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Antioxidant properties of propofol in coronary artery bypass surgery 1998

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A N T I O X I D A N T P R O P E R T I E S O F P R O P O F O L IN C O R O N A R Y A R T E R Y B Y P A S S S U R G E R Y by J I A N H A N G S U N M . B . , The Second Military Medical University of P L A , 1986 A THESIS S U B M I T T E D IN P A R T I A L F U L F U L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F S C I E N C E in T H E F A C U L T Y O F G R A D U A T E S T U D I E S (Department of Surgery) \ ; f We accept this thesis as conforming to^he required standard T H E U N I V E R S I T Y O F BRITISH C O L U M B I A September 1998 ©lianhang Sun, 1998 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 S ^ j ? / The University of British Columbia Vancouver, Canada DE-6 (2/88) A B S T R A C T Ischaemia r e p e r f u s i o n injury (IRI) is c o n s i d e r e d one of the major causes of c a r d i o p u l m o n a r y d y s f u n c t i o n i n c a r d i o p u l m o n a r y bypass ( C P B ) surgery . React ive o x y g e n intermediates have been l i n k e d to IRI . M e a s u r e s to increase antioxidant capaci ty , wi th v i t a m i n C , v i t a m i n E , and a l l o p u r i n o l , have markedly reduced tissue l i p i d p e r o x i d a t i o n and resulted i n i m p r o v e d c a r d i o p u l m o n a r y f u n c t i o n . A n intravenous anaesthetic , p r o p o f o l has been found to have antioxidant properties i n c e l l culture and i n animal studies. T h e antioxidant potential of p r o p o f o l d u r i n g C P B surgery has not been repor ted . F o l l o w i n g inst i tut ional approval and i n f o r m e d patient consent , 26 patients scheduled for C P B surgery were e n r o l l e d . Patients were anaesthetized with sufentani l - i sof lurane (control , n = l l ) , s u f e n t a n i l - l o w dose p r o p o f o l (1.5- 2.5 m g / k g bolus then 100 p g / k g / m i n p r e C P B , 50 u g / k g / m i n i n t r a - C P B ; n = 7), or h i g h dose p r o p o f o l (1 .5-2.5 m g / k g then 200 p g / k g / m i n continous i n f u s i o n ; n = 8). V e n o u s b l o o d was sampled for determinat ion of red c e l l antioxidant capacity as M D A (malondialdehyde) p r o d u c t i o n against i n vi t ro oxidat ive challenge and plasma concentrat ion of p r o p o f o l . C l i n i c a l parameters of interest i n c l u d e d per ioperat ive inotropic requirement , h a e m o d y n a m i c changes, and lung o x y g e n a t i o n . R e d c e l l antioxidant capacity increased s i g n i f i c a n t l y o n l y wi th h i g h dose p r o p o f o l . T h i s effect cont inued 2 hours after separation f r o m bypass . H i g h dose and low dose p r o p o f o l were associated with s i g n i f i c a n t l y less inotropic ii (dopamine 3-5 p g / k g / m i n ) requirement . L o w dose p r o p o f o l s i g n i f i c a n t l y increased the percentage of patients with n o r m a l cardiac index post- opera t ive ly . Improvement of cardiac f u n c t i o n d i d not p a r a l l e l the r e d u c t i o n of l i p i d p e r o x i d a t i o n . P r o p o f o l ' s effects were l i m i t e d to l i p i d membranes . T h e cardiodepresant effect of h i g h dose p r o p o f o l was manifes ted as re la t ively low cardiac index w i t h i n the first three hours after o p e r a t i o n . L u n g oxygenat ion was superior wi th low dose p r o p o f o l and isof lurane after 6 to 12 hours after operat ion, c o m p a r i n g to that w i t h i n one hour after operat ion ( P < 0 . 0 5 ) . iii T A B L E OF C O N T E N T S Abstrac t i i T a b l e of Contents iv L i s t of T a b l e s v i i i L i s t of F i g u r e s ix A c k n o w l e d g e m e n t s x Chapter 1 Int roduct ion 1.1 O v e r v i e w , 1 1.2 Free R a d i c a l s 1 1.2.1 Free R a d i c a l s and React ive O x y g e n Intermediates ( R O I s ) 1 1.2.2 Free R a d i c a l Ef fec ts 3 1.2.3 M e c h a n i s m s of the E n d o g e n o u s Release of Free R a d i c a l s 4 d u r i n g T i s s u e Injury 1.3 L i p i d P e r o x i d a t i o n and D e t e c t i o n 7 1.3.1 L i p i d P e r o x i d a t i o n 7 1.3.2 A r a c h i d o n i c A c i d M e t a b o l i s m and M D A F o r m a t i o n 8 1.3.3 M D A : A M a r k e r for L i p i d P e r o x i d a t i o n 10 1.3.4 C o n j u g a t e d D i e n e s and P h o s p h o l i p i d M o l a r R a t i o : 10 A n o t h e r C h e m i c a l M a r k e r for O x i d a t i v e Injury 1.4 Free R a d i c a l G e n e r a t i o n and M y o c a r d i a l D a m a g e d u r i n g 11 iv C A B Surgery 1.4.1 Pattern of Systemic Free R a d i c a l G e n e r a t i o n d u r i n g 11 C A B Surgery 1.4.2 M y o c a r d i a l Ischaemia R e p e r f u s i o n Injury C a u s e d B y R O I s 12 1.5 B o d y A n t i o x i d a n t Defense Systems 14 1.5.1 N o n e n z y m i c : V i t a m i n C and V i t a m i n E 15 1.5.2 M a j o r E x t r a c e l l u l a r Protec t ion M e c h a n i s m s 15 1.5.3 E n z y m i c A n t i o x i d a n t Defenses 16 1.6 Preoperat ive V i t a m i n C , V i t a m i n E , and A l l o p u r i n o l 17 T h e r a p y i n Patients U n d e r g o i n g C A B Surgery 1.7 E G b 761 and C a r v e d i l o l : U n c o m m o n l y U s e d A n t i o x i d a n t s 19 for C A B Surgery 1.7.1 E G b 761 19 1.7.2 C a r v e d i l o l 20 1.8 P r o p o f o l : A n Anaesthet ic and A n t i o x i d a n t 21 1.8.1 Structure 21 1.8.2 B a s i c P h a r m a c o k i n e t i c s 23 1.8.3 M e c h a n i s m s of A n t i o x i d a n t A c t i v i t y 24 1.8.4 A n t i o x i d a n t A c t i v i t i e s of P r o p o f o l i n A n i m a l Studies 25 1.8.5 P r o p o f o l Anaesthes ia i n C A B Surgery 29 Chapter 2 Objec t ives 31 Chapter 3 Hypotheses 32 Chapter 4 M a t e r i a l and M e t h o d s 35 4.1 C o r o n a r y A r t e r y Bypass S u r g e r y : A M o d e l for Ischemia 35 R e p e r f u s i o n Injury 4 .1 .1 S e l e c t i o n C r i t e r i a 35 4 .1 .2 Study D e s i g n 35 4 .1 .3 B l o o d Sample C o l l e c t i o n 38 4 .1 .4 C l i n i c a l D a t a C o l l e c t i o n 40 4 .1 .5 C a r d i o p u l m o n a r y Bypass 40 4 .1 .6 Data A n a l y s i s 40 4.2 M e a s u r e m e n t of in vi tro R e d C e l l M D A P r o d u c t i o n : T B A A s s a y 41 4.3 M e a s u r e m e n t of P lasma P r o p o f o l C o n c e n t r a t i o n by H P L C 43 Chapter 5 Results 48 5.1 Patient P r o f i l e 48 5.2 R e d C e l l M D A P r o d u c t i o n F o l l o w i n g i n v i t ro t B H P C h a l l e n g e 48 5.2.1 t B H P D o s e - R e s p o n s e C u r v e 48 5 .2 .2 R e d C e l l M D A P r o d u c t i o n In Response T o In V i t r o t B H P 48 (1.5 m M ) C h a l l e n g e 5.3 P l a s m a C o n c e n t r a t i o n of P r o p o f o l 49 5.4 Inotropic Requirement d u r i n g C A B Surgery 49 5.4.1 Percentage of Patients G i v e n Inotropic D r u g s 49 vi 5.4.2 Percentage of Patients G i v e n D o p a m i n e (3.5 p g / k g / m i n ) 50 5.4.3 Percentage of Patients G i v e n A d r e n a l i n e 50 5.5 H e m o d y n a m i c Changes d u r i n g 24 H o u r s P o s t - o p e r a t i o n 50 5.5.1 C a r d i a c Index 50 5 .5 .2 P u l m o n a r y C a p i l l a r y W e d g e Pressure 50 5.5 .3 C e n t r a l V e n o u s Pressure 51 5.6 A l v e o l a r A r t e r i a l O x y g e n G r a d i e n t d u r i n g 24 H o u r s Post- 51 operat ion Chapter 6 D i s c u s s i o n 6.1 E v a l u a t i o n of H y p o t h e s i s 67 6.2 What D o e s Increased R e d C e l l A n t i o x i d a n t C a p a c i t y M e a n ? 69 6.2.1 G e n e r a l i z e d Enhancement of T i s s u e O x i d a n t Status 69 6.2.2 P a r t i a l l y I m p r o v e d C a r d i o p u l m o n a r y F u n c t i o n 70 6.3 P r o p o f o l C o n c e n t r a t i o n and Its Protect ive E f f e c t s 71 6.4 M D A P r o d u c t i o n , R e d C e l l Status, and T B A A s s a y 73 6.5 Influence of N o r m o t h e r m i a or H y p o t h e r m i a for C P B o n 74 R e d C e l l A n t i o x i d a n t Status and C a r d i o p u l m o n a r y F u n c t i o n Chapter 7 C o n c l u s i o n and Recommendat ions for F u r t h e r W o r k 77 References 79 vii LIST OF T A B L E S T a b l e Page 1. Patient p r o f i l e , by group 52 2. t B H P - M D A dose-response curve for red cel ls f r o m the 53 three experimental groups 3. R e d c e l l M D A p r o d u c t i o n and plasma concentra t ion of 54 p r o p o f o l at var ious time intervals 4. Inotropic requirement d u r i n g C A B surgery , by group 55 5. C a r d i a c index , p u l m o n a r y c a p i l l a r y wedge pressure , and 56 central venous pressure d u r i n g 24 hours pos t -opera t ion 6. Percentage of patients with a cardiac index > 2.5 57 L / m i n / m 2 d u r i n g 24 hours post -operat ion 7. A l v e o l a r arterial o x y g e n gradient 58 viii LIST OF FIGURES F i g u r e Page 1. React ions i n v o l v e d i n the generat ion of superoxide by 6 N A D P H oxidase and the respiratory burst of phagocytes 2. X a n t h i n e oxidase and superoxide radica l f o r m a t i o n 6 3. Pathway by w h i c h M D A is f o r m e d as a b y - p r o d u c t i n 9 a r a c h i d o n i c ac id metabol ism 4. Structural formulae of p r o p o f o l , butylated h y d r o x y t o l u e n e 22 and v i t a m i n E 5. E f f e c t of p r o p o f o l i n i n t r a l i p i d or i n t r a l i p i d alone on 28 h y d r o g e n p e r o x i d e - i n d u c e d changes of the rat heart tissue concentra t ion of M D A 6. Schematic t ime-l ine representation of blood sampling for red 39 cell M D A product ion and plasma concentration of p r o p o f o l 7. Schematic representation of chromatograms o f extracts 47 8. t B H P dose-response curve for red c e l l M D A p r o d u c t i o n 59 9. R e d c e l l M D A p r o d u c t i o n and plasma concentra t ion of 60 p r o p o f o l 10. T h e re la t ionship of red c e l l M D A p r o d u c t i o n and plasma 61 concentra t ion of p r o p o f o l i n the h i g h dose p r o p o f o l group 11. Inotropic requirement d u r i n g C A B surgery 62 12. H e m o d y n a m i c changes d u r i n g 24 hours pos t -opera t ive ly 63 13. C a r d i a c index d u r i n g the first 3 hours pos t -opera t ive ly 64 14. C a r d i a c index versus p u l m o n a r y c a p i l l a r y wedge pressure 65 d u r i n g 24 hours post -operat ively 15. A l v e o l a r ar ter ial o x y g e n gradient d u r i n g 24 hours 66 post -operat ively ix A C K N O W L E D G E M E N T S I am grateful to D r . A . K . Q a y u m i for taking me to the p r o g r a m and for his continous guidance and support , especia l ly i n the weekly laboratory meet ings . I am grateful to D r . D . M . A n s l e y and D r . D . V . G o d i n for g i v i n g me the opportunity to work with them and for their enthusiastic support of my study a l l the t ime. I am also grateful to D r . D . R . B e v a n for his k i n d c o n c e r n about the thesis project . I w o u l d l ike to thank M a u r e e n Garnett for teaching me the T B A assay; thank Sharon D u n c a n for teaching me r a d i o i m m u n o a s s a y ; thank D a v i d F o n g for teaching me the basic laboratory techniques ; and thank Janet H a i n e s for m a k i n g slides for my thesis defense. T o my wife Jennifer and son Sean who cont inual ly p r o v i d e the i n s p i r a t i o n , and to my sister L i p i n g S u n for her u n l i m i t e d support xi Chapter 1 I N T R O D U C T I O N 1.1 O v e r v i e w Ischaemia r e p e r f u s i o n injury (IRI) has been c o n s i d e r e d as one of the major causes of c a r d i o p u l m o n a r y d y s f u n c t i o n in c o r o n a r y artery bypass ( C A B ) surgery [1-5]. React ive oxygen intermediates have been l i n k e d to IRI [2,6-8] . M e a s u r e s to increase antioxidant capaci ty , such as preoperat ive c o n d i t i o n i n g with v i t a m i n C , v i t a m i n E or a l l o p u r i n o l , have demonstrated markedly reduced tissue l i p i d p e r o x i d a t i o n in both a n i m a l and human studies, in associa t ion with i m p r o v e d c a r d i o p u l m o n a r y f u n c t i o n [1 ,9-13] . A n intravenous anaesthetic, 2 , 6 - d i i s o p r o p y l p h e n o l , or p r o p o f o l , has been shown to have antioxidant act ivity i n animal studies [14-18]. A l t h o u g h p r o p o f o l anaesthesia has been used for C A B surgery since 1987, its protect ive effects as an antioxidant d u r i n g surgery have not been repor ted . 1.2 Free R a d i c a l s 1.2.1 Free R a d i c a l s and React ive O x y g e n Intermediates (ROIs ) [19] Free radicals are molecules or fragments of m o l e c u l e s conta ining unpaired electrons i n their outer orbi ta ls . U n p a i r e d electrons tend to acquire a pair ; therefore , most free radicals are c h e m i c a l l y h i g h l y reactive and, as a result , s h o r t - l i v e d . l Free r a d i c a l reactions are chain reactions started by init iators causing h y d r o g e n r e m o v a l , w h i c h is f o l l o w e d by several steps of p r o p a g a t i o n in w h i c h the free radicals p r o d u c e d interact with one another and with s u r r o u n d i n g m o l e c u l e s , and the react ion terminates when the free radicals are converted to nonradica l products . React ive o x y g e n intermediates (ROIs) is a c o l l e c t i v e term for o x y g e n free radicals and reactive products of o x y g e n [ 2 0 ] . Free radicals of o x y g e n play an important role i n b i o l o g y and m e d i c i n e . T h e y are generated f r o m oxygen by exci tat ion (singlet oxygen) or r e d u c t i o n (superoxide a n i o n , h y d r o g e n p e r o x i d e , and h y d r o x y l r a d i c a l ) . B y d e f i n i t i o n , not al l reactive products of the r e d u c t i o n or exci tat ion of o x y g e n are free radicals ( e . g . , singlet o x y g e n , and h y d r o g e n p e r o x i d e ) . H o w e v e r , their react ivi ty and reactions resemble those of free radica ls . These products , together with the true free radica ls , are ca l led R O I s . W e l l - r e c o g n i z e d R O I s include superoxide radica l ( 0 2 ~ ), singlet o x y g e n ( 1 0 2 ) , h y d r o g e n peroxide ( H 2 0 2 ) , h y d r o x y l r a d i c a l ( O H ) , p e r o x y l radica l ( R O O ) , p e r h y d r o x y l r a d i c a l ( H O O ) , a l k o x y l r a d i c a l ( R O ) , f e r r y l haem prote in r a d i c a l , and nitr ic o x i d e ( N O ) [ 2 1 ] . T h e superoxide anion is c o m p a r a t i v e l y unreact ive and under p h y s i o l o g i c a l condit ions is conver ted , by d i s m u t a t i o n , to h y d r o g e n p e r o x i d e . T h i s is less react ive , longer l i v e d and more l i p o p h i l i c than the superoxide anion and it can diffuse considerable distances f r o m its site of generat ion . 