s o n s were made f o r MAP d a t a s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 0 5 ) , compared t o b a s e l i n e , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 5 ) , compared t o b a s e l i n e , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y n o t s i g n i f i c a n t (p > 0 . 5 ) , c ompared t o b a s e l i n e , p a i r e d s a m p l e t - t e s t INITIAL DOSE EFFECT 0.00 -5.00 -10.00 -15.00 -20.00 -25.00 -30.00 -35.00 Systolic Diastolic I S 3 1 h after CA ^ 3 h after CA l A J F i g u r e 20. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6), as compared t o t h e p r e t r e a t m e n t v a l u e s , 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l . * and * * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . T a b l e 13. Change i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s TERMINAL DOSE EFFECT ( DAY H ) P a t i e n t • T r e a t e d B a s e l i n e A f t e 1 H r r CA 3 Hr D i f f e r e n c e f r o m b a s e l i n e 1 Hr 3 Hr % c h a n g e f r o m b a s e l i n e 1 Hr 3 Hr ( mm Hg ) MO S D 161.0 102.7 147.7 103.0 138.7 94.3 -13.3 0.3 -22.3 -8.3 - 8 . 3 % -13.9% 0.3% - 8 . 1 % OW S D 161.7 94.1 169.3 101.0 149.0 91.7 7.6 6.9 -12.7 -2.5 4.7% - 7 . 9 % 7.3% - 2 . 6 % MS S D 130.8 92.8 123.5 91.0 112.5 77.5 -7.3 -1.8 -18.3 -15.3 - 5 . 5 % -14.0% - 1 . 9 % -16.4% BH S D 134.2 86.4 125.0 86.5 122.5 80.0 -9.2 0.1 -11.7 -6.4 - 6 . 9 % - 8.7% 0.1% -7.4% DA S D 128.7 88.3 126.5 86.5 127.0 84.0 -2.2 -1.8 -1.7 -4.3 - 1 . 7 % - 1 . 3 % - 2 . 1 % - 4 . 9 % CB S D 156.8 92.5 143.3 82.0 123.0 69.5 -13.5 -10.5 -33.8 -23.0 - 8 . 6 % - 2 1 . 5 % - 1 1 . 4 % -24.9% CA c a p t o p r i l S s y s t o l i c b l o o d p r e s s u r e D d i a s t o l i c b l o o d p r e s s u r e F i g u r e 2 1 . Changes i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l ( d a y H ) i n s i x m i I d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . ( 1 . 7 - 8 . 6 % ) and f r o m -1.8 t o -10.5 mm Hg ( 1 . 9 - 1 1 . 4 % ) , r e s p e c t i v e l y , a f t e r 1 h o u r and f r o m -1.7 t o 33.8 mm Hg ( 1 . 3 - 2 1 . 5 % ) and f r o m -2.5 t o -23.0 mm Hg ( 2 . 6 - 2 4 . 9 % ) , r e s p e c t i v e l y , a f t e r 3 h o u r s o f c a p t o p r i l a d m i n i s t r a t i o n , as com p a r e d t o t h e b a s e l i n e b l o o d p r e s s u r e o f d a y 14. T a b l e 14 s u m m a r i z e s t h e c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , mean a r t e r i a l p r e s s u r e and h e a r t r a t e (mean ± SEM, n=6) as com p a r e d t o t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e o f day 14. The mean (± SEM, n=6) d i f f e r e n c e s o r r e l a t i v e c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 1 and 3 h o u r s f o l l o w i n g t h e t e r m i n a l c a p t o p r i l d o s e were -6.3 ± 7.3 mm Hg o r 4.3% and -16.7 ± 9.9 mm Hg o r 1 1 . 5 % f o r s y s t o l i c and -1.1 ± 2.3 mm Hg o r 1.2% and -10.0 ± 3.2 mm Hg o r 1 0 . 7 % f o r d i a s t o l i c b l o o d p r e s s u r e , r e s p e c t i v e l y , as c o m p a r e d t o t h e t r e a t e d b a s e l i n e o f d a y 14. The d e c r e a s e i n b l o o d p r e s s u r e 1 h o u r a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l was s t a t i s t i c a l l y n o t s i g n i f i c a n t , as co m p a r e d t o t h e t r e a t e d b a s e l i n e v a l u e s , h o w e v e r , t h e d e c r e a s e i n b l o o d p r e s s u r e r e a c h e d t h e l e v e l o f s i g n i f i c a n c e 3 h o u r s f o l l o w i n g c a p t o p r i l d o s i n g (p < 0.05, p a i r e d s a m p l e t - t e s t ) ( F i g u r e 2 2 ) . The c h a n g e s i n mean a r t e r i a l p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f c a p t o p r i l f o r s i x p a t i e n t s a r e p r e s e n t e d i n F i g u r e 2 3 . F i g u r e 24 shows t h a t h e a r t r a t e d i d n o t c h a n g e o r s l i g h t l y i n c r e a s e d 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l i n t h e s i x p a t i e n t s s t u d i e d , as c ompared t o t h e c o n t r o l v a l u e s ( b a s e l i n e , d a y 1 ) . However, 3 h o u r s a f t e r t h e t e r m i n a l c a p t o p r i l d o s e h e a r t r a t e d e c r e a s e d i n f o u r o f t h e s i x p a t i e n t s s t u d i e d ( r a n g e f r o m 3 t o 6 b e a t s / m i n u t e s ) and i n c r e a s e d i n two p a t i e n t s by 2 and 8 b e a t s / m i n u t e s . T h e r e was no s i g n i f i c a n t c h a n g e i n h e a r t r a t e (mean ± SEM, n=6) 1 and 3 h o u r s f o l l o w i n g t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l T a b l e 14. Changes i n mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n TERMINAL DOSE EFFECT (DAY 14) A f t e r CA D i f f e r e n c e f r o m T r e a t e d b a s e l i n e B a s e l i n e ' ^ 1 Hr 3 Hr 1 Hr 3 Hr S y s t o l i c BP (mm Hg) 145 .5±14.5 139, .2±16.4 128 .8±11.9 -6.3±7, - 4 . 3 % 3NS -16.7±9.9* - 1 1 . 5 % D i a s t o l i c BP (mm Hg) 92 .8±2.3 91, .7±3.5 82 .8±3.8 -1.1±2, - 1 . 2 % .3NS -10.0±3.2* - 1 0 . 7 % MAp3 (mm Hg) 111 .0±2.6 104, .5±5.1 97, .3+3.3 -6.4±3, - 5 . 8 % .1 -13.7±2.9 - 1 2 . 3 % H e a r t r a t e ( b e a t s / m i n ) 71 .0±3.2 69. .2+3.7 69, ,8±3.5 -1.8±1, - 2 . 5 % 3NS -1.2±2.1^S -1 . 7 % CA c a p t o p r i l SEM s t a n d a r d e r r o r o f t h e mean MAP mean a r t e r i a l p r e s s u r e U n t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e w e r e o b t a i n e d i n s i t t i n g p o s i t i o n on d a y 1 a f t e r t h e p a t i e n t s ' a r r i v a l a t t h e h o s p i t a l . T r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e w e r e o b t a i n e d i n s i t t i n g p o s i t i o n on d a y 14 a f t e r t h e p a t i e n t s ' r e t u r n t o t h e h o s p i t a l . no s t a t i s t i c a l c o m p a r i s o n s w e r e made f o r MAP d a t a s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 , 0 0 5 ) , c o m p a r e d t o b a s e l i n e , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 5 ) , c o m p a r e d t o b a s e l i n e , p a i r e d s a m p l e t - t e s t s t a t i s t i c a l l y n o t s i g n i f i c a n t (p > 0 . 5 ) , c o m p a r e d t o b a s e l i n e , p a i r e d s a m p l e t - t e s t TERMINAL DOSE EFFECT 0.00 -5 .00---10.00--•15.00--•20.00--25.00--30.00--35.00--Systolic Diastolic Day 14 ISS [X] 1 h after CA 3 h after CA 22. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6), as compared t o t h e t r e a t e d b a s e l i n e o f d a y 14, 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l . * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05. ,50 T D A Y U O) X E E 9 O •c o t: o c • 130-110-90-70 -o O.W. M.O. -*M.S. -oB.H. -• D.A. -o C.B. BASELINE 1 HR AFTER CA 3 HR AFTER CA F i g u r e 23. Changes i n mean a r t e r i a l p r e s s u r e 1 and 3 h o u r s a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l ( d a y 14) d o s e o f c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . F i g u r e 24. Changes i n h e a r t r a t e 1 and 3 h o u r s a f t e r t h e i n i t i a l ( d a y 1) a -t e r m i n a l ( d a y 14) d o s e c a p t o p r i l i n s i x m i l d / m o d e r a t e h y p e r t e n s i . ^ p a t i e n t s . ( T a b l e 12 and 1 4 ) . 3.5.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e and H e a r t R a t e The e f f e c t s o f s h o r t - t e r m c a p t o p r i l t h e r a p y on b l o o d p r e s s u r e and h e a r t r a t e w e r e e v a l u a t e d by c o m p a r i n g t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e ( d a y 14) t o t h e p r e t r e a t m e n t b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e o f day 1. T a b l e 15 shows t h a t s y s t o l i c , as w e l l a s , d i a s t o l i c b l o o d p r e s s u r e s were l o w e r i n f i v e o f t h e s i x p a t i e n t s s t u d i e d , as co m p a r e d t o p r e t r e a t m e n t b l o o d p r e s s u r e , when t h e y r e t u r n e d t o t h e h o s p i t a l a f t e r 14 d a y s c a p t o p r i l t h e r a p y . The b a s e l i n e b l o o d p r e s s u r e r e c o r d i n g s on day 14 w e r e p e r f o r m e d a b o u t 20 h o u r s a f t e r t h e l a s t c a p t o p r i l d o s i n g . The t r e a t e d b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were l o w e r t h a n t h e p r e t r e a t m e n t b l o o d p r e s s u r e , i n t h e r a n g e f r o m -1.3 t o -26 mm Hg f o r s y s t o l i c and f r o m -7.0 t o -18.2 mm Hg f o r d i a s t o l i c b l o o d p r e s s u r e . I n one p a t i e n t (M.O.) t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e was s i m i l a r t o t h e p r e t r e a t m e n t b a s e l i n e b l o o d p r e s s u r e . The B l a c k p a t i e n t (O.W.) r e s p o n d e d s i m i l a r l y t o s h o r t - t e r m c a p t o p r i l t r e a t m e n t a s t h e C a u c a s i a n s u b j e c t s . When i n d i v i d u a l s y s t o l i c b l o o d p r e s s u r e s , r e c o r d e d a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , were c o m p a r e d t o t h e p r e t r e a t m e n t b a s e l i n e v a l u e s t h e a b s o l u t e d e c r e a s e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were i n t h e r a n g e f r o m -14.2 t o -28.2 mm Hg and -2.0 t o -20.0 mm Hg, r e s p e c t i v e l y , a f t e r 1 h o u r and f r o m -23.7 t o -44.8 mm Hg and -8.0 t o -30.0 mm Hg a f t e r 3 h o u r s o f c a p t o p r i l a d m i n i s t r a t i o n . T a b l e 16 shows t h a t mean (± SEM, n=6) t r e a t e d b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , r e c o r d e d on d a y 14, were s i g n i f i c a n t l y l o w e r t h a n p r e t r e a t m e n t v a l u e s by -14.9 ± 7.7 mm Hg ( 9 . 3 % , p < 0.005, p a i r e d s a m p l e t-T a b l e 15. D e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as c o m p a r e d t o t h e p r e t r e a t m e n t b a s e l i n e i n s i x m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s SHORT-TERM EFFECT P a t i e n t D i f f e r e n c e f r o m b a s e l i n e ( d a y 1) % c h a n g e f r o m b a s e l i n e 1 Hr 3 Hr T r e a t e d B a s e l i n e A f t e r 1 Hr CA 3 H r ( mm Hg ) MO S -1.3 -14.7 -23.7 - 9 . 0 % - 1 4 . 6 % D 0.3 0.7 -8.0 0.7% - 7 . 8 % OW S -19.7 -12.2 -32.5 - 6 . 7 % - 1 7 . 9 % D -8.9 -2.0 -11.3 - 1 . 9 % - 1 1 . 0 % MS S -14.2 -21.5 -32.5 - 1 4 . 8 % -22.4% D -11.3 -13.0 -26.5 - 1 2 . 5 % - 2 5 . 5 % BH S -17.3 -26.5 -29.0 - 1 7 . 5 % - 1 9 . 1 % D -17.8 -17.8 -24.3 - 1 7 . 0 % - 2 3 . 3 % DA S -26.0 -28.2 -27.7 - 1 8 . 2 % - 1 7 . 9 % D -18.2 -20.0 -22.5 - 1 8 . 8 % - 2 1 . 1 % CB S -11.0 -24.5 -44.8 - 1 4 . 6 % - 2 6 . 7 % D -7.0 -17.5 -30.0 - 1 7 . 6 % - 3 0 . 2 % CA c a p t o p r i l S s y s t o l i c b l o o d p r e s s u r e D d i a s t o l i c b l o o d p r e s s u r e T a b l e 16. C o m p a r i s o n o f mean (± SEM, n=6) s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , mean a r t e r i a l p r e s s u r e and h e a r t r a t e o b t a i n e d a f t e r two-weeks c a p t o p r i l t r e a t m e n t w i t h t h e u n t r e a t e d v a l u e o f d a y 1. SHORT-TERM EFFECT D i f f e r e n c e f r o m b a s e l i n e ^ ( d a y 1) T r e a t e d ^ B a s e l i n e 1 Hr A f t e r CA 3 Hr S y s t o l i c BP -14.9 ± 7 -21.3 ± 5.9** -31.7 ± 6. .6** (mm Hg) - 9.3% - 1 3 . 2 % - 1 9 . 7 % D i a s t o l i c BP -10.5 ± 6 .4* -11.6 ± 8.0* -20.4 ± 8. .0** (mm Hg) - 1 0 . 1 % - 1 1 . 2 % - 1 9 . 8 % MAP - 7.0 ± 4 .1 -13.4 ± 5.2 -20.7 ± 2. .7 (mm Hg) - 1 1 . 4 % - 1 7 . 5 % - 5.9% H e a r t r a t e - 1.6 ± 1 .3 - 3.4 ± 0.9 - 2.8 ± 1, .6^5 ( b e a t s / m i n ) - 4.7% - 3.9% - 2.3% CA c a p t o p r i l SEM s t a n d a r d e r r o r o f t h e mean MAP mean a r t e r i a l p r e s s u r e U n t r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e w e r e o b t a i n e d i n s i t t i n g p o s i t i o n on d a y 1 a f t e r t h e p a t i e n t s ' a r r i v a l a t t h e h o s p i t a l . T r e a t e d b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e w e r e o b t a i n e d i n s i t t i n g p o s i t i o n on d a y 14 a f t e r t h e p a t i e n t s ' r e t u r n t o t h e h o s p i t a l . A l l d i f f e r e n c e s w e r e c a l c u l a t e d by s u b t r a c t i n g mean b a s e l i n e b l o o d p r e s s u r e and h e a r t r a t e f r o m t h e a p p r o p r i a t e mean v a l u e s o f d a y 14. S t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 0 5 ) , c o m p a r e d t o p r e t r e a t m e n t b a s e l i n e , p a i r e d s a m p l e t - t e s t . S t a t i s t i c a l l y s i g n i f i c a n t (p < 0 . 0 5 ) , c o m p a r e d t o p r e t r e a t m e n t b a s e l i n e , p a i r e d s a m p l e t - t e s t . t e s t ) and by -10.5 ± 6.4 mm Hg ( 1 0 . 1 % , p < 0.01, p a i r e d s a m p l e t - t e s t ) , r e s p e c t i v e l y . T r e a t e d b a s e l i n e MAP was l o w e r t h a n day 1 b a s e l i n e by 11.4%. The a b s o l u t e d e c r e a s e (± SEM, n=6) i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s a f t e r t h e t e r m i n a l d o s e o f two-weeks c a p t o p r i l t h e r a p y w e r e -21.3 ± 5.9 mm Hg ( 1 3 . 2 % ) and -11.6 ± 8.0 mm Hg ( 1 1 . 2 % ) , r e s p e c t i v e l y , a f t e r 1 h o u r and -31.7 ± 6.6 mm Hg ( 1 9 . 7 % ) and -20.4 ± 8.0 mm Hg ( 1 9 . 8 % ) a f t e r 3 h o u r s , r e s p e c t i v e l y . The d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f two-weeks c a p t o p r i l t h e r a p y were s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.005 f o r b o t h b l o o d p r e s s u r e s , p a i r e d s a m p l e t - t e s t ) . The a b s o l u t e d e c r e a s e (± SEM, n=6) i n h e a r t r a t e was -2.8 ± 1 . 6 ( 2 . 3 % ) b e a t s / m i n u t e s 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , as c o m p a r e d t o t h e p r e t r e a t m e n t v a l u e s . T h i s d e c r e a s e i n h e a r t r a t e was s t a t i s t i c a l l y n o t s i g n i f i c a n t , as d e t e r m i n e d by p a i r e d s a m p l e t - t e s t . F i g u r e s 25 and F i g u r e 26 s u m m a r i z e t h e o v e r a l l c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , r e s p e c t i v e l y , d u r i n g t h e two-weeks c a p t o p r i l t h e r a p y . T h e r e was a g r e a t e r a b s o l u t e d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s a f t e r 3 h o u r s t h a n a f t e r 1 h o u r o f t h e a d m i n i s t r a t i o n o f t h e i n i t i a l o r t e r m i n a l d o s e o f c a p t o p r i l , as c ompared t o p r e t r e a t m e n t v a l u e s (-22 vs -28 mm Hg and -21 vs 32 mm Hg f o r s y s t o l i c b l o o d p r e s s u r e and -13 vs -17 mm Hg and -12 vs -20 mm Hg f o r d i a s t o l i c b l o o d p r e s s u r e , r e s p e c t i v e l y ) . However, t h e a b s o l u t e o f d e c r e a s e i n s y s t o l i c b l o o d p r e s s u r e f r o m b a s e l i n e , 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l was s i m i l a r t o t h a t o b s e r v e d 1 and 3 h o u r s a f t e r t h e i n i t i a l d o s e (-21 vs -22 mm Hg and -32 vs -28 mm Hg, r e s p e c t i v e l y ) . S i m i l a r l y , t h e e x t e n t o f r e d u c t i o n i n d i a s t o l i c b l o o d p r e s s u r e 1 and 3 h o u r s f o l l o w i n g t h e t e r m i n a l and i n i t i a l d o s e o f c a p t o p r i l w e r e s i m i l a r , as compared t o t h e p r e t r e a t m e n t v a l u e s (-12 vs -13 mm Hg and -20 v s -17 mm Hg, r e s p e c t i v e l y ) . F i g u r e 25. D e c r e a s e i n s y s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) f r o m p r e t r e a t m e n t v a l u e s a f t e r two-weeks c a p t o p r i l i n m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . * and * * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . F i g u r e 26. D e c r e a s e i n d i a s t o l i c b l o o d p r e s s u r e (mean ± SEM, n=6) f r o m p r e t r e a t m e n t v a l u e s a f t e r two-weeks c a p t o p r i l i n m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . * and * * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m b a s e l i n e , p a i r e d s a m p l e t - t e s t , p < 0.05 and p < 0.005, r e s p e c t i v e l y . F i g u r e 27 shows t h a t t h e r e was a s l i g h t d e c r e a s e i n h e a r t r a t e when t r e a t e d b a s e l i n e h e a r t r a t e , m easured on d a y 14 was c o m p a r e d t o t h e p r e t r e a t m e n t v a l u e s . The mean d i f f e r e n c e (± SEM, n=6) f r o m b a s e l i n e was -1.6 ± 1.3 b e a t s / m i n u t e s , ( 2 . 3 % ) , p < 0.25, p a i r e d s a m p l e t - t e s t ) . T h e r e was, a l s o , a t e n d e n c y f o r a d e c r e a s e i n h e a r t r a t e 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , as compared t o t h e p r e t r e a t m e n t v a l u e s (mean d i f f e r e n c e ± SEM, n=6 -2.8 ± 1.6 b e a t s / m i n u t e s , 2.3%, p < 0.1) p a i r e d s a m p l e t - t e s t ) . 3.6. C h a n g e s i n S p l a n c h n i c V a s c u l a r R e s i s t a n c e 3.6.1. E f f e c t s o f U p r i g h t P o s t u r e T a b l e 17 shows t h e c h a n g e s i n SVR d u r i n g p o s t u r a l c h a n g e f r o m s i t t i n g t o s t a n d i n g b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . Mean SVR (± SEM, n=6) i n c r e a s e d on d a y 1 and 14 upon s t a n d i n g f r o m 6.58 ± 0.54 t o 8.62 ± 0.66 mm H g-sec/ml ( 3 1 . 0 % ) and f r o m 5.34 ± 0.8 t o 7.12 ± 1.09 mm H g - sec/ml ( 3 3 . 3 % ) , r e s p e c t i v e l y . The i n c r e a s e i n SVR o b s e r v e d on d a y 1 was s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.05, p a i r e d s a m p l e t - t e s t ) . However, t h e i n c r e a s e on d a y 14 was s l i g h t l y b e l o w t h e b o r d e r l i n e s i g n i f i c a n c e ( 0 . 0 5 < p < 0.1, p a i r e d s a m p l e t - t e s t ) . A d e c r e a s e i n SVR f r o m 8.62 ± 0.66 t o 6.65 ± 0.27 mm H g.sec/ml on d a y 1 and f r o m 7.12 ± 1.09 t o 5.65 ± 0.98 mm H g . sec/ml on day 14 o c c u r r e d when p a t i e n t s r e a s s u m e d s e a t e d p o s i t i o n ( s 2 ) a f t e r s t a n d i n g . The v a l u e s o f SVR o b t a i n e d i n t h e f i r s t s e a t e d ( s i ) and r e s e a t e d ( s 2 ) p e r i o d s w e r e s i m i l a r ( 6 . 5 8 v s 6.65 mm H g . s e c / m l ) . F i g u r e 28 i l l u s t r a t e s t h e c h a n g e s i n SVR d u r i n g p o s t u r a l c hange b e f o r e and a f t e r c a p t o p r i l t h e r a p y . 80.00 n 75.00-70.00-65.00-60.00 + + + Baseline 1 Hr 3 Hr + + Baseline 1 Hr 3 Hr DAY 1 DAY 14 F i g u r e 27. A c u t e e f f e c t s o f c a p t o p r i l on h e a r t r a t e (mean ± SEM, n=6), 1 and 3 h o u r s a f t e r c a p t o p r i l on day 1 and day 14. T a b l e 17. Changes i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e f r o m s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n d u r i n g p o s t u r a l c h a n g e and b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . S p 1 a n c h n i c ( V a s c u 1 a mm Hg s e c / m l r R e ) s i s t a n c e D A Y 1 D A Y 14 P a t i e n t s i up s2 CA s i up s2 CA OW 6.27 8.04 7.10 7.48 3.99 6.17 4.41 4.54 MO 6.23 8.24 5.93 4.45 4.49 5.71 5.35 4.95 MS 4.83 6.50 6.54 5.64 3.42 4.46 3.56 4.30 BH 6.33 8.96 7.08 5.45 5.64 8.26 7.42 5.72 DA 7.54 10.99 7.32 8.11 6.18 6.76 4.06 4.43 CB 8.29 9.01 5.96 7.59 8.31 11.38 9.14 7.57 Mean ± SEM: 6.58 ±0.54 8.62* ±0.66 6.65 ±0.27 6.46 ±0.66 5.34 ±0.80 7.12 ±1.09 5.65 ±0.98 5.25 ±0.56 % c h a n g e u p r i g h t ^ 31.0 33.3 % c h a n g e d a y •18.8 -17.4 -15.0 -23.0 s i d a t a o b t a i n e d i n f i r s t s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d i n 1 h o u r a f t e r c a p t o p r i l d o s i n g SEM s t a n d a r d e r r o r o f t h e mean s t a t i s t i c a l l y s i g n i f i c a n t (p < 0.05) co m p a r e d t o s i , MANOVA % c h a n g e d u r i n g u p r i g h t , as c o m p a r e d t o s i % c h a n g e a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as co m p a r e d t o day 1 v a l u e s 3.6.2. A c u t e E f f e c t s o f C a p t o p r i l on SVR F i g u r e 28 shows t h a t SVR (mean (± SEM, n=6) a f t e r t h e i n i t i a l (CA, day 1) and t e r m i n a l (CA, d a y 14) d o s e o f c a p t o p r i l was s i g n i f i c a n t l y n o t d i f f e r e n t f r o m r e s e a t e d ( s 2 ) v a l u e s (6.46 ± 0.66 v s 6.65 ± 0.27 mm Hg.sec/ml and 5.25 ± 0.56 v s 5.65 ± 0.98 mm H g . s e c / m l , r e s p e c t i v e l y ) . I n e x a m i n i n g t h e i n d i v i d u a l d a t a i n T a b l e 17 o b t a i n e d on d a y 1 i t i s a p p a r e n t , t h a t SVR d i d n o t c h a n g e a f t e r c a p t o p r i l a d m i n i s t r a t i o n i n one p a t i e n t (O.W.) i n c r e a s e d and d e c r e a s e d i n two (D.A. and C.B.) and t h r e e p a t i e n t s (M.O., M.S. and B.H.), r e s p e c t i v e l y , as c o m p a r e d t o t h e r e s e a t e d ( s 2 ) v a l u e s . S i m i l a r l y , on d a y 14 t h e i n d i v i d u a l r e s p o n s e s o f SVR t o t h e t e r m i n a l d o s e o f c a p t o p r i l were v a r i a b l e , as c o m p a r e d t o t h e r e s e a t e d ( s 2 ) v a l u e s . A l s o , F i g u r e 28 shows t h a t t h e r e i s no s i g n i f i c a n t c h a n g e i n SVR (mean ± SEM, n=6) when d a t a o b t a i n e d a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l w e r e c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e s ( 6 . 4 6 ± 0.66 v s 6.58 ± 0.54 mm Hg s e c / m l and 5.25 ± 0.56 v s 5.34 ± 0.8 mm H g . s e c / m l , r e s p e c t i v e l y ) . T h e s e d a t a s u g g e s t no s i g n i f i c a n t c h a n g e s i n t h e r e s i s t a n c e s i t e s o f t h e h e p a t i c v a s c u l a t u r e a f t e r t h e a c u t e d o s e s o f c a p t o p r i l , as compared t o t h e s e a t e d ( s i ) o r r e s e a t e d ( s 2 ) v a l u e s . 3.6.3. S h o r t - t e r m E f f e c t s o f C a p t o p r i l on SVR T a b l e 17 and F i g u r e 28 show t h e c h a n g e s i n SVR a f t e r two-weeks t r e a t m e n t w i t h c a p t o p r i l ( d a y 1 4 ) , as compared t o t h e d a y 1 v a l u e s . I n e x a m i n i n g t h e d a t a o f d a y 1 and 14 o b t a i n e d i n t h e f o u r s t u d y p e r i o d s ( s i , up, s2 and CA) i t i s a p p a r e n t t h a t t h e v a l u e s o f t h e SVR (mean ± SEM, n=6) were l o w e r d u r i n g e a c h m e a s u r e m e n t s o f day 14 t h a n t h o s e o f d a y 1. The m a g n i t u d e o f 1 0 . 0 0 - 1 9 . 0 0 -4 . 0 0 4 1 1 1 1 1 1 1 1 1 1 s i u p s 2 C A s i u p s 2 C A D A Y 1 D A Y 1 4 F i g u r e 28. S p l a n c h n i c v a s c u l a r r e s i s t a n c e (SVR)(mean ± SEM, n=6) i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) p o s i t i o n s and p o s t - c a p t o p r i l (CA) on d a y 1 and day 14. * i n d i c a t e s s i g n i f i c a n t l y d i f f e r e n t f r o m s e a t e d ( s i ) , MANOVA, p < 0.05. t h e d e c r e a s e i n SVR, i n s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - C A (CA) p e r i o d s was 18.8%, 17.4%, 1 5 . 0 3 % and 23.04%, r e s p e c t i v e l y (mean 1 8 . 6 % ) , as c o m p a r e d t o d a y 1. T h i s d e c r e a s e was c o n s i s t e n t i n f i v e o f t h e s i x p a t i e n t s s t u d i e d . The o v e r a l l d e c r e a s e i n SVR a f t e r two-weeks c a p t o p r i l t r e a t m e n t was, h o w e v e r , s t a t i s t i c a l l y n o t d i f f e r e n t f r o m t h e v a l u e s o f day 1 (p = 0.125, MANOVA). 3.7. Serum C o n c e n t r a t i o n D a t a o f C a p t o p r i l Serum c o n c e n t r a t i o n versus t i m e p l o t s o f un c h a n g e d c a p t o p r i l f r o m t h e s i x p a t i e n t s f o r d a y 1 and d a y 14 a r e p r e s e n t e d i n F i g u r e 29. T a b l e 18 p r e s e n t s t h e p h a r m a c o k i n e t i c p a r a m e t e r s o f u n c h a n g e d c a p t o p r i l s u c h a s t h e AUCQ^, t h e pea k serum c o n c e n t r a t i o n s ( C ^ ^ ^ ) ' t h e t i m e t o r e a c h p e a k s e r u m c o n c e n t r a t i o n (t^^g^) t h e ser u m c o n c e n t r a t i o n s o f unchanged c a p t o p r i l a t t h e end o f b l o o d s a m p l i n g ( C p 3 h ) , f r o m s i x p a t i e n t s on day 1 and d a y 14, The mean v a l u e s (± SEM, n=6) and t h e c h a n g e s i n AUCQ^ and C^^^^, e x p r e s s e d i n p e r c e n t a g e , a r e a l s o p r e s e n t e d i n T a b l e 18. The mean serum c o n c e n t r a t i o n versus t i m e p r o f i l e s o f u n c h a n g e d c a p t o p r i l on d a y 1 and day 14 a r e shown i n F i g u r e 3 0 . On d a y 1, mean (± SEM, n=6) Cj^g^ °^ S97.2 ± 192.8 ng/ml was r e a c h e d b e t w e e n 30 and 180 m i n u t e s (mean ± SEM; 75.9 ± 22.2 m i n u t e s ) a f t e r d o s i n g . T h e r e a f t e r , t h e r e was an e x p o n e n t i a l d i s a p p e a r a n c e o f c a p t o p r i l f r o m s e r u m , s o t h a t by t h e end o f 180 m i n u t e s f o l l o w i n g a d m i n i s t r a t i o n o f t h e i n i t i a l d o s e o f c a p t o p r i l , s erum c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l ( Cp3^) was i n t h e r a n g e f r o m 16.4 t o 276.7 n g / m l . The AUCg^ (mean ± SEM, n=6) f o r u n c h a n g e d c a p t o p r i l was 802.73 ± 197.7 ng-h/ml a f t e r a s i n g l e d o s e o f c a p t o p r i l on d a y 1. T h e r e was l a r g e i n t e r i n d i v i d u a l v a r i a b i l i t y i n AUCQ* i n t h e r a n g e f r o m 190.4 t o 1379.5 ng-h/ml (7 f o l d 600.00 T O.W. A A Dayl • • Dayl 4 30 60 90 120 150 180 Time (minutes) 1200.00 1000.00 800.00 600.00 400.00 200.00 0.00 • ;1 \ A A Dayl • • DayU 120 150 180 210 Time (minutes) M.S. A A Dayl • • Dayl 4 a 200.001 / 1000.00 30 60 90 120 150 180 210 Time (minutes) A A Dayl • - - • OayU o 0.00 90 120 150 180 210 Time (minutes) D.A. C.B. 120 150 180 Time (minutes) 210 A A Dayl • - - • DayU 60 90 120 150 180 210 Time (minutes) F i g u r e 29. Serum c o n c e n t r a t i o n versus t i m e p r o f i l e o f u n c h a n g e d c a p t o p r i l f r o m s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n a f t e r t h e i n i t i a l ( d o t t e d l i n e ) and t e r m i n a l d o s e ( s o l i d l i n e ) o f c a p t o p r i l T a b l e 18. The d a t a o f AUCg , C^ax' W x serum c o n c e n t r a t i o n a f t e r 180 m i n u t e s o f d o s i n g ( C p 3 ^ \ o f u n c h a n g e d c a p t o p r i l f o r s i x p a t i e n t s on d a y 1 and d a y 14 AU^O ^max *max ^p3h P a t i e n t ng*h/ml ( n g / m l ) ( m i n u t e s ) ( n g / m l ) OW Day 1 279.0 184.3 37.5 16.4 Day 14 773.6 582.2 64.0 31.3 MO Day 1 190.4 276.7 180.0 276.7 Day 14 910.4 963.2 62.0 58.2 MS Day 1 756.5 588.8 56.5 105.8 Day 14 843.6 748.9 55.5 55.1 BH Day 1 1153.3 866.7 70.5 156.5 Day 14 887.7 785.8 64.0 52.4 DA Day 1 1057.8 776.5 81.0 98.7 Day 14 1187.5 1187.0 31,0 50.7 CB Day 1 1379.5 1490.3 30.0 60.2 Day 14 1236.1 955.7 36.5 62.3 Mean Day 1 ± SEM: 802.7 ±197.7 697.2 ±192.8 75.9 ±22.2 119.1 ±36.8 Mean Day 14 ± SEM 973.1^^5 ±78.1 870.5^^5 ±85.9 52.2 ±6.0 51.7 ±4,4 % i n c r e a s e i n AUCQ^ 21.2 % i n c r e a s e 24.9 SEM s t a n d a r d e r r o r o f t h e mean NS s t a t i s t i c a l l y n o t s i g n i f i c a n t (p > 0.05) compared t o d a y 1, p a i r e d t t e s t F i g u r e 30. Serum c o n c e n t r a t i o n versus t i m e p r o f i l e o f u n c h a n g e d c a p t o p r i l (mean ± SEM, n=6) a f t e r a s i n g l e d o s e (open c i r c l e ) and t h e l a s t d o s e ( c l o s e d c i r c l e ) o f two-weeks c a p t o p r i l t r e a t m e n t . d i f f e r e n c e ) . S i m i l a r l y , C^g^ i^anged f r o m 184.3 t o 1490.3 ng/ml (8 f o l d d i f f e r e n c e ) , w h i c h i n d i c a t e s l a r g e i n t e r i n d i v i d u a l v a r i a t i o n i n t h i s k i n e t i c p a r a m e t e r . On day 14, a f t e r t h e t e r m i n a l c a p t o p r i l d o s e , t h e t i m e c o u r s e o f seru m c o n c e n t r a t i o n f o r u n c h a n g e d c a p t o p r i l was s i m i l a r t o d a y 1, e x c e p t , t h a t C^gj^ o f 870.5 ± 85.9 ng/ml (mean ± SEM, n=6) was o b s e r v e d a t 52.2 ± 2.5 min and was 2 4 . 9 % h i g h e r t h a n on day 1. However, t h i s h i g h e r C^g^ on day 14 was s t a t i s t i c a l l y n o t d i f f e r e n t f r o m t h a t o f d a y 1. The i n d i v i d u a l v a l u e s o f C^gj^ w e r e l e s s v a r i a b l e t h a n on day 1, r a n g e f r o m 582.2 t o 1187.0 ng/ml (2 f o l d d i f f e r e n c e ) . S i m i l a r l y , t h e AUCQ^S o f u n c h a n g e d c a p t o p r i l f o r t h e s i x p a t i e n t s w e r e i n t h e r a n g e f r o m 773.6 t o 1236.1 ng-h/ml (1.6 f o l d d i f f e r e n c e ) , s u g g e s t i n g l e s s i n d i v i d u a l v a r i a b i l i t y i n t h i s k i n e t i c p a r a m e t e r a f t e r two-weeks t r e a t m e n t , as compared t o d a y 1. The AUCQ^ (mean ± SEM, n=6) on day 14 was 973.1 ± 78.1 ng'h/ml w h i c h i s 2 1 . 2 % l a r g e r t h a n on day 1. A d e c r e a s e , r a t h e r t h a n an i n c r e a s e i n AUCg^ was o b s e r v e d i n two p a t i e n t s (B.H. and C . B . ) . Due t o t h i s l a r g e v a r i a t i o n i n t h e r e s p o n s e s o f AUCQ*, t h e o b s e r v e d i n c r e a s e i n AUCQ*, a f t e r 14 d a y s c a p t o p r i l a d m i n i s t r a t i o n , as compared t o t h e d a y 1 v a l u e s , d i d n o t r e a c h t h e l e v e l o f s i g n i f i c a n c e , as d e t e r m i n e d by p a i r e d s a m p l e t - t e s t (p < 0 . 5 ) . A b o u t 180 m i n u t e s f o l l o w i n g t h e a d m i n i s t r a t i o n o f t h e t e r m i n a l d o s e o f c a p t o p r i l ( 1 8 1 . 8 ± 3.4 m i n u t e s , mean ± SEM, n=6), u n c h a n g e d c a p t o p r i l was i n t h e r a n g e f r o m 31.3 t o 62.3 n g / m l ) . 4. DISCUSSION 4.1. S p e c t r o p h o t o m e t r i c A n a l y s i s o f I n d o c y a n i n e G r e e n i n Human Serum U l t r a v i o l e t a b s o r p t i o n s p e c t r o p h o t o m e t r i c methods have been w i d e l y u s e d t o m e a s u r e ICG i n human p l a s m a f o l l o w i n g i n t r a v e n o u s i n j e c t i o n ( S o o n s e t al., 1990; R o bson e t al., 1990; R o c c i e t al., 1989; G r a s e l a e t al., 1987; S v e n s s o n e t al., 1982) ICG p l a s m a c o n c e n t r a t i o n s have t r a d i t i o n a l l y been d e t e r m i n e d by m e a s u r e m e n t s o f a b s o r b a n c e o f u n e x t r a c t e d p l a s m a s a m p l e s a t 8 00-805 nm ( G r a s e l a e t al., 1987; H o l l i n s e t al., 1987; G r a i n g e r e t al., 1 9 8 3 ) . T h i s method i s p a r t i c u l a r l y s u i t a b l e f o r c l i n i c a l s t u d i e s s i n c e i t i s s i m p l e , r a p i d and r e l a t i v e l y s e n s i t i v e . A l t h o u g h a d e q u a t e s e n s i t i v i t y o f t h e a s s a y methods have been shown, t h e i r s p e c i f i c i t y h ave been q u e s t i o n e d , due t o an i n t e r f e r i n g s u b s t a n c e w h i c h a b s o r b s a t t h e same w a v e l e n g t h as t h e p a r e n t compound ( D o r r and P o l l a c k 1989, G r a s e l a e t al., 1987; H e i n t z e t al., 1 9 8 5 ) . I t has been d e m o n s t r a t e d t h a t t h e i n t e r f e r i n g c o m p o u n d ( s ) has l o n g e r e l i m i n a t i o n h a l f - l i f e t h a n ICG, c a u s i n g t h e " f l a t t e n i n g " o f t h e e l i m i n a t i o n p h a s e o f ICG p l a s m a c o n c e n t r a t i o n versus t i m e c u r v e b e y o n d 15 m i n u t e s ( M e i j e r e t al., 1 9 8 8 ) . R e c e n t l y , s e v e r a l h i g h - p e r f o r m a n c e l i q u i d c h r o m a t o g r a p h i c (HPLC) methods were d e v e l o p e d t o i m p r o v e a s s a y s e n s i t i v i t y and s p e c i f i c i t y ( D o r r and P o l l a c k e t al., 1989; R a p p a p o r t and T h i e s s e n , 1982, S v e n s s o n e t al., 1 9 8 2 ) . T h e s e HPLC methods have been d e m o n s t r a t e d t o be a b l e t o d i s t i n g u i s h between t h e i n t e r f e r i n g s u b s t a n c e and p a r e n t dye t h e r e f o r e w e r e shown t o be more s p e c i f i c t h a n t h e s p e c t r o p h o t o m e t r i c method. However, when t h e s p e c t r o p h o t o m e t r i c and HPLC methods f o r m e a s u r i n g ICG i n a n i m a l s p e c i e s ( H e i n t z et al., 1986) and human p l a s m a ( S v e n s s o n et al., 1982) were c o m p a r e d , i t was c o n f i r m e d , t h a t t h e two a n a l y t i c a l methods g a v e s i m i l a r e s t i m a t i o n s o f C l p j Q Q and Qy i f b l o o d s a m p l i n g was l i m i t e d t o 15-20 m i n u t e s . F u r t h e r , G r a s e l a et al., ( 1 9 8 7 ) i n v e s t i g a t e d t h e e f f e c t s o f p o s t u r e and c i m e t i d i n e on Qy i n human s u b j e c t s and compared t h e c h a n g e s i n t h e p h a r m a c o k i n e t i c p a r a m e t e r s o f ICG and Qy by u s i n g b o t h , s p e c t r o p h o t o m e t r i c and HPLC a s s a y m e t h o d s . I t was f o u n d t h a t , a l t h o u g h e s t i m a t e d Qy v a l u e s w e r e c o n s i s t e n t l y l o w e r when ICG was a s s a y e d s p e c t r o p h o t o m e t r i c a l l y , t h e s t a t i s t i c a l i n f e r e n c e s were s i m i l a r r e g a r d l e s s o f t h e a s s a y m e t h o d o l o g y ( G r a s e l a e t al., 1 9 8 7 ) . T h e s e f i n d i n g s were s u b s t a n t i a t e d by t h e s t u d i e s o f Soons e t al., ( 1 9 9 0 ) who f o u n d t h a t d e s p i t e t h e d i f f e r e n c e s i n t h e h a l f - l i f e and v o l u m e o f d i s t r i b u t i o n o f ICG, t h e e f f e c t s o f n i f e d i p i n e on ICG c l e a r a n c e and e s t i m a t e d Qy were s i m i l a r when ICG p l a s m a c o n c e n t r a t i o n s w e r e m e a s u r e d by s p e c t r o p h o t o m e t r i c o r HPLC m e t h o d s . B a s e d on t h e s e o b s e r v a t i o n s and t h e f a c t t h a t t h e p r e s e n t l y a v a i l a b l e , UV d e t e c t o r e q u i p p e d HPLC s y s t e m i n o u r l a b o r a t o r y d i d n o t have t h e a p p r o p r i a t e w a v e l e n g t h (700 nm) t o p e r m i t t h e measurement o f t h e l o w ICG c o n c e n t r a t i o n s i n human p l a s m a (Wang, 1 9 9 1 ) ; t h e r e f o r e , i n t h e p r e s e n t s t u d y , t h e m o d i f i e d s p e c t r o p h o t o m e t r i c method ( C a e s a r e t al., 1961) has been u s e d t o a s s e s s ICG c o n c e n t r a t i o n s i n human p l a s m a . 4.1.1. V a l i d a t i o n o f t h e S p e c t r o p h o t o m e t r i c M e t h o d The s t a b i l i t y o f ICG i s a f f e c t e d by v a r i o u s f a c t o r s s u c h as l i g h t , t e m p e r a t u r e and n a t u r e o f t h e s o l v e n t ( G a t h j e e t al., 1 9 7 0 ) . I t has been shown i n p r e v i o u s s t u d i e s t h a t t h e r a t e o f d e c a y o f t h e s p e c t r a l a b s o r p t i o n o f ICG i n d i s t i l l e d w a t e r was r a p i d a t ICG c o n c e n t r a t i o n o f 1.25 mg/ml and l i g h t e x p o s u r e i n c r e a s e d t h e r a t e o f d e c a y ( G a t h j e et al., 1 9 7 0 ) . A l s o , t h e r a t e o f d e t e r i o r a t i o n i n aqueous s o l u t i o n s o c c u r s more r a p i d l y i n d i l u t e t h a n i n c o n c e n t r a t e d s o l u t i o n s ( F o x , 1 9 6 0 ) . The r e s u l t s o f t h e p r e s e n t s t u d y r e g a r d i n g t h e s t a b i l i t y o f ICG i n d e i o n i z e d w a t e r c o n f i r m s t h e s e f i n d i n g s . The s t a b i l i t y o f ICG i n human p l a s m a i s g r e a t l y i m p r o v e d m a i n l y due t o t h e p r e s e n c e o f a l b u m i n w h i c h f o r m s c o m p l e x e s w i t h t h e l a r g e m o l e c u l e s o f ICG, t h e r e b y p r e v e n t i n g f u r t h e r d e c o m p o s i t i o n ( P a u m g a r t n e r , 1975; G a t h j e et al., 1 9 7 0 ) . A s h i f t i n t h e a b s o r p t i o n s p e c t r u m t o h i g h e r w a v e l e n g t h s f r o m 790 t o 805 nm p r o v i d e s e v i d e n c e t h a t ICG b i n d s t o p l a s m a p r o t e i n s ( m a i n l y a l b u m i n ) ( P a u m g a r t n e r , 1 9 7 5 ) . I n t h e p r e s e n t s t u d y , t h e r a t e o f d e c a y o f ICG i n human s e r u m was v e r y l o w ( F i g u r e 3) a t ICG c o n c e n t r a t i o n s 0.2 and 6.0 [ig/ml d u r i n g t h e o b s e r v a t i o n p e r i o d o f 48 h o u r s . T h i s was i n d i c a t e d by t h e f a c t t h a t t h e s l o p e s o f t h e two r e g r e s s i o n l i n e s w e r e c l o s e t o z e r o . T h e s e r e s u l t s s u g g e s t t h a t ICG i s s t a b l e i n human serum f o r 48 h o u r s when s t o r e d a t -20°C and p r o t e c t e d f r o m l i g h t . A l l p a t i e n t s e r u m s a m p l e s i n t h i s s t u d y were a n a l y z e d w i t h i n 48 h o u r s . The r e s u l t s o f t h e a s s a y v a l i d a t i o n p r o c e d u r e s o f t h e p r e s e n t s t u d y showed a d e q u a t e a c c u r a c y i n t h e q u a n t i t a t i o n o f ICG i n p a t i e n t serum. The i n t e r - d a y c o e f f i c i e n t s o f v a r i a t i o n r a n g e d f r o m 9.8% ( 0 . 2 /ig/ml) and 1.6% ( 5 . 0 /ig/ml) ( T a b l e 2 ) . The i n t r a - d a y c o e f f i c i e n t s o f v a r i a t i o n f o r c o n c e n t r a t i o n s 0.2, 1.0 and 5.0 {ig/ml w e r e 8.4%, 4.9% and 2.1%, r e s p e c t i v e l y . S t a n d a r d c u r v e s were r e p r o d u c i b l e f r o m d a y t o day w i t h c o e f f i c i e n t s o f v a r i a t i o n o f 1.6% f o r t h e s l o p e s ( F i g u r e 4 ) . A l i n e a r r e l a t i o n s h i p between a b s o r b a n c e and c o n c e n t r a t i o n o f ICG i n human b i l e and 0.5% human a l b u m i n was o b s e r v e d o n l y up t o 7.5 /ig/ml and i n human d u o d e n a l f l u i d up t o 5 ng/ml ( B j o r n s s o n et al., 1 9 8 2 ) . I n t h e p r e s e n t s t u d y , a l i n e a r r e l a t i o n s h i p was o b s e r v e d between a b s o r b a n c e and ICG c o n c e n t r a t i o n i n t h e r a n g e f r o m 0.2 t o 5.0 ng/m} ( F i g u r e 6 ) . 4.2. E s t i m a t i o n o f Qy by ICG C l e a r a n c e The e s t i m a t i o n o f Qy u s i n g ICG c l e a r a n c e has been v a l i d a t e d i n b o t h a n i m a l s and humans ( G r a i n g e r et al., 1 9 8 3 ) . A t l o w d o s e s u s e d i n t h i s s t u d y t h e h e p a t i c c l e a r a n c e o f ICG i s l i m i t e d by t h e r a t e o f i t s d e l i v e r y t o t h e l i v e r ( P a u m g a r t n e r , 1 9 7 5 ) . E s t i m a t i o n o f Qy by ICG c l e a r a n c e was b a s e d on c e r t a i n a s s u m p t i o n s ( R o b s o n et al., 1 9 9 0 ) . F i r s t , i t was assumed t h a t no c h a n g e i n t h e h e p a t i c e x t r a c t i o n o f ICG o c c u r r e d d u r i n g t h e s t u d y . Hence, t h e d e t e r m i n e d ICG c l e a r a n c e w o u l d be e x p e c t e d t o r e f l e c t c h a n g e s i n Qy and n o t an a l t e r e d h e p a t i c e x t r a c t i o n r a t i o due t o c a p t o p r i l t h e r a p y . To e s t a b l i s h t h a t c a p t o p r i l d o e s n o t i n t e r f e r e w i t h t h e h e p a t i c e x t r a c t i o n o f ICG r e q u i r e s t h e c a t h e t e r i z a t i o n o f t h e h e p a t i c v e i n . S i n c e , t h i s i s a h i g h l y i n v a s i v e t e c h n i q u e , i t c o u l d n o t be j u s t i f i e d i n t h i s s t u d y ( S o o n s et al., 1 9 9 0 ) . However, d i r e c t m e a s u r e m e n t s o f t h e h e p a t i c e x t r a c t i o n o f ICG have shown no c h a n g e s a f t e r s i n g l e o r a l d o s e s o f c a p t o p r i l i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n ( C r o s s l e y et al., 1 9 8 4 ) , o r l i v e r c i r r h o s i s ( E r i k s s o n et al., 1 9 8 4 ) . F u r t h e r , t h e a s s u m p t i o n o f 1 0 0 % h e p a t i c e x t r a c t i o n o f ICG has been f r e q u e n t l y made, p a r t i c u l a r l y i n t h o s e s t u d i e s w h i c h m e a s u r e d r e l a t i v e c h a n g e s i n Qy ( S o o n s et al., 1990; Modi et al., 1 9 8 8 ) . However, h e p a t i c e x t r a c t i o n r a t i o i n h e a l t h y s u b j e c t s has been f o u n d t o be i n t h e r a n g e f r o m 0.70 t o 0.78 (Wynne et al., 1990; C e a s a r e t al., 1961; C r o s s l e y e t al., 1984; G r a i n g e r e t al., 1 9 8 3 ) . S i n c e , i n t h e p r e s e n t s t u d y t h e ICG c l e a r a n c e method was u s e d t o e s t i m a t e r e l a t i v e c h a n g e s i n Qy, t h e h e p a t i c e x t r a c t i o n r a t i o was c o n s i d e r e d t o be 1 ( S o o n s et al., 1 9 9 0 ) . S e c o n d , i t was assumed t h a t ICG r a p i d l y d i s t r i b u t e d i n t o t h e p l a s m a c o m p a r t m e n t where i t c o m p l e t e l y bound t o p l a s m a p r o t e i n s . T h i s has been p r e v i o u s l y d e m o n s t r a t e d by C h e r r i c k et al., ( 1 9 6 0 ) i n n o r m a l s u b j e c t s . I n humans, t h e r e s t i n g t o t a l l i v e r b l o o d f l o w i s a b o u t 800-1200 m l / m i n ( R i c h a r d s o n and W i t h r i n g t o n , 1 9 8 1 ) . G e o r g e , ( 1 9 7 9 ) r e p o r t e d v a l u e s i n t h e r a n g e f r o m 1090-1790 m l / m i n i n h e a l t h y man. I n e s s e n t i a l h y p e r t e n s i o n and i n p a t i e n t s w i t h r e n a l a r t e r y s t e n o s i s was s i g n i f i c a n t l y l o w e r by - 1 0 % and - 1 6 % , r e s p e c t i v e l y , t h a n i n c o n t r o l s u b j e c t s ( M e s s e r l i et al., 1 9 7 5 ) . Daneshmend et al., ( 1 9 8 1 ) n o t e d o f 1214 ± 146 ml/ m i n i n h e a l t h y s u b j e c t s a s s e s s e d by ICG c l e a r a n c e . C r o s s l e y et al., ( 1 9 8 4 ) r e p o r t e d (± SEM) o f 1127 ± 115 m l / m i n i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n u s i n g t h e ICG c l e a r a n c e m e t h o d . I n t h e p r e s e n t s t u d y , p r e t r e a t m e n t (± SEM, n = 6) was 1114 ± 74 m l / m i n w h i c h i s c o m p a t i b l e w i t h t h e v a l u e s r e p o r t e d i n p r e v i o u s s t u d i e s . When t h e a b s o l u t e v a l u e was e x p r e s s e d p e r u n i t body w e i g h t o r body s u r f a c e a r e a , r e s t i n g b a s e l i n e (± SEM) v a l u e s were 11.8 ± 0.6 m l / m i n / k g and 517.8 ± 27.2 ml/min/m^, r e s p e c t i v e l y ( T a b l e 9 ) . 4.3. Serum C o n c e n t r a t i o n D a t a o f ICG Serum c o n c e n t r a t i o n versus t i m e d a t a o f ICG w e r e f i t by t h e c o m p u t e r p r o g r a m AUTOAN (Sedman and Wagner, 1976) and t h e k i n e t i c p a r a m e t e r s and t h e p h a r m a c o k i n e t i c model o b t a i n e d . The d i s a p p e a r a n c e o f ICG f r o m serum was f i t t o a s i n g l e c o m p a r t m e n t m o d e l , b u t , o f t e n f i t b e t t e r t o a two c o m p a r t m e n t m o d e l . P r e v i o u s s t u d i e s a l s o r e p o r t e d b i e x p o n e n t i a l d e c a y f o r ICG, when b l o o d s a m p l i n g was e x t e n d e d a f t e r 15-20 m i n u t e s ( G r a i n g e r et al., 1 9 8 3 ) . However, i n t h e p r e s e n t s t u d y , when ICG d e c a y i n serum was f i t as a b i e x p o n e n t i a l f u n c t i o n , o n l y 2 d a t a p o i n t s were u s e d t o c a l c u l a t e t h e k i n e t i c p a r a m e t e r s . T h u s , p a r a m e t e r e s t i m a t e s b a s e d on t h e t w o - c o m p a r t m e n t f i t a r e l e s s s t a t i s t i c a l l y r e l i a b l e t h a n t h o s e o f t h e o n e - c o m p a r t m e n t m o d e l . T h e r e f o r e , i n t h i s s t u d y f o r t h e e s t i m a t i o n o f k i n e t i c p a r a m e t e r s t h e s i n g l e c o m p a r t m e n t model was u s e d . T h i s i s c o n s i s t e n t w i t h p r e v i o u s l y r e p o r t e d s t u d i e s (Wynne et al., 1990 and 1989; Robson et al., 1 9 9 0 ) . T h e r e was no c h a n g e i n t h e t e r m i n a l e l i m i n a t i o n t j / 2 °f ^^G a f t e r two-weeks o f c a p t o p r i l t h e r a p y ( 4 . 0 3 ± 0.68 vs 3.97 ± 0.52 m i n u t e s , mean ± SD, n = 2 4 ) . The v a l u e s o f t2/2» " i " p r e s e n t s t u d y , a r e i n a g r e e m e n t w i t h t h e f i n d i n g s o f S h e p h e r d et al., ( 1 9 8 5 ) who has r e p o r t e d 3.37 ± 0.51 and 3.89 ± 0.94 m i n u t e s f o r t j ^ 2 o f ^CG, b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t , i n h e a l t h y s u b j e c t s . G r a s e l a et al., ( 1 9 8 7 ) has n o t e d h i g h e r and Geneve et al., ( 1 9 9 0 ) l o w e r t j ^ 2 v a l u e s f o r ICG i n h e a l t h y s u b j e c t s ( 5 . 6 and 3.0 m i n u t e s , r e s p e c t i v e l y ) . I n c o n t r a s t t o S v e n s s o n et al., ( 1 9 8 6 ) who r e p o r t e d no d e t e c t a b l e l e v e l s o f ICG i n t h e p l a s m a o f two h e a l t h y s u b j e c t s f o l l o w i n g f i v e i n j e c t i o n s o f 0.5 mg/kg i . v . b o l u s d o s e s o f ICG a t ^ 1 h o u r i n t e r v a l s , i n t h e p r e s e n t s t u d y , t r a c e amounts o f ICG were d e t e c t e d i n t h e s erum p r i o r t o t h e s e c o n d , t h i r d and f o u r t h ICG i n j e c t i o n s . However, t h e amount o f ICG was a l w a y s l e s s t h a n 0.2 ng/ml, t h e l o w e r l i m i t o f d e t e c t i o n o f t h e HPLC method u s e d i n t h e s t u d i e s o f S v e n s s o n et al., ( 1 9 8 6 ) . I n t h e p r e s e n t s t u d y , i n one p a t i e n t (M.O.) t h e r e was no d e t e c t a b l e l e v e l o f ICG p r i o r t o t h e n e x t ICG i n j e c t i o n on any o f t h e s t u d y d a y s . S i n c e t h e r e s i d u a l ICG c o n c e n t r a t i o n was o n l y ~ 1.6% o f t h e h i g h e s t m e a s u r e d ICG c o n c e n t r a t i o n and t h e t e r m i n a l t 2 ^ 2 ~ -^^  m i n u t e s , i t s c o n t r i b u t i o n t o t h e t o t a l AUC was n o t s i g n i f i c a n t . 4.4. C hanges i n C l p j ^ e and 4.4.1. E f f e c t s o f P o s t u r a l Change on C l p j ^ g and B e f o r e and A f t e r C a p t o p r i l Numerous s t u d i e s have d e m o n s t r a t e d a d e c r e a s e i n Qp| due t o p o s t u r a l c h a n g e f r o m s u p i n e ( C u l b e r t s o n et al., 1951, Daneshmend et al., 1981) o r s e a t e d ( M o d i et al., 1988) t o s t a n d i n g . The d e c r e a s e i n i s assumed t o be m a i n l y due t o a c t i v e v a s o c o n s t r i c t i o n i n t h e s p l a n c h n i c c i r c u l a t i o n m e d i a t e d t h r o u g h t h e a c t i v a t i o n o f t h e s y m p a t h e t i c n e r v o u s s y s t e m ( W i l k i n s et al., 1 9 5 1 ) . I n h e a l t h y s u b j e c t s s t a n d i n g f o r 15 m i n u t e s a f t e r l y i n g c a u s e d a d e c r e a s e i n ICG b l o o d c l e a r a n c e {i.e. e s t i m a t e d l i v e r b l o o d f l o w ) by 3 7 % (Daneshmend et al., 1 9 8 1 ) . Modi et al., ( 1 9 8 8 ) o b s e r v e d a s i g n i f i c a n t (« 15 t o 40%) d e c r e a s e i n Q^, a s s e s s e d by t h e ICG c l e a r a n c e m e t h o d , a f t e r 2 h o u r s s t a n d i n g i n h e a l t h y s u b j e c t s , as compared t o s e a t e d . I n an e a r l i e r r e p o r t by C u l b e r t s t o n e e t al., ( 1 9 5 1 ) , d e c r e a s e d on t h e a v e r a g e = 3 8 % i n n o r m o t e n s i v e and ~ 2 9 % i n h y p e r t e n s i v e s u b j e c t s when body p o s t u r e was ch a n g e d f r o m s u p i n e t o t h e u p r i g h t (Q^ was e s t i m a t e d by t h e BSP e x t r a c t i o n m e t h o d ) . I t i s w e l l e s t a b l i s h e d , t h a t s t a n d i n g i s a c o n v e n i e n t p h y s i o l o g i c a l s t i m u l u s w h i c h c a u s e s a r e p r o d u c i b l e d e c r e a s e i n (Daneshmend e t al., 1 9 8 1 ) . Daneshmend e t al., ( 1 9 8 1 ) u s e d p o s t u r a l c h a n g e as a p h y s i o l o g i c a l v a r i a b l e a f f e c t i n g Q^ and s u g g e s t e d i t s use t o s t u d y t h e c h a n g e s i n k i n e t i c s o f h i g h c l e a r a n c e d r u g s . Modi e t a / . , ( 1 9 8 8 ) a p p l i e d p o s t u r a l s h i f t f r o m s e a t e d t o u p r i g h t t o p r o d u c e t r a n s i e n t c h a n g e s i n Q^ and s i m u l a t e t h e e f f e c t o f f o o d on Qy. The p u r p o s e f o r i n c l u d i n g m e a s u r e m e n t s o f Qy i n t h e u p r i g h t p o s t u r e i n t h e p r e s e n t s t u d y was as f o l l o w s : 1. To r e p r o d u c e t h e w e l l e s t a b l i s h e d d e c r e a s e i n Qy, a f t e r p o s t u r a l s h i f t f r o m s i t t i n g t o u p r i g h t , i n o r d e r t o d e m o n s t r a t e , t h a t t h e ICG c l e a r a n c e method i s s e n s i t i v e enough t o d e t e c t c h a n g e s i n Qy, i n t h e m a g n i t u d e o f t h a t i n d u c e d by p o s t u r a l c h a n g e i n p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n . 