2 T h e major danger of increased tissue concentrations of h y d r o g e n peroxide is the p r o d u c t i o n of a h y d r o x y l radica l by the H a b e r W e i s s or F e n t o n reac t ion : 0 2 " + H 2 0 2 --> 0 2 + O H - + O H The h y d r o x y l radica l has a short h a l f - l i f e , and is extremely react ive . F o r example , it w i l l r a p i d l y react with unsaturated fatty ac id side chains , result ing i n l i p i d p e r o x i d a t i o n . F o r t u n a t e l y , the H a b e r - W e i s s react ion is very slow under p h y s i o l o g i c a l c o n d i t i o n s . It is , h o w e v e r , accelerated by metal catalysts. T h i s process is ca l led the F e n t o n reac t ion . E x o g e n o u s H 2 0 2 has been used as a source of R O I s for experimental study because (1) H 2 0 2 and its metabolite O H are k n o w n to be important in the pathogenesis of IRI ; (2) H 2 0 2 can penetrate the c e l l m e m b r a n e , thereby reaching in t race l lu lar sites [15,22] . 1.2.2 Free R a d i c a l Ef fec ts A l t h o u g h o x y g e n is essential for aerobic l i fe f o r m s , too m u c h o x y g e n or inappropriate m e t a b o l i s m of o x y g e n can be toxic to the o r g a n i s m [23]. P h y s i o l o g i c a l l y , free radicals are essential to many n o r m a l b i o l o g i c a l process [21]. (1) Superoxide can be generated by a variety of cells to p e r f o r m useful funct ions in the b o d y : they are part of the cascade of events i n tissue response to i n v a d i n g m i c r o o r g a n i s m s and f o r e i g n mater ia l through the a n t i m i c r o b i a l act ion of phagocyt ic cel ls (neutrophi ls , m o n o c y t e s , and eosinophi ls ) [24,25] ; (2) T h e y are intermediates i n and/or products of e n z y m e - c a t a l y z e d react ions , for example the act ion of xanthine oxidase ; 3 (3) T h e y are regulatory molecules i n b i o c h e m i c a l processes . F o r example , lymphocytes and f ibroblasts constantly generate smal l amounts of superoxide radica l as growth regulators [26]. (4) T h e y are i n v o l v e d i n c y c l o o x y g e n a s e and l ipoxygenase act ion in e i c o s a n o i d m e t a b o l i s m . (5) T h e y are i n v o l v e d in the synthesis of adrenocor t i ca l hormones and in the f u n c t i o n a l d i v i s i o n of the cortex [25]. P a t h o l o g i c a l l y , abnormal free radica l reactions may be e l i c i ted by p h y s i o l o g i c a l free radicals i f the contro l mechanisms are d e f e c t i v e , or i f there is a m a r k e d increase i n the p r o d u c t i o n of free radicals under normal condit ions of self pro tec t ion . Free radica l reactions may damage v i r t u a l l y any b i o m o l e c u l e : e n z y m e s , proteins , carbohydrates , l i p i d s or n u c l e i c ac ids . T h e genetic m a t e r i a l , membranes c o m p o s e d p r e d o m i n a n t l y o f l i p i d s and proteins , and subcel lu lar structures (plasma membrane , m i t o c h o n d r i a , m i c r o s o m e s and lysosomes) are a l l potential sites of l i p i d p e r o x i d a t i o n damage [23,26] . N o organ is spared f r o m such oxidat ive damage. A g i n g and many d i s o r d e r s , such as cancer , a therosc lerosis , and neural d i s o r d e r s , have a l l been related to such oxidat ive i n j u r y [26-28]. 1.2.3 M e c h a n i s m s of the endogenous release of Free R a d i c a l s d u r i n g T i s s u e Injury. [9 ,21,25,29] 1. Phagocyte recruitment and act ivat ion at the site of in jury ( F i g u r e 1). 2. Xanthine oxidase and other s u p e r o x i d e - p r o d u c i n g enzymes ( F i g u r e 2). Studies of xanthine oxidase d i s t r i b u t i o n i n cardiac tissue have s h o w n that the 4 enzyme is l o c a l i z e d in oxidat ion-sensi t ive vascular e n d o t h e l i a l cel ls rather than i n myocytes [30]. 3. D i s r u p t e d m i t o c h o n d r i a l e lectron transport , e . g . d u r i n g i s c h e m i a , a l l o w i n g leakage of electrons onto o x y g e n d u r i n g r e p e r f u s i o n . 4. A number of c e l l types, i n c l u d i n g endothel ia l c e l l s , m a c r o p h a g e s , and smooth muscle c e l l s , have been shown f r o m studies i n c e l l culture to be capable of p r o d u c i n g superoxide r a d i c a l s . 5 NADPH + 2O2 Oxidase * NADP+ + H + + 2 O2 H2O2 CI MPO HOC1 Figure 1. Reactions involved in the generation of superoxide by NADPH oxidase and the respiratory burst of phagocytes. NADPH, nicotinamide adenine dinucleotide phosphate; MPO, myeloperoxidase; HOG, hypochlorous acid. Allopurinol I1- Xanthine oxidase Xanthine NADPH • NADP+ + H + or • Uric Acid Hypoxanthine O2 • O2 -• Figure 2. Xanthine oxidase and by-product superoxide radical formation. 6 1.3 L i p i d P e r o x i d a t i o n and D e t e c t i o n 1.3.1 L i p i d p e r o x i d a t i o n . T h e most c o m m o n target of R O I s is membrane l i p i d s because of their c h e m i c a l nature (cholesterol unsaturat ion, conjugated unsaturated l inkages o f polyunsaturated fatty acids) and of their regular s tructural arrangement (monolayers i n l i p o p r o t e i n s , bi layers i n c e l l membranes) [31]. H o w e v e r , auto-oxidat ion of the l ip ids of l i v i n g organisms is u s u a l l y a s low, compar tmenta l ized process because molecular o x y g e n is a weak oxidant [19]. L i p i d p e r o x i d a t i o n is a process in w h i c h a l i p i d free r a d i c a l R- is f o r m e d by the effect of a free radica l ini t ia tor . T h e free r a d i c a l then reacts with molecular o x y g e n , p r o d u c i n g a peroxy free radica l R O O - . A c h a i n react ion is started, the effect of w h i c h is not restricted to l i p i d s , but m a y , under pathologica l c o n d i t i o n s , damage n e i g h b o r i n g b i o m o l e c u l e s (proteins , carbohydrates , n u c l e i c acids) [19]. M o r e o v e r , by m e d i a t i o n of stable products ( compar ing to unstable products) of the process , such as alkanes [19,32] , remote molecules may also be damaged through l o c a l d i f f u s i o n or c i r c u l a t i o n . M a r k e d r e d u c t i o n of energy metabol ism by aldehyde products of o x i d a t i o n ( m a l o n d i a l d e h y d e , h y d r o x y p e n t e n a l , and h y d r o x y n o n e n a l ) , and by various h y d r o p e r o x i d e s has been d e s c r i b e d [32], i n c l u d i n g i n h i b i t i o n of g l y c o l y t i c enzymes , and reduct ion of m i t o c h o n d r i a l r e s p i r a t i o n . Other m e m b r a n e - b o u n d enzymes are also affected [33]. 7 1.3 .2 A r a c h i d o n i c A c i d M e t a b o l i s m and M D A F o r m a t i o n [25,34] M D A (malondialdehyde) is f o r m e d f r o m p e r o x i d a t i o n of polyunsaturated fatty acids with conjugated double b o u n d s , mainly v i a the a r a c h i d o n i c ac id metabol ism pathway i n v i v o . M a l o n d i a l d e h y d e is f o r m e d not only as a result of c y c l o o x y g e n a s e activity as a b y - p r o d u c t of thromboxane A 2 (TxA2) synthesis , but also by l ipoxygenase activity as a b y - p r o d u c t of h y d r o p e r o x y fatty acids ( F i g u r e 3). 8 Phospholipid ^ Phospholipase A2 Arachidonic acid Figure 3. Pathway by which MDA is formed as a by-product in arachidonic acid metabolism. Tx A2, thromboxane A2; TxB2, thromboxane B2; HHT, (12S-12-hydroxy-5Z,8E,10E)-heptadecatrienic acid; MDA, malondialdehyde. 9 1.3.3 M D A : A M a r k e r for L i p i d P e r o x i d a t i o n M a l o n d i a l d e h y d e is metastable, and detectable i n plasma [1,35-37] , cel ls [38-40] , tissues [15,41-43] , and subcel lular structures such as m i t o c h o n d r i a [16,44] and microsomes [45]. T h e concentra t ion of M D A provides a measure of the extent of l i p i d p e r o x i d a t i o n and antioxidant status of the body [1 ,15 ,39 ,45 ,46] . T h e r e f o r e , M D A has been w i d e l y used as a marker for l i p i d p e r o x i d a t i o n . In healthy persons , the average plasma M D A concentra t ion is about 0.7 p m o l / L for age less than 30 years , and about 1.2 p m o l / L for i n d i v i d u a l s of more than 40 years [35]. These levels are undetectable wi th the classic thiobarbi tur ic ac id ( T B A ) assay, but can be detected by more sensit ive and specif ic h i g h - p e r f o r m a n c e l i q u i d chromatography ( H P L C ) wi th f luorescence detection [47-49]. 1.3.4 C o n j u g a t e d D i e n e s and P h o s p h o l i p i d M o l a r R a t i o : A n o t h e r C h e m i c a l M a r k e r for O x i d a t i v e Injury In vi t ro experiments showed that free radicals can cause i s o m e r i z a t i o n of polyunsaturated fatty a c y l chains , generating products wi th diene conjugat ion but without p e r o x i d a t i o n [50,51] . T h e i s o m e r i z a t i o n most s tudied has been the c o n v e r s i o n of l i n o l e i c acid (18:2(9,12)) to 9 , 1 1 - o c t a d e c a d i e n o i c ac id (18:2(9,11)) . T h i s accounts for over 90% of the diene c o n j u g a t i o n i n human plasma, t issue, and tissue f luids [52]. H P L C can measure both the isomer 18:2(9,11) and the parent c o m p o u n d 18:2(9,12) i n p l a s m a . M o l a r ratio is the 10 ratio of 18:(9,11) to 18:2(9,12) [4,53] . T h e molar ratio i n the free fatty acid f rac t ion is affected by h e p a r i n , but the molar ratio i n the p h o s p h o l i p i d - ester if ied f r a c t i o n is not [54]. T h e r e f o r e the p h o s p h o l i p i d m o l a r ratio is measured. 1.4 Free R a d i c a l G e n e r a t i o n and M y o c a r d i a l D a m a g e d u r i n g C A B Surgery 1.4.1 Pattern of Systemic Free R a d i c a l G e n e r a t i o n d u r i n g C A B S u r g e r y H E A R T . R e p e r f u s i o n of m y o c a r d i u m after the p e r i o d of aortic cross- c l a m p i n g or coronary o c c l u s i o n can lead to the release of R O I s f r o m a variety of pathways in phagocytes , endothel ial and m y o c a r d i a l cel ls [8 ,55-58] . Ser ia l b l o o d s a m p l i n g f r o m systemic ar ter ia l , m i x e d venous and c o r o n a r y sinus catheters reveals , h o w e v e r , that the increase i n M D A and molar ratio i n coronary venous b l o o d is s imi lar to, or less than, the increases in m i x e d venous and arterial b l o o d [4]. E v e n though neutrophils have been shown to accumulate i n the m y o c a r d i u m d u r i n g early r e p e r f u s i o n , their ac t ivat ion d u r i n g oxidat ive stress does not occur [2]. T h u s , it seems u n l i k e l y that the m y o c a r d i u m is a major source of systemic R O I s d u r i n g C P B . L U N G . A c t i v a t e d neutrophils w i t h i n the lungs may be important i n the p r o d u c t i o n of R O I s . T h e lungs are not vent i la ted , and they are par t ia l ly co l lapsed d u r i n g bypass . W h e n p u l m o n a r y p e r f u s i o n is restored at the cessation of bypass , there is white c e l l sequestration w i t h i n the lungs [59-61]. A c t i v a t e d complement components [60-62], markers of white c e l l i l degranulat ion [61-63] and markers of free r a d i c a l act ivi ty are a l l detectable in the p u l m o n a r y eff luent b l o o d at this t ime. Bypass A p p a r a t u s . N e u t r o p h i l s are activated in the c i r c u l a t i o n d u r i n g bypass [64-66]. T h e y stick to the surfaces of the tubes and to the oxygenator of the ext racorporeal c i r c u l a t i o n apparatus. T h i s is f o l l o w e d by rapid act ivat ion and degranulat ion [92]. C o m p l e m e n t is also act ivated, p r o b a b l y v i a the alternative pathway, due to the contact of the b l o o d with f o r e i g n surfaces , i n c l u d i n g the p u m p , t u b i n g , oxygenator , and b l o o d gas interface [67-71]. T h e activated complement i n turn activates neutrophils to p r o d u c e R O I s [72]. T h e effects of increased oxidat ive stress related to the bypass apparatus should occur m a i n l y d u r i n g , rather than f o l l o w i n g , bypass . 1.4.2 M y o c a r d i a l Ischaemia R e p e r f u s i o n Injury C a u s e d B y R O I s Ischaemia r e p e r f u s i o n injury (IRI) is a very c o m p l e x p a t h o p h y s i o l o g i c a l process . Factors associated with IRI inc lude f o r m a t i o n of R O I s , p r o d u c t i o n of platelet act ivat ing factor ( P A F ) , complement ac t iva t ion , platelet and leukocyte ac t ivat ion , p r o d u c t i o n of arachidonic acid metabol i tes , f o r m a t i o n of inf lammatory mediators such as his tamine , serotonin , k i n i n and b r a d y k i n i n as wel l as i m m u n o l o g i c a l l y - p r o v o k e d types of acute reactions [72]. It is c o n s i d e r e d that i n the complex m u t i f a c t o r i a l pathogenesis of IRI , R O I f o r m a t i o n , P A F p r o d u c t i o n , and complement ac t iva t ion may play the most important roles [72-75]. H o w e v e r , this sect ion of the thesis w i l l O N L Y focus on the p a t h o p h y s i o l o g y of IRI caused by R O I s . 