2. To e s t a b l i s h w h e t h e r a two-week t r e a t m e n t s c h e d u l e w i t h c a p t o p r i l a l t e r s t h e m a g n i t u d e o f r e s p o n s e t o p o s t u r a l c h a n g e . 3. To r e l a t e t h e m a g n i t u d e o f c h a n g e s i n Qy upon s t a n d i n g t o t h o s e o b s e r v e d a f t e r c a p t o p r i l t r e a t m e n t . I n t h e p r e s e n t s t u d y , i n u n t r e a t e d p a t i e n t s a c h a n g e i n p o s t u r e f r o m s e a t e d t o u p r i g h t r e s u l t e d i n a s i g n i f i c a n t d e c r e a s e i n C l p j ^ g and Qy. The a b s o l u t e d e c r e a s e (± SEM) i n C l p j Q g and Qy upon s t a n d i n g was 152.3 ± 18.3 m l / m i n ( 2 4 . 7 % ) and 250 ± 36 m l / m i n ( 2 2 . 5 % ) , r e s p e c t i v e l y , as c o m p a r e d t o t h e s e a t e d v a l u e s (Day 1, F i g u r e 10 and F i g u r e 1 3 ) . G r a s e l a e t al., (1987) r e p o r t e d a ~ 2 3 % d e c r e a s e i n t h e s y s t e m i c c l e a r a n c e o f ICG when h e a l t h y s u b j e c t s moved f r o m l y i n g t o s t a n d i n g p o s i t i o n w h i c h i s s i m i l a r t o t h e ~ 2 5 % r e d u c t i o n i n C l p j Q g i n u p r i g h t p o s t u r e f o u n d i n t h e c u r r e n t s t u d y . The o b s e r v e d ==23% d e c r e a s e i n Qy, i n t h e p r e s e n t s t u d y , b e f o r e c a p t o p r i l t r e a t m e n t i s l o w e r t h a n t h e d e c r e a s e i n Qy on s t a n d i n g r e p o r t e d i n h e a l t h y s u b j e c t s ( 3 7 % and 3 2 % Daneshmend e t al., 1981 and Modi e t al., 1988, r e s p e c t i v e l y ) , b u t c o m p a t i b l e w i t h t h e p r e v i o u s l y r e p o r t e d 2 9 % d e c r e a s e i n Qy i n h y p e r t e n s i v e s u b j e c t s ( C u l b e r t s o n e t al., 1 9 5 1 ) . A t e n d e n c y f o r s l i g h t l y s m a l l e r d e c r e a s e i n Qy i n h y p e r t e n s i v e s u b j e c t s c o m p a r e d t o t h e n o r m o t e n s i v e s , i n s t a n d i n g p o s i t i o n , was a l s o o b s e r v e d i n t h e s t u d y by C u l b e r t s o n e t al., ( 1 9 5 1 ) , i n w h i c h Qy d e c r e a s e d by 3 8 % i n n o r m o t e n s i v e s and 2 9 % i n h y p e r t e n s i v e s u b j e c t s . A f t e r two-weeks c a p t o p r i l t r e a t m e n t t h e a b s o l u t e d e c r e a s e (± SEM) i n C l p j Q Q and upon s t a n d i n g was 210.9 ± 38.8 m l / m i n ( 2 6 . 6 % ) and 344 ± 68 ml / m i n ( 2 4 . 7 % ) , r e s p e c t i v e l y , as compared t o t h e s e a t e d v a l u e (Day 14, F i g u r e 10 and F i g u r e 1 3 ) . A l t h o u g h t h e a b s o l u t e d e c r e a s e i n C l p j Q Q and Q^ when s u b j e c t s move f r o m s e a t e d t o t h e u p r i g h t p o s i t i o n was g r e a t e r by 3 8 . 5 % and 3 7 . 3 % a f t e r two-weeks c a p t o p r i l t h e r a p y , t h e d e c r e a s e , e x p r e s s e d as a p e r c e n t a g e o f t h e s e a t e d v a l u e , was s i m i l a r b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t ( 2 4 . 7 % vs 2 6 . 6 % and 2 2 . 5 % vs 2 4 . 7 % , r e s p e c t i v e l y ) ( T a b l e 6 and T a b l e 9 ) . The a p p a r e n t l y g r e a t e r d e c r e a s e i n C l p j Q Q and upon s t a n d i n g a f t e r s h o r t - t e r m c a p t o p r i l t r e a t m e n t i s a t t r i b u t e d t o t h e h i g h e r s e a t e d C l p j Q Q and 0^ v a l u e o b s e r v e d a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as co m p a r e d t o t h e u n t r e a t e d v a l u e s ( 6 1 6 . 9 vs 793.7 m l / m i n f o r C l p j Q Q and 1389 vs 1114 m l / m i n f o r Q^). T h e r e f o r e , i t c a n be c o n c l u d e d t h a t t h e two-weeks t r e a t m e n t w i t h c a p t o p r i l , i n d o s e s , w h i c h p r o d u c e d s i g n i f i c a n t r e d u c t i o n i n b l o o d p r e s s u r e d i d n o t a l t e r t h e m a g n i t u d e o f h o m e o s t a t i c r e s p o n s e i n a s s o c i a t e d w i t h p o s t u r a l c h a n g e f r o m s e a t e d t o u p r i g h t i n m i l d / m o d e r a t e h y p e r t e n s i v e p a t i e n t s . When C l p j Q Q and w e r e n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a t h e r e s u l t s were s i m i l a r t o t h o s e o f a b s o l u t e v a l u e s ( T a b l e 6 and 9, F i g u r e 10 and 1 3 ) . T h e r e i s e v i d e n c e t o s u p p o r t t h e r e s u l t s o f t h e p r e s e n t s t u d y . V a n d e n b u r g et al., ( 1 9 8 3 ) s t u d i e d t h e e f f e c t s o f two and f o u r - w e e k s c a p t o p r i l t r e a t m e n t on t h e r e s p o n s e s o f t h e s y m p a t h e t i c n e r v o u s s y s t e m t o p o s t u r a l c h a n g e s f r o m s u p i n e t o s t a n d i n g and s i t t i n g i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . They f o u n d t h a t w h i l e o r a l d o s e s o f c a p t o p r i l ( 2 5 -150 mg t.i.d.) s i g n i f i c a n t l y d e c r e a s e d b l o o d p r e s s u r e , t h e a c u t e c h a n g e s i n h e a r t r a t e , b l o o d p r e s s u r e , p l a s m a n o r a d r e n a l i n e c a u s e d by p o s t u r a l change were n o t a l t e r e d by p r o l o n g e d c a p t o p r i l t h e r a p y . S i m i l a r l y , M u i e s a n e t al., (1982) r e p o r t e d no c h a n g e i n t h e a c u t e r e s p o n s e s o f h e a r t r a t e and p l a s m a c a t e c h o l a m i n e s t o p o s t u r a l change a f t e r o r a l c a p t o p r i l d o s e s o f 300-600 mg/day f o r 8 weeks i n s u b j e c t s w i t h e s s e n t i a l h y p e r t e n s i o n . T h e s e r e s u l t s , s u p p o r t e d by t h e p r e s e n t s t u d y , s u g g e s t t h a t t h e a c t i v i t y o f t h e s y m p a t h e t i c n e r v o u s s y s t e m i s n o t a l t e r e d a f t e r p r o l o n g e d t h e r a p y w i t h c a p t o p r i l . The f a c t t h a t t h e d e c r e a s e i n Qy upon s t a n d i n g , as c o m p a r e d t o t h e s e a t e d ( s i ) v a l u e was s i m i l a r b e f o r e and a f t e r two-weeks c a p t o p r i l t h e r a p y s u g g e s t s t h a t t h e s y m p a t h e t i c n e r v o u s s y s t e m m e d i a t e d r e s p o n s e o f Qy, c a u s e d by p o s t u r a l c h a n g e , i s n o t a l t e r e d by p r o l o n g e d c a p t o p r i l . S i x t y m i n u t e s a f t e r r e a s s u m i n g t h e s e a t e d p o s i t i o n ( s 2 ) , t h e C l p j Q Q and Qy i n c r e a s e d by ~ 2 5 % and « 2 1 % , r e s p e c t i v e l y , b e f o r e c a p t o p r i l t r e a t m e n t and by « 2 4 % and =22%, r e s p e c t i v e l y , a f t e r two-weeks c a p t o p r i l t h e r a p y , as c o m p a r e d t o t h e v a l u e s o b t a i n e d i n t h e u p r i g h t p o s i t i o n . T h e s e r e s u l t s s u g g e s t t h a t t h e m a g n i t u d e o f i n c r e a s e i n C l p j Q Q and Qy d u r i n g t h e r e s e a t e d p e r i o d s w e r e s i m i l a r b e f o r e and a f t e r c a p t o p r i l t h e r a p y , as com p a r e d t o t h e u p r i g h t v a l u e s . T h e r e was no s i g n i f i c a n t d i f f e r e n c e between t h e mean C l p j Q Q and Qy v a l u e s o b t a i n e d i n t h e s e a t e d ( s i ) and r e s e a t e d ( s 2 ) p o s i t i o n s ( T a b l e 6 and T a b l e 9 ) . However, i n d i v i d u a l d a t a showed g r e a t e r v a r i a b i l i t y d u r i n g t h e r e s e a t e d p e r i o d t h a n i n t h e u p r i g h t p o s t u r e when com p a r e d t o t h e s e a t e d v a l u e s ( F i g u r e 9 and F i g u r e 1 2 ) . A l t h o u g h no e x p l a n a t i o n f o r t h i s v a r i a b i l i t y i n Qy i n t h e r e s e a t e d p o s i t i o n was f o u n d , i t was a l s o o b s e r v e d d u r i n g t h e r e c o v e r y p e r i o d when n o r m o t e n s i v e p a t i e n t s r e a s s u m e d l y i n g p o s i t i o n a f t e r b e i n g u p r i g h t ( C u l b e r t s o n e t al. 1 9 5 1 ) . 4.4.2. A c u t e E f f e c t s o f C a p t o p r i l on C l p j Q g and S e v e r a l s t u d i e s h ave a t t e m p t e d t o d e t e r m i n e t h e e f f e c t s o f c a p t o p r i l on a f t e r s i n g l e - d o s e a d m i n i s t r a t i o n i n human s u b j e c t s . M o s t o f t h e s e s t u d i e s h a v e been c a r r i e d o u t i n e i t h e r h e a l t h y s u b j e c t s ( S h e p h e r d et al., 1 9 8 5 ) , i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e ( F a x o n et al., 1984; L e v i n e e t al., 1 9 8 4 ) , i n p a t i e n t s w i t h l i v e r c i r r h o s i s ( E r i k s s o n e t al., 1 9 8 4 ) , o r i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n ( C r o s s l e y e t al., 1 9 8 4 ) . T h e r e a r e c o n f l i c t i n g r e p o r t s r e g a r d i n g t h e a c u t e e f f e c t s o f c a p t o p r i l on Q^. T h i s may p a r t i a l l y be e x p l a i n e d by e i t h e r t h e d i f f e r e n t d o s e s o f c a p t o p r i l a d m i n i s t e r e d ( G e neve e t al., 1 9 9 0 ) , t h e d i f f e r e n t t e c h n i q u e s u s e d t o e s t i m a t e ( B r a d l e y , 1 9 7 4 ) , a n d / o r t h e d i f f e r e n t d i s e a s e s t a t e s o f t h e p a t i e n t s ( G a s i c e t al., 1 9 8 9 ) . S h e p h e r d et al., ( 1 9 8 5 ) e x a m i n e d t h e e f f e c t s o f c a p t o p r i l , n i t r a t e s and p r o p r a n o l o l on i n h e a l t h y s u b j e c t s . I n t h i s s t u d y a s i n g l e 25 mg o r a l d o s e o f c a p t o p r i l was u s e d and was e s t i m a t e d by t h e ICG c l e a r a n c e method 100 m i n f o l l o w i n g c a p t o p r i l a d m i n i s t r a t i o n . The r e a s o n t o e s t i m a t e a t t h i s t i m e p o i n t was t h a t c a p t o p r i l e x h i b i t e d m a x i m a l b l o o d p r e s s u r e l o w e r i n g e f f e c t a f t e r s i n g l e - d o s e a d m i n i s t r a t i o n i n h e a l t h y s u b j e c t s b e t w e e n 90 and 120 m i n u t e s ( S h e p h e r d e t al., 1 9 8 5 ) . I t was n o t e d , t h a t w h i l e p r o p r a n o l o l and g l y c e r y l t r i n i t r a t e s i g n i f i c a n t l y r e d u c e d Q^, c a p t o p r i l c a u s e d no c h a n g e , d e s p i t e t h e s i g n i f i c a n t f a l l i n b l o o d p r e s s u r e . I t has been n o t e d ( G a s i c e t al., 1 9 8 9 ) , t h a t u n d e r n o r m a l p h y s i o l o g i c a l c o n d i t i o n s RAS may n o t p l a y a m a j o r r e g u l a t o r y r o l e w i t h i n t h e s p l a n c h n i c v a s c u l a r b e d , b u t may o b t a i n i m p o r t a n c e i n c o n d i t i o n s w i t h c o m p r o m i s e d h a e m o d y n a m i c s , f o r e x a m p l e , c o n g e s t i v e h e a r t f a i l u r e . C r e a g e r e t al., ( 1 9 8 1 ) s t u d i e d t h e a c u t e e f f e c t s o f 100 mg o r a l d o s e o f c a p t o p r i l on r e g i o n a l b l o o d f l o w i n human s u b j e c t s w i t h c o n g e s t i v e h e a r t f a i l u r e . I n t h e 11 p a t i e n t s s p l a n c h n i c b l o o d f l o w ( a s s e s s e d by ICG c l e a r a n c e ) d e c r e a s e d f r o m 1.8 ± 0.4 t o 1.5 ± 0.3 m l / m i n / k g ( 1 7 % , p=0.051) and r e n a l b l o o d f l o w i n c r e a s e d by 60 % b e t w e e n 60 t o 120 m i n u t e s a f t e r a s i n g l e o r a l d o s e o f c a p t o p r i l . A l s o , t o t a l s y s t e m i c v a s c u l a r r e s i s t a n c e d e c r e a s e d by 27%. I t has been c o n c l u d e d ( C r a e g e r et al., 1 9 8 1 ) , t h a t s e l e c t i v e p e r i p h e r a l v a s o d i l a t i o n o c c u r r e d a f t e r a s i n g l e d o s e o f c a p t o p r i l ; t h a t i s , b l o o d f l o w t o t h e k i d n e y s i n c r e a s e d and t o t h e l i v e r and l i m b s d e c r e a s e d , i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e . L e v i n e et al., ( 1 9 8 4 ) r e p o r t e d no s t a t i s t i c a l l y s i g n i f i c a n t c h a n g e i n Qy ( e s t i m a t e d ICG b l o o d c l e a r a n c e ) and h e p a t i c v a s c u l a r r e s i s t a n c e , 90 m i n u t e s f o l l o w i n g t h e a d m i n i s t r a t i o n o f 25 t o 100 mg o r a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e . However, i n t h e 11 p a t i e n t s mean Qy d e c r e a s e d f r o m by ~ 3 0 % , a s s e s s e d by t h e ICG c l e a r a n c e method and h e p a t i c v a s c u l a r r e s i s t a n c e d e c r e a s e d by 1 1 % ( L e v i n e et al., 1 9 8 4 ) . L a r g e i n t e r p a t i e n t v a r i a b i l i t y was o b s e r v e d i n t h i s s t u d y , w h i c h r e s u l t e d i n no s t a t i s t i c a l l y s i g n i f i c a n t c h a n g e i n Qy. The l a r g e i n t e r p a t i e n t v a r i a t i o n may be e x p l a i n e d by t h e g r e a t d i f f e r e n c e s r e g a r d i n g t h e age o f t h e p a t i e n t s e x a m i n e d i n t h i s s t u d y ( 2 1 - 7 1 y e a r s ) . I t i s w e l l r e c o g n i z e d , t h a t Qy d e c l i n e s s i g n i f i c a n t l y w i t h a d v a n c i n g age (Wynne e t al., 1989 and 1 9 9 0 ) . Wynne e t al., ( 1 9 8 9 ) r e p o r t e d a s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n between age and Qy ( I C G c l e a r a n c e method) i n 65 h e a l t h y s u b j e c t s b e t w e e n 24 and 91 y e a r s o f a g e . T h e r e f o r e , t h e r e s p o n s e s t o c a p t o p r i l t r e a t m e n t may be more v a r i a b l e when p a t i e n t s w i t h w i d e age r a n g e a r e s e l e c t e d t o s t u d y c h a n g e s i n QH-E r i k s s o n e t al., ( 1 9 8 4 ) i n v e s t i g a t e d t h e a c u t e e f f e c t s o f 12.5 and 25 mg o r a l d o s e o f c a p t o p r i l on Qy i n s e v e n p a t i e n t s w i t h l i v e r c i r r h o s i s and p o r t a l h y p e r t e n s i o n . was e s t i m a t e d by t h e c o n s t a n t i n f u s i o n o f ICG u s i n g h e p a t i c v e n o u s c a t h e t e r i z a t i o n . I t was n o t e d , t h a t w h i l e mean a r t e r i a l p r e s s u r e s i g n i f i c a n t l y d e c r e a s e d 3 0 , 60 and 90 m i n u t e s f o l l o w i n g c a p t o p r i l a d m i n i s t r a t i o n , r e m a i n e d u n a l t e r e d . However, a d e c r e a s e i n mean a r t e r i a l p r e s s u r e and an u n c h a n g e d s u g g e s t a d e c r e a s e i n SVR {i.e. SVR = MAP / 0 ^ ) . An i m p o r t a n t f i n d i n g o f t h i s s t u d y was t h a t t h e h e p a t i c e x t r a c t i o n r a t i o o f ICG was u n a f f e c t e d by c a p t o p r i l t h e r a p y . A l t h o u g h a l a r g e number o f s t u d i e s have i n v e s t i g a t e d t h e p h a r m a c o l o g i c a l e f f e c t s o f c a p t o p r i l i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n , v e r y few s t u d i e s have e x a m i n e d i t s i n f l u e n c e on Q^. I n t h e s t u d i e s o f C r o s s l e y et al., ( 1 9 8 4 ) t h e a c u t e e f f e c t s o f 50 t o 100 mg o r a l d o s e o f c a p t o p r i l on was e x a m i n e d i n s i x p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . I n t h i s s t u d y , Q^ was d e t e r m i n e d by t h e c o n s t a n t i n f u s i o n o f ICG and t h e c a t h e t e r i z a t i o n o f t h e h e p a t i c v e i n . A b o u t 50 m i n u t e s f o l l o w i n g c a p t o p r i l a d m i n i s t r a t i o n , a u n i f o r m and s i g n i f i c a n t r e d u c t i o n i n f r o m 1127 ± 115 t o 841 ± 93 ml/min ( 2 5 % , p < 0.001) was n o t e d . C o n c o m i t a n t l y , mean a r t e r i a l p r e s s u r e d e c r e a s e d s i g n i f i c a n t l y ( 8 % ) and t o t a l s y s t e m i c v a s c u l a r r e s i s t a n c e d e c r e a s e d by 1 3 % ( n o n - s i g n i f i c a n t ) . T h e r e was no s i g n i f i c a n t c h a n g e i n c a r d i a c o u t p u t d e s p i t e t h e l a r g e ( 2 7 % ) i n c r e a s e i n one p a t i e n t w i t h c o n g e s t i v e h e a r t f a i l u r e and a s l i g h t i n c r e a s e i n two o t h e r s . I n t h e p r e s e n t s t u d y , t h e a c u t e e f f e c t s o f c a p t o p r i l w ere e v a l u a t e d 1 h o u r a f t e r t h e i n i t i a l c a p t o p r i l d o s e on d a y 1 and t h e t e r m i n a l d o s e o f two-weeks c a p t o p r i l t h e r a p y , on day 14. C a p t o p r i l has been p r e v i o u s l y shown t o e x h i b i t i t s m a ximal b l o o d p r e s s u r e l o w e r i n g e f f e c t w i t h i n 0.5 t o 1.5 h o u r s i n h y p e r t e n s i v e p a t i e n t s ( T a r a z i e t al., 1 9 8 0 ) . T h e r e was no s i g n i f i c a n t c h a n g e i n C l p j ^ g and 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l d o s e o f c a p t o p r i l i n p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n , w h e t h e r e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a , as c o m p a r e d t o t h e c o n t r o l v a l u e s ( r e s e a t e d , s 2 ) v a l u e s (Day 1, T a b l e 6 and T a b l e 9 ) . However, a s l i g h t 5.2% and ~ 6.0% d e c r e a s e i n C l p j Q g and Qy, r e s p e c t i v e l y , was o b s e r v e d when d a t a o b t a i n e d 1 h o u r a f t e r c a p t o p r i l d o s i n g w ere c o m p a r e d t o t h e c o n t r o l v a l u e s (Day 1, T a b l e 6 and T a b l e 9 ) . However, t h i s d e c r e a s e i n ICG c l e a r a n c e and Qy a f t e r c a p t o p r i l a d m i n i s t r a t i o n i s s i m i l a r o r e v e n s m a l l e r i n m a g n i t u d e t h a n t h e d i f f e r e n c e s b e t w e e n t h e two s e a t e d p o s i t i o n s b e f o r e c a p t o p r i l t r e a t m e n t ( 6 . 3 % vs 5.2% f o r C l p j Q Q and 6.3% vs 6.0% f o r Qy) ( T a b l e 6 and 9 ) . S i m i l a r l y , t h e t e r m i n a l d o s e o f two-weeks c a p t o p r i l t h e r a p y c a u s e d no s i g n i f i c a n t c h a n g e s i n C l p j Q Q and Qy, as c o m p a r e d t o t h e r e s e a t e d v a l u e s (Day 14, T a b l e 6 and 9 ) . T h e r e was a s l i g h t , 5.2% and 6.1% d e c r e a s e i n C l p j Q Q and Qy, r e s p e c t i v e l y , 1 h o u r a f t e r c a p t o p r i l d o s i n g , as compared t o t h e r e s e a t e d ( s 2 ) v a l u e s , s i m i l a r t o t h a t o b s e r v e d a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l on d a y 1 (Day 14, T a b l e 6 and 9 ) . The f a c t t h a t t h e r e s p o n s e t o t h e t e r m i n a l d o s e o f c a p t o p r i l was s i m i l a r t o t h a t a f t e r t h e i n i t i a l d o s e s u g g e s t s t h a t two-weeks c a p t o p r i l t h e r a p y d o e s n o t i n t e r f e r e w i t h t h e a c u t e r e s p o n s e s o f Qy t o c a p t o p r i l a d m i n i s t r a t i o n i n p a t i e n t s w i t h m i l d - m o d e r a t e h y p e r t e n s i o n . T h e s e r e s u l t s a g r e e w i t h t h e f i n d i n g s o f S h e p h e r d e t al., ( 1 9 8 5 ) , E r i k s s o n e t al., ( 1 9 8 4 ) and L e v i n e e t al., ( 1 9 8 4 ) , who o b s e r v e d no s i g n i f i c a n t c h a n g e i n Qy a f t e r a s i n g l e c a p t o p r i l d o s e . However, t h e r e s u l t s o f t h e p r e s e n t s t u d y a r e d i f f e r e n t f r o m t h e s t u d i e s o f C r o s s l e y e t al., ( 1 9 8 4 ) and C r a e g e r e t al., ( 1 9 8 1 ) who o b s e r v e d a s i g n i f i c a n t d e c r e a s e i n Qy i n p a t i e n t s w i t h h y p e r t e n s i o n and c o n g e s t i v e h e a r t f a i l u r e , r e s p e c t i v e l y . The l a c k o f r e s p o n s e i n Qy a f t e r an a c u t e d o s e o f c a p t o p r i l o b s e r v e d i n t h i s s t u d y c o u l d n o t be c a u s e d by p o o r a b s o r p t i o n o f t h e d r u g , s i n c e t h e s e r u m c o n c e n t r a t i o n s o f c a p t o p r i l i n c r e a s e d r a p i d l y a f t e r a d m i n i s t r a t i o n and w e r e s i m i l a r t o t h e c o n c e n t r a t i o n s r e p o r t e d i n o t h e r s t u d i e s ( J a r r o t t e t al., 1982; K r i p a l a n i e t al., 1980) ( F i g u r e 2 9 ) . I n a d d i t i o n , s i g n i f i c a n t r e d u c t i o n s i n b o t h , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e o b s e r v e d 1 h o u r a f t e r t h e f i r s t d o s e o f c a p t o p r i l s u g g e s t i n g a p h a r m a c o l o g i c a l l y a c t i v e l e v e l o f t h e d r u g . D i f f e r e n c e s f r o m t h e s t u d i e s o f C r o s s l e y e t al., (1984) may a r i s e s f r o m t h e d i f f e r e n t body p o s i t i o n s o f t h e s u b j e c t s i n w h i c h was e s t i m a t e d ( l y i n g vs s i t t i n g ) . S h e p h e r d e t al., ( 1 9 8 5 ) , h o w e v e r , o b s e r v e d no s i g n i f i c a n t c h a n g e s i n a s s e s s e d by t h e ICG c l e a r a n c e method i n normal s u b j e c t s when p a t i e n t s w e r e s i t t i n g o r l y i n g . D i r e c t c o m p a r i s o n between t h e p r e s e n t s t u d y and t h a t p e r f o r m e d by C r o s s l e y e t al., ( 1 9 8 4 ) i s d i f f i c u l t due t o t h e d i f f e r e n t methods u s e d f o r t h e e s t i m a t i o n o f Q^. The c a t h e t e r i z a t i o n o f t h e h e p a t i c v e i n u s e d i n t h e s t u d y o f C r o s s l e y e t al., ( 1 9 8 4 ) has t h e a d v a n t a g e t h a t t h e h e p a t i c e x t r a c t i o n r a t i o o f ICG c a n be d e t e r m i n e d , b u t i s an i n v a s i v e t e c h n i q u e ( G e o r g e , 1 9 7 9 ) . The p l a c e m e n t o f t h e c a t h e t e r i n t h e h e p a t i c v e i n may c a u s e v e n o u s spasm ( B r a d l e y e t al., 1945) w h i c h may a f f e c t t h e r e s u l t s o f t h e s t u d y . A n o t h e r l i m i t a t i o n o f t h e method i s t h a t t h e c o n c e n t r a t i o n s o f ICG i n t h e b l o o d s a m p l e s o b t a i n e d f r o m t h e h e p a t i c v e i n a r e i n f l u e n c e d by t h e p o s i t i o n o f t h e c a t h e t e r (Ohnhaus, 1979; G e o r g e , 1 9 7 9 ) . The l a c k o f c h a n g e i n Q|.^, d e s p i t e a s i g n i f i c a n t f a l l i n a r t e r i a l b l o o d p r e s s u r e may be e x p l a i n e d by t h e " h y d r o d y n a m i c " i n t e r a c t i o n between t h e h e p a t i c a r t e r y and p o r t a l v e i n ( S h e p h e r d e t al., 1 9 8 5 ) . A c c o r d i n g t o t h i s t h e o r y s i m u l t a n e o u s d i l a t i o n o f b o t h , h e p a t i c a r t e r y and p o r t a l v e i n p r o d u c e s an i n c r e a s e i n one f l o w and a r e d u c t i o n i n t h e o t h e r , t h u s , a c o n s t a n t b l o o d f l o w m a i n t a i n e d i n t h e l i v e r ( R i c h a r d s o n and W i t h r i n g t o n , 1 9 8 1 ) . I t has been d e m o n s t r a t e d , t h a t c a p t o p r i l c a u s e s d i l a t a t i o n i n t h e v e i n s ( S i m o n et al., 1 9 8 5 ) , as w e l l a s , i n t h e a r t e r i e s ( T a r a z i et al., 1 9 8 0 ) . M o s t r e c e n t l y , s i g n i f i c a n t d a i l y v a r i a t i o n i n e s t i m a t e d Qy has been r e p o r t e d i n h e a l t h y s u b j e c t s when Qy was e s t i m a t e d by t h e ICG c l e a r a n c e method f o u r t i m e s a d a y (2:00 am, 8:00 am, 2:00 pm and 8:00 pm) (Lemmer and N o l d , 1 9 9 1 ) . The p l a s m a c l e a r a n c e o f ICG and Qy d e c r e a s e d by 2 4 % and 26%, r e s p e c t i v e l y , when v a l u e s , e s t i m a t e d i n t h e m o r n i n g ( 8 : 0 0 am), w e r e compared t o t h o s e m e a s u r e d i n t h e e a r l y a f t e r n o o n ( 2 : 0 0 pm). F i g u r e 31 shows t h e c i r c a d i a n r h y t h m i n e s t i m a t e d Qy o b t a i n e d f r o m t h e s t u d i e s o f Lemmer and N o l d , ( 1 9 9 1 ) t o g e t h e r w i t h t h e Qy d a t a o b t a i n e d i n t h e p r e s e n t s t u d y on d a y 1 and 14. The s l i g h t =; 5-6% and 1 1 - 1 4 % d e c r e a s e s i n Qy o b s e r v e d when r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) d a t a , r e s p e c t i v e l y , were compared t o t h e f i r s t s e a t e d ( s i ) v a l u e s a r e s i m i l a r t o t h e d e c r e a s e i n Qy when e x t r a p o l a t e d d a t a o f Lemmer and N o l d , ( 1 9 9 1 ) a r e u s e d f o r t h e c o m p a r i s o n ( 1 7 % ) . S i n c e t h e f o u r ICG i n j e c t i o n s f o r t h e e s t i m a t i o n o f Qy i n t h e c u r r e n t s t u d y w e r e p e r f o r m e d b e t w e e n « 8:30 am and 2:00 pm ( s t e e p p h a s e o f t h e c i r c a d i a n v a r i a t i o n c u r v e ) , a d e c r e a s e i n Qy v a l u e s d u r i n g t h e c o u r s e o f t h e s t u d y m i g h t be e x p e c t e d . B a s e d on t h e r e p o r t s o f Lemmer and N o l d , ( 1 9 9 1 ) t h e a p p a r e n t d e c r e a s e i n Qy a f t e r t h e a c u t e d o s e o f c a p t o p r i l when com p a r e d t o t h e s e a t e d ( s i ) v a l u e s may be due t o t h e c i r c a d i a n v a r i a t i o n i n Qy, r a t h e r t h a n a d i r e c t e f f e c t o f c a p t o p r i l . M o r e o v e r , t h e d e c r e a s e i n e s t i m a t e d Qy a f t e r p o s t u r a l c h a n g e f r o m s i t t i n g t o u p r i g h t were ~ 2 3 % and ~ 2 5 % b e f o r e and a f t e r c a p t o p r i l t h e r a p y , r e s p e c t i v e l y . T h i s c hange i n Qy i s much g r e a t e r i n m a g n i t u d e t h a n t h a t a f t e r t h e a c u t e d o s e s o f c a p t o p r i l w h e t h e r c o m p a r e d t o t h e r e s e a t e d ( s 2 ) o r s e a t e d ( s i ) v a l u e s . S t a t i s t i c a l c o m p a r i s o n s b e t w e e n t h e e f f e c t s o f p o s t u r a l c h a n g e and a c u t e d o s e s o f c a p t o p r i l on Qy s u g g e s t , t h a t u p r i g h t p o s i t i o n has more p r o n o u n c e d e f f e c t on Liver blood flow data (L/mIn) Clock time 8:30 12:00 14:00 A Day 1 o Day 14 1.11 1.39 1.04 1.27 0.98 1.19 H 1 1 h H 1 h-16 18 20 SI 10 12 14 S*2 CA Clock time (h) F i g u r e 3 1 . Changes i n d u r i n g t h e c o u r s e o f day 1 (open t r i a n g l e s ) and day 14 (open c i r c l e s ) , as compared t o t h e c h a n g e s i n Qu due t o c i r c a d i a n v a r i a t i o n ( b a s e d on Lemmer and N o l d , 1 9 9 1 ) . Qy t h a n t h e a c u t e a d m i n i s t r a t i o n o f c a p t o p r i l (p < 0.05, p a i r e d s a m p l e t -t e s t ) . T h e r e f o r e , t h e b i o l o g i c a l s i g n i f i c a n c e o f t h i s s m a l l c h a n g e i n Qy i s u n c e r t a i n . I n c o n c l u s i o n , t h e r e was no a p p a r e n t a c u t e c h a n g e i n C l p j ^ g and Qy a f t e r c a p t o p r i l a d m i n i s t r a t i o n . The d e c r e a s e i n Qy d u r i n g t h e c o u r s e o f day 1 and day 14 may be e x p l a i n e d by t h e c i r c a d i a n v a r i a t i o n i n Qy. 4.4.3. S h o r t - t e r m E f f e c t s o f C a p t o p r i l on C l p j g g and Qy T h e r e i s l i t t l e i n f o r m a t i o n r e g a r d i n g t h e e f f e c t s o f c a p t o p r i l on Qy a f t e r l o n g - t e r m a d m i n i s t r a t i o n e i t h e r i n human o r a n i m a l s p e c i e s . C o n s i d e r i n g t h e c o m p l e x haemodynamic c h a n g e s a s s o c i a t e d w i t h c a p t o p r i l t h e r a p y , t h e r e s u l t s o f s i n g l e - d o s e s t u d i e s m i g h t be s u b s t a n t i a l l y d i f f e r e n t f r o m t h o s e a f t e r p r o l o n g e d c a p t o p r i l t h e r a p y ( B r o g d e n e t a / . , 1988; C r o s s l e y e t al., 1984) S t u d i e s i n a n e s t h e t i z e d , n o r m o t e n s i v e and s p o n t a n e o u s l y h y p e r t e n s i v e r a t s h ave d e m o n s t r a t e d a s i g n i f i c a n t « 2 5 % and ~ 3 4 % i n c r e a s e i n Qy, r e s p e c t i v e l y , a f t e r o r a l t r e a t m e n t s w i t h 100 mg c a p t o p r i l f o r s i x weeks ( R o z s a e t al., 1 9 9 1 ) . S i m i l a r l y , R i c h e r e t al., ( 1 9 8 4 ) have r e p o r t e d a s i g n i f i c a n t 2 - f o l d i n c r e a s e i n Qy and 5 6 % d e c r e a s e i n h e p a t i c v a s c u l a r r e s i s t a n c e a f t e r 8 d a y s t r e a t m e n t w i t h 100 mg/kg o r a l d o s e o f c a p t o p r i l i n a n e s t h e t i z e d , s p o n t a n e o u s l y h y p e r t e n s i v e r a t s . I n c o n t r a s t , i n a s t u d y i n v o l v i n g human s u b j e c t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n ( V e n t u r a e t al., 1985) no s i g n i f i c a n t c h a n g e i n Qy, e s t i m a t e d by t h e ICG c l e a r a n c e method, have been o b s e r v e d a f t e r 90 m i n u t e s and 12-weeks o f t r e a t m e n t w i t h 50 mg d a i l y o r a l d o s e o f c a p t o p r i l . T h e r e was, h o w e v e r , a s l i g h t ( 7 % ) d e c r e a s e i n SVR a f t e r 12 weeks t r e a t m e n t w i t h c a p t o p r i l . The r e s u l t s o f t h e p r e s e n t s t u d y d e m o n s t r a t e a s t a t i s t i c a l l y s i g n i f i c a n t i n c r e a s e i n C l p j Q g by ~ 2 5 - 2 9 % (p = 0 . 0 3 9 ) a f t e r two-weeks c a p t o p r i l t r e a t m e n t , i n a l l f o u r p h a s e s o f t h e s t u d y , as comp a r e d t o t h e d a y 1 v a l u e s ( T a b l e 7 ) . S i m i l a r l y , i n c r e a s e d a l m o s t u n i f o r m l y by ~ 2 1 - 2 5 % a f t e r two-weeks c a p t o p r i l t h e r a p y , i n t h e f o u r p h a s e s o f t h e s t u d y , as compared t o day 1 ( F i g u r e 1 4 ) . The m a g n i t u d e o f i n c r e a s e i n was s i m i l a r when d a t a were n o r m a l i z e d t o body w e i g h t and body s u r f a c e a r e a ; h o w e v e r , t h e p e r c e n t i n c r e a s e r e l a t i v e t o d a y 1 v a l u e s were s l i g h t l y l o w e r t h a n t h o s e o f t h e a b s o l u t e v a l u e s (~ 1 9 - 2 4 % , and « 2 0 - 2 2 % , r e s p e c t i v e l y ) ( F i g u r e 1 4 ) . These r e s u l t s c o n f i r m t h e f i n d i n g s o f R o z s a e t al., ( 1 9 9 1 ) who o b s e r v e d a ~ 3 4 % i n c r e a s e i n a f t e r s i x weeks t r e a t m e n t w i t h c a p t o p r i l i n s p o n t a n e o u s l y h y p e r t e n s i v e r a t s , b u t d i f f e r e n t f r o m t h e f i n d i n g s o f V e n t u r a e t al., ( 1 9 8 5 ) i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . The l a c k o f c h a n g e i n a f t e r 12-weeks t r e a t m e n t w i t h c a p t o p r i l may be due t o t h e l o w e r c a p t o p r i l d o s e u s e d i n t h i s s t u d y ( 2 5 mg t w i c e d a i l y t o a maximum o f 75 mg). F i g u r e 1 5 shows t h a t t h e d i f f e r e n c e s b e t w e e n t h e two s t u d y d a y s ( b e f o r e and a f t e r two-weeks c a p t o p r i l t h e r a p y ) were t h e same r e g a r d l e s s w h i c h s t u d y p h a s e s w e r e c o m p a r e d . The s t a t i s t i c a l t e s t , h o w e v e r , j u s t f a i l e d t o a c h i e v e t h e l e v e l o f s i g n i f i c a n c e when t h e e f f e c t s o f s h o r t - t e r m c a p t o p r i l t r e a t m e n t on QH were c o m p a r e d t o t h o s e o f day 1 (p = 0 . 0 6 2 , p = 0.075 and p = 0.074 f o r a b s o l u t e Q^ and p e r u n i t body w e i g h t and body s u r f a c e a r e a , r e s p e c t i v e l y ) . The l a c k o f s t a t i s t i c a l s i g n i f i c a n c e i s a t t r i b u t e d t o t h e one p a t i e n t (C.B.) who e x h i b i t e d a d e c r e a s e i n Q^ a f t e r s h o r t - t e r m c a p t o p r i l t h e r a p y . When t h e s t a t i s t i c a l t e s t was r e p e a t e d by e x c l u d i n g t h e d a t a o f t h i s p a t i e n t , t h e i n c r e a s e s i n Q^ a f t e r two-weeks c a p t o p r i l t h e r a p y , w h e t h e r e x p r e s s e d i n a b s o l u t e v a l u e s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a , w e r e s t a t i s t i c a l l y s i g n i f i c a n t , as compared t o t h e d a y 1 v a l u e s (p = 0 . 0 1 1 , p = 0.014 and p = 0.014, r e s p e c t i v e l y ) . I n p a t i e n t C.B. b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s on day 14 were b e l o w p r e t r e a t m e n t v a l u e s by 11 and 7 mm Hg, r e s p e c t i v e l y , i n d i c a t i n g good p a t i e n t c o m p l i a n c e ( T a b l e 1 5 ) . To f i n d e x p l a n a t i o n t h e s e d i v e r g e n t r e s u l t i s d i f f i c u l t w i t h o u t t h e measurements o f c h a n g e s i n p a r a m e t e r s s u c h as c a r d i a c o u t p u t and t o t a l p e r i p h e r a l r e s i s t a n c e . A s i g n i f i c a n t r e d u c t i o n i n t o t a l p e r i p h e r a l r e s i s t a n c e and an i n c r e a s e i n SVR, f o r e x a m p l e , w o u l d s u g g e s t t h a t o t h e r v a s c u l a r beds were p r e f e r e n t i a l l y p e r f u s e d a f t e r c a p t o p r i l t h e r a p y i n t h i s p a t i e n t ( C r o s s l e y et al., 1 9 8 4 ) . F u r t h e r , a s i g n i f i c a n t d e c r e a s e i n c a r d i a c o u t p u t w o u l d e x p l a i n a d e c r e a s e i n Qy i n t h i s p a t i e n t ( L e v i n e et al., 1 9 8 4 ) . Greenway and L a u t t , ( 1 9 7 2 ) p r o p o s e d t h a t t h e a n g i o t e n s i n I I i n d u c e d v a s o c o n s t r i c t i o n i n t h e c a p a c i t a n c e v e s s e l s o f t h e s p l a n c h n i c c i r c u l a t i o n r e s u l t s i n t h e m o b i l i z a t i o n o f s p l a n c h n i c b l o o d p o o l and a d e c r e a s e i n b l o o d v olume by a maximum o f 2 0 % . C o n v e r s e l y , a r e d u c t i o n i n a n g i o t e n s i n I I , and d i l a t a t i o n o f t h e s p l a n c h n i c c a p a c i t a n c e v e s s e l s , as a r e s u l t o f c a p t o p r i l t r e a t m e n t may i n c r e a s e l i v e r b l o o d v o l u m e by p o o l i n g o f b l o o d t o t h e s p l a n c h n i c c i r c u l a t i o n . T h i s has been s u g g e s t e d by S t a d e a g e r et al., (1989) who o b s e r v e d an a p p r o x i m a t e 2 5 - 2 8 % i n c r e a s e i n Qy a f t e r a c u t e e n a l a p r i l a d m i n i s t r a t i o n . A s i g n i f i c a n t c o r r e l a t i o n b e t w e e n l i v e r b l o o d v o l u m e and Qy has been r e p o r t e d by Wynne e t al., ( 1 9 8 9 ) , s u g g e s t i n g t h a t e n h a n c e d l i v e r b l o o d v o l u m e r e s u l t s i n an i n c r e a s e i n Qy. T h e r e i s e x p e r i m e n t a l and c l i n i c a l e v i d e n c e t h a t t h e l o n g - t e r m b l o o d p r e s s u r e r e d u c i n g e f f e c t s o f ACE i n h i b i t o r s c o r r e l a t e b e t t e r w i t h t h e i n h i b i t i o n o f ACE i n c e r t a i n t i s s u e s t h e n t h e i n h i b i t i o n o f ACE i n p l a s m a ( D z a u , 1988; Waeber e t al., 1 9 8 9 ) . S i n c e ACE i s i d e n t i c a l t o t h e k i n i n a s e I I w h i c h d e g r a d e s t h e v a s o d i l a t o r y b r a d y k i n i n , ACE i n h i b i t i o n may l e a d t o t h e a c c u m u l a t i o n o f t h e p o t e n t v a s o d i l a t o r b r a d y k i n i n i n d i f f e r e n t t i s s u e s ( A n t o n a c c i o et al., 1981) w h i c h may c o n t r i b u t e t o t h e l o n g - t e r m e f f e c t s o f t h e s e d r u g s . C a p t o p r i l has been shown t o i n c r e a s e t h e l e v e l s o f v a s o d i l a t o r p r o s t a g l a n d i n s e i t h e r d i r e c t l y o r t h r o u g h t h e i n c r e a s e o f b r a d y k i n i n ( S w a r t z and W i l l i a m s , 1 9 8 2 ) . F u r t h e r , some o f t h e d i s u l f i d e m e t a b o l i t e s o f c a p t o p r i l have been shown t o be more p o t e n t i n h i b i t o r s o f ACE t h a n t h e p a r e n t d r u g (Drummer et al., 1 9 8 5 ) . A l s o , t h e s e d i s u l f i d e m e t a b o l i t e s may s e r v e as a " d e p o t " f o r m o f c a p t o p r i l f r o m w h i c h c a p t o p r i l may be r e g e n e r a t e d ( O n d e t t i 1 9 8 8 ) . I t has been s u g g e s t e d , t h a t t h i s i n t e r c o n v e r s i o n between d i s u l f i d e m e t a b o l i t e s c o n t r i b u t e s t o t h e l o n g - t e r m h y p e r t e n s i v e e f f e c t s o f c a p t o p r i l . W h e t h e r t h e s e v a s o d i l a t o r y e f f e c t s o f c a p t o p r i l c o n t r i b u t e t o t h e o b s e r v e d i n c r e a s e i n and d e c r e a s e d SVR a f t e r two-weeks c a p t o p r i l t r e a t m e n t r e m a i n s t o be d e t e r m i n e d . 4.5. Changes i n S p l a n c h n i c V a s c u l a r R e s i s t a n c e 4.5.1. C a l c u l a t i o n o f S p l a n c h n i c V a s c u l a r R e s i s t a n c e SVR i s d e t e r m i n e d by t h e d i f f e r e n c e b e t w e e n mean a r t e r i a l p r e s s u r e a-d h e p a t i c v e n o u s p r e s s u r e d i v i d e d by t o t a l ( G a s i c et al., 1 9 8 9 ) . I n t - e p r e s e n t s t u d y , h o w e v e r , b e c a u s e o f t h e d i f f i c u l t i e s o f m e a s u r i n g h e p a t ' c v e n o u s p r e s s u r e a n d , s i n c e h e p a t i c v e n o u s p r e s s u r e i s s m a l l c o m p a r e d t o t - e mean a r t e r i a l p r e s s u r e (= 1 0 % ) , f o r t h e c a l c u l a t i o n o f t o t a l h e p a t i c a-d p o r t a l r e s i s t a n c e , t h e h e p a t i c v e n o u s p r e s s u r e has been i g n o r e d ( E c h t e n k c - p et al., 1983; M e s s e r l i et al., 1975; C u l b e r t s o n e t al. 1951; W i l k i n s et a l . . 1 9 5 1 ) . F u r t h e r , p r e v i o u s c l i n i c a l s t u d i e s r e p o r t e d no s i g n i f i c a n t change 'n h e p a t i c v e n o u s p r e s s u r e a f t e r c a p t o p r i l a d m i n i s t r a t i o n i n p a t i e n t s wi:h l i v e r c i r r h o s i s ( E r i k s s o n e t al., 1 9 8 4 ) . S i n c e ICG c l e a r a n c e methrd d e t e r m i n e s t o t a l l i v e r b l o o d f l o w , w h i c h i s t h e sum o f h e p a t i c a r t e r i a l and p o r t a l v e n o u s f l o w , t h e t e r m SVR r e f e r s t o t h e t o t a l h e p a t i c v a s c u l a r r e s i s t a n c e p l u s t h e r e s i s t a n c e o f t h e v e s s e l s i n t h e s p l a n c h n i c r e g i o n ( 7 . e . s p l e e n , p a n c r e a s , i n t e s t i n e and s t o m a c h ) ( E c h t e n k a m p e t al., ( 1 9 8 3 ) . 4.5.2. E f f e c t s o f P o s t u r a l Change on SVR B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t I t h as been r e p o r t e d by C u l b e r t s o n e t al., ( 1 9 5 1 ) t h a t t h e s i g n i f i c a n t r e d u c t i o n i n e s t i m a t e d Qy o b s e r v e d i n t h e i r s t u d y when s u b j e c t s were t i l t e d f r o m l y i n g t o s t a n d i n g was n o t a s s o c i a t e d w i t h a s i g n i f i c a n t c h a n g e i n mean a r t e r i a l p r e s s u r e . S i n c e SVR, i n t h e s t u d i e s o f C u l b e r t s o n e t al. ( 1 9 5 1 ) , was c a l c u l a t e d as t h e r a t i o o f mean a r t e r i a l p r e s s u r e and e s t i m a t e d l i v e r b l o o d f l o w , a s i g n i f i c a n t ~ 3 9 % and ~ 4 5 % i n c r e a s e i n SVR was n o t e d i n t h e h y p e r t e n s i v e and n o r m o t e n s i v e p a t i e n t s , r e s p e c t i v e l y . The r e s u l t s o f t h e p r e s e n t s t u d y r e a f f i r m t h e s e f i n d i n g s . T h u s , a s i g n i f i c a n t i n c r e a s e i n SVR (± SEM) f r o m 6.6 ± 0.54 t o 8.6 ± 0.66 mm Hg-sec/ml ( 3 1 . 0 % ) was o b s e r v e d upon s t a n d i n g i n t h e u n t r e a t e d p a t i e n t s on d a y 1, as a r e s u l t o f t h e s i g n i f i c a n t i n c r e a s e i n Qy and s m a l l c h a n g e i n mean a r t e r i a l p r e s s u r e ( T a b l e 17, F i g u r e 2 8 ) . T h i s i s ~ 8% l e s s t h a n t h e i n c r e a s e i n SVR r e p o r t e d by C u l b e r t s o n e t al., ( 1 9 5 1 ) i n h y p e r t e n s i v e p a t i e n t s . The s m a l l e r i n c r e a s e i n SVR upon s t a n d i n g , as co m p a r e d t o t h e v a l u e s r e p o r t e d by C u l b e r t s o n e t al., (1951) may be due t o t h e d i f f e r e n t p o s t u r e s u s e d i n t h e s e s t u d i e s ( s u p i n e t o u p r i g h t versus s e a t e d t o s u p i n e ) . The i n c r e a s e i n SVR on s t a n d i n g was c o n s i s t e n t among t h e s i x p a t i e n t s s t u d i e d . F o l l o w i n g two-weeks o f c a p t o p r i l t h e r a p y , a v e r a g e SVR (± SEM) i n c r e a s e d f r o m 5.3 ± 0.8 t o 7.1 ± 1.1 mm Hg-sec/ml ( 3 3 . 3 % ) i n u p r i g h t p o s i t i o n , as c o m p a r e d t o t h e s e a t e d v a l u e s ( T a b l e 17, F i g u r e 2 8 ) . The i n c r e a s e i n SVR was c o n s i s t e n t among t h e s i x p a t i e n t s s t u d i e d , h o w e v e r , t h e o v e r a l l i n c r e a s e d u r i n g s t a n d i n g was n o t s t a t i s t i c a l l y s i g n i f i c a n t a f t e r two-weeks o f c a p t o p r i l t h e r a p y . A l t h o u g h , SVRs a f t e r two-weeks o f c a p t o p r i l t r e a t m e n t w ere l o w e r by ~ 1 9 % and 1 7 % i n s e a t e d and u p r i g h t p o s i t i o n s , r e s p e c t i v e l y , as c o m p a r e d t o t h o s e b e f o r e c a p t o p r i l t r e a t m e n t ( F i g u r e 2 8 ) , t h e m a g n i t u d e o f i n c r e a s e i n SVR upon s t a n d i n g was s i m i l a r b e f o r e and a f t e r c a p t o p r i l t h e r a p y ( 3 3 . 3 % v s 3 1 . 0 % ) . T h e s e r e s u l t s s u g g e s t t h a t two-weeks o f c a p t o p r i l t h e r a p y d i d n o t a l t e r t h e r e f l e x r e s p o n s e s o f SVR t o p o s t u r a l c h a n g e i n m i l d t o m o d e r a t e h y p e r t e n s i v e p a t i e n t s . 4.5.3. A c u t e E f f e c t s o f C a p t o p r i l on SVR D e s p i t e t h e s i g n i f i c a n t r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s ( 1 3 . 4 % and 13.0%, r e s p e c t i v e l y , p < 0.05) 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l c a p t o p r i l d o s e ( T a b l e 12) t h e r e was no s i g n i f i c a n t c h a n g e i n SVR (Day 1, T a b l e 1 7 ) . I n c o n t r a s t t o t h e i n i t i a l c a p t o p r i l d o s e , t h e t e r m i n a l d o s e o f c a p t o p r i l d i d n o t c h a n g e s i g n i f i c a n t l y t h e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 1 h o u r a f t e r a d m i n i s t r a t i o n ( F i g u r e 22) and SVR r e m a i n e d u n a l t e r e d . The a b s e n c e o f a r e d u c t i o n i n SVR i s s i m i l a r t o t h e f i n d i n g s o f L e v i n e e t al., ( 1 9 8 4 ) who o b s e r v e d s i g n i f i c a n t r e d u c t i o n i n t o t a l s y s t e m i c v a s c u l a r r e s i s t a n c e 90 m i n u t e s a f t e r c a p t o p r i l d o s i n g w i t h o u t a c h a n g e i n SVR i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e . 4.5.4. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on SVR I t i s w e l l e s t a b l i s h e d , t h a t t h e h y p e r t e n s i v e e f f e c t s o f c a p t o p r i l a f t e r a c u t e , as w e l l as p r o l o n g e d a d m i n i s t r a t i o n a r e a s s o c i a t e d w i t h a d e c r e a s e i n t o t a l p e r i p h e r a l r e s i s t a n c e ( T a r a z i e t al., 1980; W e n t i n g e t al., 1 9 8 2 ) . The ~ 1 5 - 2 3 % r e d u c t i o n i n SVR a f t e r two-weeks c a p t o p r i l t h e r a p y , o b s e r v e d i n t h e p r e s e n t s t u d y s u g g e s t s t h a t v a s o d i l a t i o n o c c u r i n t h e a r t e r i o l e s o f t h e s p l a n c h n i c a r e a ( F i g u r e 2 8 ) . T h i s d e c r e a s e i n SVR may r e f l e c t a r e d u c t i o n i n t o t a l p e r i p h e r a l r e s i s t a n c e a f t e r c o n t i n u o u s t h e r a p y w i t h c a p t o p r i l . P r e v i o u s c l i n i c a l s t u d i e s r e p o r t e d 1 1 % and 1 8 % d e c r e a s e i n t o t a l p e r i p h e r a l r e s i s t a n c e a f t e r 4-weeks and 1-week c a p t o p r i l t r e a t m e n t i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n ( W e n t i n g e t al., 1982; T a r a z i e t al., 1 9 8 0 ) , w h i c h a r e s i m i l a r i n m a g n i t u d e t o t h a t o b s e r v e d i n t h e p r e s e n t s t u d y f o r SVR. However, l a r g e r d e c r e a s e s o f up t o 3 0 % i n t o t a l p e r i p h e r a l r e s i s t a n c e have a l s o been r e p o r t e d a f t e r a c u t e o r c h r o n i c t r e a t m e n t w i t h c a p t o p r i l ( B r o g d e n e t al., 1 9 8 8 ) . W h e t h e r t h e o b s e r v e d i n c r e a s e i n Qy and d e c r e a s e i n SVR a r e c o n s e q u e n c e s o f e i t h e r a d i r e c t i n t e r a c t i o n o f c a p t o p r i l w i t h t h e r e n i n -a n g i o t e n s i n s y s t e m i n t h e s p l a n c h n i c v a s c u l a r s y s t e m , an enhancement o f a s y m p a t h e t i c m o d u l a t i n g e f f e c t ( S t a d e a g e r e t al., 1989) o r a r e s u l t o f c o m p l e x haemodynamic c h a n g e s ( L e v i n e e t al., 1984) i s d i f f i c u l t t o e s t a b l i s h . S t a t i s t i c a l s i g n i f i c a n c e , a t t h e 0.05 p r o b a b i l i t y l e v e l , was n o t o b s e r v e d when t h e SVR d a t a o f s i x p a t i e n t s were c a l c u l a t e d (MANOVA, p = 0 . 1 2 ) . T h e s e d a t a , h o w e v e r , s u g g e s t t h a t a s u b s t a n t i a l r e d u c t i o n i n SVR o c c u r r e d a f t e r 14 d a y s c a p t o p r i l t h e r a p y , i n c o n t r a s t t o t h e e f f e c t s o f a s i n g l e - d o s e o f c a p t o p r i l , w h e r e no c h a n g e i n SVR was n o t e d . A s s u m i n g t h a t t h e c h a n g e s i n SVR r e f l e c t c h a n g e s i n t o t a l p e r i p h e r a l r e s i s t a n c e , t h e r e s u l t s o f t h e p r e s e n t s t u d y a r e i n a g r e e m e n t w i t h t h e s t u d i e s o f Simon e t al., ( 1 9 8 5 ) who o b s e r v e d a more p r o n o u n c e d d e c r e a s e i n t o t a l p e r i p h e r a l r e s i s t a n c e a f t e r 5 d a y s t r e a t m e n t w i t h c a p t o p r i l t h a n a f t e r s i n g l e d o s e a d m i n i s t r a t i o n i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . I t has been s u g g e s t e d ( S i m o n et al., 1985) t h a t t h e e f f e c t s o f ACE i n h i b i t i o n a p p e a r e d e a r l i e r i n t h e l a r g e a r t e r i e s t h a n i n t h e a r t e r i o l e s . S i n c e t h e a r t e r i o l e s p r o v i d e t h e l a r g e s t r e s i s t a n c e t o b l o o d f l o w ( S h e p h e r d and V a n h o u t t e , 1980) t h e l a c k o f c h a n g e s i n a f t e r a c u t e d o s i n g w i t h c a p t o p r i l and i n c r e a s e d a f t e r two-weeks t r e a t m e n t may be e x p l a i n e d by t h e f i n d i n g s o f Simon e t al., ( 1 9 8 5 ) . An i n c r e a s e i n QH i n t h e p r e s e n c e o f s i g n i f i c a n t r e d u c t i o n i n a r t e r i a l b l o o d p r e s s u r e may o c c u r when t o t a l p e r i p h e r a l r e s i s t a n c e ( i n c l u d i n g t h e r e s i s t a n c e i n t h e s p l a n c h n i c r e g i o n ) d e c r e a s e s more t h a n a r t e r i a l p r e s s u r e . I n t h e p r e s e n t s t u d y , SVR d e c r e a s e d an a v e r a g e o f - 1 9 % a f t e r two-weeks c a p t o p r i l t h e r a p y ( F i g u r e 28) and s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e d e c l i n e d by =13% and ==11%, r e s p e c t i v e l y , ( T a b l e 16) 1 h o u r a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l . T h e r e f o r e , t h e r e l a t i v e l y s m a l l d e c r e a s e i n b l o o d p r e s s u r e , as compared t o t h e SVR, s u g g e s t s an i n c r e a s e i n QH u n d e r t h e s e d e s c r i b e d e x p e r i m e n t a l c o n d i t i o n s . 