12 In the m y o c a r d i u m , the reduct ion of o x y g e n to water proceeds by two pathways. T h e m i t o c h o n d r i a l cy tochrome oxidase system reduces 95% of oxygen to water by tetravalent reduct ion without the p r o d u c t i o n of R O I s . T h e r e m a i n i n g 5% of o x y g e n enters the univalent reduct ive pathway and several R O I s , such as superoxide anions , h y d r o g e n peroxide and the h y d r o x y l r a d i c a l , are p r o d u c e d [8]. T h e m y o c a r d i a l damage d u r i n g C A B surgery l i k e l y starts d u r i n g i schaemia . A t this t ime, o x y g e n is no longer a v a i l a b l e , but a cer tain amount of R O I s might be st i l l formed f r o m res idual m o l e c u l a r o x y g e n . (1) D u r i n g this p e r i o d , the components of the m i t o c h o n d r i a l e lec t ron transport chain become reduced [76,77] , a l l o w i n g leakage of electrons onto res idual m o l e c u l a r o x y g e n , leading to the f o r m a t i o n o f superoxide radicals [21]. M o s t l i k e l y , in the early phase of i schaemia , R O I p r o d u c t i o n f r o m m i t o c h o n d r i a is neutral ized by superoxide dismutase ( S O D ) . Increasing the dura t ion of ischaemia leads to a progress ive decl ine in S O D a c t i v i t y , l e a v i n g the m i t o c h o n d r i a less capable of deal ing with the increased r a d i c a l f lux [78-80]. (2) R O I s may be generated by xanthine oxidase , because cardiac tissue produces u r i c ac id and superoxide radicals d u r i n g i schaemia and r e p e r f u s i o n [81]. (3) R O I s may be generated w i t h i n membranes , i n associa t ion with the arachidonic ac id cascade. D u r i n g r e p e r f u s i o n , o x y g e n is ava i lable , and R O I s can be p r o d u c e d through the f o l l o w i n g mechanisms : (1) R e p e r f u s i o n re-energizes the m i t o c h o n d r i a , but electron egress through c y t o c h r o m e oxidase is reduced 13 because of the lack of adenosine diphosphate ( A D P ) causing f o r m a t i o n of R O I s [8]. (2) R O I s again may be p r o d u c e d through the xanthine oxidase pathway [81]. (3) N e u t r o p h i l s c o u l d also be act ivated, generat ing R O I s . E v e n though neutrophils have not been demonstrated to contribute to R O I generation in the m y o c a r d i u m d u r i n g r e p e r f u s i o n [2,6] , there is evidence that neutrophils do accumulate i n the m y o c a r d i u m d u r i n g r e p e r f u s i o n [2,7] . F u r t h e r m o r e , the deple t ion of c i r c u l a t i n g neutrophils has been associated with decreased m y o c a r d i a l damage i n models of i schaemia r e p e r f u s i o n injury [7,82]. T h u s , it seems that i schaemia induces alterations capable of reducing endogenous defense mechanisms against R O I chal lenge . T h e p r i m e alteration appears to l ie at the level of m i t o c h o n d r i a l antioxidant enzymes with S O D activity be ing reduced by 50% after severe i schaemia [8]. F u r t h e r m o r e , r e p e r f u s i o n is l i k e l y to stimulate the p r o d u c t i o n of R O I s to an extent greater than the n e u t r a l i z i n g capacity of m i t o c h o n d r i a l antioxidant enzyme defenses. If i schaemia is b r i e f ( < 30 to 60 m i n ) , r e p e r f u s i o n may not result i n i r revers ible oxidat ive damage [2,8], p r o b a b l y because the defense mechanisms are able to protect m y o c a r d i a l cel ls against the burst o f R O I s generated by r e a d m i s s i o n of o x y g e n with coronary f l o w . R e p e r f u s i o n after a longer p e r i o d of i schaemia , when the defense mechanisms are i m p a i r e d , causes m y o c a r d i a l damage, w h i c h may lead to i r r e v e r s i b l e loss of contract i le f u n c t i o n . 1.5 E n d o g e n o u s A n t i o x i d a n t Defense System 14 C e l l s and tissues usual ly have adequate in t race l lu lar and extracel lular antioxidant defenses. P h y s i o l o g i c a l l y , those located i n t r a c e l l u l a r ^ are appropriate for deal ing with aberrant generat ion of R O I s ; those located ex t race l lular ly are appropriate for b i n d i n g metal ions , d e l o c a l i s e d haem proteins and for i n h i b i t i n g p e r o x i d a t i o n processes [83]. T h e major antioxidants i n h u m a n plasma and their effect iveness against R O I s generated in the aqueous phase are: ascorbate = p r o t e i n b i l i r u b i n > urate > t o c o p h e r o l . P lasma l i p i d p e r o x i d a t i o n only occurs when ascorbate is complete ly c o n s u m e d . In ascorbate-replete p lasma, the l ip ids are protected [84]. T h e range of antioxidants and radica l scavengers is s u m m a r i z e d as f o l l o w s : 1.5.1 N o n e n z y m i c : V i t a m i n C and V i t a m i n E These are chain b r e a k i n g and h y d r o x y l radica l scavenger antioxidants . V i t a m i n E is h i g h l y l i p o p h i l i c . It contains s h i e l d i n g methyl groups in the v i c i n i t y of the p h e n o l i c h y d r o x y l group of the c h r o m o p h o r i c m o i e t y , and it is opt imal ly p o s i t i o n e d i n the membrane by its p h y t y l side c h a i n [85]. In m y o c a r d i u m , it has been ident i f ied i n both m y o c a r d i a l c y t o s o l i c and m i t o c h o n d r i a l membranes and presumably protects them f r o m l i p i d p e r o x i d a t i o n [86,87] . V i t a m i n C is water s o l u b l e . It is active in cy tosol and i n the extracel lular f l u i d . It functions s y n e r g i s t i c a l l y wi th v i t a m i n E and it must be present to regenerate v i t a m i n E . 1.5.2 M a j o r E x t r a c e l l u l a r Protec t ion M e c h a n i s m s [21] 15 1. U r i c a c i d : scavenges h y d r o x y l radica l and singlet o x y g e n ; it is also a chelator of i r o n and copper . 2. C a e r u l o p l a s m i n : acts as an antioxidant by virtue of its fe r rox idase ac t iv i ty . 3. T r a n s f e r r i n : sequesters i r o n (III), render ing it u n a v a i l a b l e for ca ta lyz ing the H a b e r - W e i s s react ion w h i c h initiates l i p i d p e r o x i d a t i o n or catalyzes the d e c o m p o s i t i o n of l i p i d h y d r o p e r o x i d e s . 4. A l b u m i n : binds metals , especia l ly copper but also i r o n w e a k l y . 5. Beta carotene: transported p r i m a r i l y w i t h i n l o w - d e n s i t y l ipoproteins [88], scavenges p e r o x y l radicals [89]. 1.5.3 E n z y m i c A n t i o x i d a n t Defenses 1. S u p e r o x i d e dismutase ( S O D ) : is present i n the manganese f o r m ( M n - S O D ) i n m i t o c h o n d r i a and in the copper or z inc f o r m ( C u - S O D , Z n - S O D ) i n c y t o p l a s m . It disposes of superoxide radicals by d i s m u t a t i o n to h y d r o g e n peroxide and o x y g e n , w h i c h is 10 times faster than by spontaneous decay [90]. 2. Gluta thione peroxidase ( G P X ) : present i n the c y t o s o l , detoxif ies h y d r o g e n peroxide and l i p i d peroxides in the presence of reduced glutathione ( G S H ) . 3. Catalase : detoxif ies h y d r o g e n peroxide In the m y o c a r d i u m , S O D and G P X are present at s ignif icant concentrat ions , whi le catalase, at very low concentra t ion . S O D was shown as the first l ine of defense against R O I chal lenge , and G P X as the second line [8]. 16 R e d c e l l s , i n contrast to m y o c a r d i a l c e l l s , have large amounts of catalase [91] as w e l l as S O D and G P X . In animal studies, it was s h o w n that human and murine red ce l l s , p r o b a b l y by virtue of catalase ac t iv i ty , complete ly protected nucleated cells (L1210 murine leukemia) against exogenous oxidat ive chal lenge i n vitro [91]. R e p e r f u s i o n with h u m a n red cells increased ventr icular f u n c t i o n and decreased m y o c a r d i a l h y d r o g e n p e r o x i d e levels of i s c h e m i c , isolated rat hearts. R e p e r f u s i o n with red cel ls that lacked catalase (aminotriazole- treated) and/or glutathione ( N - e t h y l m a l e i m i d e - t r e a t e d ) d i d not increase ventr icular f u n c t i o n or decrease m y o c a r d i a l h y d r o g e n peroxide concentrat ion as m u c h as r e p e r f u s i o n with untreated red cel ls [92]. 1.6 Preoperat ive V i t a m i n C , V i t a m i n E , and A l l o p u r i n o l T h e r a p y i n Patients U n d e r g o i n g C A B Surgery A c c o r d i n g to a p u b l i c survey , only 9% of the A m e r i c a n p o p u l a t i o n f o l l o w diets that meet the r e c o m m e n d e d guidel ines for the antioxidants v i t a m i n E and v i t a m i n C . F u r t h e r m o r e , the low choles terol diets p r e s c r i b e d for some patients may exacerbate any p r i o r i n s u f f i c i e n c y of l i p i d - p h a s e antioxidants [93]. V i t a m i n E p r o b a b l y is the most important antioxidant i n the l i p i d phase [94]. Its concentra t ion i n m y o c a r d i u m was shown to decrease" d u r i n g C A B surgery [95]. H i g h dose v i t a m i n C (250 m g / k g ) , g i v e n int ravenously 30 m i n before C P B and at the time of aortic d e c l a m p i n g (125 m g / k g each t ime) , has shown 17 protect ive effects on m y o c a r d i u m , manifested as s i g n i f i c a n t l y lower plasma levels of M D A , C P K , C P K - M B , and L D H as w e l l as s i g n i f i c a n t l y higher cardiac index after operat ion [36]. A popular r e g i m e n is v i t a m i n C and v i t a m i n E (1000 mg and 100 to 800 I U d a i l y , up to one week before surgery) c o m b i n e d to give patients preopera t ively [96-99]. U n f o r t u n a t e l y , this r e g i m e n for C A B surgery has not resulted any measurable r e d u c t i o n i n m y o c a r d i a l IRI a l though it prevented p o s t - s u r g i c a l v i t a m i n E deplet ion i n plasma [96]. In the treatment of atherosclerosis , this supplementat ion r e g i m e n has s i g n i f i c a n t l y reduced p r o g r e s s i o n of atherosclerosis c o n f i r m e d m o r p h o l o g i c a l l y by h i g h resolut ion B - m o d e ul t rasonography [100] or by angiography [101]. A l l o p u r i n o l is a purine analogue. It has been used e f f e c t i v e l y in the treatment of h y p e r u r i c e m i a [102,103] . Its antioxidant effects l i k e l y include selective i n h i b i t i o n of xanthine oxidase . It may also attenuate the increase of m y e l o p e r o x i d a s e act ivi ty i n IRI [9 ,104,105] , presumably by decreas ing inf lux of neutrophils d u r i n g r e p e r f u s i o n . Other mechanisms of a l l o p u r i n o l in r e d u c i n g IRI independent of xanthine oxidase i n h i b i t i o n may m a i n l y inc lude reduct ion i n l y s o s o m a l enzyme release f r o m neutrophils [106] and f a c i l i t a t i o n of m i t o c h o n d r i a l e lectron transport [107]. In animal models of IRI , a l l o p u r i n o l has e f f e c t i v e l y increased c e l l and tissue antioxidant capaci ty , reduced l i p i d p e r o x i d a t i o n , and s i g n i f i c a n t l y i m p r o v e d c a r d i o p u l m o n a r y f u n c t i o n [9 ,10 ,108-110] . 18 In C A B surgery , preoperat ive c o n d i t i o n i n g w i t h a l l o p u r i n o l alone or together wi th v i t a m i n C and v i t a m i n E has shown [1 ,11-13 ,111-116] i m p r o v e d m y o c a r d i a l c o n t r a c t i l i t y , increased incidence of spontaneous r e v e r s i o n to sinus r h y t h m , reduced metabol ic changes (e .g . p l a s m a M D A , C P K - M B ) [ 1 ] , and decreased hospi ta l mortal i ty rate. 1.7 E G b 761 and C a r v e d i l o l : U n c o m m o n l y U s e d A n t i o x i d a n t s for C A B Surgery E G b 761 and C a r v e d i l o l are f o u n d to have antioxidant ac t iv i ty . T h e y have rarely been tr ied as antioxidants i n C B P surgery out of N o r t h A m e r i c a . H e r e is only a b r i e f d e s c r i p t i o n of the two d r u g s . 1.7.1 E G b 761 E G b is a titrated and standardized extract of green leaves of G i n k g o B i l o b a . It is a complex mixture c o m p o s e d of f l a v o n o i d substances, terpenes, p r o a n t h o c y a n i d i n s , organic ac ids , and other constituents [102]. T h e extract is standardized at 6 and 24% (w/w) of terpenes and f l a v o n o i d heterosides . A s a free r a d i c a l scavenger , its protect ive effects have been demonstrated on the m i t o c h o n d r i a l [103 ,117 ,118] , c e l l u l a r [119,120] , and tissue [119] levels by decreased M D A p r o d u c t i o n [119,121] , inhibi ted n e u t r o p h i l f u n c t i o n and adhesion to e n d o t h e l i u m [122], decreased ret inal [123], neural [117,120,124] and m y o c a r d i a l damage caused by R O I s . 19 In patients u n d e r g o i n g C A B surgery , pretreatment w i t h E G b 761 was associated with decreased T B A - r e a c t i v e species i n m y o c a r d i u m , and m y o c a r d i a l i m p r o v e m e n t (not s i g n i f i c a n t l y ) in postoperat ive r e c o v e r y [121]. 1.7.2 C a r v e d i l o l C a r v e d i l o l is a v a s o d i l a t i n g , beta-adrenoceptor antagonist current ly used for the treatment of m i l d to moderate hyper tens ion [125-127]. C a r v e d i l o l and some of its h y d r o x y l a t e d metabolites are potent ant ioxidants . In p h y s i o c h e m i c a l , b i o c h e m i c a l and ce l lu lar assays, c a r v e d i l o l and several of its metabolites di rec t ly scavenged R O I s [128], prevented l i p i d p e r o x i d a t i o n i n cardiac and b r a i n membranes , both i n vi tro and i n v i v o [129] and prevented the d e p l e t i o n of endogenous antioxidants , such as v i t a m i n E and glutathione. M o r e o v e r , c a r v e d i l o l and its metabolites prevented the o x i d a t i o n of L D L (low density l ipoprote in) to o x i d i z e d L D L , the latter be ing d i r e c t l y cytotoxic and k n o w n to activate monocytes /macrophages and to stimulate f o a m c e l l f o r m a t i o n [130]. C a r v e d i l o l has been shown to produce s igni f i cant c a r d i o p r o t e c t i o n in experimental a n i m a l models (using rat, d o g , and pig) of acute m y o c a r d i a l i n f a r c t i o n [131-133], with the most dramatic effect be ing o b s e r v e d i n the p i g model of m y o c a r d i a l IRI , where the r e d u c t i o n in infarct size reached 91%. These results suggest its c l i n i c a l use in patients u n d e r g o i n g C A B surgery [134]. 