4.6. C hanges i n B l o o d P r e s s u r e 4.6.1. E f f e c t s o f P o s t u r a l Change on B l o o d P r e s s u r e B e f o r e and A f t e r C a p t o p r i l The h y d r o s t a t i c c h a n g e s t h a t o c c u r d u r i n g p o s t u r a l s h i f t f r o m s u p i n e t o s t a n d i n g a r e w e l l e s t a b l i s h e d ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . The r e d i s t r i b u t i o n o f b l o o d t o t h e l e g s r e s u l t s i n a d e c r e a s e i n c a r d i a c o u t p u t w h i c h i s c o u n t e r a c t e d by t h e r e f l e x c o n s t r i c t i o n o f t h e p e r i p h e r a l v e s s e l s i n o r d e r t o m a i n t a i n a r t e r i a l p r e s s u r e ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . Hence, t h e o b s e r v e d d e c r e a s e i n Q^ d u r i n g s t a n d i n g i s a r e s u l t o f t h i s c o m p e n s a t o r y m e c h a n i s m t o m a i n t a i n s y s t e m i c a r t e r i a l b l o o d p r e s s u r e . I t has been r e p o r t e d e a r l i e r ( C u l b e r t s o n e t al., 1951) t h a t when n o r m o t e n s i v e o r h y p e r t e n s i v e p a t i e n t s w e r e t i l t e d t o u p r i g h t p o s i t i o n , t h e l a r g e r e d u c t i o n i n Qy was n o t a s s o c i a t e d w i t h l a r g e c h a n g e s i n mean a r t e r i a l p r e s s u r e . I n c o n t r a s t , V a n d e n b e r g et al., ( 1 9 8 3 ) , r e p o r t e d s i g n i f i c a n t i n c r e a s e i n d i a s t o l i c and s l i g h t i n c r e a s e i n s y s t o l i c b l o o d p r e s s u r e s upon s t a n d i n g . T h i s s u g g e s t t h a t mean a r t e r i a l p r e s s u r e c a n be m i s l e a d i n g c o n s i d e r i n g t h e c h a n g e s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s . T h i s i s due t o t h e f a c t t h a t mean a r t e r i a l p r e s s u r e i s n o t e x a c t l y e q u a l t o t h e a v e r a g e s y s t o l i c and d i a s t o l i c p r e s s u r e s , b e c a u s e p r e s s u r e u s u a l l y r e m a i n s f o r a s h o r t e r p e r i o d o f t i m e a t t h e h i g h e s t p r e s s u r e d u r i n g c o n t r a c t i o n o f t h e v e n t r i c l e ( s y s t o l i c ) , t h a n on t h e l o w e r p r e s s u r e d u r i n g r e f i l l i n g t h e v e n t r i c l e ( d i a s t o l i c ) ( G u y t o n , 1 9 8 4 ) . The r e s u l t i n g mean p r e s s u r e i s c l o s e r t o t h e d i a s t o l i c t h a n t o t h e s y s t o l i c p r e s s u r e . However, mean a r t e r i a l p r e s s u r e i s i m p o r t a n t s i n c e i t d e t e r m i n e s t h e a v e r a g e b l o o d f l o w r a t e t h r o u g h t h e s y s t e m i c v e s s e l s ( G u y t o n , 1 9 8 4 ) . I n t h e p r e s e n t s t u d y , d i a s t o l i c b l o o d p r e s s u r e i n c r e a s e d s l i g h t l y by = 7 and 5 mm Hg when s u b j e c t s were i n s t a n d i n g p o s i t i o n , b e f o r e and a f t e r 14 d a y s c a p t o p r i l t h e r a p y , r e s p e c t i v e l y . S y s t o l i c b l o o d p r e s s u r e , h o w e v e r , r e m a i n e d u n a l t e r e d ( F i g u r e 16 and 1 7 ) . The o b s e r v e d i n c r e a s e i n d i a s t o l i c b l o o d p r e s s u r e i n s t a n d i n g p o s i t i o n i s i n a g r e e m e n t w i t h t h e s t u d i e s o f V a n d e n b e r g et al., ( 1 9 8 3 ) . 4.6.2. A c u t e E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e The e f f i c a c y o f c a p t o p r i l i n d e c r e a s i n g b l o o d p r e s s u r e has been amply d e m o n s t r a t e d i n p a t i e n t s w i t h h y p e r t e n s i o n ( B r o g d e n e t al., 1988; T a r a z i e t al., 1980; M c A r e a v e y and R o b e r t s o n 1990; W e n t i n g e t al., 1 9 8 2 ) . A r e d u c t i o n i n s u p i n e o r s t a n d i n g s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s by a b o u t 10 t o 2 0 % a f t e r a s i n g l e d o s e o f c a p t o p r i l i n p a t i e n t s w i t h h y p e r t e n s i o n was r e p o r t e d by B r o g d e n e t al., ( 1 9 8 8 ) . Mean a r t e r i a l p r e s s u r e d e c r e a s e d f r o m 141.9 ± 6.9 t o 130.2 ± 6.7 mm Hg, 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f 50-100 mg o r a l d o s e o f c a p t o p r i l i n h y p e r t e n s i v e p a t i e n t s ( C r o s s l e y e t al., 1 9 8 4 ) . I n a n o t h e r s t u d y , when a 50 mg c a p t o p r i l d o s e was a d m i n i s t e r e d t o p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n mean a r t e r i a l p r e s s u r e d e c r e a s e d f r o m 141 ± 6 t o 119 ± 7 mm Hg ( 1 5 . 6 % ) 2 h o u r s a f t e r d r u g a d m i n i s t r a t i o n ( W e n t i n g e t al., 1 9 8 2 ) . T a r a z i e t al., ( 1 9 8 0 ) r e p o r t e d a d e c r e a s e i n mean a r t e r i a l p r e s s u r e f r o m 139,0 ± 4.7 t o 120.0 ± 5.9 mm Hg, 30 m i n u t e s a f t e r c a p t o p r i l t r e a t m e n t i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . In t h e p r e s e n t s t u d y , mean a r t e r i a l p r e s s u r e d e c r e a s e d f r o m 118.0 ± 3.0 t o 104.9 ± 5.4 mm Hg ( 1 1 . 1 % ) 1 h o u r a f t e r a s i n g l e d o s e o f c a p t o p r i l ( T a b l e 1 2 ) . T h i s = 1 1 % r e d u c t i o n i n mean a r t e r i a l p r e s s u r e i s i n a g r e e m e n t w i t h p r e v i o u s s t u d i e s o f C r o s s l e y e t al., ( 1 9 8 4 ) and T a r a z i e t al., (1980) who r e p o r t e d a 8% and ~ 1 4 % d e c r e a s e i n mean a r t e r i a l p r e s s u r e , r e s p e c t i v e l y , a f t e r c a p t o p r i l a d m i n i s t r a t i o n . S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were s i g n i f i c a n t l y r e d u c e d f r o m 160.5 ± 5.3 t o 138.9 ± 10.2 mm Hg ( 1 3 . 4 % ) and f r o m 103.3 ± 1.0 t o 89.8 ± 4.3 mm Hg ( 1 3 . 0 % ) , r e s p e c t i v e l y 1 h o u r a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l ( T a b l e 12 and F i g u r e 2 0 ) . The mean d i f f e r e n c e f r o m p r e t r e a t m e n t v a l u e s 1 h o u r a f t e r t h e i n i t i a l c a p t o p r i l d o s e was ~ 22 mm Hg f o r s y s t o l i c and 13 mm Hg f o r d i a s t o l i c b l o o d p r e s s u r e . I n c o n t r a s t t o t h e r e p o r t s o f B r o g d e n e t al., ( 1 9 8 8 ) maximal b l o o d p r e s s u r e r e d u c t i o n was o b s e r v e d a f t e r 3 h o u r s o f c a p t o p r i l a d m i n i s t r a t i o n when s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s and mean a r t e r i a l p r e s s u r e (mean ± SEM) were f o u n d t o be 132.4 ± 9.3 mm Hg, 86.6 ± 6.3 mm Hg, and 101.0 ± 6.6 mm Hg, r e s p e c t i v e l y , ( T a b l e 12, F i g u r e 2 0 ) . Th e s e b l o o d p r e s s u r e v a l u e s 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l were l o w e r t h a n t h e p r e t r e a t m e n t v a l u e s by ~ 18%, ~ 16% and ~ 14%, r e s p e c t i v e l y . The a b s o l u t e r e d u c t i o n s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 3 h o u r s a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l w e r e ^ 28 mm Hg and 17 mm Hg, r e s p e c t i v e l y , as c ompared t o t h e p r e t r e a t m e n t b l o o d p r e s s u r e s ( F i g u r e 2 0 ) . P a r a t i e t a / . , ( 1 9 8 9 ) f o u n d t h a t t h e t i m e r e q u i r e d f o r m a x i m a l r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e was between 2 and 4 h o u r s a f t e r t h e a d m i n i s t r a t i o n o f a s i n g l e 100 mg o r a l d o s e o f c a p t o p r i l . The r e s u l t s o f t h e p r e s e n t s t u d y s u b s t a n t i a t e t h e s e f i n d i n g s . A l l p a t i e n t s r e s p o n d e d w e l l t o t h e f i r s t d o s e o f c a p t o p r i l 3 h o u r s a f t e r a d m i n i s t r a t i o n , i n c l u d i n g t h e one b l a c k p a t i e n t (O.W.). A l e s s e r r e s p o n s e t o c a p t o p r i l i n b l a c k p a t i e n t s , as c ompared t o t h e w h i t e s u b j e c t s , has been r e p o r t e d p r e v i o u s l y ( V e t e r a n s A d m i n i s t r a t i o n C o o p e r a t i v e S t u d y G r o u p , 1 9 8 4 ) . However, t h i s r e d u c e d r e s p o n s e t o c a p t o p r i l c o u l d n o t be s u b s t a n t i a t e d i n t h e one b l a c k p a t i e n t i n t h e p r e s e n t s t u d y . The h i g h e s t p r e t r e a t m e n t s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e r e c o r d e d i n p a t i e n t O.W. (181.5 mm Hg) and p a t i e n t D.A. ( 1 0 6 . 5 mm H g ) , r e s p e c t i v e l y ( T a b l e 3 ) . The l a r g e s t a b s o l u t e r e d u c t i o n i n b l o o d p r e s s u r e 1 h o u r and 3 h o u r a f t e r t h e a d m i n i s t r a t i o n o f a s i n g l e d o s e o f c a p t o p r i l was o b s e r v e d i n p a t i e n t B.H.: 53 mm Hg ( 3 5 % ) and 57 mm Hg ( 3 8 % ) f o r s y s t o l i c , 29 mm Hg ( 2 8 % ) and 41 mm Hg ( 4 0 % ) f o r d i a s t o l i c b l o o d p r e s s u r e , r e s p e c t i v e l y ( T a b l e 1 1 ) . T h i s p r o f o u n d b l o o d p r e s s u r e r e d u c t i o n may be a m i l d c a s e o f f i r s t d o s e h y p o t e n s i o n as r e p o r t e d by s e v e r a l i n v e s t i g a t o r s (Hodsman e t a / . , 1983; B r o g d e n e t a/., 1988; L e e s e t a/., 1 9 9 0 ) . F i r s t d o s e h y p o t e n s i o n ( a d e c r e a s e i n s u p i n e s y s t o l i c b l o o d p r e s s u r e > 50 mm Hg) (Hodsman e t a / . , 1983) most o f t e n d e v e l o p e d i n p a t i e n t s w i t h e i t h e r h i g h p r e t r e a t m e n t p l a s m a r e n i n and a n g i o t e n s i n I I c o n c e n t r a t i o n s o r s e c o n d a r y h y p e r t e n s i o n . In a d d i t i o n , i t may o c c u r i n t h o s e p a t i e n t s who were p r e v i o u s l y t r e a t e d w i t h an ACE i n h i b i t o r ( B r o g d e n e t al., 1 9 8 8 ) . L e e s e t al., ( 1 9 9 0 ) s u g g e s t e d t h a t f i r s t -d o s e h y p o t e n s i o n may be r e l a t e d t o e x c e s s c o n v e r t i n g enzyme c a p a c i t y . P a t i e n t B.H. a l s o d e v e l o p e d m i l d symptoms o f n o n - p r o d u c t i v e c ough a f t e r r e p e a t e d t r e a t m e n t w i t h c a p t o p r i l , h o w e v e r , d i s c o n t i n u a t i o n o f t h e c a p t o p r i l t h e r a p y was n o t n e c e s s a r y . No o t h e r s i d e e f f e c t s were o b s e r v e d d u r i n g c a p t o p r i l t h e r a p y . S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were r e d u c e d s l i g h t l y 1 h o u r a f t e r t h e t e r m i n a l d o s e o f t h e two-weeks c a p t o p r i l t h e r a p y by 5.3 ± 7.3 mm Hg ( 4 . 3 % ) and 1.1 ± 2.3 mm Hg ( 1 . 2 % ) , r e s p e c t i v e l y , as c o m p a r e d t o t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e o f d a y 14; h o w e v e r , t h i s d e c r e a s e was n o t s t a t i s t i c a l l y s i g n i f i c a n t . I n c o n t r a s t , 3 h o u r s a f t e r t h e t e r m i n a l d o s e s y s t o l i c and d i a s t o l i c p r e s s u r e s were r e d u c e d s i g n i f i c a n t l y by ~ 17 mm Hg ( 1 1 . 5 % ) and ~ 10 mm Hg ( 1 0 . 7 % ) , r e s p e c t i v e l y ( T a b l e 14, F i g u r e 2 2 ) . The m a g n i t u d e o f d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e was much s m a l l e r t h a n t h a t a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l , as compared t o t h e b a s e l i n e v a l u e s o f d a y 1 and day 14 ( F i g u r e 2 2 ) . The s m a l l e r a b s o l u t e r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , as c o m p a r e d t o t h o s e o b s e r v e d a f t e r t h e i n i t i a l d o s e r e f l e c t s t h e s i g n i f i c a n t l y l o w e r t r e a t e d b a s e l i n e b l o o d p r e s s u r e o f d a y 14. T h i s i s i n a g r e e m e n t w i t h t h e s i g n i f i c a n t c o r r e l a t i o n b e t w e e n t h e i n i t i a l b l o o d p r e s s u r e and t h e r e d u c t i o n i n b l o o d p r e s s u r e , r e p o r t e d by Sumner e t al., ( 1 9 8 8 ) . T h u s , t h e h i g h e r t h e i n i t i a l b l o o d p r e s s u r e t h e g r e a t e r t h e r e d u c t i o n i n b l o o d p r e s s u r e due t o a n t i h y p e r t e n s i v e t h e r a p y (Sumner e t al., 1 9 8 8 ) . 4.6.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on B l o o d P r e s s u r e I n t h e p r e s e n t s t u d y , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s were m a i n t a i n e d b e l o w t h e b a s e l i n e v a l u e o f d a y 1, p r i o r t o t h e t e r m i n a l c a p t o p r i l d o s e on d a y 14. C l e a r l y , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s a f t e r r e a d m i s s i o n t o t h e h o s p i t a l on d a y 14 w e r e s i g n i f i c a n t l y l o w e r by 14.9 ± 7.7 mm Hg ( 9 . 3 % , p < 0.005) and 10.5 ± 6.4 mm Hg ( 1 0 . 1 % , p < 0 . 0 5 ) , r e s p e c t i v e l y , c o m p a r e d t o t h e p r e t r e a t m e n t b l o o d p r e s s u r e o f d a y 1 ( T a b l e 16, F i g u r e 25 and 2 6 ) . B a s e l i n e b l o o d p r e s s u r e m e a s u r e m e n t s on d a y 14 were p e r f o r m e d a p p r o x i m a t e l y 20 h o u r s a f t e r t h e i n t a k e o f t h e c a p t o p r i l d o s e on t h e p r e v i o u s d a y , b e f o r e p a t i e n t s r e t u r n e d t o t h e h o s p i t a l . T h e s e r e s u l t s a r e i n a g r e e m e n t w i t h t h e f i n d i n g s o f P a r a t i e t al., ( 1 9 8 9 ) and M a n c i a e t al., ( 1 9 8 7 ) who r e p o r t e d 22-24 h o u r b l o o d p r e s s u r e r e d u c t i o n f o l l o w i n g once d a i l y t r e a t m e n t w i t h 100 mg c a p t o p r i l . The 2 4 - h o u r a m b u l a t o r y b l o o d p r e s s u r e m o n i t o r i n g u s e d i n t h e s e s t u d i e s p r o v i d e d a u t o m a t i c r e a d i n g s o f b l o o d p r e s s u r e and h e a r t r a t e a t 10 o r 20 m i n u t e s i n t e r v a l s and were p e r f o r m e d 1 month a f t e r s t a r t i n g t r e a t m e n t w i t h c a p t o p r i l . P a r a t i e t al., (1989) a l s o r e p o r t e d p o s i t i v e c o r r e l a t i o n b e t w e e n t h e e a r l y r e d u c t i o n s i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s (2-4 h o u r a f t e r t h e a d m i n i s t r a t i o n o f 100 mg o r a l d o s e o f c a p t o p r i l ) and t h e c h a n g e s i n b l o o d p r e s s u r e a f t e r 24 h o u r i n t h o s e e s s e n t i a l h y p e r t e n s i v e p a t i e n t s , who r e s p o n d e d w e l l t o c a p t o p r i l t h e r a p y . T h i s s u g g e s t s t h a t b l o o d p r e s s u r e r e d u c t i o n a f t e r 22-24 h o u r s c a n be p r e d i c t e d by t h e e a r l y , p e a k r e d u c t i o n i n b l o o d p r e s s u r e i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . I n t h e p r e s e n t s t u d y , h o w ever, mean d i a s t o l i c b l o o d p r e s s u r e (± SEM) was 92.8 ± 2.3 mm Hg w h i c h i s s l i g h t l y g r e a t e r t h a n 90 mm Hg, t h e g e n e r a l l y a c c e p t e d l e v e l o f " n o r m a l " d i a s t o l i c b l o o d p r e s s u r e ( S h e p h e r d and V a n h o u t t e , 1980) A t t h e end o f t h e two-week c a p t o p r i l t r e a t m e n t , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e l o w e r t h a n p r e t r e a t m e n t v a l u e s by « 21 mm Hg ( 1 3 % ) and ~ 12 mm Hg ( 1 1 % ) , r e s p e c t i v e l y , a f t e r 1 h o u r and by ~ 32 ( 2 0 % ) and 20 mm Hg ( 2 0 % ) , r e s p e c t i v e l y , a f t e r 3 h o u r s o f t h e a d m i n i s t r a t i o n o f t h e t e r m i n a l d o s e o f c a p t o p r i l ( F i g u r e 25 and 2 6 ) . The a b s o l u t e r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , 1 and 3 h o u r s a f t e r t h e t e r m i n a l c a p t o p r i l d o s e w e r e s i m i l a r t o t h e a b s o l u t e r e d u c t i o n o b s e r v e d 1 and 3 h o u r s a f t e r t h e i n i t i a l c a p t o p r i l d o s e (-21 v s -22 mm Hg and -32 v s - 28 mm Hg, r e s p e c t i v e l y , f o r s y s t o l i c and -12 v s 13 mm Hg and -20 and 17 mm Hg, r e s p e c t i v e l y , f o r d i a s t o l i c b l o o d p r e s s u r e ) ( F i g u r e 25 and 2 6 ) . T h i s s u g g e s t s t h a t o n c e d a i l y t r e a t m e n t w i t h 100 mg c a p t o p r i l m a i n t a i n s b l o o d p r e s s u r e b e l o w t h e p r e t r e a t m e n t v a l u e s and p r o v i d e s b a l a n c e d b l o o d p r e s s u r e c o n t r o l , w h i c h i s i n a g r e e m e n t w i t h t h e s t u d i e s o f P a r a t i e t a / . , ( 1 9 8 9 ) . I t i s w e l l e s t a b l i s h e d , t h a t t h e d e c r e a s e i n a r t e r i a l b l o o d p r e s s u r e a f t e r c a p t o p r i l a d m i n i s t r a t i o n i s m e d i a t e d t h r o u g h a f a l l i n t o t a l p e r i p h e r a l r e s i s t a n c e ( T a r a z i e t a l . , 1980; W e n t i n g e t a / . , 1 9 8 2 ) . A r e d u c t i o n i n t o t a l p e r i p h e r a l r e s i s t a n c e was r e p o r t e d 30 t o 90 m i n u t e s a f t e r o r a l a d m i n i s t r a t i o n o f c a p t o p r i l ( F o u a d e t a l . , 1 9 8 0 ) . I n t h e p r e s e n t s t u d y , we c o u l d n o t e s t i m a t e t o t a l p e r i p h e r a l r e s i s t a n c e s i n c e c a r d i a c o u t p u t was n o t m e a s u r e d . B a s e d on p r e v i o u s l y r e p o r t e d r e s u l t s , t h e a c u t e o r s h o r t - t e r m e f f e c t s o f c a p t o p r i l on c a r d i a c o u t p u t u s u a l l y d e m o n s t r a t e no c h a n g e i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n ( T a r a z i e t a l . , 1 9 8 0 ) . T h e r e f o r e , t h e s i g n i f i c a n t r e d u c t i o n i n b l o o d p r e s s u r e o b s e r v e d i n t h i s s t u d y w i t h no c h a n g e i n c a r d i a c o u t p u t w o u l d i m p l y a d e c r e a s e i n t o t a l p e r i p h e r a l r e s i s t a n c e . The f a c t t h a t SVR d i d n o t c h a n g e i n t h e p r e s e n t s t u d y , a p p r o x i m a t e l y 1 h o u r a f t e r a c u t e a d m i n i s t r a t i o n s o f c a p t o p r i l . s u g g e s t s t h a t o t h e r r e g i o n a l beds may c o n t r i b u t e t o t h e r e d u c t i o n o f t o t a l p e r i p h e r a l r e s i s t a n c e . I n d e e d , a 1 0 7 % i n c r e a s e i n f o r e a r m b l o o d f l o w has been r e p o r t e d i n n o r m a l s u b j e c t s a f t e r a s i n g l e - d o s e o f c a p t o p r i l and r e n a l b l o o d f l o w i n c r e a s e d by 6 0 % i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e ( F a x o n e t a l . , 1 9 8 4 ) . I n c o n t r a s t , a f t e r two-weeks t r e a t m e n t w i t h c a p t o p r i l SVR d e c r e a s e d on a v e r a g e by =: 1 9 % i n t h e f o u r p h a s e s o f t h e s t u d y , as c o m p a r e d t o t h e day 1 v a l u e s . A l t h o u g h , t h e o v e r a l l d e c r e a s e i n SVR d o e s n o t a c h i e v e t h e l e v e l o f s i g n i f i c a n c e (p = 0 . 1 2 5 ) , i t may s u g g e s t t h a t a f t e r p r o l o n g e d t r e a t m e n t w i t h c a p t o p r i l t h e r e d u c t i o n i n SVR c o n t r i b u t e s t o t h e o v e r a l l r e d u c t i o n i n t o t a l p e r i p h e r a l r e s i s t a n c e . 4.7. Changes i n H e a r t R a t e 4.7.1. E f f e c t s o f P o s t u r a l Change on H e a r t R a t e B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t I t i s w e l l e s t a b l i s h e d t h a t h e a r t r a t e g e n e r a l l y i n c r e a s e s when h e a l t h y s u b j e c t s c h a n g e p o s i t i o n f r o m s u p i n e t o u p r i g h t due t o t h e d e c r e a s e i n v e n o u s r e t u r n ( S h e p h e r d and V a n h o u t t e , 1 9 8 0 ) . M u i e s a n e t a / . , (1982) r e p o r t e d an i n c r e a s e i n h e a r t r a t e i n s t a n d i n g p o s i t i o n by 5 b e a t s / m i n w h i c h r e m a i n e d u n a l t e r e d a f t e r e i g h t weeks o f t r e a t m e n t w i t h c a p t o p r i l , i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . V a n d e n b u r g e t al., ( 1 9 8 3 ) n o t e d a much g r e a t e r i n c r e a s e i n h e a r t r a t e (10 b e a t s / m i n ) when p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n c h a n g e d p o s i t i o n f r o m l y i n g t o s t a n d i n g . In a g r e e m e n t w i t h t h e s t u d i e s o f M u i e s a n e t al., ( 1 9 8 2 ) t h e m a g n i t u d e o f change i n h e a r t r a t e i n s t a n d i n g p o s i t i o n was u n a f f e c t e d by two and f o u r weeks c a p t o p r i l t h e r a p y . The r e s u l t s o f t h e p r e s e n t s t u d y s u b s t a n t i a t e t h e f i n d i n g s o f M u i e s a n et al., (1982) t h a t h e a r t r a t e i n c r e a s e d s i g n i f i c a n t l y upon s t a n d i n g by 4 and 5 b e a t s / m i n b e f o r e and a f t e r two-weeks c a p t o p r i l t h e r a p y , r e s p e c t i v e l y ( F i g u r e 1 8 ) . A l s o , i t i s i n a g r e e m e n t w i t h t h e s t u d i e s o f V a n d e n b u r g et al., (1983) t h a t two-weeks c a p t o p r i l t h e r a p y d o e s n o t i n t e r f e r e w i t h t h e a c u t e c h a n g e s i n h e a r t r a t e c a u s e d by p o s t u r a l c h a n g e i n p a t i e n t s w i t h e s s e n t i a l h y p e r t e n s i o n . 4.7.2. E f f e c t s o f A c u t e and S h o r t - T e r m C a p t o p r i l T r e a t m e n t on H e a r t R a t e I t has been r e p o r t e d p r e v i o u s l y , t h a t i n s p i t e o f t h e s i g n i f i c a n t l o w e r i n g o f a r t e r i a l p r e s s u r e and p e r i p h e r a l r e s i s t a n c e , h e a r t r a t e d o es n o t u s u a l l y show a s i g n i f i c a n t i n c r e a s e i n h y p e r t e n s i v e p a t i e n t s a f t e r a c u t e o r s h o r t - t e r m c a p t o p r i l t r e a t m e n t ( T a r a z i et al., 1980; C r o s s l e y et al., 1 9 8 4 ) . T h i s has a l s o been d e m o n s t r a t e d , by P a r a t i et al., ( 1 9 8 9 ) i n p a t i e n t s w i t h h y p e r t e n s i o n , where i t was f o u n d t h a t no c h a n g e i n h e a r t r a t e o c c u r r e d d u r i n g t h e 24 h o u r p e r i o d f o l l o w i n g 100 mg c a p t o p r i l d o s e o n c e d a i l y f o r 1 month, as c o m p a r e d t o t h e p l a c e b o t r e a t e d g r o u p ( P a r a t i e t a l . , 1 9 8 9 ) . W e n t i n g e t a l . , ( 1 9 8 2 ) r e p o r t e d no a c u t e c h a n g e s i n h e a r t r a t e i n h y p e r t e n s i v e p a t i e n t s f o l l o w i n g a s i n g l e c a p t o p r i l d o s e . They n o t e d , h o w e v e r , a s i g n i f i c a n t d e c r e a s e i n h e a r t r a t e f r o m 76 ± 3 t o 69 ± 2 b e a t s / m i n , a f t e r 4 weeks o f c a p t o p r i l t h e r a p y . I n c o n t r a s t , F a g a r d e t a l . , ( 1 9 8 2 ) r e p o r t e d a s l i g h t i n c r e a s e i n h e a r t r a t e 75 m i n u t e s a f t e r c a p t o p r i l t r e a t m e n t i n p a t i e n t s w i t h h y p e r t e n s i o n . The r e s u l t s o f t h e p r e s e n t s t u d y a r e i n a g r e e m e n t w i t h t h e f i n d i n g s o f T a r a z i e t al., ( 1 9 8 0 ) , C r o s s l e y e t al., ( 1 9 8 4 ) and P a r a t i e t al., ( 1 9 8 9 ) . T h e r e was no c h a n g e i n h e a r t r a t e 3 h o u r s f o l l o w i n g t h e a d m i n i s t r a t i o n o f t h e i n i t i a l d o s e o f c a p t o p r i l (72.6 ± 4.1 vs 73.6 ± 3.5 b e a t s / m i n ) ( T a b l e 1 2 ) . I n t h r e e p a t i e n t s ( C . B . , O.W., M.S.), h o w e v e r , h e a r t r a t e i n c r e a s e d i n t h e r a n g e o f 2-7 b e a t s / m i n ( F i g u r e 2 4 ) . F o l l o w i n g two-weeks t r e a t m e n t w i t h c a p t o p r i l , p r i o r t o t h e t e r m i n a l d o s e , h e a r t r a t e was n o t s i g n i f i c a n t l y d i f f e r e n t f r o m c o n t r o l v a l u e ( 7 1 . 0 ± 3.2 vs 72.6 ± 4 . 1 ) ( F i g u r e 1 8 ) . The t e r m i n a l d o s e o f c a p t o p r i l d i d n o t c h a n g e t h e h e a r t r a t e , h o w e ver a s l i g h t ( n o n - s i g n i f i c a n t ) d e c r e a s e was o b s e r v e d when h e a r t r a t e v a l u e s a t t h e end o f t h e s t u d y were c o m p a r e d t o t h e u n t r e a t e d v a l u e s ( 7 2 . 6 ± 4.1 v s 69.8 ± 3.5) ( F i g u r e 2 7 ) . S y s t e m i c v a s o d i l a t i o n u s u a l l y c a u s e s a r e f l e x i n c r e a s e i n h e a r t r a t e ( S h e p h e r d and V a n h o u t t e , 1980) w h i c h was n o t o b s e r v e d i n t h i s s t u d y . The l a c k o f i n c r e a s e i n h e a r t r a t e a f t e r c a p t o p r i l t r e a t m e n t c o u l d be e x p l a i n e d by ( 1 ) an i n t e r f e r e n c e w i t h t h e s y m p a t h e t i c n e r v o u s s y s t e m and c o n s e q u e n t l y , an a l t e r a t i o n i n b a r o r e c e p t o r r e f l e x e s ( M u i e s a n e t a l . , 1982) o r ( 2 ) a c o n c o m i t a n t a r t e r i o l a r and v e n o u s v a s o d i l a t a t i o n ( T a r a z i e t a l . , 1 9 8 0 ) . 4.8. Changes i n H e m a t o c r i t 4.8.1. E f f e c t s o f P o s t u r a l Change on H e m a t o c r i t B e f o r e and A f t e r C a p t o p r i l T r e a t m e n t P o s t u r a l c h a n g e f r o m s u p i n e t o s t a n d i n g has been shown t o p r o d u c e a r e d u c t i o n i n t h e p l a s m a v o l u m e o f h e a l t h y s u b j e c t s (Hagan e t al., 1978; D i x o n and P a t e r s o n , 1 9 7 8 ) . T h i s has been shown t o o c c u r as a c o n s e q u e n c e o f i n c r e a s e d c a p i l l a r y p r e s s u r e and p l a s m a e f f l u x i n t o t h e i n t e r s t i t i a l s p a c e (Hagan et al., 1 9 7 8 ) . I n t h e s t u d i e s o f Hagan e t al., ( 1 9 7 8 ) t h e r e d u c t i o n i n t h e p l a s m a v o l u m e a f t e r 35 m i n u t e s s t a n d i n g was a s s o c i a t e d w i t h a r i s e i n h e m a t o c r i t , h e m o g l o b i n and p l a s m a p r o t e i n s by 10.3%, 1 0 . 8 % and 20.8%, r e s p e c t i v e l y . I t has been s u g g e s t e d , t h a t a minimum o f 20 m i n u t e s r e q u i r e d t o s t a b i l i z e t h e p l a s m a v o l u m e i n a new p o s t u r e , h o w e v e r , maximal s t a b i l i t y was a c h i e v e d o n l y a f t e r 40 and 60 m i n u t e s (Hagan et al., 1 9 7 8 ) . T h e s e o b s e r v a t i o n s a r e i m p o r t a n t i n r e l a t i o n t o t h e p r e s e n t s t u d y b e c a u s e o f t h e f o l l o w i n g r e a s o n s : 1. ICG h i g h l y bounds t o p l a s m a p r o t e i n s a f t e r i n t r a v e n o u s a d m i n i s t r a t i o n ( P a u m g a r t n e r , 1 9 7 5 ) . S i n c e t h e c o n c e n t r a t i o n s o f p l a s m a p r o t e i n s p r o g r e s s i v e l y c h a n g e upon p o s t u r a l s h i f t f r o m s i t t i n g t o s t a n d i n g (Hagan et al., 1978) b l o o d s a m p l i n g b e f o r e s t a b i l i z a t i o n o f p l a s m a volume ( 4 0 - 6 0 m i n u t e s ) c o u l d p r o d u c e e r r o n e o u s d e t e r m i n a t i o n s o f ICG serum c o n c e n t r a t i o n s . H e n c e , i n t h e p r e s e n t s t u d y p a t i e n t s r e m a i n e d i n t h e assumed p o s i t i o n f o r a minimum o f 60 m i n u t e s and p o s t u r e was m a i n t a i n e d d u r i n g b l o o d s a m p l i n g f o r ICG i n o r d e r t o m i n i m i z e t h e c h a n g e s i n p l a s m a p r o t e i n c o n c e n t r a t i o n s . 2. The h e m a t o c r i t i s an i m p o r t a n t f a c t o r t o c o n v e r t C l p j Q g t o S i n c e i t s v a l u e i s i n f l u e n c e d by p o s t u r a l c h a n g e , e s t i m a t i o n o f t h e h e m a t o c r i t s h o u l d be p e r f o r m e d a f t e r t h e s t a b i l i z a t i o n o f t h e p l a s m a v o l u m e f o l l o w i n g p o s i t i o n a l c h a n g e . I n t h e p r e s e n t s t u d y , b l o o d s a m p l i n g f o r h e m a t o c r i t was p e r f o r m e d d u r i n g t h e b l o o d s a m p l i n g f o r ICG (=: 8 min a f t e r ICG i n j e c t i o n ) and 60 m i n u t e s a f t e r t h e p a t i e n t s assumed a new p o s i t i o n , t h e r e b y m i n i m i z i n g t h e t r a n s i e n t c h a n g e s i n h e m a t o c r i t due t o t h e p o s t u r a l c h a n g e . The o b s e r v e d =:4% and ^5% s i g n i f i c a n t i n c r e a s e i n h e m a t o c r i t i n t h e u p r i g h t p o s i t i o n , b e f o r e and a f t e r c a p t o p r i l t h e r a p y , r e s p e c t i v e l y , i s s m a l l e r t h a n t h e r e p o r t e d = 1 0 % i n c r e a s e i n h e a l t h y s u b j e c t s (Hagan e t al., 1 9 7 8 ) . The r e s u l t s o f t h e p r e s e n t s t u d y , h o w e v e r , c o n f i r m s t h e r e p o r t e d i n c r e a s e i n h e m a t o c r i t i n s t a n d i n g p o s i t i o n i n p a t i e n t s w i t h m i l d t o m o d e r a t e h y p e r t e n s i o n , as a c o n s e q u e n c e o f t h e p l a s m a v o l u m e c h a n g e s upon s t a n d i n g . F u r t h e r , t h e s e r e s u l t s s u g g e s t t h a t a two-week c a p t o p r i l t r e a t m e n t d o e s n o t a p p e a r t o a l t e r t h e a c u t e c h a n g e s i n p l a s m a v o l u m e due t o p o s t u r a l c h a n g e . 4.8.2. A c u t e E f f e c t s o f C a p t o p r i l on H e m a t o c r i t T h e r e was no s i g n i f i c a n t c h a n g e i n h e m a t o c r i t a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l . A s l i g h t d e c r e a s e w h i c h was l e s s t h a n 1% was o b s e r v e d on b o t h s t u d y d a y s when h e m a t o c r i t v a l u e s o b t a i n e d 1 h o u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n w e r e compared t o c o n t r o l v a l u e s ( s e a t e d , s i ) ( T a b l e 8 ) . 4.8.3. S h o r t - T e r m E f f e c t s o f C a p t o p r i l on H e m a t o c r i t H e m a t o c r i t v a l u e s d e c r e a s e d a f t e r 14 d a y s c a p t o p r i l t r e a t m e n t by a b o u t 5%, when c o m p a r e d t o d a y 1 ( T a b l e 8 ) . One p o s s i b l e e x p l a n a t i o n o f t h e d e c r e a s e i n h e m a t o c r i t may be an i n c r e a s e i n p l a s m a v o l u m e (Hagan et al., 1 9 7 8 ) . I t has been n o t e d by T a r a z i et al., ( 1 9 8 0 ) , t h a t p l a s m a volume i n c r e a s e d s l i g h t l y , b u t s i g n i f i c a n t l y ( 5 . 1 % ± 2.11%, p < 0.05) i n t h o s e h y p e r t e n s i v e p a t i e n t s whose b l o o d p r e s s u r e was d e c r e a s e d a f t e r 5 d a y s t r e a t m e n t w i t h c a p t o p r i l . I t has been s u g g e s t e d ( T a r a z i et al., 1 9 8 0 ) , t h a t t h i s i n c r e a s e i n p l a s m a v o l u m e may i n d i c a t e v e n o d i l a t i o n , w i t h i n t r a v a s c u l a r r e d i s t r i b u t i o n o f e x t r a c e l l u l a r f l u i d v o l u m e . A l t h o u g h t h e b i o l o g i c a l s i g n i f i c a n c e o f t h i s s m a l l p l a s m a v o l u m e i n c r e a s e has been q u e s t i o n e d ( T a r a z i et al., 1 9 8 0 ) , i t may p a r t i a l l y e x p l a i n t h e d e c r e a s e d h e m a t o c r i t s o b s e r v e d i n t h e p r e s e n t s t u d y . 4.9. Serum C o n c e n t r a t i o n D a t a o f C a p t o p r i l The p h a r m a c o k i n e t i c b e h a v i o r o f c a p t o p r i l i n p a t i e n t s w i t h h y p e r t e n s i o n i s w e l l e s t a b l i s h e d (Kubo and Cody 1985; J a r r o t t e t al., 1982; R i c h e r e t al., 1 9 8 4 ) . I n t h e s t u d y p r o t o c o l b l o o d s a m p l i n g f o r u n c h a n g e d c a p t o p r i l was d e s i g n e d w i t h t h e p u r p o s e t o show ( 1 ) t h a t c a p t o p r i l was w e l l a b s o r b e d a f t e r o r a l a d m i n i s t r a t i o n and ( 2 ) t h a t t h e e s t i m a t i o n o f was p e r f o r m e d a r o u n d o r a f t e r t h e p e a k c a p t o p r i l serum c o n c e n t r a t i o n was a c h i e v e d . On b o t h s t u d y d a y s t h e a b s o r p t i o n o f c a p t o p r i l f r o m t h e g a s t r o i n t e s t i n a l t r a c t was r a p i d . Serum c o n c e n t r a t i o n s o f u n c h a n g e d c a p t o p r i l on d a y 1 and day 14 w e r e i n t h e r a n g e f r o m 41 t o 1490 ng/ml and 111 t o 1187 n g / m l , r e s p e c t i v e l y , b e t w e e n 20 and 40 m i n u t e s ( F i g u r e 2 9 ) . One p a t i e n t (M.O.) e x h i b i t e d v e r y l o w serum l e v e l s o f u n c h a n g e d c a p t o p r i l i n t h e f i r s t 150 m i n u t e s on d a y 1 w h i c h i n c r e a s e d t o 276.7 ng/ml a t 180 m i n u t e s . T h i s may be e x p l a i n e d by e i t h e r t h e p o o r a b s o r p t i o n o f c a p t o p r i l i n t h i s p a t i e n t o r h i g h p r o t e i n a n d / o r enzyme b i n d i n g o f c a p t o p r i l . P e a k s e r u m l e v e l s o f unch a n g e d c a p t o p r i l (0^ 3 , ^ ) t'''"^ r e q u i r e d t o r e a c h C^^^ (^max) ^^ -^  - ^2.2 m i n u t e s (mean ± SEM) a f t e r t h e f i r s t c a p t o p r i l d o s e and 52.2 ± 6.0 m i n u t e s a f t e r two-weeks c a p t o p r i l t r e a t m e n t ( T a b l e 1 8 ) . The t^ ^ g ^ v a l u e s f o r u n c h a n g e d c a p t o p r i l w e r e h i g h e r t h a n t h o s e r e p o r t e d by J a r r o t t e t al., (1982) who f o u n d t h a t C^ -^ ^^  w e r e r e a c h e d a t 53 ± 22.8 m i n u t e s a f t e r 100 mg o r a l d o s e o f c a p t o p r i l i n h y p e r t e n s i v e s u b j e c t s . In a n o t h e r s t u d y , (Cody et al., 1982) h i g h e r t ^ ^ ^ v a l u e o f 85.8 ± 11.4 m i n u t e s was r e p o r t e d a f t e r a s i n g l e c a p t o p r i l d o s e , w h i c h i s s l i g h t l y h i g h e r t h a n t h e t ^ ^ ^ ^ o f u n c h a n g e d c a p t o p r i l f o u n d i n t h e c u r r e n t s t u d y . P r e v i o u s s t u d i e s ( Cody e t al., 1982; J a r r o t t e t al., 1982) n o t e d s i g n i f i c a n t l y l o w e r *max fo"^ u n c h a n g e d c a p t o p r i l f o l l o w i n g s h o r t - t e r m o r c h r o n i c t h e r a p y w h i c h was n o t o b s e r v e d i n t h e p r e s e n t s t u d y . T h i s may be e x p l a i n e d by t h e s l o w i n c r e a s e i n u n c h a n g e d c a p t o p r i l serum c o n c e n t r a t i o n i n p a t i e n t M.O. a f t e r t h e i n i t i a l c a p t o p r i l d o s e . I n t h e p r e s e n t s t u d y , a v e r a g e C^^^ o f unch a n g e d c a p t o p r i l a f t e r a s i n g l e - d o s e was 697 n g / m l , w h i c h i s h i g h e r t h a n t h e 361 ng/ml C^^^ v a l u e n o t e d by J a r r o t t e t al., ( 1 9 8 2 ) , b u t s i m i l a r t o t h e 800 ng/ml v a l u e r e p o r t e d by K r i p a l a n i e t al., ( 1 9 8 0 ) . T h e r e was, however a l a r g e i n t e r i n d i v i d u a l v a r i a t i o n i n Cj^g^^ o f u n c h a n g e d c a p t o p r i l a f t e r t h e f i r s t d o s e o f c a p t o p r i l , r a n g i n g f r o m 184.3 t o 1490.3 ng/ml ( 8 . 1 f o l d d i f f e r e n c e ) ( T a b l e 1 8 ) . On d a y 14, C ^ ^ j ^ was l e s s v a r i a b l e t h a n on d a y 1 ( r a n g e f r o m 582.2 t o 1187.0 ng/ml (2 f o l d d i f f e r e n c e ) . T h e r e was r a p i d d i s a p p e a r a n c e o f u n c h a n g e d c a p t o p r i l f r o m t h e b l o o d t h e r e a f t e r , so t h a t t h e c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l was 119 ± 36.8 ng/ml on d a y 1 and 51.7 ± 4.4 ng/ml on d a y 14, 3 h o u r s a f t e r d o s i n g . The r a t e o f e l i m i n a t i o n o f u n c h a n g e d c a p t o p r i l was h i g h e r a f t e r two-weeks c a p t o p r i l a d m i n i s t r a t i o n . The a v e r a g e Cmax o f i n t a c t d r u g was h i g h e r a f t e r two-weeks c a p t o p r i l t h e r a p y t h a n a f t e r t h e f i r s t d o s e (871 ng/ml v s 697 n g / m l ) . A l s o , t h e AUC f o r u n c h a n g e d c a p t o p r i l a f t e r two-weeks c a p t o p r i l t h e r a p y was g r e a t e r by 3 3 . 7 % t h a n t h a t a f t e r t h e f i r s t c a p t o p r i l d o s e ( 1 0 3 8 . 8 ng.h/ml v s 776.9 n g . h / m l ) . J a r r o t t e t a l . , ( 1 9 8 2 ) n o t e d a t w o - f o l d i n c r e a s e i n t h e AUC a f t e r c h r o n i c a d m i n i s t r a t i o n o f c a p t o p r i l w h i c h i s s i m i l a r t o t h e f i n d i n g s o f t h e p r e s e n t s t u d y . However, Cody e t a l . , ( 1 9 8 2 ) f o u n d no c h a n g e i n t h e AUC o f u n c h a n g e d c a p t o p r i l i n p a t i e n t s w i t h c o n g e s t i v e h e a r t f a i l u r e a f t e r 5 d a y s t r e a t m e n t w i t h 25 mg c a p t o p r i l 3 t i m e s a d a y . 5. SUMMARY AND CONCLUSIONS 5. 1 . UV S p e c t r o p h o t o m e t r i c A n a l y s i s o f ICG i n Human Serum ICG i n se r u m was a n a l y z e d s p e c t r o p h o t o m e t r i c a l l y by t h e m o d i f i e d method o f C a e s a r et al., ( 1 9 6 1 ) . M o d i f i c a t i o n s r e g a r d i n g t h e p r e p a r a t i o n o f s t a n d a r d c u r v e s a m p l e s have been d e s c r i b e d p r e v i o u s l y by D o r r et al., ( 1 9 8 9 ) and R a p p a p o r t & T h i e s s e n , ( 1 9 8 2 ) . The p r e l i m i n a r y e x p e r i m e n t s c o n f i r m e d t h a t ICG was s t a b l e i n human serum f o r 4 8 h o u r s when s t o r e d a t - 2 0 ° . The a c c u r a c y o f t h e s p e c t r o p h o t o m e t r i c a s s a y has been e s t a b l i s h e d by d e t e r m i n i n g t h e r e p r o d u c i b i l i t y o f t h e a s s a y . I n t e r - and i n t r a d a y c o e f f i c i e n t s o f v a r i a t i o n w ere l e s s t h a n 10%. S t a n d a r d c u r v e s w e r e l i n e a r i n t h e c o n c e n t r a t i o n r a n g e o f 0.2 - 5.0 jug/ml w i t h a c o r r e l a t i o n c o e f f i c i e n t o f r'^ = 0.999. The c o e f f i c i e n t o f v a r i a t i o n was < 10 %. 5.2. E f f e c t s o f P o s t u r a l Change 5 . 2 . 1 . C l p i c g and QH U p r i g h t p o s i t i o n s i g n i f i c a n t l y d e c r e a s e d C l p j Q Q and Q^ f r o m 6 1 6 . 9 ± 43.9 t o 4 6 4 . 6 ± 3 6 . 9 m l / m i n (mean ± SEM) and f r o m 1 1 1 4 ± 74 t o 8 6 3 ± 62 ml/min (mean ± SEM), r e s p e c t i v e l y , b e f o r e c a p t o p r i l t r e a t m e n t , as compared t o b a s e l i n e v a l u e . S i m i l a r l y , a f t e r 14 d a y s t r e a t m e n t w i t h 100 mg d a i l y o r a l d o s e s o f c a p t o p r i l , C l p j Q Q and were s i g n i f i c a n t l y d e c r e a s e d f r o m 793.7 ± 9 1 . 0 t o 5 8 2 . 8 ± 74.0 m l / m i n and f r o m 1389 ± 164 t o 1045 ± 132 m l / m i n , r e s p e c t i v e l y , i n t h e u p r i g h t p o s i t i o n . When com p a r e d t o s i t t i n g v a l u e s , t h e a b s o l u t e d e c r e a s e i n C l p j Q Q and Qy i n s t a n d i n g p o s i t i o n was 152.3 ± 18.3 m l / m i n o r 2 4 . 7 % and 250 ± 36 m l / m i n o r 2 2 . 5 % , r e s p e c t i v e l y , b e f o r e c a p t o p r i l t r e a t m e n t and 210.9 ± 38.8 m l / m i n o r 2 6 . 6 % and 344 ± 68 m l / m i n o r 24.7%, r e s p e c t i v e l y , a f t e r s h o r t - t e r m t r e a t m e n t w i t h t h e d r u g . T h e r e was no s i g n i f i c a n t d i f f e r e n c e i n t h e r e s p o n s e t o p o s t u r a l c h a n g e b e f o r e and a f t e r c a p t o p r i l t h e r a p y . T h e r e was no s i g n i f i c a n t d i f f e r e n c e i n Qy between t h e two s e a t e d ( s i and s 2 ) m e a s u r e m e n t s . 5.2.2. H e m a t o c r i t , S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e , H e a r t R a t e The s t a n d i n g p o s i t i o n b e f o r e , as w e l l as a f t e r , c a p t o p r i l t h e r a p y was a s s o c i a t e d w i t h a s t a t i s t i c a l l y s i g n i f i c a n t i n c r e a s e i n h e m a t o c r i t by 3.8% and 5.0%, r e s p e c t i v e l y . D i a s t o l i c b l o o d p r e s s u r e i n c r e a s e d s l i g h t l y by 5-7 mm Hg on b o t h s t u d y d a y s i n u p r i g h t p o s i t i o n , b u t s y s t o l i c b l o o d p r e s s u r e and mean a r t e r i a l p r e s s u r e w e r e u n a l t e r e d . H e a r t r a t e i n c r e a s e d s i g n i f i c a n t l y by 4 and 6 b e a t s / m i n i n s t a n d i n g p o s i t i o n b e f o r e and a f t e r c a p t o p r i l t r e a t m e n t . 5.2.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e S p l a n c h n i c v a s c u l a r r e s i s t a n c e (mean ± SEM) i n c r e a s e d s i g n i f i c a n t l y i n s t a n d i n g p o s i t i o n f r o m 6.58 ± 0.5 t o 8.62 ± 0.7 mm H g - s e c / m l ( 3 1 . 0 % ) on day 1 and f r o m 5.34 ± 0.8 t o 7.12 ± 1.1 mm Hg-sec/ml ( 3 3 . 3 % ) , a f t e r 14 d a y s c a p t o p r i l a d m i n i s t r a t i o n . 5.3. A c u t e E f f e c t s o f C a p t o p r i l 5.3.1. C l p i c G and QH The a c u t e e f f e c t s o f c a p t o p r i l on C l p j ^ g and QH has been i n v e s t i g a t e d i n two o c c a s i o n s , 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l . T h e r e was no s i g n i f i c a n t c h a n g e i n C l p j ^ Q and Q^ a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l , as c o m p a r e d t o t h e c o n t r o l v a l u e s . However, a s l i g h t , n o t s i g n i f i c a n t , d e c r e a s e i n C l p j ^ Q ( 5 . 2 % ) and Q^ ( 6 . 0 % ) was o b s e r v e d a f t e r t h e i n i t i a l and t e r m i n a l d o s e o f c a p t o p r i l , r e s p e c t i v e l y . T h i s d e c r e a s e i n Q^, 1 h o u r a f t e r c a p t o p r i l a d m i n i s t r a t i o n w e re s i m i l a r i n m a g n i t u d e t o t h e d i f f e r e n c e s e e n i n QH b e t w e e n t h e s e a t e d ( s i ) and r e s e a t e d ( s 2 ) m e a s u r e m e n t s on d a y 1 and 14 ( 6 . 3 % and 8.5%, r e s p e c t i v e l y ) . T h e s e r e s u l t s s u g g e s t , t h a t t h e s l i g h t d e c r e a s e i n QH 1 h o u r a f t e r c a p t o p r i l d o s i n g i s , most p r o b a b l y , due t o o t h e r f a c t o r s r a t h e r t h a n a d i r e c t p h a r m a c o l o g i c a l e f f e c t o f t h e d r u g . When t h e QH v a l u e s o b t a i n e d 1 h o u r a f t e r t h e i n i t i a l and t e r m i n a l c a p t o p r i l d o s e were c o m p a r e d t o t h o s e o f s e a t e d ( s i ) v a l u e s , a d e c r e a s e i n QH f r o m 1114 ± 74 t o 980 ± 92 m l / m i n ( 1 2 . 0 % ) and 1389 ± 1193 ± 119 ( 1 4 . 1 % ) , r e s p e c t i v e l y , has been n o t i c e d . S i n c e t h e d e c r e a s e i n QH d u r i n g t h e c o u r s e o f t h e two s t u d y d a y s was s i m i l a r t o t h a t c a u s e d by d i u r n a l c h a n g e s , c i r c a d i a n v a r i a t i o n i n Q^ has been s u g g e s t e d t o e x p l a i n t h e a p p a r e n t d e c r e a s e i n Q^. 5.3.2. S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e and H e a r t R a t e S y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s s i g n i f i c a n t l y d e c r e a s e d by 21.5 ± 6.5 mm Hg ( 1 3 . 4 % ) and 13.4 ± 4.3 mm Hg ( 1 3 . 0 % ) , 1 h o u r a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l , as c o m p a r e d t o c o n t r o l v a l u e s . B o t h , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , were f u r t h e r d e c r e a s e d 3 h o u r s a f t e r a s i n g l e - d o s e o f c a p t o p r i l , r e s u l t i n g i n an a b s o l u t e d e c r e a s e f r o m p r e t r e a t m e n t v a l u e s by 28.1 ± 6.7 mm Hg ( 1 7 . 5 % ) and 16.6 ± 6.4 mm Hg ( 1 6 . 1 % ) , r e s p e c t i v e l y . One h o u r a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e n o t s i g n i f i c a n t l y l o w e r t h a n t h e t r e a t e d b a s e l i n e b l o o d p r e s s u r e s on d a y 14. However, 3 h o u r s a f t e r t a k i n g t h e t e r m i n a l c a p t o p r i l d o s e , s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s w e r e s i g n i f i c a n t l y l o w e r by 16.7 ± 9.9 mm Hg ( 1 1 . 5 % ) and 10.0 ± 3.2 mm Hg ( 1 0 . 7 % ) , t h a n t h e t r e a t e d b a s e l i n e v a l u e s o f d a y 14. The r e l a t i v e l y s m a l l e r d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e , a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , as compared t o t h e c h a n g e s a f t e r t h e i n i t i a l d o s e i s a t t r i b u t e d t o t h e l o w e r b a s e l i n e v a l u e s a f t e r two-weeks t r e a t m e n t w i t h t h e d r u g . The a b s o l u t e d e c r e a s e i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , 1 and 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , when compared t o t h e p r e t r e a t m e n t v a l u e s , w e r e s i m i l a r t o t h a t o b s e r v e d a f t e r t h e i n i t i a l c a p t o p r i l d o s e (22 vs 21 mm Hg and 28 vs 32 mm Hg, r e s p e c t i v e l y , f o r s y s t o l i c p r e s s u r e , 13 vs 12 mm Hg and 17 vs 20 mm Hg, r e s p e c t i v e l y f o r d i a s t o l i c p r e s s u r e ) . When com p a r e d t o c o n t r o l v a l u e s , h e a r t r a t e d i d n o t c h a n g e s i g n i f i c a n t l y a f t e r t h e a c u t e d o s e s o f c a p t o p r i l . 5.3.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e D e s p i t e t h e s i g n i f i c a n t d e c r e a s e i n a r t e r i a l b l o o d p r e s s u r e , 1 h o u r a f t e r t h e i n i t i a l d o s e o f c a p t o p r i l , no s i g n i f i c a n t c h a n g e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e was n o t e d . S i m i l a r l y , s p l a n c h n i c v a s c u l a r r e s i s t a n c e was u n a f f e c t e d by t h e t e r m i n a l d o s e o f c a p t o p r i l , e s t i m a t e d 1 h o u r a f t e r t h e i n t a k e o f c a p t o p r i l . T h e s e d a t a s u g g e s t t h a t no s i g n i f i c a n t c h a n g e s o c c u r i n t h e s p l a n c h n i c v a s c u l a r r e s i s t a n c e 1 h o u r a f t e r a c u t e d o s i n g w i t h c a p t o p r i l . 5.4. S h o r t - t e r m E f f e c t s o f C a p t o p r i l 5.4.1. C l p i c G and The s h o r t - t e r m e f f e c t s o f c a p t o p r i l on C l p j ^ Q and w e r e d e t e r m i n e d by c o m p a r i n g d a t a o b t a i n e d a f t e r two-weeks c a p t o p r i l t r e a t m e n t ( d a y 14) t o t h o s e o f t h e p r e t r e a t m e n t v a l u e s ( d a y 1 ) . F o l l o w i n g two-weeks o r a l c a p t o p r i l t r e a t m e n t ( 1 00 mg/day) C l p j Q g s i g n i f i c a n t l y i n c r e a s e d by 176.8 ± 57.4 ( 2 8 . 7 % ) , 118.2 ± 51.6 ( 2 5 . 5 % ) , 145.9 ± 81.8 ( 2 5 . 2 % ) and 137.9 ± 57.1 ml / m i n ( 2 5 . 2 % ) i n a l l f o u r p h a s e s o f t h e s t u d y , s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l ( C A ) , as c o m p a r e d t o t h e a p p r o p r i a t e v a l u e s o f d a y 1. S i m i l a r l y , has been f o u n d t o i n c r e a s e by 275 ± 107.3 ( 2 4 . 7 % ) , 182.0 ± 90.6 ( 2 1 . 1 % ) , 227.8 ± 147.8 ( 2 1 . 8 % ) and 212.8 ± 92.5 m l / m i n ( 2 1 . 7 % ) m e a s u r e d i n t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t - c a p t o p r i l (CA) s t u d y p h a s e s , r e s p e c t i v e l y . The i n c r e a s e i n Q^ a f t e r 14 d a y s c a p t o p r i l t r e a t m e n t f o l l o w e d an a l m o s t p a r a l l e l p a t t e r n w i t h t h e d a y 1 d a t a . However, t h e d i f f e r e n c e i n Q^ a f t e r s h o r t - t e r m t r e a t m e n t , as c o m p a r e d t o t h e d a y 1 v a l u e s , j u s t f a i l e d t o a c h i e v e t h e l e v e l o f s i g n i f i c a n c e w h e t h e r was e x p r e s s e d i n a b s o l u t e t e r m s o r p e r u n i t body w e i g h t o r body s u r f a c e a r e a (p = 0.06, MANOVA). The l a c k o f s t a t i s t i c a l s i g n i f i c a n c e has been a t t r i b u t e d t o t h e d i f f e r e n t r e s p o n s e o f one p a t i e n t who e x h i b i t e d a d e c r e a s e r a t h e r t h a n i n c r e a s e i n Q^ a f t e r two-weeks t h e r a p y . E x c l u d i n g t h i s p a t i e n t ' s d a t a f r o m t h e s t a t i s t i c a l c o m p a r i s o n , t h e i n c r e a s e i n Qy a f t e r 14 d a y s c a p t o p r i l a d m i n i s t r a t i o n was s t a t i s t i c a l l y s i g n i f i c a n t (MANOVA, p < 0 . 