20 1.8 P r o p o f o l : A n Anesthet ic and A n t i o x i d a n t P r o p o f o l is a short -act ing intravenous anesthetic , w h i c h is h i g h l y l i p i d - soluble . It is w i d e l y used in both ambulatory and h o s p i t a l i z e d patients. It permits both eff ic ient contro l of anesthetic depth and r a p i d , control lable recovery [135]. A s an antioxidant , p r o p o f o l has been s h o w n to have protective effects i n attenuating m y o c a r d i a l IRI i n animal models [14,15] . 1.8.1 Structure P r o p o f o l , 2 , 6 - d i i s o p r o p y l p h e n o l (molecular weight 178.27) , is c h e m i c a l l y s i m i l a r to phenol -based free r a d i c a l scavengers such as butylated hydroxyto luene and the endogenous antioxidant v i t a m i n E ( F i g u r e 4) [17 ,136,137] . A l l these three compounds carry a h y d r o x y l substituent on a phenyl r i n g , w h i c h is k n o w n to confer free radica l s c a v e n g i n g propert ies [136]. 21 OH (CH3)2CH CH(CH3)2 Propofol OH (CH3)3C C(CH3)3 Butylated hydroxytoluene CH3 CH3 HO CH3 C H 3 CI12-(CH2-CH2 - CH-CH2) - H C H 3 Vitamin E C H 3 Figure 4. Structural formulae of propofol (2,6-diisopropylphenol), butylated hydroxytoluene, and vitamin E (alpha tocopherol). All three compounds carry a hydroxyl substituent on their phenol rings, which is considered to confer free radical scavenging properties. 22 1.8.2 B a s i c P h a r m a c o k i n e t i c s [137] A d m i n i s t r a t i o n of p r o p o f o l , 2 - 2 . 5 m g / k g g i v e n iv over 15 seconds or less, produces unconsciousness w i t h i n about 30 seconds . A w a k e n i n g is very rapid and complete wi th m i n i m a l res idual central nervous system effects , w h i c h seems to be the most important advantage over other drugs used to produce i n d u c t i o n o f anesthesia . C l e a r a n c e of p r o p o f o l f r o m the plasma exceeds hepatic b l o o d f l o w , e m p h a s i z i n g that tissue uptake as w e l l as m e t a b o l i s m is important i n r e m o v a l of this drug f r o m the p l a s m a . Less than 0.3% of a dose is excreted unchanged in the u r i n e . T h e e l i m i n a t i o n h a l f - l i f e is 0.5 to 1.5 h o u r s . Despi te the rapid clearance of p r o p o f o l by m e t a b o l i s m , there is no evidence of i m p a i r e d e l i m i n a t i o n in patients with c i r r h o s i s or renal d y s f u n c t i o n . Patients older than 60 years of age exhibi t a reduced rate of plasma clearance o f p r o p o f o l . T h e r e may be a modest c u m u l a t i v e effect , especia l ly i n e lder ly patients r e c e i v i n g continuous intravenous i n f u s i o n s . P lasma C o n c e n t r a t i o n of P r o p o f o l d u r i n g C A B S u r g e r y : P r o p o f o l is a weak organic a c i d that is b o u n d extensively to plasma a l b u m i n , wi th a free f rac t ion of only 2-3% [138]. H a e m o d i l u t i o n d u r i n g c a r d i o p u l m o n a r y bypass is associated wi th decreases in the concentrations of plasma prote ins , a decrease in total p r o p o f o l concentrat ion d i s p r o p o r t i o n a l to the decreases in the concentrations of plasma proteins [139,140] , and a 1.5 to 3 f o l d increase in the f r a c t i o n of u n b o u n d p r o p o f o l [141,142] . 23 D i s p r o p o r t i o n a l decreases i n total p lasma concentra t ion of p r o p o f o l dur ing bypass may be attributed not only to h a e m o d i l u t i o n but also to p r o p o f o l sequestration w i t h i n the extracorporeal c i r c u i t , because the decrease of p r o p o f o l concentra t ion was up to 50% more than that predic ted by h a e m o d i l u t i o n alone [139,140] . Reasons for the increase i n the f rac t ion of u n b o u n d p r o p o f o l : T h e use of hepar in d u r i n g bypass causes an increase in n o n - e s t e r i f i e d fatty acids because of ac t ivat ion of l i p o p r o t e i n l ipase [143]. N o n - e s t e r i f i e d fatty acids are thought to be responsible for the decrease i n drug b i n d i n g to plasma proteins after h e p a r i n [144]. A n increased free f r a c t i o n of p r o p o f o l may contribute to the p r o l o n g e d effect of p r o p o f o l when the plasma concentra t ion of p r o p o f o l was low [145]. 1.8.3 M e c h a n i s m s of A n t i o x i d a n t A c t i v i t y P h e n o l - b a s e d antioxidants ( R - O H ) scavenge R O I s ( X ) by a process of h y d r o g e n abstract ion, and thereby themselves become a (less reactive) p h e n o x y l radica l ( R - ) R - O H + X - — > R - 0 + X H S p i n resonance spect roscopy, one of the most s p e c i f i c methods for charac ter iz ing r a d i c a l reactions [16 ,136 ,146 ,147] , was used to investigate this m e c h a n i s m . A n in vi t ro study was c a r r i e d out in a l i q u i d phase to examine the way i n w h i c h p r o p o f o l reacts with R O I s and, i n par t i cular , to ident i fy i f a p r o p o f o l - 24 d e r i v e d p h e n o x y l radica l is generated [136]. P r o p o f o l was demonstrated to act as an antioxidant by reacting with free radicals to f o r m a p h e n o x y l r a d i c a l - a property c o m m o n to al l phenol -based free radica l scavengers , such as v i t a m i n E . A n o t h e r i n vi t ro study was car r ied out u s i n g isolated rat l i v e r m i t o c h o n d r i a [16]. ' H - N M R spectra of m i t o c h o n d r i a l l i p i d extracts indicated that 95% of the added p r o p o f o l remained intact after a 30 m i n incubat ion under condi t ions of low oxidat ive stress. T h e e lec t ron spin resonance spectrum of p r o p o f o l , incubated i n the presence of E D T A - F e 2 + and H 2 0 2 as initiators of radica l p r o d u c t i o n , showed a radica l that was most l i k e l y a d e c o m p o s i t i o n product of the p h e n o x y l radica l of p r o p o f o l . It was c o n c l u d e d f r o m the study that p r o p o f o l acted as a chain r e a c t i o n - b r e a k i n g antioxidant by f o r m i n g a stable radica l [16,148]. 1.8.4 A n t i o x i d a n t A c t i v i t i e s of P r o p o f o l i n A n i m a l Studies 1. P r o p o f o l Inhibits L i p i d P e r o x i d a t i o n i n Isolated L i v e r M i t o c h o n d r i a of the Rat . 1.1 u M p r o p o f o l p r o d u c e d about 50% i n h i b i t i o n of M D A (or T B A - reactive substances) p r o d u c t i o n [16,17] , whi le 8 p M p r o p o f o l complete ly suppressed the p r o d u c t i o n of M D A [16]. 2. P r o p o f o l Attenuates IRI i n the Isolated Rat H e a r t . [14] D u r i n g r e p e r f u s i o n after g l o b a l i s c h e m i a , 100 u M p r o p o f o l increased coronary f l o w and reduced L D H release and the hearts showed lower left 25 ventr icular end-dias to l i c pressure . H i s t o l o g i c a l l y , the in jury was less severe i n p r o p o f o l - t r e a t e d hearts in terms of interst i t ial edema, m y o f i b e r degenerat ion, and f o r m a t i o n of m y o c a r d i a l h y p e r c o n t r a c t i o n bands . 3. P r o p o f o l Attenuates M e c h a n i c a l and M e t a b o l i c D a m a g e Induced by Exogenous H y d r o g e n Peroxide in the Isolated Rat Hear t [15]. 25 p-M or 50 u,M p r o p o f o l complete ly suppressed the p r o d u c t i o n of tissue M D A ( F i g u r e 5), s i g n i f i c a n t l y attenuated m e c h a n i c a l d y s f u n c t i o n ( increased left ventr icular end-dias to l ic pressure , decreased left vent r i cular pressure) and metabol ic changes (decreased tissue concentrat ions of A T P and creatine phosphate) i n d u c e d by exogenous h y d r o g e n peroxide (600 p ,M) . 4. In a p r e v i o u s study f r o m our laboratory us ing a swine m o d e l of heart - lung transplantat ion, p r o p o f o l at p lasma concentrations of 10 to 20 u M s ignif i cant ly increased red ce l l antioxidant capacity against i n v i t ro oxidat ive challenge (1.5 u M t-butyl h y d r o g e n p e r o x i d e ) . T h i s effect may be indicat ive of a genera l ized enhancement of tissue antioxidant status, and might confer protect ion against c a r d i o p u l m o n a r y IRI [18,19] . 5. In a study c a r r i e d out i n aqueous suspension , 50 p-g/ml p r o p o f o l decreased M D A p r o d u c t i o n by 38%. [45] 6. P r o p o f o l d i d N O T : (1) P r o p o f o l d i d not have any detectable effect on plasma or red c e l l antioxidant enzyme activity i n a swine m o d e l of heart and lung transplantat ion. It d i d not prevent red c e l l glutathione d e p l e t i o n against i n vi tro peroxidat ive challenge [18], p r o b a b l y because p r o p o f o l m a i n l y acts at 26 the l e v e l of the plasma membrane as c o m p a r e d to the c y t o s o l i c or extracel lular compartment . (2) P r o p o f o l (25 p M or 50 p M ) d i d not complete ly attenuate m e c h a n i c a l and metabolic changes induced by exogenous h y d r o g e n peroxide i n the isolated rat [15] or rabbit [149] heart, i n spite of the complete i n h i b i t i o n o f l i p i d p e r o x i d a t i o n . T h e r e f o r e , factors other than l i p i d p e r o x i d a t i o n may play an important role i n m y o c a r d i a l damage induced by R O I s . In fact , o x i d a t i o n of protein or n o n p r o t e i n s u l f h y d r y l groups has been demonstrated to contribute to m y o c a r d i a l damage induced by R O I s [150]. These b i o c h e m i c a l alterations, w h i c h are not attributed to l i p i d p e r o x i d a t i o n o f the c e l l m e m b r a n e , may account for the incomplete protec t ion by p r o p o f o l of m e c h a n i c a l and metabolic derangements induced by R O I s [15]. (3) P r o p o f o l d i d not show any radica l scavenging act ivi ty at concentrat ions < 10 p g / m l i n an experiment car r ied out i n aqueous suspension i n vi t ro [45]. 27 £ 4 « R ^ O 2 o I D_ m £ 4 « R ^ O R- =5 CM D_ CM I I I + cvi CQ O X CM o *3 CL ^ O LO f t N Q. CT3 CO X o o o o o o O OO (D t CN ( J M Ajp B/|A|u) VQIAI 5 13 o «! &> DC - u •8 • T3 i a a' <u bX) 1 a © a 73 .1 s- o a .& I .9. o p o a o S i § S w) "e3' d I © © V PH a o a .s s I o WO © 45 « .a a .a O N O N 1 i g I •8' » 5 a 3 i JS u 1.8.5 P r o p o f o l Anaes thes ia i n C A B Surgery P r o p o f o l has the advantage of c o n v e y i n g very r a p i d and complete awakening , w h i c h results early extubation after surgery and early intensive care unit discharge [151,152] . It has been used since 1987 i n C A B surgery as total intravenous anaesthesia [151, 153-172] or post -operat ive sedation [173- 178]. H y p o t e n s i o n is a major side effect of p r o p o f o l anaesthesia [137, 145,179] . T h i s is due to a decrease i n p e r i p h e r a l vascular resistance caused by p r o p o f o l . [145 ,180 ,181] . P r o p o f o l as c o m p a r e d to isof lurane or enflurane d i d not show any s ignif icant changes [152,157,166,180] i n terms of m y o c a r d i a l contract i l i ty [157,180], cardiac output [180], inot ropic requirement [152], coronary p e r f u s i o n pressure [157] or per ioperat ive m y o c a r d i a l i n f a r c t i o n [152]. In earl ier studies, p r o p o f o l was associated wi th decreased m y o c a r d i a l b l o o d f low (by 26%), m y o c a r d i a l o x y g e n c o n s u m p t i o n (by 31%) [182], and cardiac index [113,182,183] and was suggested to lead to m y o c a r d i a l i schaemia i n patients with coronary artery disease [182]. A s an antioxidant the protect ive effects of p r o p o f o l on m y o c a r d i u m i n experimental studies were achieved at higher than r e c o m m e n d e d c l i n i c a l doses for C A B surgery . Because of this , it was suggested that the scavenging activity of p r o p o f o l d u r i n g c l i n i c a l anaesthesia is l i k e l y to be very l i m i t e d [45]. Its potential as an antioxidant in C A B surgery has not been invest igated. In our previous study in the swine m o d e l of ischaemia r e p e r f u s i o n injury 29 [18], p r o p o f o l was shown to have antioxidant propert ies at c l i n i c a l l y relevant plasma concentrat ions , w h i c h encouraged us to p r o c e e d with this c l i n i c a l study. 30 Chapter 2 O B J E C T I V E S T h e objectives of the thesis project were : (1) to determine i f p r o p o f o l i n r e c o m m e n d e d c l i n i c a l dosage enhances red c e l l antioxidant capacity d u r i n g coronary artery bypass ( C A B ) s u r g e r y ; (2) to investigate the effect o f p r o p o f o l on patient 's c a r d i o p u l m o n a r y funct ions p e r i o p e r a t i v e l y ; (3) to determine the m a x i m a l l y effec t ive dose or m a x i m a l i n f u s i o n rate of p r o p o f o l as both an antioxidant and anesthetic for C A B surgery . Because of the s m a l l sample size o f the study (see chapter 4, sec t ion 4 .1 .2 ) , this project was des igned to show statistical d i f ferences only i n laboratory data (red c e l l M D A p r o d u c t i o n against i n y i t ro ox idat ive chal lenge) rather than that i n c l i n i c a l data ( e . g . , c a r d i o p u l m o n a r y funct ions) . 31 Chapter 3 H Y P O T H E S E S 1. Isoflurane (less than 2% end tidal) w i l l not m o d i f y the red c e l l antioxidant status (experimental c o n t r o l ) . Isoflurane has been reported to inhibi t the p r o d u c t i o n of superoxide radicals by neutrophils at concentrations i n excess of 2% end t i d a l , and enhance the p r o d u c t i o n of superoxide radicals by neutrophils at concentrations up to 2% [184]. T h e concentrat ion of i sof lurane for our study is less than 2% end t i d a l . T h i s might s l ight ly increase the p r o d u c t i o n of superoxide radica ls , but the magnitude of this effect should not be large enough to inf luence the red c e l l antioxidant status g i v e n the m a r k e d protect ion a f f o r d e d by plasma antioxidants . 