0 2 ) . 5.4.2. H e m a t o c r i t , S y s t o l i c and D i a s t o l i c B l o o d P r e s s u r e and H e a r t R a t e E x c e p t f o r t h e p o s t - c a p t o p r i l (CA) measurement t h e r e was a s i g n i f i c a n t r e d u c t i o n i n h e m a t o c r i t by 5.5%, 4.4% and 5 . 1 % d u r i n g t h e s e a t e d , u p r i g h t and p o s t - c a p t o p r i l p h a s e s o f t h e s t u d y , a f t e r two-weeks c a p t o p r i l t r e a t m e n t , as c o m p a r e d t o t h e d a y 1 v a l u e s . T h i s r e d u c t i o n i n h e m a t o c r i t c a n p a r t i a l l y be e x p l a i n e d by an i n c r e a s e i n p l a s m a v o l u m e , as a r e s u l t o f c a p t o p r i l t h e r a p y . The c l i n i c a l s i g n i f i c a n c e o f t h i s r e d u c t i o n i n h e m a t o c r i t i s u n c e r t a i n . On d a y 14, t r e a t e d b a s e l i n e s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s (mean ± SEM) were 145.5 ± 14.5 mm Hg and 92.8 ± 2.3 mm Hg, r e s p e c t i v e l y . T h e s e v a l u e s w e r e s i g n i f i c a n t l y l o w e r by 14.9 ± 7.7 mm Hg ( 9 . 3 % ) and 10.5 ± 6.4 mm Hg ( 1 0 . 1 % ) , r e s p e c t i v e l y , t h a n t h o s e o f t h e p r e t r e a t m e n t v a l u e s . S i n c e t h e b a s e l i n e b l o o d p r e s s u r e r e c o r d i n g s on d a y 14 w e r e p e r f o r m e d a p p r o x i m a t e l y 20 h o u r s a f t e r t h e i n t a k e o f t h e l a s t c a p t o p r i l d o s e , t h e s e r e s u l t s s u g g e s t t h a t d u r i n g p r o l o n g e d t r e a t m e n t w i t h c a p t o p r i l , b l o o d p r e s s u r e i s m a i n t a i n e d b e l o w t h e p r e t r e a t m e n t v a l u e s , a minimum o f 20 h o u r s a f t e r c a p t o p r i l d o s i n g . T h i s p r o l o n g e d a n t i h y p e r t e n s i v e e f f e c t o f c a p t o p r i l has been o b s e r v e d i n a l l o f t h e s i x p a t i e n t s s t u d i e d . H e a r t r a t e d e c r e a s e d s l i g h t l y , b u t n o t s i g n i f i c a n t l y ( 2 . 3 % ) , 3 h o u r s a f t e r t h e t e r m i n a l d o s e o f c a p t o p r i l , as c o m p a r e d t o p r e t r e a t m e n t v a l u e s . 5.4.3. S p l a n c h n i c V a s c u l a r R e s i s t a n c e When co m p a r e d t o t h e s e a t e d ( s i ) , u p r i g h t ( u p ) , r e s e a t e d ( s 2 ) and p o s t -c a p t o p r i l (CA) s t u d y p h a s e s o f d a y 1, t h e r e was a d e c r e a s e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e by 1 8.8%, 17.4%, 1 5 . 0 % and 2 3 . 0 % , r e s p e c t i v e l y , (mean 1 8 . 6 % ) , a f t e r 14 d a y s c a p t o p r i l t r e a t m e n t . The d i f f e r e n c e f r o m day 1 v a l u e s , h o w e v e r , was s t a t i s t i c a l l y n o t s i g n i f i c a n t (p = 0.125, MANOVA). However, t h e d e c r e a s e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e a f t e r two-weeks c a p t o p r i l t r e a t m e n t s u g g e s t s c h a n g e s i n t o t a l p e r i p h e r a l r e s i s t a n c e a f t e r p r o l o n g e d c a p t o p r i l t h e r a p y . 5.5. Serum C o n c e n t r a t i o n D a t a o f Unchanged C a p t o p r i l Serum c o n c e n t r a t i o n vs t i m e d a t a o f u n c h a n g e d c a p t o p r i l shows t h a t c a p t o p r i l was r a p i d l y a b s o r b e d a f t e r o r a l a d m i n i s t r a t i o n and r e a c h e d maximum serum c o n c e n t r a t i o n a t 75.9 ± 22.2 m i n u t e s (mean ± SEM) on d a y 1 and 52.2 ± 2.5 m i n u t e s on d a y 14. The Cj^gj^ (mean ± SEM) o f u n c h a n g e d c a p t o p r i l was f o u n d i n t h e r a n g e f r o m 184.3 t o 1490.3 ng/ml (mean 697.2 ± 192.8 ng/ml) on d a y 1 and f r o m 582.2 t o 1187.0 ng/ml (mean 870.5 ± 85.9 n g / m l ) . T h e s e d a t a s u g g e s t t h a t a d e q u a t e amounts o f t h e p h a r m a c o l o g i c a l l y a c t i v e d r u g r e a c h e d t h e s y s t e m i c c i r c u l a t i o n on b o t h s t u d y d a y s . A l t h o u g h t h e C^^^^ (mean ± SEM) was 2 4 . 9 % h i g h e r a f t e r two-weeks c a p t o p r i l t h e r a p y t h a n t h a t a f t e r a s i n g l e -d o s e , t h e d i f f e r e n c e i n C^^^^ on d a y 14 was s t a t i s t i c a l l y n o t s i g n i f i c a n t , as c o m p a r e d t o t h e d a y 1 v a l u e . S i m i l a r l y , AUCg* (mean ± SEM) f o r u n c h a n g e d c a p t o p r i l was f o u n d t o be 973.1 ± 78.1 n g * h / m l , a f t e r t h e i n i t i a l c a p t o p r i l d o s e w h i c h i s 2 1 . 2 % h i g h e r t h a n t h e o b s e r v e d 802.7 ± 197.7 ng-h/ml AUCQ* f o l l o w i n g two-weeks c a p t o p r i l t r e a t m e n t . However, t h e i n c r e a s e i n AUCQ^, a f t e r 14 d a y s c a p t o p r i l a d m i n i s t r a t i o n was s t a t i s t i c a l l y n o t s i g n i f i c a n t . A r a p i d d e c l i n e i n t h e serum c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l was o b s e r v e d , so t h a t 3 h o u r s a f t e r c a p t o p r i l a d m i n i s t r a t i o n t h e serum c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l (mean ± SEM), on d a y 1 and 14, was 119.1 ± 36.8 ng/ml on d a y 1 and 51.7 ± 4.4 n g / m l , r e s p e c t i v e l y . :5.6. C o n c l u s i o n s The u p r i g h t p o s t u r e i n d u c e d a s t a t i s t i c a l l y s i g n i f i c a n t d e c r e a s e i n w h i c h r e s p o n s e was n o t a l t e r e d a f t e r s h o r t - t e r m t r e a t m e n t w i t h c a p t o p r i l . The a p p l i e d s p e c t r o p h o t o m e t r i c method has been p r o v e d t o be s e n s i t i v e enough t o m e a s u r e c h a n g e s i n Q^, i n t h e m a g n i t u d e c a u s e d by p o s t u r a l c h a n g e f r o m s i t t i n g t o u p r i g h t . The o b s e r v e d c h a n g e s i n h e a r t r a t e , b l o o d p r e s s u r e and s p l a n c h n i c v a s c u l a r r e s i s t a n c e upon p o s t u r a l c h a n g e a r e i n a g r e e m e n t w i t h p r e v i o u s s t u d i e s . The f a c t t h a t t h e a c u t e c h a n g e s i n h e p a t i c b l o o d f l o w , s p l a n c h n i c v a s c u l a r r e s i s t a n c e and h e a r t r a t e i n d u c e d by u p r i g h t p o s t u r e w e r e n o t a l t e r e d by p r o l o n g e d t r e a t m e n t w i t h c a p t o p r i l s u g g e s t s t h a t c a p t o p r i l d o e s n o t i n t e r f e r e w i t h t h e h o m e o s t a t i c r e s p o n s e s t o p o s t u r a l c h a n g e i n p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n . D e s p i t e t h e s i g n i f i c a n t r e d u c t i o n i n s y s t o l i c and d i a s t o l i c b l o o d p r e s s u r e s , c a p t o p r i l has no a p p a r e n t a c u t e e f f e c t on and s p l a n c h n i c v a s c u l a r r e s i s t a n c e as m e a s u r e d 1 h o u r p o s t - d o s e . T h i s was d e m o n s t r a t e d i n two s e p a r a t e o c c a s i o n s i n t h e same s u b j e c t . The l a c k o f c h a n g e s i n a f t e r t h e a c u t e d o s e s o f c a p t o p r i l c a n n o t be e x p l a i n e d by p o o r a b s o r p t i o n o f t h e c a p t o p r i l s i n c e s erum c o n c e n t r a t i o n o f u n c h a n g e d c a p t o p r i l i n c r e a s e d r a p i d l y a f t e r a d m i n i s t r a t i o n and r e a c h e d p h a r m a c o l o g i c a l l y a c t i v e l e v e l . Once d a i l y a d m i n i s t r a t i o n o f c a p t o p r i l p r o v i d e d s u s t a i n e d b l o o d p r e s s u r e l o w e r i n g e f f e c t , i n s p i t e o f t h e r a p i d d i s a p p e a r a n c e o f t h e p h a r m a c o l o g i c a l l y a c t i v e d r u g f r o m t h e s y s t e m i c c i r c u l a t i o n . D e s p i t e t h e f a c t t h a t c a p t o p r i l has no a p p a r e n t a c u t e e f f e c t on Qy t h e r e i s a s i g n i f i c a n t i n c r e a s e i n Qy on c o n t i n u e d a d m i n i s t r a t i o n . The s u b s t a n t i a l d e c r e a s e i n s p l a n c h n i c v a s c u l a r r e s i s t a n c e s u g g e s t s p l a n c h n i c v a s o d i l a t i o n a f t e r p r o l o n g e d c a p t o p r i l t h e r a p y . The c a p t o p r i l i n d u c e d i n c r e a s e i n l i v e r b l o o d f l o w on c o n t i n u e d c a p t o p r i l a d m i n i s t r a t i o n s h o u l d be c o n s i d e r e d when d r u g s , e x h i b i t i n g h i g h h e p a t i c c l e a r a n c e a r e c o a d m i n i s t e r e d . F u r t h e r s t u d i e s a r e n e c e s s a r y t o e s t a b l i s h t h e c l i n i c a l s i g n i f i c a n c e and t h e e x t e n t o f c h a n g e i n t h e k i n e t i c p a r a m e t e r s o f c o a d m i n i s t e r e d h i g h c l e a r a n c e d r u g s , where l i v e r b l o o d f l o w a l t e r a t i o n s w o u l d be e x p e c t e d t o i m p a c t c l e a r a n c e . 6. REFERENCES A t l a s , S.A., C a s e , B.D., S e a l e y J . E . , L a r a g h , J.H. and M c K i n s t r y , D.N.: I n t e r r u p t i o n o f t h e R e n i n - A n g i o t e n s i n S y s t e m i n H y p e r t e n s i v e P a t i e n t s by C a p t o p r i l I n d u c e s S u s t a i n e d R e d u c t i o n i n A l d o s t e r o n e S e c r e t i o n , P o t a s s i u m R e t e n t i o n and N a t r i u r e s i s , Hypertension 1:274-280, 1979. A n t o n a c c i o M.J., A s a a d , M., R u b i n , B., H o r o v i t z , Z.P.: C a p t o p r i l : F a c t o r s I n v o l v e d i n i t s M e c h a n i s m o f A c t i o n . In: A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t o r s . H o r o v i t z , Z.P., e d . B a l t i m o r e . U r b a n and S c h w a r z e n b e r g . pp 161-180, 1981. B a l l , S.G.: The S y m p a t h e t i c N e r v o u s S y s t e m and C o n v e r t i n g Enzyme I n h i b i t i o n , J . Cardiovasc. Pharmacol. 1 3 ( S u p p l . 3 ) : S 1 7 - S 2 1 , 1989. B e n o w i t z N.L. and B o u r n e H.R.: In: 1989 B a s i c and C l i n i c a l P h a r m a c o l o g y , K a t z u n g B.G. e d . 4'-'' E d i t i o n . A p p l e t o n & Lan g e . N o r w o l k , Conn, pp 119-139, 1989. B j o r n s s o n , O.G., Murphy, R. and C h a d w i c k , V.S.: P h y s i c o c h e m i c a l S t u d i e s o f I n d o c y a n i n e G r e e n ( I C G ) : A b s o r b a n c e / C o n c e n t r a t i o n R e l a t i o n s h i p , pH T o l e r a n c e and A s s a y P r e c i s i o n i n V a r i o u s S o l v e n t s , Experientia 3 8 : 1 4 4 1 -1442, 1982. B r a d l e y , E.L.: M e a s u r e m e n t o f H e p a t i c B l o o d F l o w i n Man, Surgery 75:783-7 8 9 , 1974. B r a d l e y , S.E., I n g e l f i n g e r , F . J . , B r a d l e y , G.P. and C u r r y , J . J . : The E s t i m a t i o n o f H e p a t i c B l o o d F l o w i n Man, J . Clin. Invest. 24:890-897, 1945. B r o g d e n , R.N., T odd, P.A. and S o r k i n , E.M.: C a p t o p r i l . An Up d a t e o f i t s P h a r m a c o d y n a m i c and P h a r m a c o k i n e t i c P r o p e r t i e s , and T h e r a p e u t i c Use i n H y p e r t e n s i o n and C o n g e s t i v e H e a r t F a i l u r e , Drugs 36:540-600 1988. B r u n n e r , H.R., Waeber, B. and N u s s b e r g e r , J . : A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n V e r s u s B l o c k a d e o f t h e R e n i n - A n g i o t e n s i s S y s t e m , Aw. J . Med., 8 7 ( s u p p l 6 B ) : 1 5 S - 1 8 S , 1989. B u r c z y n s k i , F . J . , P u s h k a , K.L., S i t a r , D.S. and Greenway, C.V.: H e p a t i c P l a s m a F l o w : A c c u r a c y o f E s t i m a t i o n f r o m B o l u s I n j e c t i o n s o f I n d o c y a n i n e G r e e n , Am. J . Physiol. 245 ( H e a r t C i r c . P h y s i o l . ) 2 1 : H953-H962, 1987. B u r n i e r , M., Waeber, B., N u s s b e r g e r , J . and B r u n n e r , H.R.: P h a r m a c o k i n e t i c s o f A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t o r s , Br. J. din. Pharmac. 28, 1 33S-140S, 1989. B u r n s , E., B a l l , C.E., C h r i s t i e , J . P . , B r o a d h e a d , G.D., T u c k e r , G.T. and Bax, D.S.: D i r e c t and I n d i r e c t Measurement o f t h e H e p a t i c E x t r a c t i o n r a t i o o f I n d o c y a n i n e G r e e n i n t h e R a t , Clin. Sci. 76, 5 0 3 - 5 0 8 , 1989. C a e s a r , J . , S h a l d o n , S., C h i a n d u s s i , L., G u e v a r a , L. and S h e r l o c k S.: The Use o f I n d o c y a n i n e G r e e n i n t h e M e a s u r e m e n t o f H e p a t i c B l o o d F l o w and as a T e s t o f H e p a t i c F u n c t i o n , Clin.Sci., 2 1 : 4 3 - 5 7 , 1961. C a m p b e l l , D.J. and H a b e n e r , J . F . : A n g i o t e n s i n o g e n Gene I s E x p r e s s e d and D i f f e r e n t i a l l y R e g u l a t e d i n M u l t i p l e T i s s u e s o f t h e R a t , J . Clin. Invest. 7 8 : 3 1 - 3 9 , 1986. C a m p b e l l , D.J.: C i r c u l a t i n g and T i s s u e A n g i o t e n s i n S y s t e m s , J . Clin. Invest., 7 9 : 1 - 6 , 1987. C h e r r i c k , G., S t e i n , S.W., L e e v y , C M . and D a v i d s o n , Ch.S.: I n d o c y a n i n e G r e e n : O b s e r v a t i o n s on i t s P h y s i c a l P r o p e r t i e s , P l a s m a D e c a y , and H e p a t i c E x t r a c t i o n , J . Clin. Invest. 3 9 : 5 9 2 - 6 0 0 , 1960. Cody, R . J . , C o v i t , A., S h a e r , G. and W i l l i a m s , G.: C a p t o p r i l P h a r m a c o k i n e t i c s i n C h r o n i c H e a r t F a i l u r e : C o r r e l a t i o n w i t h A c c u t e Hemodynamic and Hormonal R e s p o n s e , Am. Heart J. 103:480-484, 1982. C ohen, M.L. and K u r z , K.D.: A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t i o n i n T i s s u e s f r o m S p o n t a n e o u s l y H y p e r t e n s i v e R a t s A f t e r T r e a t m e n t w i t h C a p t o p r i l o r MK-421, J . Pharmacol. Exp. Ther. 2 2 0 : 6 3 - 6 9 , 198 1 . C r e a g e r , M.A,, H a l p e r i n , J . L . , B e r n a r d , D.B., F a x o n , D.P., M e l i d o s s i a n , R.N., G a v r a s , H. and Ryan, T . J . : A c u t e R e g i o n a l C i r c u l a t o r y and R e n a l Hemodynamic E f f e c t s o f C o n v e r t i n g - E n z y m e I n h i b i t i o n i n P a t i e n t s w i t h C o n g e s t i v e H e a r t F a i l u r e , Circulation 64: 4 8 3 - 4 8 9 , 1981. C r o s s l e y , I.R., B i h a r i , D., Gim s o n , A.E.S., W e s t a b y , D., R i c h a r d s o n , P . J . and W i l l i a m s , R. : E f f e c t s o f C o n v e r t i n g Enzyme I n h i b i t o r on H e p a t i c B l o o d F l o w i n Man, Am. J. Med. 7 6 ( 5 B ) : 6 2 - 6 5 , 1984. C u l b e r t s o n , J.W., W i l k i n s , R.W., I n g e l f i n g e r , F . J . and B r a d l e y , S.E.: The E f f e c t o f U p r i g h t P o s t u r e Upon H e p a t i c B l o o d F l o w i n N o r m o t e n s i v e and H y p e r t e n s i v e S u b j e c t s , J . Clin. Invest., 3 0 : 3 0 5 - 3 1 1 , 1951. Daneshmend, T.K., J a c k s o n , L. and R o b e r t s , C.J.C.: P h y s i o l o g i c a l and P h a r m a c o l o g i c a l v a r i a b i l i t y i n E s t i m a t e d H e p a t i c B l o o d F l o w i n Man, Br. J. Clin. Pharmac. 11, 4 9 1 - 4 9 6 , 1981. D i x o n , M. and P a t e r s o n , C.R.: P o s t u r e and t h e C o m p o s i t i o n o f P l a s m a , Clin. Chem. 2 4 : 8 2 4 - 8 2 6 , 1978. D o r r , M.B. and P o l l a c k , G.M.: S p e c i f i c A s s a y f o r t h e Q u a n t i t a t i o n o f I n d o c y a n i n e G r e e n i n R a t Pl a s m a U s i n g H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h y w i t h F l u o r e s c e n c e D e t e c t i o n , J . Pharm. Sci. 7 8 : 3 2 8 - 3 3 3 , 1989. Drummer, O.H., K o u r t i s , S. and J a r r o t t B.: I n h i b i t i o n o f A n g i o t e n s i n C o n v e r t i n g Enzyme by M e t a b o l i t e s o f C a p t o p r i l , Clin. Exp. Pharmacol. Physiol. 9 ( S u p p l ) : 1 2 - 1 3 , 1985. D u c h i n , K.L., S i n g h v i , S.M., W i l l a r d , D.A., M i g d a l o f , B.H. and M c K i n s t r y , D.N.: C a p t o p r i l K i n e t i c s , Clin. Pharmacol. Ther. 3 1 : 452-458 1982. D z a u , V . J . : C i r c u l a t i n g V e r s u s L o c a l R e n i n - A n g i o t e n s i n S y s t e m i n C a r d i o v a s c u l a r H o m e o s t a s i s , C / r c u / a t / o n 7 7 ( s u p p l I ) : I 4 - I 1 3 , 1988. E c h t e n k a m p , S.F., D a v i s , J.O., Freeman, R.H., D i e t z , J.R. and V i l l a r e a l , D.: S p l a n c h n i c and R e n e a l C o n t r i b u t i o n s t o C i r c u l a t o r y H o m e o s t a s i s i n Sod i u m D e p l e t i o n , Am. J. Physiol. 245 ( H e a r t C i r c . P h y s i o l . ) 14: H573-H579, 1983 E r i k s s o n , L.S., K a g e d a l , B. and Wahren, J . : E f f e c t s o f C a p t o p r i l on H e p a t i c V enous P r e s s u r e and B l o o d F l o w i n P a t i e n t s w i t h L i v e r C i r r h o s i s , Am. J . Med. 7 6 ( 5 B ) : 6 5 - 7 0 , 1984. E s c o u r r o u , P., F r e u n d , P.R., R o w e l l , L.B. and J o h n s o n , D.G.: S p l a n c h n i c V a s o c o n s t r i c t i o n i n H e a t - S t r e s s e d Men: R o l e o f R e n i n - A n g i o t e n s i n S y s t e m , J . Appl. Physiol., 52:1438-1443, 1982. F a g a r d , R., B u l p i t t , C , L i j n e n , P. and Amery, A.: R e s p o n s e o f t h e S y s t e m i c and P u l m o n a r y C i r c u l a t i o n t o C o n v e r t i n g - E n z y m e I n h i b i t i o n ( C a p t o p r i l ) a t R e s t and D u r i n g i n H y p e r t e n s i v e P a t i e n t s , Circulation 65:33-39, 1982. F a x o n , D.P., C r e a g e r , M.A., H a l p e r i n , J . L . , B e r n a r d , D.B. and Ryan, T . J . : R e d i s t r i b u t i o n o f R e g i o n a l B l o o d F l o w F o l l o w i n g A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n , Am. J. Med. 31:104-110, 1984. F e e l y , J . , Wade, D., M c A l l i s t e r , C.B., W i l k i n s o n , G.R., and R o b e r t s o n , D.: E f f e c t o f H y p o t e n s i o n on L i v e r B l o o d F l o w and L i d o c a i n e D i s p o s i t i o n , N. Engl. J . Med. 307:866-869, 1982. F o u a d , F.M., Ceimo, J.M.K., T a r a z i , R.C. and B r a v o , E.L.: C o n t r a s t s and S i m i l a r i t i e s o f A c u t e Hemodynamic R e s p o n s e s t o S p e c i f i c A n t a g o n i s m I I ( [ S a r - ^ , Thr°]AII) and t o I n h i b i t i o n o f C o n v e r t i n g Enzyme ( C a p t o p r i l ) , Circulation 61:163, 1980. F o x , I . J . and Wood, E.H.: I n d o c y a n i n e G r e e n : P h y s i c a l and P h y s i o l o g i c P r o p e r t i e s , Proc. Staff Meetings Mayo Clinic 35:732-744, 1950. F u n k e , P.T., I v a s h k i v , E., M a l l e y , M.F. and Cohen, A . I . : Gas C h r o m a t o g r a p h y / S e l e c t e d I o n M o n i t o r i n g Mass S p e c t r o m e t r i c D e t e r m i n a t i o n o f C a p t o p r i l i n Human B l o o d . Anal. Chem. 52:1095-1089, 1980. G a s i c , S., H e i n z , G., L k e i n b l o e s e m , C. and K o r n , A.: E f f e c t s o f ACE I n h i b i t i o n w i t h C i l a z a p r i l on S p l a n c h n i c and S y s t e m i c Haemodynamics i n Man, Br. J. din. Pharmac. 27: 225S-234S, 1989. G a s i c , S., K l e i n b l o e s e m , C H . , H e i n z , G. and W a l h a u s l , W.: C o n t r i b u t i o n o f S p l a n c h n i c and P e r i p h e r a l V a s c u l a r T i s s u e s t o t h e D i s p o s a l o f A n g i o t e n s i n - I I and t o R e g i o n a l C o n v e r s i o n R a t e s o f A n g i o t e n s i n - I : A P i l o t S t u d y i n Humans, J . Cardiovasc. Pharmacol. 17:615-520, 1991. G a t h j e , J . , S t e u e r , R.R. and N i c h o l e s , K.R.K.: S t a b i l i t y S t u d i e s on I n d o c y a n i n e G r e e n Dye, J . Appl. Physiol. 2 9 : 1 8 1 - 1 8 5 , 1970. G a v r a s , H., L i a n g , C.S. and B r u n n e r , H.R.: R e d i s t r i b u t i o n o f R e g i o n a l B l o o d F l o w a f t e r I n h i b i t i o n o f t h e A n g i o t e n s i n - C o n v e r t i n g Enzyme, Circ. Res. Supp. I. 4 3 : 1 5 9 - 1 6 3 , 1978. G e n e v e , J . , Le D i n h , T., B r o u a r d , A., B a i l s , M., S e g r e s t a a , J.M. and C a u l i n , C.: Changes i n I n d o c y a n i n e G r e e n K i n e t i c s A f t e r t h e A d m i n i s t r a t i o n o f E n a l a p r i l t o H e a l t h y S u b j e c t s , Br. J. din. Pharmac. 3 0 , 297-300, 1990. G e o r g e , C F . : Drug K i n e t i c s and H e p a t i c B l o o d F l o w , Clin. Pharmacokin. 4:433-438, 1979. G i b a l d i , M., P e r r i e r , 0. In: P h a r m a c o k i n e t i c s : D r u g s and t h e P h a r m a c e u t i c a l S c i e n c e s , V o l 15, 2"° E d i t i o n . M a r c e l D e k k e r I n c , 1982. G o l d s h m i d t , J . E . and T a l l a r i d e , R . J . : P h a r m a c o l o g i c a l E v i d e n c e T h a t C a p t o p r i l P o s s e s s e s an E n d o t h e l i u m - M e d i a t e d Component o f V a s o d i l a t i o n : E f f e c t o f S u l p h y d r y l G r o u p s on E n d o t h e l i u m - D e r i v e d R e l a x i n g F a c t o r , J . Pharmacol. Exp. Ther. 2 5 7 : 1 1 3 6 - 1 1 4 5 , 1991. G r a i n g e r , S.L., K e e l i n g , P.W.N., Brown, I.M.H., M a r i g o l d , J.H. and Thompson, R.P.H.: C l e a r a n c e and N o n - I n v a s i v e D e t e r m i n a t i o n o f t h e H e p a t i c E x t r a c t i o n o f I n d o c y a n i n e G r e e n i n Baboons and Man, Clin. Sci. 64:207-2 1 2 , 1983. G r a s e l a , D.M., R o c c i , M.L. and V l a s s e s , P.H.: E x p e r i m e n t a l Impact o f A s s a y -D e p e n d e n t D i f f e r e n c e s i n P l a s m a I n d o c y a n i n e G r e e n C o n c e n t r a t i o n D e t e r m i n a t i o n s , J . Pharmacokin. Biopharm. 1 5 : 6 0 1 - 6 1 3 , 1987. Gr e e n w a y , C.V. and L a u t t W.W.: H e p a t i c C i r c u l a t i o n . In: Handbook o f P h v s i o l o q y - T h e G a s t r o i n t e s t i n a l S y s t e m I . M o t i l i t y and C i r c u l a t i o n , B e t h e s d a , M.D.: Am. P h y s i o l . S o c . pp 1519-1564, 1987. Greenway, C V . and L a u t t , W.W.: E f f e c t s o f I n f u s i o n s o f C a t e c h o l a m i n e s , A n g i o t e n s i n , V a s o p r e s s i n and H i s t a m i n e on H e p a t i c B l o o d Volume i n t h e a n e s t h e t i z e d C a t , Br. J. Pharmacol. 44:177-184, 1972. G u y t o n , A . C In: P h v s i o l o q v o f t h e Human Body, 6*'^  E d i t i o n . S o u n d e r s C o l l a g e P u b l i s h i n g . P h i l a d e l p h i a , PA. pp 3 0 1 - 3 1 8 , 1984. Hagan, R.D., D i a z , F . J . and H o r v a t h , S.M.: P l a s m a Volume Changes w i t h Movement t o S u p i n e and S t a n d i n g P o s i t i o n s , J . Appl. Physiol. 4 5 ( 3 ) : 4 1 4 -4 1 8 , 1978. H e i n t z , R., S v e n s s o n , C.K., S t o e c k e l , K., Po w e r s , G .J. and L a l k a , D.: I n d o c y a n i n e G r e e n : P h a r m a c o k i n e t i c s i n t h e R a b b i t and R e l e v a n t S t u d i e s o f I t s S t a b i l i t y and P u r i t y J . Pharm. Sci. 7 5 : 3 9 8 - 4 0 2 , 1986. H e n t h o r n , T.K., Avram, M.J. and K r e j c i e , T . C : I n t r a v a s c u l a r M i x i n g and Drug d i s t r i b u t i o n : The C o n c u r r e n t d i s p o s i t i o n o f T h i o p e n t a l and I n d o c y a n i n e g r e e n , Clin. Pharmacol. Ther. 4 5 : 5 6 - 6 5 , 1989. Hodsman, G.P., M u r r a y , G.D., U s h e r w o o d , T.P., Webb, D.J. and R o b e r t s o n , J . I . S . : F a c t o r s R e l a t e d t o F i r s t Dose H y p o t e n s i v e E f f e c t o f C a p t o p r i l : P r e d i c t i o n and T r e a t m e n t , Br. Med. J. 2 8 6 : 8 3 2 - 8 3 4 , 1983. H o l l i n s , B., Noe, B. and H e n d e r s o n , J.M.: F l u o r o m e t r i c D e t e r m i n a t i o n o f I n d o c y a n i n e G r e e n i n P l a s m a , Clin. Chem. 3 3 / 6 : 7 6 5 - 7 6 8 , 1987. H u e t , P.M., V i l l e n e v u e , J . P . , M a r l e a u , D. and V i a l l e t , A.: H e p a t i c C i r c u l a t i o n : A p p l i c a b l e Human M e t h o d o l o g y . In: H e p a t i c C i r c u l a t i o n i n H e a l t h and D i s e a s e . L a u t t W.W. e d . Raven P r e s s , NY. pp 5 7-74, 1981. J a r r o t t , B., Drummer, 0., H o o p e r , R., A n d e r s o n , A . I . E . , M i a c h , P . J . and L o u i s , W.: P h a r m a c o k i n e t i c P r o p e r t i e s o f C a p t o p r i l A f t e r A c u t e and C h r o n i c A d m i n i s t a r t i o n t o H y p e r t e n s i v e S u b j e c t s , Am. J. Cardiol. 