2. H i g h dose p r o p o f o l (200 p g / k g / m i n ) w i l l enhance antioxidant capacity of red cells against i n vi tro oxidat ive chal lenge , whi le low dose p r o p o f o l (50 p g / k g / m i n ) may not. T h e antioxidant propert ies of p r o p o f o l are dose-dependent . In an experiment c a r r i e d out i n aqueous suspension , p r o p o f o l at concentrat ions < 10 p g / m l d i d not show any radica l scavenging ac t iv i ty , whereas 50 p g / m l p r o p o f o l decreased M D A p r o d u c t i o n by 38%[45]. In our p r e v i o u s study i n a swine model o f hear t - lung transplantation, p r o p o f o l at p l a s m a concentrat ions of 7-12 p g / m l and 12-25 p g / m l resulted in decreased red c e l l M D A p r o d u c t i o n more than 25% and 50%[18] . T h u s , by cont inous i n f u s i o n wi th 32 high dose p r o p o f o l , we may reach 7-12 p g / m l or more for the plasma concentrat ion of p r o p o f o l d u r i n g bypass . H o w e v e r , w i t h low dose p r o p o f o l , the plasma concentra t ion of p r o p o f o l may be too low to protect the red cells against in vi t ro oxidat ive chal lenge . 3. 200 p g / k g / m i n is the m a x i m a l i n f u s i o n rate of p r o p o f o l for C A B surgery . T h e antioxidant effects of p r o p o f o l appear to be dose-dependent . In our previous study in swine , l i m i t e d enhancement of antioxidant status was achieved with plasma p r o p o f o l concentrat ion greater than 25 p.g/ml [18]. T h e m a x i m u m r e c o m m e n d e d c l i n i c a l i n f u s i o n rate of p r o p o f o l for C A B surgery is 200 p . g / k g / m i n [166]. A t this rate, the plasma concentra t ion of p r o p o f o l is greater than 7 p g / m l . 4. T h e antioxidant effect of p r o p o f o l on red c e l l M D A p r o d u c t i o n may continue after bypass . P r o p o f o l is h i g h l y l i p o p h i l i c . It m a i n l y distributes to membranous structures such as c y t o s o l i c and m i t o c h o n d r i a l membranes . U s i n g isolated rat l iver m i t o c h o n d r i a , it was s h o w n , by spin resonance spec t roscopy , that 95% of the p r o p o f o l remained intact even after 30 m i n i n c u b a t i o n under condi t ions of low oxidat ive stress, and p r o p o f o l d i d not seem to be m e t a b o l i z e d by m i t o c h o n d r i a in vi t ro [16]. T h i s impl ies that p r o p o f o l may r e m a i n in the red c e l l membrane even after p r o p o f o l anaesthesia is d i s c o n t i n u e d . 5. P r o p o f o l w i l l i m p r o v e the performance of the heart after bypass and w i l l decrease inotropic support required p e r i o p e r a t i v e l y . 33 A l l o p u r i n o l , an antioxidant when used p r e o p e r a t i v e l y , e f fec t ive ly i m p r o v e d m y o c a r d i a l f u n c t i o n , and reduced the i n o t r o p i c support required p e r i o p e r a t i v e l y [1 ,11-13 ,111 ,112 ,114 ,116 ,185] . G i v e n that p r o p o f o l has protect ive effects on the m y o c a r d i u m against oxidative chal lenge , l ike a l l o p u r i n o l , it might lead to i m p r o v e d m y o c a r d i a l f u n c t i o n , and decreased inotropic requirement p e r i o p e r a t i v e l y . 6. P r o p o f o l anesthesia w i l l have the benefit o f ear ly extubat ion after C A B surgery . V e r y r a p i d and complete awakening with m i n i m a l r e s i d u a l central nervous system effects is the most important advantage of p r o p o f o l over other drugs used to produce i n d u c t i o n of anesthesia [137]. T h e use of p r o p o f o l anesthesia for C A B surgery has been reported to be responsible for early extubation [151,152] . 34 Chapter 4 M A T E R I A L A N D M E T H O D S 4.1 C o r o n a r y A r t e r y Bypass S u r g e r y : A M o d e l of Ischaemia R e p e r f u s i o n Injury F o l l o w i n g inst i tut ional a p p r o v a l and i n f o r m e d patient consent , 26 patients scheduled for C A B surgery were r a n d o m l y selected. 4 .1 .1 Se lec t ion C r i t e r i a I n c l u s i o n c r i t e r i a : M a l e or female 35 years of age or older H a e m o d y n a m i c a l l y stable with documented c o r o n a r y artery disease H i s t o r y of recent (less than six months) m y o c a r d i a l i n f a r c t i o n Unstable angina L e f t ventr ic le d y s f u n c t i o n E x c l u s i o n c r i t e r i a : H a e m o d y n a m i c a l l y unstable , H i s t o r y of e v o l v i n g m y o c a r d i a l i n f a r c t i o n , A c u t e l y fa i led percutaneous t ransluminal coronary angioplasty or p r e v i o u s C A B surgery , A S A or s teroid therapy w i t h i n 7 days of surgery . 4 .1 .2 Study D e s i g n 35 Sample Size D e t e r m i n a t i o n . Because M D A has been w i d e l y used as a marker for l i p i d p e r o x i d a t i o n [1 ,15 ,36 ,39 ,41 ,43 ,45 ,55 ] and the suppressed red c e l l M D A p r o d u c t i o n may be indicat ive of g e n e r a l i z e d enhancement of tissue antioxidant status, the c a l c u l a t i o n of sample size for the study was based on the di f ferences of red c e l l M D A p r o d u c t i o n between i sof lurane and p r o p o f o l g r o u p s . A t present , there are no data avai lable o n the re la t ionship of red c e l l M D A p r o d u c t i o n and p r o p o f o l concentrat ions i n patients u n d e r g o i n g C A B surgery . T h e r e f o r e , data f r o m a swine m o d e l of hear t - lung transplantation [18] were used to calculate the sample size for this project . In the i sof lurane group of the swine m o d e l , the average red c e l l M D A p r o d u c t i o n (pO) is about 80 n M / g m rbc with a standard d e v i a t i o n (CTO) o f about 30 n M / g m r b c . In the p r o p o f o l g r o u p , the M D A p r o d u c t i o n ( u l ) is about 60 n M / g m rbc with a standard d e v i a t i o n (c?l) o f about 20 n M / g m rbc when the plasma p r o p o f o l concentra t ion is about 7 p g / m l (25% i n h i b i t i o n of M D A p r o d u c t i o n ) . W e define T y p e I error as 0.05 and type II error as 0.1 ( i . e . , test power 90%). T h e n for this one- ta i l test, Z a = 1.645, and Z[3 = 1.282. A c c o r d i n g to L a c h i n ' s method of sample size d e t e r m i n a t i o n and power analysis for c l i n i c a l trials [186], the total sample size is N = [ ( Z a * a 0 + Z p * a l ) / ( u l - uO) ] 2 = 14 T h e r e f o r e , the total sample size is 14. That means for the h i g h dose p r o p o f o l group, in w h i c h plasma p r o p o f o l concentrat ion was expected to reach close to 7 p g / m l to s i g n i f i c a n t l y suppress red c e l l M D A p r o d u c t i o n , at least 7 patients should be recrui ted for this group and for the isof lurane g r o u p . 36 Patients were r a n d o m l y selected, and p u r p o s e l y ass igned to one of the three study g r o u p s . T h e anesthetist i n v o l v e d i n the care of the patient was aware of the exper imental maneuver , w h i c h was b l i n d e d to the researchers responsible for the laboratory and c l i n i c a l outcome analyses . C o n t r o l group ( i sof lurane-sufentani l ) : Sample s ize : 1 1 ( 7 have data on M D A p r o d u c t i o n . ) A n e s t h e s i a : Sufentani l 0 .5-10 p g / k g Isoflurane (0-2%) i n a i r / o x y g e n < F i O 2 = 0 .5 . L o w dose p r o p o f o l group (propofol - sufentani l ) Sample s ize : 7 A n e s t h e s i a : P r o p o f o l : Induct ion 1.5-2.5 m g / k g , bolus P r e - C P B 100 p g / k g / m i n , cont inuous i n f u s i o n I n t r a - C P B 50 p g / k g / m i n continuous i n f u s i o n P o s t - C P B as above In I C U as above S u f e n t a n i l : 0.3-1 p g / k g i n i t i a l l y , and then 1 p g / k g every 5 minutes i f r e q u i r e d to mainta in haemodynamics > 20% above ward c o n t r o l levels H i g h dose p r o p o f o l group (propofol - sufentani l ) Sample s ize : 8 ( 7 have data on M D A p r o d u c t i o n . ) A n e s t h e s i a : 37 P r o p o f o l : Induct ion 1.5-2.5 m g / k g , bolus P r e - C P B 200 p g / k g / m i n , cont inuous i n f u s i o n I n t r a - C P B as above P o s t - C P B 50 p g / k g / m i n , continuous i n f u s i o n In I C U as above S u f e n t a n i l : the same as i n the low dose p r o p o f o l group 4.1 .3 B l o o d Sample C o l l e c t i o n V e n o u s b l o o d sampl ing (7 m l each time) for the measurement of red c e l l M D A p r o d u c t i o n was p e r f o r m e d over seven time intervals at base l ine , 30 m i n p o s t - i n d u c t i o n , 30 m i n c a r d i o p u l m o n a r y bypass ( C P B ) , 5, 10 and 30 m i n post aortic cross c l a m p i n g ( A C C ) , and 120 m i n p o s t - C P B ( F i g u r e 6). These samples were i mmedi a t e l y h e p a r i n i z e d and stored i n the c o l d r o o m ( 4 ° C ) unt i l the next m o r n i n g to be analyzed for p e r o x i d e - i n d u c e d T B A f o r m a t i o n . V e n o u s b l o o d for determining plasma concentrat ion of p r o p o f o l was col lec ted over 4 time intervals at 30 m i n p o s t - i n d u c t i o n , 30 m i n C P B , 30 m i n post- A C C , and 120 m i n p o s t - C P B ( F i g u r e 6). These samples were immediate ly h e p a r i n i z e d and centr i fuged ( x l 5 0 0 , for 10 m i n ) . T h e plasma was placed in 1.5 m l c r y o v i a l s and immediate ly f r o z e n and stored at - 7 0 ° C u n t i l they c o u l d be analyzed by H P L C . 38 R e d C e l l M D A ' • 1 Preind 30'Postind 30'CPB 5'PostACC 10'PostACC 30'PostACC 120'PostCPB Propofol Concentration Figure 6. Schematic time-line representation of blood sampling for red cell MDA production and plasma concentration of propofol. 39 4.1 .4 C l i n i c a l Data C o l l e c t i o n C l i n i c a l data, notably per ioperat ive inot ropic requirement , post -operat ive cardiac index and post -operat ive extubation t ime, were taken f r o m the m e d i c a l r e c o r d s . 4 .1 .5 C a r d i o p u l m o n a r y Bypass T h e patients were perfused d u r i n g c a r d i o p u l m o n a r y bypass with nonpulsat i le f low at 2.0 to 2.8 L / m 2 / m i n with the use of standard C o b e pumps ( C o b e l a b o r a t o r i e s , L a k e w o o d , C o l o r a d o ) , mainta ining mean arter ial pressure at 55 to 70 m m H g . T h e oxygenator was a p o l y p r o p y l e n e h o l l o w f iber C o b e O p t i m a ( C o b e L a b o r a t o r i e s , L a k e w o o d , C o l o r a d o ) wi th a 1450 m l c r y s t a l l o i d p r i m e r . D u r i n g bypass , the lungs were not venti lated and the endotracheal tube was open to the air , so that the lungs were f l a c c i d and par t ia l ly c o l l a p s e d . F o l l o w i n g c r o s s - c l a m p i n g of the aorta, the s u r g i c a l technique consisted o f sequential m y o c a r d i a l r e v a s c u l a r i z a t i o n by v e i n and internal mammary artery grafts . Patients were c o o l e d to 3 2 ° to 3 4 ° C . Sys temic h e p a r i n i z a t i o n (300 U / k g ) was instituted short ly before aort ic c a n n u l a t i o n and was reversed immediate ly before aortic decannula t ion w i t h protamine (180- 300 m g / m 2 ) . T h e lungs were reventi lated immediate ly before the cessat ion o f bypass . 4 .1 .6 Data A n a l y s i s T h e p o o l e d t test is used to evaluate the s i g n i f i c a n c e of the differences 40 between two group means. T h e A N O V A test is used to evaluate the s ignif i cance of the dif ferences among the means of more than two groups . T h e C h i square test is used to evaluate the s i g n i f i c a n c e of the dif ferences between percentages. W h e n the smallest expected value is less than 5, F i s h e r ' s exact test is used instead of the C h i square test. A P value < 0.05 is considered to be s igni f i cant . 4.2 M e a s u r e m e n t of in vi tro R e d C e l l M D A P r o d u c t i o n : T B A assay. M D A is f o r m e d d u r i n g i s c h e m i a - r e p e r f u s i o n injury through the arachidonic ac id metabol ism pathway ( F i g u r e 3). H o w e v e r , the concentrat ion of M D A d u r i n g C A B surgery is too low to be detected by our T B A assay. T h e r e f o r e , we c h a l l e n g e d the red cel ls i n vi t ro with i n c r e a s i n g concentrat ions (0.5, 1.0, 1.5, 2 .0 , 2.5 m M ) of t - b u t y l h y d r o p e r o x i d e , thereby a c h i e v i n g M D A levels h i g h enough to be detected by this assay. T h i s approach measures red ce l l antioxidant capacity in the presence of an in vi t ro oxidat ive chal lenge . M o r e s p e c i f i c a l l y , the procedure used in our T B A assays was as f o l l o w s (mainly adapted f r o m a p u b l i s h e d report by D r . G o d i n ) [39]: Reagents and solutions (for 35 test tubes): D o u b l e - d i s t i l l e d water was used . 0.9% N a C l - NaN3 (sa l ine /az ide) . N a C l (4.5 g) and azide (65 m g , f r o m S i g m a , Canada) was d i s s o l v e d in 500 m l of d i s t i l l e d water. 41 28% T C A ( t r ichloroacet ic acid) - 0.1 M N a arsenite , f r o m S i g m a , C a n a d a . 0.5% T B A ( thiobarbi tur ic acid) i n 0.025 M N a O H . 105 m g T B A ( S i g m a , Canada) was d i s s o l v e d i n 10.5 m l 0.05 M N a O H and 10.5 m l d i s t i l l e d water. t B H P ( t - b u t y l h y d r o p e r o x i d e ) . 100 uJ of 70% t B H P (Sigma) was di luted with 6.9 m l s a l i n e / a z i d e to get 100 m M T B H , w h i c h was further d i luted with sa l ine /azide to different concentrations of T B H (1.0, 2 .0 , 3 .0 , 4 .0 , 5 .0) . D u r i n g peroxidat ive chal lenge , 0.5 m l t B H P in dif ferent concentrat ions is reacted with 0.5 m l of test sample to achieve the effec t ive t B H P concentrat ions , w h i c h are 0 .5 , 1.0, 1.5, 2 .0 , 2.5 m M . P r o c e d u r e : 1) C e n t r i f u g e b l o o d at 1000 r p m for 5 m i n at 4 ° C . 2) R e m o v e plasma and white cells by aspira t ion . 3) W a s h red cells twice with sa l ine /az ide by c e n t r i f u g a t i o n . 4) W e i g h aliquots of 50 p i packed red cells i n 1.5 m l m i c r o c e n t r i f u g e tubes. 5) A d d 0.45 m l c o l d sa l ine /azide to the m i c r o c e n t r i f u g e tubes. 6) Preincubate for 5 m i n at 3 7 ° C . 7) Start peroxidat ive chal lenge with 0.5 m l t B H P ( S i g m a , Canada) i n different concentrations and incubate 30 m i n at 3 7 ° C . 8) Stop react ion with 0.5 m l c o l d 28% T C A - a r s e n i t e . 9) C e n t r i f u g e 5 m i n at 12000 x g and transfer 1.0 m l al iquot of supernatant to 100 m m glass tubes. 42 10) A d d 0.5 m l 0.5% T B A i n 0.025 M N a O H to each glass tube. 11) B o i l 15 m i n to develop the co lor for spectrophotometery . 12) R e a d absorbance at 532 nm and 453 nm with a P e r k i n E l m e r L a m b d a 6 spectrophotometer . 13) C a l c u l a t e the concentra t ion of M D A . delta = (abs@532 - b l a n k @ 5 3 2 ) - 20% (abs@453 - b l a n k @ 4 5 3 ) M D A ( n m o l e s / g m R B C ) = (de l ta -0 .0053) / l .931 * 5 0 / R B C weight i n gram 4.3 M e a s u r e m e n t of P lasma P r o p o f o l C o n c e n t r a t i o n by H P L C H i g h - p e r f o r m a n c e l i q u i d chromatography ( H P L C ) or gas c h r o m a t o g r a p h y ( G C ) [48,187-189] can determine p r o p o f o l concentra t ion in plasma or in whole b l o o d . B o t h H P L C and G C methods had g i v e n equivalent results [188]. F l u o r e s c e n c e detect ion has been used for H P L C d e t e r m i n a t i o n o f p r o p o f o l concentra t ion , because it is more sensitive than c lass ica l u l t r a v i o l e t detect ion. S i g n i f i c a n t di f ferences i n p r o p o f o l concentra t ion between plasma and whole b l o o d specimens were observed [188]. T h i s d i s c r e p a n c y i n concentrations resul ted f r o m the i n f u s i o n or c learance of p r o p o f o l , and the lag i n r e d i s t r i b u t i o n across b l o o d c e l l membranes . W h o l e b l o o d sample c o l l e c t i o n is easier and more convenient for the c l i n i c i a n , but plasma concentrations are more di rec t ly related to the act ivi ty o f a d r u g i n the target organ than are whole b l o o d concentrat ions . T h e r e f o r e , p l a s m a samples are p r e f e r r e d , but immediate cent r i fugat ion is needed. 43 T h e details of the determinat ion of p r o p o f o l concentrat ions i n p lasma by H P L C with f luorescence detect ion were as f o l l o w s ( m a i n l y adapted f r o m a p u b l i s h e d report by D r . P l u m m e r ) [48]: Reagents and so lut ions : D o u b l e - d i s t i l l e d water was used . C y c l o h e x a n e (spectroscopic grade) , 2- p r o p a n o l , t r i f l u o r o a c e t i c acid and s o d i u m d i h y d r o g e n orthophosphate were obtained f r o m S i g m a (Canada) . A c e t o n i t r i l e ( H P L C grade) was obtained f r o m C a l e d o n ( C a n a d a ) . T e t r a m e t h y l a m m o n i u m h y d r o x i d e ( T M A H ) (25% i n methanol) and t h y m o l were obtained f r o m F l u k a ( A l d r i c h , C a n a d a ) . Internal standard s o l u t i o n . A so lut ion of t h y m o l was prepared i n methanol (1 m g / m l ) and further di luted wi th methanol to an appropriate w o r k i n g concentra t ion . Phosphate b u f f e r s o l u t i o n (0.1 M ) . S o d i u m d i h y d r o g e n orthophosphate (13.6 g) was d i s s o l v e d i n 1 1 of d i s t i l l e d water. D i l u t e T M A H s o l u t i o n . T M A H (25% i n methanol) (1.5 ml) was added to 2 - p r o p a n o l (18.5 m l ) . H P L C m o b i l e phase. T h e H P L C m o b i l e phase consis ted of 600 m l of acetoni t r i le , 400 m l of d i s t i l l e d water and 1 m l of t r i f l u o r o a c e t i c a c i d . T h e m o b i l e phase was degassed by the passage of h e l i u m p r i o r to use . A p p a r a t u s : 44 T h e 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 used consis ted of a G o l d H P L C System ( B e c k m a n , Canada) set to d e l i v e r a solvent f l o w of 1.5 m l / m i n , and R F 5000 F l u r o m e t e r ( S h i m a c l z u , Canada) f luorescence detector . T h e exci tat ion and e m i s s i o n wavelengths were 276 and 310 n m , r e s p e c t i v e l y , and both m o n o c h r o m a t o r slit widths were 10 n m . T h e signals were r e c o r d e d us ing a A l l t e c h L i c h r o s h e r e R P 18 encpd reversed-phase c o l u m n (5 p m part ic le s ize , 150 x 4.6 m m I . D . ; M a n d e l S c i e n t i f i c , C a n a d a was used at ambient temperature. P r o c e d u r e : T o a sample of plasma (0.5 m l ) , internal standard s o l u t i o n (20 p l ) , phosphate buffer (1 ml) and cyc lohexane (5 ml) were added . T h e mixture was then p l a c e d o n an i n v e r s i o n mixer for 15 m i n at 60 r p m . F o l l o w i n g centr i fugat ion (1150 x g for 5 m i n ) , an al iquot of the c y c l o h e x a n e layer (4.5 ml) was t ransferred to a tube conta ining dilute T M A H s o l u t i o n (50 p l ) . T h e solvent was evaporated to dryness at ambient temperature under a stream of ni t rogen. T h e dry residue was then r e d i s s o l v e d i n H P L C m o b i l e phase (200 pl) and an al iquot (100 pl) of the so lut ion was subjected to H P L C analys is . T y p i c a l chromatograms of extracts conta ining p r o p o f o l are s h o w n i n F i g u r e 7. A c a l i b r a t i o n graph was prepared by the a d d i t i o n of k n o w n quantities of p r o p o f o l to aliquots of contro l b l o o d and extracted a c c o r d i n g to the above procedure . T h e peak-height ratio of p r o p o f o l to t h y m o l was plotted against the concentra t ion of p r o p o f o l added. T h e concentra t ion of p r o p o f o l i n test 45 amples was ca lcula ted us ing the regress ion parameters obtained f r o m the a l i b r a t i o n g r a p h . 46 0 1 2 3 4 5 JULi 0 1 2 3 4 5 i 1 1 1 1 1 0 1 2 3 4 5 Times (minutes) A B C Figure 7. Schematic representation of chromatograms of extracts from ( A ) control human blood, ( B ) blood containing propofol (1 u.g/ml), and (C ) blood obtained from a patient having received propofol intravenously. Thymol was added as the internal standard. Peaks 1 and 2 are thymol and propofol, respectively. Chapter 5 R E S U L T S 5.1 Patient P r o f i l e T h e patients ' age, sex, body surface area and b o d y weight are s h o w n in T a b l e 1. T h e hematocri t values p r e - C P B and d u r i n g C P B , the d u r a t i o n of C P B and aortic c r o s s - c l a m p i n g and extubation t ime, are also i n c l u d e d i n T a b l e 1. 5.2 R e d C e l l M D A P r o d u c t i o n F o l l o w i n g i n vi t ro t B H P C h a l l e n g e 5.2.1 t B H P D o s e - R e s p o n s e C u r v e T h e red c e l l M D A p r o d u c t i o n f o l l o w i n g t B H P chal lenge is dose- dependent. F o r each sample , the M D A p r o d u c t i o n begins to rise i n response to 1.0 m M t B H P challenge and reaches a plateau when t B H P concentra t ion is 2.0 m M . T h e steep p o r t i o n of the curve is related to t B H P concentra t ion between 1.0 and 2.0 m M . T h e r e f o r e , f r o m the var ious concentra t ions , 1.5 m M of t B H P was selected for the analysis of antioxidant capaci ty of red ce l l s . F i g u r e 8 e x e m p l i f i e s this s i g m o i d curve w h i c h is based on the average M D A p r o d u c t i o n of the baseline (pre- induct ion) b l o o d samples of the three groups (Table 2). 5 .2 .2 R e d C e l l M D A P r o d u c t i o n in Response to i n vi t ro t B H P (1.5 m M ) C h a l l e n g e 48 R e d c e l l M D A p r o d u c t i o n is s u m m a r i z e d i n T a b l e 3 and F i g u r e 9. T h e pattern of M D A p r o d u c t i o n seems s i m i l a r in the isof lurane and low dose p r o p o f o l groups . A sustained s ignif icant decrease i n M D A p r o d u c t i o n is seen only with h i g h dose p r o p o f o l , and this effect appears to persist post- operat ively . 5.3 Plasma C o n c e n t r a t i o n of P r o p o f o l A v e r a g e plasma concentrations of p r o p o f o l measured by H P L C are s u m m a r i z e d i n T a b l e 3 and F i g u r e 9. T h e average plasma concentra t ion of p r o p o f o l was decreased by 18% i n low dose p r o p o f o l and increased by 29% in h i g h dose p r o p o f o l at 30 m i n C P B c o m p a r e d to that before C P B (30 m i n post- in du ct ion) . T h e p r o p o f o l concentrat ion was s i g n i f i c a n t l y higher i n the h i g h dose p r o p o f o l group than in the low dose p r o p o f o l group d u r i n g C P B . In the h i g h dose p r o p o f o l g r o u p , there was a c o r r e l a t i o n (R = 0.78213) between red c e l l M D A p r o d u c t i o n (Y) and plasma concentra t ion of p r o p o f o l (X) (F igure 10): Y = 35.945 - 16.75 l o g X S u c h a c o r r e l a t i o n d i d not exist i n the low dose p r o p o f o l g r o u p . 5.4 Inotropic R e q u i r e m e n t d u r i n g C A B Surgery (Table 4, F i g u r e 11) 5.4.1 Percentage of Patients G i v e n Inotropic D r u g s T h e r e were no s ignif icant differences among the g r o u p s . 49 5.4.2 Percentage of Patients G i v e n D o p a m i n e (3-5 p / k g / m i n ) T h e patients i n i sof lurane needed more dopamine than those i n the low dose or h i g h dose p r o p o f o l groups (57% vs . 14%, P < 0 .05) . 5.4.3 Percentage of Patients G i v e n A d r e n a l i n e T h e patients i n the isof lurane group needed more adrenal ine than those in the low dose or h i g h dose p r o p o f o l groups (73% versus 43% or 57%). H o w e v e r , the dif ferences d i d not attain statistical s i g n i f i c a n c e . 5.5 H a e m o d y n a m i c Changes d u r i n g 24 H o u r s P o s t - o p e r a t i o n 5.5.1 C a r d i a c Index ( T a b l e 5, F i g u r e 12) T h e percentage of the cardiac index > 2.5 L / m i n / m 2 i n the low dose p r o p o f o l group is s i g n i f i c a n t l y higher than that in the i sof lurane group d u r i n g the first 3 hours post -operat ion (Table 6, F i g u r e 13). T h e r e are no s ignif icant differences among the groups otherwise . 5 .5.2 P u l m o n a r y C a p i l l a r y W e d g e Pressure (Table 5, F i g u r e 12) In the isof lurane g r o u p , the p u l m o n a r y c a p i l l a r y wedge pressure is s i g n i f i c a n t l y higher (P < 0.05) d u r i n g the 19-24 hour p e r i o d than it is at 1 or 2 hours p o s t - o p e r a t i o n . W h e n it is plotted against cardiac index ( F i g u r e 14), one can see that the cardiac index is low even with h i g h p u l m o n a r y c a p i l l a r y wedge pressure , and the percentage of cardiac index > 3 L / m i n / m 2 is 50 s i g n i f i c a n t l y higher (P < 0.05) i n the low dose p r o p o f o l than that in isoflurane g r o u p . 5.5.3 C e n t r a l V e n o u s Pressure (Table 5, F i g u r e 12) T h e central venous pressure is re la t ively stable throughout the surgery . There are no s ignif icant differences among the g r o u p s . 5.6 A l v e o l a r A r t e r i a l O x y g e n G r a d i e n t d u r i n g 24 H o u r s P o s t - o p e r a t i o n (Table 7 , F i g u r e 15) T h e r e is a s ignif icant improvement in oxygenat ion (P < 0.05) in the first 12 hours after surgery in the isoflurane or low dose p r o p o f o l g r o u p s . T h e r e are no s ignif icant changes i n the h i g h dose p r o p o f o l g r o u p . 51 a IH "•s o 13 9 a s 2 a = "•8 •9 C o i •S J , u u «< .9 9, ffl & PH u t a PH ^3 1—1 f N <s +1 +1 +1 T f l-H i-H i-H i-H fN t » i-H r-4 +1 +1 +1 m © ro © i-H i-H m (~~ 0 0 l-H i-H +1 +1 +1 o ir> 0 0 IT) 0 0 T f ^ H i-H ^ H l-H <N i-H © © © +1 +1 +1 in T f IT. fN f N i-H ^ H i-H © © © +1 +1 +1 l-H i-H fN T f T f T f SO r- T f +1 +1 +1 ON » 0 0 l > so i-H © +1 +1 +1 T f © ON ON ON l-H l-H l-H 1/5 IT) +1 +1 +1 t-~ IT. IT, so SO SO fN i-H © ON SO 0 0 l-H l-H l > 0 0 o o •a o a < PH a © a *a 2 a < 4) i . i . eg "O o> N j£> OS s a s I •s « ii s o B v> a <s "8 .ts 2 a s i •13 C H SO fN o o Vi ii u fi 2 .8 o a <u u cs 6 JS H .9 a 9 "w O J- w • • f i o 08 U u << CS r 9 a o & a o i ii ii VI o +1 = 9 Vi CS -o Vi VI B. I Q a 3 & a be fi o 9 93 Table 2. tBHP-MDA Dose-Response Curve for Red Cells from the Three Experimental Groups. MDA Production (n moles/g rbc) tBHP (mM) 0.5 1.0 1.5 2.0 2.5 Isoflurane (n = 7) 1.16 ± 0.47 45.6 ± 4.2 122 ± 5 190 ± 4 198 ± 7 Propofol-Low (n = 7) 2.73 ± 1.45 46.6 ± 7.5 122 ± 12 187 ± 10 193 ± 8 Propofol-High (n = 7) 1.91 ± 0.62 33.4 ± 3.6 106 + 5 180 ±6 196 ± 5 Note: Data are from the first baseline (pre-induction) samples only, used to show the tBHP- MDA dose-response curve. Data are expressed as mean ± SEM. 53 u u < I Vi o PH o f N o PH © r o U U i Vi O |PH an O PH i r , P9 PH u o r o a '1 o r o ' i -a •S • r o V © i-H OS +1 +1 +1 t ~ l-H f N f N 0 0 l-H i-H 1/5 V O i-H in +1 +1 +1 v o r o os f N ^ H i-H f N v o l-H +1 +1 +1 1—1 r o v o r o f N T f i-H l-H V O 0 0 i-H +1 +1 +1 f N f N i-H r o f N T f ^ H l-H V O +1 r o IT) +1 f N f N r o i-H +1 T f f N +1 f N OS o o I +1 r o T f +1 l-H i r , f N i r . i-H +1 +1 +1 f N T f 0 0 f N r s o i-H l-H i-H •a © I r o +1 f N f N f N +1 0 0 T f +1 © T f 0 0 +1 ^ H ? ! a a II 1 I <2 o a I <2 o a i + i r , +1 T f r o oo +1 o 0 0 + v o i-5 +1 0 0 os f N +1 OS © Sf J 3 6J) s O I a a s- o a o '-8 -3 2 a Q "53 u •s I . .s a. 9 I. o O N 2 c a> Vi o •a 1 o •a o a lU i r , o O ' V PH 3 o a ! a? O a i r , o a 2 o. o c o 13 v u SS o s +1 a a on « -s vi Vi I I Q & O o a o a. a Vi O T3 •a J= V c/3 O o Table 4. Inotropic Requirement during CAB Surgery, by Group Inotrope Required Any Inotropic Drug Dopamine 3-5 u,g/kg/min Adrenaline Isoflurane 10/11 (91) 4/7 (57) * + 8/11 (73) Propofol-Low 7/7 (100) 1/7 (14) 3/7 (43) Propofol-High 6/7 (86) 1/7 (14) 4/7 (57) Note: Data are expressed as number (%). * P < 0.05 the isoflurane group versus low dose propofol group, + P < 0.05 the isoflurane group versus high dose propofol group for dopamine 3-5 p-g/kg/min. 55 VO T f f N i Ov oo r o f N 1̂ - r o l*N f N © +1 Ov f N f N © +1 r o f N © +1 Ov r i f N © +1 V O r i T f © +1 Ov r i f N © +1 0 0 r i r o © +1 0 0 r i r o © +1 0 0 r i o +1 r i I'H f N © +1 0 0 r i f N © +1 f N r o r o © +1 r o r o © +1 i > r i r o © +1 r o r o f N © +1 «/5 r i © +1 1/5 r o © +1 V O r o s o © +1 r o r o o o I VO © +1 i n r o oo © +1 0 0 r o r s © +1 i-H r o o v r i r o © +1 i > r i v o © +1 r o r o f N © +1 r o r i 1/5 o © +1 o r o T f © +1 vO r i •a o I o - J I o a, I •a © ^ H T f l > f N i-H f N +1 +1 +1 +1 +1 +1 k > i-H 1/5 l-H v© l-H r o ^ H f N i-H O ^ H i-H f N l-H i-H f N f N +1 +1 +1 +1 +1 +1 r o l-H r o l-H l-H l-H l-H l-H O l-H O i-H f N f N f N i-H l-H i-H +1 +1 +1 +1 +1 +1 T f l-H T f l-H f N i-H f N ^ H o i-H o i-H l-H r o f N ^ H n +1 +1 +1 +1 + l IT) l-H T f l-H T f l-H r o »-H i - H 1 l-H © ^ H f N f N f N f N O l-H +1 +1 +1 +1 +1 +1 tn i-H f N i-H r o i — i f N ^ H o i-H l-H l-H l-H f N r o f N l-H i-H +1 +1 +1 +1 +1 +1 IT/ ^ H 1/5 i-H T f i-H r o i-H r o i-H f N i-H ^ H r o f N f N l-H T f +1 +1 +1 +1 +1 +1 T f ^ H r o ^ H T f i-H f N i-H f N ^ H T f ^ H f N l-H f N f N ^ H f N +1 +1 +1 +1 +1 +1 f N l-H r o l-H 0 0 ^ H f N i-H f N l-H T f l-H »H f N l-H l-H f N +1 +1 +1 +1 +1 9 ± 0  l-H T—1 v o ^ H r o © l-H f N l-H 9 ± 0  o o c. •a • o Cu o Table 6. Percentage of Patients with a Cardiac Index > 2.5 L/min/m2 during 24 hours Post- operation. Time (hr) 1^3 4^6 7^12 13^18 19-24 Isoflurane 9 /22 (41) * 6/17 (35) 6/8 (75) 7/10 (70) 5/5 (100) Propofol-Low 10/13 (77) * 3/11 (27) 6/7 (86) 5/5 (100) 2/3 (67) Propofol-High 4/5 (80) 4/7 (57) 4/4 (100) 3/4 (75) 2/2 (100) Note: * P < 0.05 between the isoflurane and low dose propofol groups. Data are expressed as number (%). 