4 9 : 1 5 4 7 - 1 5 4 9 , 1982. J o h n s t o n , C . I . , C l a p p i s o n , B.H., A n d e r s o n , W.P., Y a s u j i m a , M.: E f f e c t o f A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n on C i r c u l a t i n g and L o c a l K i n i n L e v e l s , Am. J. Cardiol. 4 9 : 1 4 0 1 - 1 4 0 4 , 1982. J o h n s t o n , C . I . , M c G r a t h , B.P., M a t t h e w s , P.G.: L o n g - t e r m E f f e c t s o f C a p t o p r i l (SQ 14225) on B l o o d P r e s s u r e and Hormone L e v e l s i n E s s e n t i a l H y p e r t e n s i o n , Lancet 2:493-495, 1979. K a d i n , H.: C a p t o p r i l . In: A n a l y t i c a l P r o f i l e s o f Drug S u b s t a n c e s , Volume 11. F l o r e y K. e d . A c a d e m i c P r e s s , NY. pp 79-137, 1982. K r i p a l a n i , K . J . , M c K i n s t r y , D.N., S i n g h v i , S.M., W i l l a r d , D.A., V u k o v i c h , R.A. and M i g d a l o f , B.H.: D i s p o s i t i o n o f C a p t o p r i l i n Normal S u b j e c t s , Clin. Pharmacol. Ther. 27: 6 3 6 - 6 4 1 , 1980. Kubo, S.H., Cody, R . J . : C l i n i c a l P h a r m a c o k i n e t i c s o f t h e A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t o r s A R e v i e w , Clin. Pharmacokinet. 10: 377-3 9 1 , 1985. L e e s , K.R., M a c F a d y e n , R . J . and R e i d J . L . : T i s s u e A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t i o n . R e l e v a n t t o C l i n i c a l P r a c t i c e ? , Am. J. Hypertens. 3:266S-272S, 1990. Lemmer, B. and N o l d , G.: C i r c a d i a n Changes i n E s t i m a t e d H e p a t i c B l o o d F l o w i n H e a l t h y S u b j e c t s , Br. J. din. Pharmc. 3 2 : 6 2 7 - 6 2 9 , 1991. L e v i n e , B.T., O l i v a r i , M. and Cohn, J.N.: Hemodynamic and R e g i o n a l B l o o d F l o w R e s p o n s e t o C a p t o p r i l i n C o n g e s t i v e H e a r t F a i l u r e , Am. J. Med. 7 6 : 3 8 - 4 2 , 1984. L j u n g , B., J a n d h y a l a , B. and K j e l l s t e d t , A.: A n g i o t e n s i n I C o n v e r t i n g Enzyme A c t i v i t y i n P o r t a l V e i n S t u d i e d i n N o r m o t e n s i v e R a t s and i n M o d e l s o f P r i m a r y and S e c o n d a r y H y p e r t e n s i o n , Acta Physiol. Scand. I l l , 409-416, 1981. M a n c i a , G., P a r a t i , G., P o m i d o s s i , G., Colombo, A., C u s p i d i , C , L a t t u a d a , S., A n t i v a l l e , M., R i n d i , M., L i b r e t t i , A., B o t t a , G. and Z a n c h e t t i , A.: E v a l u a t i o n o f t h e A n t i h y p e r t e n s i v e E f f e c t o f Once a Day C a p t o p r i l by 24 Hour A m b u l a t o r y B l o o d P r e s s u r e M o n i t o r i n g , J . Hypertens. 5 ( s u p p l 5 ) : S591-S593. 1987 M a n c i a , G., P a r a t i , G., P o m i d o s s i , G., G r a s s i , G., B e r t i n i e r i , G., B u c c i n o , N., F e r r a r i , A., G r e g o r i n i , L., R u p o l i , L. and Z a n c h e t t i , A.: M o d i f i c a t i o n s o f A r t e r i a l B a r o r e f l e x e s by C a p t o p r i l i n E s s e n t i a l H y p e r t e n s i o n , Aw. J. Cardiol. 49: 1415-1419. 1982 M c A r e a v e y , D. and R o b e r t s o n , J . I . S . : A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t o r s and M o d e r a t e H y p e r t e n s i o n , Drugs 4 0 : 3 2 6 - 3 4 5 , 1990. McLean , A . J . , Skews, H., B o b i k , A. and D u d l e y , F . J . : I n t e r a c t i o n between O r a l P r o p a n o l o l and H y d r a l a z i n e , Clin. Pharmacol. Ther. 2 7 : 7 2 6 - 7 3 2 , 1980. McMahon, F.G. In: Management o f E s s e n t i a l H y p e r t e n s i o n The new Low-Dose E r a 2"" E d i t i o n . F u t u r a P u b l i s h i n g Comp. I n c . Mount K i s c o , NY. pp 1-30, 1984. M e i j e r , D.K.F., W e e r t , B. and V e r m e e r , G.A.: P h a r m a c o k i n e t i c s o f B i l i a r y E x c r e t i o n i n Man. V I . I n d o c y a n i n e G r e e n , Eur. J. Clin. Pharmacol. 35: 29 5 - 3 0 3 , 1988. M e s s e r l i , F.H., G e n e s t , J . , N o w a c z y n s k i , W., K u c h e l , 0., Honda, M., L a t o u r , Y. and Dumont, G.: S p l a n c h n i c B l o o d F l o w i n E s s e n t i a l H y p e r t e n s i o n and i n H y p e r t e n s i v e P a t i e n t s w i t h R e n a l A r t e r y S t e n o s i s , Circulation 5 1 : 1 1 1 4 - 1 1 1 9 , 1975. M e s s e r l i , F.H., N o w a c z y n s k i , W., Honda, M., G e n e s t , J . , B o u c h e r , R., K u c h e l , 0. and R o j o - O r t e g a , J.M.: E f f e c t s o f A n g i o t e n s i n I I on S t e r o i d M e t a b o l i s m and H e p a t i c B l o o d f l o w i n Man, Circ. Res. 4 0 : 2 0 4 - 2 0 7 , 1977. M o d i , M.W., H a s s e t t , J.M. and L a l k a D.: I n f l u e n c e o f P o s t u r e on H e p a t i c P e r f u s i o n and t h e P r e s y s t e m i c B i o t r a n s f o r m a t i o n o f P r o p r a n o l o l : S i m u l a t i o n o f t h e Food E f f e c t , Clin. Pharmacol. Ther. 4 4 : 2 6 8 - 2 7 4 , 1988. M o o k h e r j e e , S., A n d e r s o n , G.H., E i c h , R., H i l l , N., S m u l y a n , H., S t r e e t e n D.H.P., V a r d a n , S. and W a r n e r , R.: A c u t e E f f e c t s o f C a p t o p r i l on C a r d i o p u l m o n a r y Hemodynamics and R e n i n - A n g i o t e n s i n - A l d o s t e r o n e and B r a d y k i n i n P r o f i l e i n H y p e r t e n s i o n , Am. Heart J. 1 0 5 : 1 0 6 - 1 1 2 , 1983. M o r g a n , D.J. and S m a l l w o o d , R.A.: C l i n i c a l S i g n i f i c a n c e o f P h a r m a c o k i n e t i c M o d e l s o f H e p a t i c E l i m i n a t i o n , Clin. Pharmacokinet. 1 8 : 6 1 - 7 6 , 1990. M u i e s a n , G., A l i c a n d r i , C.L., A g a b i t i - R o s e i , E., F a r i e l l o , R., B e s c h i , M., B o n i , E., C a s t e l l a n o , M., M o n i t i , E., M u i e s a n , L., R o m a n e l l i , G. and Z a n e l l i , A.: A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n , C a t e c h o l a m i n e s and Hemodynamics i n E s s e n t i a l H y p e r t e n s i o n , Am. J . Cardiol. 49:1420-1424, 1982. N i e s , A.S., S h a n d , D.G. and W i l k i n s o n , G.R.: A l t e r e d H e p a t i c B l o o d F l o w and D r u g D i s p o s i t i o n , Clin. Pharmacokin. 1: 135-155, 1976. Ôhman, P.K., K a k e d a k , B., L a r s s o n , R. and K a r l b e r g , B.E.: P h a r m a k o c i n e t i c s o f C a p t o p r i l and I t s E f f e c t s on B l o o d P r e s s u r e D u r i n g A c u t e and C h r o n i c A d m i n i s t r a t i o n and i n R e l a t i o n t o Food I n t a k e , J . Cardiovasc. Pharmacol. 7:S20-24, 1985. O n d e t t i , M.A.: S t r u c t u r a l R e l a t i o n s h i p o f A n g i o t e n s i n C o n v e r t i n g - E n z y m e I n h i b i t o r s t o P h a r m a c o l o g i c A c t i v i t y , Circulation 7 7 ( s u p p l I ) : 1 7 4 - 1 7 8 , 1988. Onhaus, E.E.: M e t h o d s o f t h e A s s e s s m e n t o f t h e E f f e c t o f D r u g s on L i v e r B l o o d F l o w i n Man, Br. J . din. Pharmac. 7:223-229, 1979. O ' R e i l l y , T., MacMathuna, P., K e e l i n g , P.W.N, and F e e l y , J . : C o m p a r i s o n o f t h e S p e c t r o p h o t o m e t r i c and H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h i c A n a l y s i s o f I n d o c y a n i n e G r e e n i n E s t i m a t i n g S y s t e m i c C l e a r a n c e i n P a t i e n t s w i t h C h r o n i c L i v e r D i s e a s e , J . Chromatogr. 4 1 7 : 1 9 0 - 1 9 6 , 1987. P a r a t i , G., R a v o g l i , A., T r a z z i , S., Omboni, S., F r a t t o l a , A., L a t t u a d a , S., L i b r e t t i , A. and M a n c i a , J . : B a l a n c e d 24-Hour B l o o d P r e s s u r e C o n t r o l by A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t o r s A d m i n i s t e r e d Once D a i l y , J . Hum. Hypertens. 3:3-9, 1989. P a u m g a r t n e r , G. In: The H a n d l i n g o f I n d o c y a n i n e G r e e n by t h e L i v e r . 1, Schwabe & Co. V e r l a g , B a s e l / S t u t t g a r t e d . 1975. P e r e i r a , C M . and Tam, Y.K.: S i m p l i f i e d D e t e r m i n a t i o n o f C a p t o p r i l i n P l a s m a by H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h y , J . Chromatogr. 4 9 5 : 3 4 9 - 3 5 3 , 1989. R a i a , J . J . , J r . , B a r o n e , J.A., B y e r l y , W.G. and L a c y , C. R.: A n g i o t e n s i n -C o n v e r t i n g Enzyme I n h i b i t o r s : a C o m p a r a t i v e R e v i e w , DICP,The Annals of Pharmacotherapy, 2 4 : 5 0 6 - 5 2 5 , 1990. R a p p a p o r t , P.L. and T h i e s s e n , J . J . : H i g h - P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h i c A n a l y s i s o f I n d o c y a n i n e G r e e n , J . Pharm. Sci. 7 1 : 1 5 7 - 1 6 1 , 1982. R i c h a r d s o n , P.D.I, and W i t h r i n g t o n , P.G.: L i v e r B l o o d F l o w I . I n t r i n s i c and N e r v o u s C o n t r o l o f L i v e r B l o o d F l o w Gastroenterology, 8 1 : 159-73, 1981. R i c h e r . C , Do u s s a u , M.P. and G i u d i c e l l i , J . F . : E f f e c t s o f C a p t o p r i l and E n a l a p r i l on R e g i o n a l V a s c u l a r R e s i s t a n c e and R e a c t i v i t y i n S p o n t a n e o u s l y H y p e r t e n s i v e R a t s , Hypertension 5:312-320, 1983. R o b s o n , S . C , M u t c h , E., B o y s , R . J . and Woodhouse, K.W.: A p p a r e n t L i v e r B l o o d F l o w D u r i n g P r e g n a n c y : a S e r i a l S t u d y U s i n g I n d o c y a n i n e G r e e n C l e a r a n c e , Br. J. Obstet. Gynaecol. 9 7 : 7 2 0 - 7 2 4 , 1990. R o c c i , M.L. V l a s s e s , P.H., L e n e r , M.E., F r u n c i l l o , R.A. and S i r g o M.A.: C o m p a r a t i v e E v a l u a t i o n o f t h e E f f e c t s o f L a b e t o l o l , V e r a p a m i l and D i l t i a z e m on A n t i p y r i n e and I n d o c y a n i n e G r e e n C l e a r a n c e s , J . Clin. Pharmacol. 2 9 : 8 9 1 - 8 9 5 , 1989. R o z s a , ZS. and S o n k o d i , S.: The E f f e c t o f C a p t o p r i l on M e s e n t e r i c B l o o d F l o w i n S p o n t a n e o u s l y H y p e r t e n s i v e R a t s Clin. Res. 39:124A, 1991. R o u t l e d g e , P.A. and S h a n d , D.G.: C l i n i c a l P h a r m a c o k i n e t i c s o f P r o p r a n o l o l , Clin. Pharmacokinet. 4:73-90, 1979. R o w l a n d , M., Benêt, L.Z. and Graham, G.G.: C l e a r a n c e C o n c e p t s i n P h a r m a c o k i n e t i c s , J . Pharmacokin. Biopharm. 1:123-136, 1973. R o w l a n d , M., B l a s c h k e , T.F., M e f f i n , P . J . and W i l l i a m s , R.L.: P h a r m a c o k i n e t i c s i n D i s e a s e S t a t e s M o d i f y i n g H e p a t i c and M e t a b o l i c F u n c t i o n . In: The E f f e c t o f D i s e a s e S t a t e s on Drug P h a r m a c o k i n e t i c s . B e n e t , L.Z. e d . A m e r i c a n P h a r m a c e u t i c a l A s s o c i a t i o n . W a s h i n g t o n , DC. pp 5 3 - 7 7 , 1976. S c h n e c k , D.W. and V a r y , J . E . : M e c h a n i s m by w h i c h H y d r a l a z i n e I n c r e a s e s P r o p a n o l o l B i o a v a i l a b i l i t y , Clin. Pharmacol. Ther. 3 5 : 4 4 7 - 4 5 3 , 1984. Sedman, A . J . and Wagner, J.G.: A D e c i s i o n M a k i n g P h a r m a c o k i n e t i c Computer P r o g r a m , P u b l i c a t i o n D i s t r i b u t i o n S e r v i c e , 615 E a s t U n i v e r s i t y A v e . , Ann A r b o r , M i c h i g a n 4 8106, (AUTOAN) 1976. S h e p h e r d , A.N., H a y e s , P.C., J a c y n a , M., M o r r i s o n , L. and B o u c h i e r , I.A.D.: The I n f l u e n c e o f C a p t o p r i l , The N i t r a t e s and P r o p r a n o l o l on A p p a r e n t L i v e r B l o o d F l o w , Br. J . din. Pharmac. 19:393-397, 1985. S h e p h e r d , J . T . and V a n h o u t t e , P.M. In The Human C a r d i o v a s c u l a r S y s t e m F a c t s and C o n c e p t s . Raven P r e s s . New Y o r k , NY. pp 158 1980. S i m o n , A . C , L e v e n s o n , J.A., B o u t h i e r , J . , M a a r e k , B. and S a f a r , M.E.: E f f e c t s o f A c u t e and C h r o n i c A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n on L a r g e A r t e r i e s i n Human H y p e r t e n s i o n , J . Cardiovasc. Pharmacol. 7 : S 4 5 - S 5 1 , 1985. S i n g h v i , S.M., M c K i n s t r y , D.N., Shaw, J.M., W i l l a r d , D.A., M i g d a l o f , B.H.: E f f e c t o f Food on t h e B i o a v a i l a b i l i t y o f C a p t o p r i l i n H e a l t h y S u b j e c t s , J . Clin. Pharmacol. 2 2 : 1 3 5 - 1 4 0 , 1985. S o o n s , P.A., K r o o n , J.M, and B r e i m e r , D.D.: E f f e c t s o f S i n g l e - D o s e and S h o r t - T e r m O r a l N i f e d i p i n e on I n d o c y a n i n e G r e e n C l e a r a n c e as A s s e s s e d by S p e c t r o p h o t o m e t r y and H i g h P e r f o r m a n c e L i q u i d C h r o m a t o g r a p h y , J . Clin. Pharmacol. 3 0 : 6 9 3 - 6 9 8 , 1990. Sumner, D.J., M e r e d i t h , P.A., Howie, C A . and E l l i o t t , H.L.: I n i t i a l B l o o d P r e s s u r e as a P r e d i c t o r o f t h e R e s p o n s e t o A n t i h y p e r t e n s i v e t h e r a p y , Br. J. din. Pharmac. 2 6 : 7 1 5 - 7 2 0 , 1988. S t a d e a g e r , C , H e s s e , B., N e n r i k s e n , 0., C h r i s t e n s e n , N . J . , B o n d e - P e t e r s e n , F., M e h l s e n , J . and G i e s e , J . : E f f e c t s o f A n g i o t e n s i n B l o c k a d e on t h e S p l a n c h n i c C i r c u l a t i o n i n N o r m o t e n s i v e Humans, J . Appl. Physiol. 6 7 ( 2 ) : 7 8 6 - 7 9 1 , 1989. S v e n s s o n , C.K., E d w a r d s , D.J., L a l k a , D., M a u r i e l l o , P.M. and M i d d l e t o n , E.: C o m p a r i s o n o f C h r o m a t o g r a p h i c A n a l y s i s o f I n d o c y a n i n e G r e e n i n P l a s m a F o l l o w i n g A d m i n i s t r a t i o n o f M u l t i p l e D o s e s t o Humans, J . Pharm. Sci. 7 5 : 1 3 0 5 - 1 3 0 6 , 1982. S w a r t z , S.L. and W i l l i a m s , G . H . : A n g i o t e n s i n - C o n v e r t i n g Enzyme I n h i b i t i o n and P r o s t a g l a n d i n s , Am. J . Cardiol. 4 9 : 1 4 0 5 - 1 4 0 9 , 1982. T a r a z i , R . C , B r a v o , E.L., F o u a d , F.M., Omvik, P. and Cody, R . J . , J R . : Hemodynamic and Volume Changes A s s o c i a t e d w i t h C a p t o p r i l , Hypertension 2: 5 7 6 - 5 8 5 , 1980. T y g s t r u p , N. and W i n k l e r , K. : G a l a c t o s e B l o o d C l e a r a n c e as a Meas u r e o f H e p a t i c B l o o d F l o w , Clin. Sci. 17:1-9, 1958. U n g e r , T., G o h l k e , P. G a n t e n , D. and L a n g , R.E.: C o n v e r t i n g Enzyme I n h i b i t o r s and T h e i r E f f e c t s on t h e R e n i n - A n g i o t e n s i n S y s t e m o f t h e B l o o d V e s s e l W a l l , J . Cardiovasc. Pharmol. 1 3 ( S u p p l 3 ) : S 8 - S 1 6 , 1989. V a n d e n b u r g , M.J., H o l l y , J.M.P., G o o d w i n , F . J . , Sharman, V.L. and M a r s h , F.P.: The E f f e c t o f C a p t o p r i l and P r o p r a n o l o l on t h e R e s p o n s e s t o P o s t u r e and I s o m e t r i c E x e r c i s e i n P a t i e n t s w i t h E s s e n t i a l H y p e r t e n s i o n , Eur. J. Clin. Pharmacol. 25:721-728, 1983. V a n h o u t t e , P.M., A u c h - S c h w e l k , K.W., B i o n d i , M.L., L o r e n z , R.R., S c h i n i , V.B. and V i d a l , M.J.: Why A r e C o n v e r t i n g Enzyme I n h i b i t o r s V a s o d i l a t o r s ? Br. J. din. Pharmac. 28:95S-104S, 1989. V e n t u r a , H.O,, F r o h l i c h , E.D., M e s s e r l i , F.H., K o b r i n , I . and K a r d o n , M.B.: C a r d i o v a s c u l a r E f f e c t s and R e g i o n a l B l o o d F l o w D i s t r i b u t i o n A s s o c i a t e d w i t h A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t i o n ( C a p t o p r i l ) i n E s s e n t i a l H y p e r t e n s i o n , Am. J. Cardiol. 55:1023-1026, 1985. V i l l e n e u v e , J . P . , H u o t , R., M a r l e a u , D. and H u e t , P.M.: The E s t i m a t i o n o f H e p a t i c B l o o d F l o w w i t h I n d o c y a n i n e G r e e n : C o m p a r i s o n between t h e C o n t i n u o u s I n f u s i o n and S i n g l e I n j e c t i o n M e t h o d s , Am. J . Gastroent. 7 7 : 2 3 3 - 2 3 7 , 1982. Waeber, B., N u s s b e r g e r , J . , J u i l l e r a t , L. and B r u n n e r , H.: A n g i o t e n s i n C o n v e r t i n g Enzyme I n h i b i t i o n : D i s c r e p a n c y Between A n t i h y p e r t e n s i v e E f f e c t and S u p p r e s s i o n o f Enzyme A c t i v i t y , J . Cardiovasc. Pharmacol. 1 4 : S 5 3 - S 5 9 , 1989. Wagner, J . D i s o r d e r s o f t h e C i r c u l a t i o n . In: An I n t r o d u c t i o n t o t h e P r i n c i p l e s o f D i s e a s e . 2"" E d i t i o n . W.B. S a u n d e r s Comp., pp 280-296, 1982 Wang, J . , P r o t e i n B i n d i n g D i s p l a c e m e n t I n t e r a c t i o n s B etween P r o p a f e n o n e , 5-h y d r o x y p r o p a f e n o n e and o t h e r A n t i a r r h y t h m i c D r u g s ; HPLC A n a l y s i s o f I n d o c y a n i n e G r e e n , M.Sc. T h e s i s , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C., 1990. W e n t i n g , G . J . , De B r u y n , J.H.B., Man I n ' t V e l d , A . J . , W o i t t i e z , A . J . J . , D e r k x , F.H.M. and S c h a l e k a m p , M a a r t e n A.D.H.: Hemodynamic E f f e c t s o f C a p t o p r i l i n E s s e n t i a l H y p e r t e n s i o n , R e n o v a s c u l a r H y p e r t e n s i o n and C a r d i a c F a i l u r e : C o r r e l a t i o n s W i t h S h o r t - and Long-Term E f f e c t s on Pl a s m a R e n i n , Am. J . Cardiol. 4 9 : 1 4 5 3 - 1 4 5 9 , 1982. W i l k i n s , R.W., C u l b e r t s o n , J.W. and I n g e l f i n g e r , F . J . : The E f f e c t o f S p l a n c h n i c S ympatechtomy i n H y p e r t e n s i v e P a t i e n t s Upon E s t i m a t e d H e p a t i c B l o o d F l o w i n t h e U p r i g h t as C o n t r a s t e d w i t h t h e H o r i z o n t a l P o s i t i o n , J . Clin. Invest. 3 0 : 3 1 2 - 3 1 7 . , 1951. W i l k i n s o n , G.R. and Sh a n d , D.G.: A P h y s i o l o g i c a l A p p r o a c h t o H e p a t i c Drug C l e a r a n c e , C77A7. Pharm. Ther. 18:337-390, 1975. W i l k i n s o n , G.R.: P h a r m a c o k i n e t i c s i n D i s e a s e S t a t e s M o d i f y i n g Body P e r f u s i o n . In: The E f f e c t o f D i s e a s e S t a t e s on Drug P h a r m a c o k i n e t i c s . B e n e t , L.Z. e d . A m e r i c a n P h a r m a c e u t i c a l A s s o c i a t i o n . W a s h i n g t o n , DC. pp 13-32, 1976. Wynne, H.A., Cope, L.H., M u t c h , E., R a w l i n s , M.D., Woodhouse, K.W. and Jame s , O.F.W.: The E f f e c t o f Age upon L i v e r Volume and A p p a r e n t L i v e r B l o o d F l o w i n H e a l t h y Man, Hepatology 9:297-301, 1989. Wynne, H.A., G o u d e v e n o s , J . , R a w l i n s , M.D., James, O.F.W., Adams, P.C. and Woodhouse, K.W.: H e p a t i c D r ug C l e a r a n c e : t h e E f f e c t o f Age U s i n g I n d o c y a n i n e G r e e n a s a Model Compound, Br. J. din. Pharmac. 30:634-6 3 7 , 1990. Z a n n a d , F. and G i l g e n k r a n t z , J-M.: ACE I n h i b i t o r s i n H y p e r t e n s i o n : A Eu r o p e a n V i e w p o i n t , C a r d / o / o g y 7 6 ( s u p p l . 2 ) : 3 1 - 4 1 , 1989. APPENDIX A p p e n d i x 1. S e m i - l o g a r i t h m i c p l o t s o f ICG serum c o n c e n t r a t i o n versus t i m e c u r v e s f r o m s i x p a t i e n t s w i t h m i l d / m o d e r a t e h y p e r t e n s i o n o b t a i n e d on day 1 and d a y 14 i n s e a t e d ( s i , open c i r c l e s ) , u p r i g h t ( u p , c l o s e d c i r c l e s ) , r e s e a t e d ( s 2 , open t r i a n g l e s ) and 1 ho u r a f t e r c a p t o p r i l d o s i n g (CA, c l o s e d t r i a n g l e s ) . 0.100^  1 1 1 1 1 1 1 1 1 0.100 H 1 1 1 1 1 1 1 1 1 0 1 4 < • 10 12 U II U 0 Z 4 I I to II 14 « IS Time (minutas) Tlm« (minutoj) M.O. DAY 1 0 o - ICGsl • • - ICGup 1 i - ICGsi * 4. - ICGCA DAY U -O I C G J I - • ICGup - i ICGJ2 -4 ICGCA Time (minutes) TlmB (minutas) DAY 1 E 3 E 3 DAY 14 o o ICGst • • ICGup Tim* (minutas) Time (mlnut«) A p p e n d i x 1. C o n t ' d C.B. DAY 1 ^ C.B. 0 o ICGil • • ICGup 1 A ICGai i A ICGCA E \ cs c S. 10.000 I s DAY U - o I C G J I - • ICGup -A ICGsi -A ICGCA Tima (minutes) Time (minutes) A p p e n d i x 2. C l p ( n o r m a l i z e d t o bo d y w e i g h t and bo d y s u r f a c e a r e a ) d a t a o f ICG b e f o r e and a f t e r t h e i n i t i a l d o s e ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f c a p t o p r i l C l p / b o d y w e i g h t o f ICG ( m l / m i n / k g ) P a t 1 A n t D a y 1 D a y 14 r a t i t:il t s l up s2 CA s l up s2 CA MO OW MS BH DA CB 5.8 7.0 8.2 5.8 6.1 6.4 4.1 5.9 6.1 4.1 4.2 5.2 5.6 6.3 6.3 4.9 6.4 7.5 6.6 6.0 6.4 4.6 5.1 5.7 7.8 11.4 10.3 7.1 6.7 6.7 6.4 7.5 8.0 4.7 5.9 4.1 6.6 10.2 9.5 5.2 9.1 5.4 6.9 8.8 7.6 6.1 9.0 5.1 Mean: ± SEM: 6.5 ± 0.4 4.9 + 0.4 ± 6.2 0.4 5.7 ± 0.3 8.3 ± 0.8 6,1 ± 0.6 7.7 ± 0,9 ± 7.2 0,6 C l p / b o d y s u r f a c e a r e a o f ICG (ml/rain/m2) P f l f i p n t D a y 1 D a y 14 s l up s2 CA s l up s2 CA MO OW MS BH DA CB 280.5 306.6 356,9 258.3 248.4 269.7 200.7 256,4 265.0 183.6 169.8 222.6 271.0 277.1 273.3 218.4 260.3 317.8 261.7 278.1 204.8 208,3 244.0 381.2 498.5 450.5 318.5 274.1 282.9 310.3 327.3 349.8 209,7 241.7 172.9 320.5 447.7 416.2 231.3 370.2 228.4 337.7 384.3 333.7 271.5 364.4 216.3 Mean: 286.7 216.3 ± SEM: ± 16.3 ± 15.8 269.7 253.2 13.0 ± 18.2 367.6 268.6 ± 37.7 ± 29.0 335.7 318.0 ± 37.8 ± 25.6 s l d a t a o b t a i n e d i n s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s2 d a t a o b t a i n e d i n t h e r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f c a p t o p r i l SEM s t a n d a r d e r r o r o f t h e mean A p p e n d i x 3. d a t a b e f o r e and a f t e r t h e i n i t i a l ( d a y 1) and t e r m i n a l d o s e ( d a y 14) o f c a p t o p r i l QH ( m l / m i n ) D a y l D a y 14 P a t i e n t s i up s2 CA s i up s2 CA MO 1212 8 8 9 1154 1374 1615 1315 1358 1431 OW 1139 992 1057 1011 1835 1205 1648 1415 MS 1402 1080 1074 1074 1770 1426 1635 1311 BH 1062 770 898 825 1169 814 849 997 DA 970 683 1017 799 1040 932 1404 1313 CB 897 766 1057 798 902 580 729 690 Mean: 1114 863 1043 980 1389 1045 1271 1193 ± SEM: ± 73.9 ±61.9 ± 34.3 ± 92.1 ± 163.5 ± 132.4 ± 160.4 ± 119.1 QH / b o d y w e i g h t ( m l / m i n / k g ) D a y l D a y 14 P a t i e n t s i up s2 CA s i up s2 CA MO 10.2 7.5 9.7 11.6 13.6 11.1 11.4 12.1 OW 12.3 10.7 11.4 10.9 19.8 13.0 17.8 15.3 MS 14.6 11.2 11.2 11.2 18.4 14.9 17.0 13.7 BH 11.5 8.4 9.8 9.0 12.7 8.8 9.2 10.8 DA 11.4 8.0 12.0 9.4 12.2 11.0 16.5 15.4 CB 10.7 9.1 12.6 9.5 10.7 6.9 8.7 8.2 Mean: 11.8 9.2 11.1 10.3 14.6 10.9 13.4 12.6 ± SEM: + 0.6 ± 0.6 ± 0.5 ± 0.4 ± 1.5 ± 1.2 ± 1.7 ± 1.1 QH / b o d y s u r f a c e a r e a (ml/min / m 2 ) P a t i e n t s i up s2 CA s i up s2 CA MO 497.3 364.8 473.7 563.8 662.9 539.6 557.4 587.2 OW 537.9 468.8 499.3 477.5 867.0 569.3 778.6 668.3 MS 637.3 490.7 488.0 488.0 804.4 647.9 743.2 595.9 BH 516.6 374.7 436.8 401.5 568.8 395.7 413.0 484.9 DA 464.2 326.6 486.6 382.2 437.3 445.9 671.8 628.3 CB 453.3 387.1 534.2 403.3 456.2 293.0 368.3 348.8 Mean: 517.8 402.1 486.4 452.7 632.8 481.9 588.7 552.2 ± SEM: ± 27.2 ± 26.1 ± 13.0 ± 28.4 ± 72.7 ± 52.6 ± 70.1 ± 47.7 s i d a t a o b t a i n e d i n s e a t e d p o s i t i o n up d a t a o b t a i n e d i n u p r i g h t p o s i t i o n s 2 d a t a o b t a i n e d i n r e s e a t e d p o s i t i o n CA d a t a o b t a i n e d 1 h o u r a f t e r t h e a d m i n i s t r a t i o n o f c a p t o p r i l SEM s t a n d a r d e r r o r o f t h e mean 

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