57 Table 7. Alveolar Arterial Oxygen Gradient (mmHg) Admission 1-6 Hrs Post-operation 6- 12 Hrs Post-operation Isoflurane 195 + 19 * # 148 + 18 * 124 ±21 # Propofol-Low 145 ± 9 ** 94 ± 6 ** 97 ±26 Propofol-High 162 ± 19 149 ± 27 127 ± 32 Note: In the isoflurane group, * P < 0.05 ( # P < 0.001) between admission and 1-6 hours ( 6-12 hours) postoperation. In the low dose propofol group, ** P < 0.0005 between admission and 1-6 hours postoperation. P > 0.05 between each group at any time or duration. Data are expressed as mean ± SEM. 58 Figure 8. t BHP dose-response curve for red cell MDA production. Data is exemplified only from the blood samples taken at preinduction. Data are expressed as mean ± SEM.  n S) 100 S o 50 E S 0 Y = 105.7 - 58.422 X R = 0.824 0 0.5 1 1.5 Log [Propofol] (ug/ml plasma) Figure 10. The relationship of red cell MDA production and plasma concentration of propofol in the high dose propofol group. 61 100 - T3 0) 80 - k. '5 rr 60- 0) 40- 0) Q. 20 - O o c 0- Any Inotrope Dopamine 3-5 ug/kg/min • Isoflurane rj Propofol-Low • Propofol-High Epinephrine Figure 11. Inotropic requirement during CAB surgery. The requirement for dopamine 3-5 pg/kg/min is significantly less in the low dose or high dose propofol groups than that in the isoflurane group, P < 0.05. 62 -gl7 E14 > 0 O .Isoflurane -Propofol-Low -Propofol-High • Isoflurane . Propofol-Low .Propofol-High 13- 19-24 . Isoflurane • Propofol-Low • Propofol-High Time ( hr, postoperative) 13- 19- 24 Figure 12. Hemodynamic changes during 24 hours post-operatively. For cardiac index and central venous pressure, there are no significant differences between the groups using the pooled ttest. In the isoflurane group, the pulmonary capillary wedge pressure is significantly higher (P < 0.05) during 19-24 hour period than it is at 1 or 2 hours post-operatively. 7.5 S 5 c E d, 2.5 0 CI during 1st 3 Hrs Postoperation • Isoflurane A Propofol-Low o Propofol-High A A - 0 - ^ - ^ A ^ ^ - - A - • m a m Figure 13. Cardiac index during the firsr 3 hours post-operatively. The percentage of patients with a CI > 2.5 L/min/m2 in the low dose propofol group is significantly higher than that in the isoflurane group. There are no significant differences between the high dose and low dose propofol or isoflurane groups. 64 4 f 3.5- ™ 3 S 2 . 5 - ° 9 o A A A 6 0 A o * 1 i i • Isoflurane A Propofol-Low o Propofol-High o 10 12 14 16 18 20 PCWP(mmHg) Figure 14. Cardiac index versus pulmonary capillary wedge pressure during 24 hours post-operatively. Data are expressed as mean of different time intervals as seen in Figure 11. The CI is low in the isoflurane group, even with high PCWP. The CI is high in the low dose propofol group, in which the aortic cross-clamping time is longest among three groups. There is no difference between the high dose and low dose propofol or the isoflurane groups. The percentage of patients with a CI>3L/min/m2 is significantly higher in the low dose propofol group (6 put of 8) than that in the isoflurane group( 1 out of 8), P < 0.05. 65 I E B CS o ra < 300 250 200 150 100 50 0 Alveolar Arterial Oxygen Gradient *+ • Isoflurane • Propofol-Low • Propofol-High + i a n Admission 1-6 Hrs Postoperation 6-12 Hrs Postoperation Figure 15. Alveolar arterial oxygen gradient during 24 hours post-operation. * P < 0.05 (+ P < 0.001) between 1-6 (6-12) hours post-operation and admission in the isoflurane group. **, P< 0.001 between 1-6 hours post-operation and admission in the low dose propofol group. 66 Chapter 6 DISCUSSION 6.1 E v a l u a t i o n of Hypotheses Isoflurane at a concentrat ion less than 2% end t i d a l , used as contro l for this study, d i d not m o d i f y red c e l l antioxidant status. T h e red c e l l antioxidant capacity d i d not change s i g n i f i c a n t l y 30 m i n p o s t - i n d u c t i o n in c o m p a r i s o n to p r e - i n d u c t i o n . R e p e r f u s i o n i tself d i d not reduce the red c e l l antioxidant capaci ty in any o f the g r o u p s . T h i s may be because R O I s p r o d u c e d f r o m heart and lungs were largely d e t o x i f i e d by plasma antioxidant systems before they reached the red cells to exert s ignif icant effects . T h i s implicates the bypass machine as a major contr ibutor to the systemic p r o d u c t i o n of R O I s . T h e antioxidant properties of p r o p o f o l are dose-dependent . H i g h dose p r o p o f o l s i g n i f i c a n t l y increased the red c e l l antioxidant capaci ty throughout the surgery . T h i s effect appears to continue p o s t - s u r g i c a l l y , even at two hours after bypass when the plasma p r o p o f o l concentra t ion was very l o w . L o w dose p r o p o f o l , on the other h a n d , increased the red c e l l antioxidant capacity before bypass , but this effect was not sustained d u r i n g or after bypass . B y continuous i n f u s i o n with h i g h dose p r o p o f o l , the average plasma concentrat ion of p r o p o f o l reached 7.2 p g / m l before bypass and 9.3 p g / m l while on bypass , wi th resultant suppress ion of red c e l l M D A p r o d u c t i o n of 67 more than 50%. T h i s effect on M D A p r o d u c t i o n is greater than it was in our previous swine m o d e l [18], i n w h i c h the swine red c e l l M D A p r o d u c t i o n was suppressed by only 25% when the plasma p r o p o f o l concentra t ion was between 7 and 12 p-g/ml. In the latter swine m o d e l , a decrease i n red c e l l M D A p r o d u c t i o n of 50% r e q u i r e d a plasma p r o p o f o l concentra t ion of 12 to 25 L i g / m l . L o w dose p r o p o f o l had c a r d i o p u l m o n a r y protect ive effects , manifested as s ignif i cant ly higher percentage of patients wi th cardiac index > 2.5 L / m i n / m 2 d u r i n g the 1st 3 hours post -operat ively and with cardiac index > 3 L / m i n / m 2 d u r i n g 24 hours post -operat ively c o m p a r e d to that with isof lurane (P < 0 .05) , and a greater degree of recovery i n lung o x y g e n a t i o n 1-12 hours after surgery as c o m p a r e d with i sof lurane (P < 0 .001) . H i g h dose p r o p o f o l d i d not increase cardiac index p o s t - o p e r a t i v e l y . H i g h dose, as w e l l as low dose p r o p o f o l , were associated with s i g n i f i c a n t l y less inot ropic requirement , and prevented the increase i n p u l m o n a r y c a p i l l a r y wedge pressure w h i c h was seen in the isof lurane g r o u p . Isoflurane d i d not show any detectable protective effect on the heart. M o r e o v e r , it was associated with a s i g n i f i c a n t l y increased p u l m o n a r y c a p i l l a r y wedge pressure without any increase i n cardiac index . H o w e v e r , i sof lurane is associated wi th greater recovery i n lung oxygenat ion 1-12 hours post -operat ion c o m p a r e d with that of the same group at a d m i s s i o n to I C U after opera t ion , P < 0 .001 . T h e average extubation time i n the h i g h dose p r o p o f o l group was shorter than that in the isof lurane controls , but the d i f f e r e n c e was not statist ically s ignif icant [151,152] . 6.2 What D o e s Increased R e d C e l l A n t i o x i d a n t C a p a c i t y M e a n ? 6.2.1 G e n e r a l i z e d Enhancement of T i s s u e O x i d a n t Status T h e relat ionship of red c e l l antioxidant status and tissue antioxidat ive capacity has not been c l a r i f i e d , par t ia l ly because h u m a n tissues, especia l ly heart and l u n g , can not be obtained for analys is . T h u s , the re la t ionship can only be i n f e r r e d indi rec t ly f r o m the organ f u n c t i o n a l p e r f o r m a n c e or f r o m animal exper iments . In a swine m o d e l of hear t - lung transplantat ion [39], the suscept ibi l i ty of swine red cells to in vi t ro oxidat ive challenge was s i g n i f i c a n t l y r e d u c e d , manifested as s i g n i f i c a n t l y decreased red c e l l M D A p r o d u c t i o n . R e d c e l l M D A levels correla ted s i g n i f i c a n t l y wi th the f u n c t i o n a l v i a b i l i t y of the transplanted l u n g , as assessed by lung water content - a convenient measure of lung f u n c t i o n a l integri ty . In a comparat ive study on red cells of diabetic rats and h u m a n diabetics [192], the red c e l l p r o d u c t i o n of M D A was increased in response to i n vi t ro challenge with h y d r o g e n p e r o x i d e . In the diabetic patients, the extent of this increase i n suscept ibi l i ty of red c e l l l i p i d s to oxidat ion p a r a l l e l e d the severity of diabetic c o m p l i c a t i o n s present . 69 T o t h et a l . [190] f o u n d that p e r f u s i o n of isolated rat lungs with free radica l generating systems caused vascular leakage and edema [190]. T h e i n c l u s i o n of red cells i n this m o d e l prevented such o x i d a n t - i n d u c e d damage. V a n A s b e c k et a l . [191] reported that p r i o r i n s u f f l a t i o n of red cel ls into rat lungs protected the animals against early death due to o x y g e n tox ic i ty . F u r t h e r m o r e , it was found that catalase [91,92] and/or glutathione [92] present i n intact red cells can decrease m y o c a r d i a l h y d r o g e n peroxide levels and r e p e r f u s i o n injury [92], and prevent death of somatic cel ls resul t ing f r o m i n vitro oxidat ive challenge [91]. T h e r e f o r e , it seems that red c e l l antioxidant capaci ty is associated with tissue oxidat ive status, and intact red cells can protect tissues f r o m oxidat ive stress. T h i s is more important for tissues such as h u m a n heart, w h i c h unl ike red cells is vulnerable to oxidat ive injury due to their p o o r oxidat ive status relative to red cells - i n c l u d i n g very low concentrat ions of catalase [9,92] . 6 .2.2 Par t ia l ly I m p r o v e d C a r d i o p u l m o n a r y F u n c t i o n R O I s are generated d u r i n g C P B and have been i m p l i c a t e d as a cause of m y o c a r d i a l injury [8 ,193,194] . A s noted ear l ier , R O I s may damage any b i o m o l e c u l e i n c l u d i n g l i p i d s , proteins , carbohydrates , and n u c l e i c acids [26] A s m e n t i o n e d , the heart and lungs may be protected by the antioxidant capacity of intact red cells or by a genera l ized antioxidant ac t ion of p r o p o f o l manifest i n oxidat ion-sensi t ive tissues as w e l l as red c e l l s . In our study, p r o p o f o l i m p r o v e d c a r d i o p u l m o n a r y f u n c t i o n . T h i s may be due to its free 70 radica l scavenging activity against l o c a l l y or sys temica l ly p r o d u c e d R O I s . T h e enhanced tissue antioxidat ive status w o u l d be expected to preserve c e l l membrane integri ty , with resultant i m p r o v e d c a r d i o p u l m o n a r y f u n c t i o n . S i m i l a r results have been achieved i n animal models of IRI [14 ,15 ,149] . It should be noted, h o w e v e r , that the i m p r o v e m e n t i n c a r d i o p u l m o n a r y f u n c t i o n w i t h i n 24 hours post -operat ively d i d not p a r a l l e l the i n h i b i t i o n of in vi tro red c e l l l i p i d p e r o x i d a t i o n in this study, where s ignif icant c a r d i o p u l m o n a r y protec t ion was also seen i n the low dose p r o p o f o l group i n the absence of red c e l l pro tec t ion . Other investigators have reported that even complete e l i m i n a t i o n of l i p i d p e r o x i d a t i o n i n d u c e d by exogenous h y d r o g e n peroxide only m i l d l y attenuated the cardiac d y s f u n c t i o n i n the isolated rat [15] or rabbit [149] heart. T h e r e f o r e , factors other than l i p i d p e r o x i d a t i o n may play a more important role [195-197]. O x i d a t i o n of p r o t e i n or nonprote in s u l f h y d r y l groups [195] and nucle ic acids [196] have been c o n s i d e r e d as potential causes of d i m i n i s h e d m y o c a r d i a l contract i le p e r f o r m a n c e . In this m u l t i f a c t o r i a l pathogenesis of IRI d u r i n g C A B surgery , factors such as p r o d u c t i o n of P A F or other mediators may also play an important role [72 ,73 ,75] . 6.3 P r o p o f o l C o n c e n t r a t i o n and Its Protect ive E f f e c t s P r o p o f o l i n plasma is b o u n d extensively to plasma a l b u m i n , wi th a free f rac t ion of only 2-3% [138]. It is this smal l free f r a c t i o n , h o w e v e r , that may determine the protect ive effect of p r o p o f o l on red cells and tissues. T h e 71 amount of p r o p o f o l i n b l o o d cel ls and i n plasma accounts for the total b l o o d concentrat ion of p r o p o f o l . T h e r e is a lag in p r o p o f o l d i s t r i b u t i o n into red cells and tissues, w h i c h explains why the plasma concentra t ion is more than the whole b l o o d concentra t ion d u r i n g continuous i n f u s i o n . F a n et a l . reported that plasma concentrations were 30% higher than whole b l o o d concentrat ions d u r i n g p r o p o f o l i n f u s i o n i f the b l o o d was centr i fuged i m m e d i a t e l y to determine the plasma concentrat ions ; even f o l l o w i n g storage for 1 hour before c e n t r i f u g a t i o n , the plasma concentrat ion was s t i l l 10% higher than that in whole b l o o d [188]. In our study, we were not able to establish a c o r r e l a t i o n between plasma p r o p o f o l concentra t ion and red c e l l antioxidant status i n the low dose p r o p o f o l g r o u p . It may be that the amount of p r o p o f o l dis tr ibuted into red cel ls f r o m the plasma was too s m a l l to cause a s igni f i cant change i n suscept ibi l i ty to oxidat ive chal lenge . O n the other h a n d , i n the h i g h dose p r o p o f o l g r o u p , a s ignif icant c o r r e l a t i o n was es tabl ished, p a r a l l e l i n g the result we obtained i n the swine m o d e l [18]. U n d e r the latter c o n d i t i o n , the amount of p r o p o f o l i n red cells was suff i c ient to reduce p e r o x i d e - i n d u c e d red c e l l M D A p r o d u c t i o n . W i t h the ini t ia t ion of C P B , hematocri t was decreased by 39%. Interest ingly, the plasma concentrat ion of p r o p o f o l was decreased by only 18% in the low dose p r o p o f o l group and was increased by 29% i n the h i g h dose p r o p o f o l group after 30 m i n of C P B . It has been reported that plasma p r o p o f o l concentrat ion decreases more than predic ted on the basis of acute h a e m o d i l u t i o n alone [140]. T h i s suggests the b i n d i n g of p r o p o f o l to the 72 extracorporeal c i r c u i t . A t this point , it is d i f f i c u l t to e x p l a i n this d i s c r e p a n c y . U n l i k e the plasma concentrat ion of p r o p o f o l , the free f rac t ion of p r o p o f o l i n plasma behaves d i f f e r e n t l y d u r i n g C P B . T h e free f r a c t i o n of p r o p o f o l does not decrease d u r i n g C P B . Indeed, a 1.5 to 3 f o l d increase in this free f r a c t i o n was reported [141,142] . T h i s may be because h e p a r i n activates l i p o p r o t e i n lipase to h y d r o l y z e plasma t r i g l y c e r i d e s into n o n - esterif ied fatty acids [143,198] . These compounds c o m p e t i t i v e l y inhibi t the b i n d i n g of var ious drugs i n c l u d i n g p r o p o f o l to plasma proteins [144]. U n f o r t u n a t e l y , we d i d not measure the free f r a c t i o n of p r o p o f o l i n p l a s m a . W e observed the sustained suppress ion of red c e l l M D A p r o d u c t i o n in the h i g h dose p r o p o f o l group even at 2 hours post C P B when the p l a s m a p r o p o f o l concentrat ion was very l o w . T h i s may p o s s i b l y be because of an unchanged (or increased) free f r a c t i o n of p r o p o f o l in plasma p e r i o p e r a t i v e l y , and a cumulat ive effect of p r o p o f o l with continuous i n f u s i o n . 6.4 M D A P r o d u c t i o n , R e d C e l l A n t i o x i d a n t Status, and T B A A s s a y M a l o n d i a l d e h y d e is f o r m e d d u r i n g l i p i d p e r o x i d a t i o n . It has been w i d e l y used as a marker for l i p i d p e r o x i d a t i o n [ 1 , 1 5 , 3 6 , 3 9 , 4 1 , 4 3 , 4 5 , 5 5 ] . T h e r e are basica l ly two assays avai lable for the measurement of M D A i n p l a s m a , c e l l s , and tissues: the T B A assay and H P L C . T h e T B A assay is based on the reactivity of the color less m a l o n d i a l d e h y d e ( M D A ) with t h i o b a r b i t u r i c acid ( T B A ) to produce a red adduct , w h i c h is measurable by spect rophotometry . In 73 contrast to H P L C , the T B A assay is a convenient , easy to p e r f o r m , r a p i d , and cost -effect ive test. It is , h o w e v e r , not very sensit ive and not very spec i f i c [76,199-202] . N o r m a l levels of M D A i n plasma or cel ls or tissues are too low to be detected by this test. Besides M D A , there is the generat ion of n o n - l i p i d - related, m a l o n d i a l d e h y d e - l i k e , T B A - r e a c t i v e substances that lead to overes t imat ion of the M D A p r o d u c t i o n [203]. T h e nature of this substance is not c lear , but s ia l ic a c i d , g lycoconjugates , sugars and , i n genera l , aldehydes have been demonstrated to be able to cross-react wi th T B A [202,204 ,205] . F o r example , auto-oxidat ion of l i n o l e i c ac id generates at least nine b r e a k d o w n products that give posi t ive responses to the T B A reac t ion [206]. F l u o r o m e t r i c detect ion has been used to i m p r o v e the s p e c i f i c i t y o f the T B A assay [207]. W i t h respect to the red c e l l T B A assay, G i l b e r t et a l . r e c o m m e n d e d a method to correct for errors caused by generat ion of interfer ing compounds d u r i n g red c e l l l i p i d p e r o x i d a t i o n [208]. T h e interfer ing compounds are not considered as the products of l i p i d p e r o x i d a t i o n but are d e r i v e d f r o m erythrocyte hemolysate and reduced glutathione. Interference results f r o m c a r r y o v e r absorbance at 532 n m , equivalent to 20% of the intensity of the m a x i m u m absorpt ion peak at 453 n m . T h e i m p r o v e d accuracy of the method was cor r obor a te d with a s p e c i f i c H P L C . T h i s method f o r m e d the basis for our T B A assay. 6.5 Influence of N o r m o t h e r m i a or H y p o t h e r m i a for C P B o n R e d C e l l A n t i o x i d a n t Status and C a r d i o p u l m o n a r y F u n c t i o n 74 H y p o t h e r m i a is c o m m o n l y used for C P B with re la t ive ly long periods of p e r f u s i o n , while n o r m o t h e r m i c C P B is e m p l o y e d for re la t ive ly short operative procedures and otherwise u n c o m p l i c a t e d cases. In this s tudy, we had one n o r m o t h e r m i c C P B patient i n each g r o u p . Induced h y p o t h e r m i a for C P B itself is b e n e f i c i a l for the patient [209]. It apparently does not have any adverse p h y s i o l o g i c a l consequences [210]. It does greatly depress body metabol ism [210], w h i c h might reduce the p r o d u c t i o n of R O I s because of decreased o x y g e n c o n s u m p t i o n , espec ia l ly for the i s c h e m i c and reperfused heart and lungs , i n w h i c h antioxidant systems may be i m p a i r e d d u r i n g IRI [78-80]. R e d cells are somewhat d i f f e r e n t . T h e y do not experience IRI d u r i n g C P B as do the heart and l u n g s , and their antioxidant defense is re la t ively intact. T h e i r antioxidant status might be enhanced to some degree, because of reduced body m e t a b o l i s m with p o s s i b l y reduced total p r o d u c t i o n of R O I s . H o w e v e r , i n this study we d i d not notice any s i g n i f i c a n t dif ferences between h y p o t h e r m i c and n o r m o t h e r m i c C P B i n terms of red c e l l antioxidant status, plasma concentra t ion of p r o p o f o l , or c a r d i o p u l m o n a r y f u n c t i o n . T h i s may be because the effect of h y p o t h e r m i a on R O I p r o d u c t i o n might be n e g l i g i b l e i n c o m p a r i s o n to that of i s c h e m i a - r e p e r f u s i o n and the bypass machine . In fact , even with deep h y p o t h e r m i a ( 1 5 ° to 2 0 ° C ) , tissue l i p i d p e r o x i d a t i o n is s t i l l prevalent [211]. U n f o r t u n a t e l y , no study has been done to compare h y p o t h e r m i c and n o r m o t h e r m i c C P B i n terms of oxidat ive or 75 antioxidative status, and our small sample size makes it too early to make any conclus ions on this important matter. 76 Chapter 7 C O N C L U S I O N A N D R E C O M M E N D A T I O N S FOR F U R T H E R WORK T h e antioxidant effect of p r o p o f o l on red cells is dose-dependent . H i g h dose p r o p o f o l s i g n i f i c a n t l y enhanced red c e l l antioxidant capac i ty . P lasma concentrations of p r o p o f o l i n the range of 7 to 9 p g / m l suppressed red c e l l M D A p r o d u c t i o n by more than 50%. T h i s effect was associated w i t h i m p r o v e d cardiac f u n c t i o n c o m p a r e d to i s o f l u r a n e , as manifested by s i g n i f i c a n t l y less inotropic requirement (dopamine 3.5 p g / k g / m i n ) , and stable p u l m o n a r y c a p i l l a r y wedge pressure (In the isof lurane g r o u p , it was s i g n i f i c a n t l y increased at about 24 hours c o m p a r e d to 1 or 2 hours after surgery without an increase i n cardiac index . ) and/or s i g n i f i c a n t l y higher percentage of patients with n o r m a l cardiac index p o s t - s u r g i c a l l y . H o w e v e r , the s u p p r e s s i o n of l i p i d p e r o x i d a t i o n d i d not p a r a l l e l the improvement in c a r d i o p u l m o n a r y f u n c t i o n . Because of its h i g h l i p i d s o l u b i l i t y , p r o p o f o l distr ibutes to membranous structures such as plasma and m i t o c h o n d r i a l membranes , r e d u c i n g the damaging effects by R O I s on them. H o w e v e r , it p r o b a b l y c o u l d not prevent the o x i d a t i o n of structures such as prote in or n o n p r o t e i n s u l f h y d r y l groups and nucle ic ac ids , w h i c h have been cons idered important i n m y o c a r d i a l contrac t i l i ty . M e a n w h i l e , h i g h dose p r o p o f o l , l ike other anesthetics , also has negative inot ropic effects on the heart. C o m p a r e d to low dose p r o p o f o l , it was associated wi th a low (not statist ically s ignif icant i n our study p r o b a b l y because of smal l sample size) cardiac index d u r i n g early (1 to 3 hours post- 77 operative) p e r i o d of time after the opera t ion , and not s i g n i f i c a n t r e c o v e r y i n lung oxygenat ion w i t h i n 12 hours p o s t - o p e r a t i v e l y . H o w e v e r , the l o n g - t e r m effect of h i g h dose p r o p o f o l on c a r d i o p u l m o n a r y f u n c t i o n c o u l d not be determined by the study. A n expanded c l i n i c a l t r ial to determine the effects of p r o p o f o l on c a r d i o p u l m o n a r y m o b i l i t y and mortal i ty f o l l o w i n g C A B surgery is r e q u i r e d . Intermediate doses of p r o p o f o l may be tr ied to o p t i m i z e the balance of increasing c a r d i o p u l m o n a r y f u n c t i o n with the s u p p r e s s i o n of l i p i d p e r o x i d a t i o n and a v o i d i n g the potential detr imental effects of h i g h dose p r o p o f o l on the heart and lungs i n the immediate post -operat ive p e r i o d . 78 R E F E R E N C E S 1. Movahed A, Nair K G , Ashavaid T F , Kumar P. Free radical generation and the role of allopurinol as a cardioprotective agent during coronary artery bypass grafting surgery. Can J Cardiol 1996;12:138-144. 2. Curello S, Ceconi C, de Giuli F, et al. Oxidative stress during reperfusion of human hearts: potential sources of oxygen free radicals. Cardiovasc Res 1995;29:118-125. 3. Tortolani AJ , Powell SR, Misik V , Weglicki WB, Pogo GJ, Kramer JH. Detection of alkoxyl and carbon-centered free radicals in coronary sinus blood from patients undergoing elective cardioplegia. Free Rad Biol Med 1993;14:421-426. 4. Davies SW, Underwood SM, Wickens D G , Feneck RO, Dormandy T L , Walesby RK. Systemic pattern of free radical generation during coronary bypass surgery. Br Heart J 1990;64:236-240. 5. Lucchesi BR. Myocardial ischemia, reperfusion and free radical injury. Am J Cardiol 1990;65:141-231. 6. Sakebe T, Nakakimura K. Advances in brain protection. Masui 1994;43 Supple:S110-119. 7. Engler RL , Schmid Schonbein GW, Pavelec RS. Leucocyte capillary plugging in myocardial ischemia and reperfusion in the dog. Am J Pathol 1983;111:98-111. 8. Ferrari R, Ceconi C, Curello S, Alfieri O, Visioli O. Myocardial damage during ischaemia and reperfusion. Eur Heart J 1993; 14(Supplement G):25-30. 9. Godin D V , Ko K M . Allopurinol and ischemia/reperfusion injury: new use for an old drug? Can J Cardiol 1991;7:163-169. 10 Qayumi A K , Jamieson WRE, Godin D V , et al. Response to allopurinol pretreatment in a swine model of heart-lung transplantation. J Invest Surg 1990;3:331-340. 11. Paajanen H , Harmoinen A, Sisto T, et al. Effect of antioxidants on postoperative hyperamylasemia in coronary bypass surgery. Pancreas 1996;13:236-240. 79 12. C a s t e l l i P , C o n d e m i A M , B r a m b i l l a s c a C , et a l . Improvement of cardiac f u n c t i o n by a l l o p u r i n o l i n patients u n d e r g o i n g cardiac s u r g e r y . J C a r d i o v a s c P h a r m a c o l 1995 ;25 :119-125 . 13. J o h n s o n W D , K a y s e r K L , B r e n o w i t z J B , Saedi S F . A r a n d o m i z e d c o n t r o l l e d tr ial o f a l l o p u r i n o l i n coronary bypass surgery . A m Hear t J 1991;121:20-24 . 14. K O S H , Y u C W , L e e S K , et a l . P r o p o f o l attenuates i s c h e m i a - r e p e r f u s i o n injury in the isolated rat heart. A n e s t h A n a l g 1997;85 :719-24. 15. K o k i t a N , H a r a A . P r o p o f o l attenuates h y d r o g e n p e r o x i d e - i n d u c e d m e c h a n i c a l and metabolic derangements i n the isolated rat heart. A n e s t h e s i o l o g y 1996 ;84 :117-127 . 16. E r i k s s o n O , P o l l e s e l l o P , Saris N E L . I n h i b i t i o n of l i p i d p e r o x i d a t i o n in isolated rat l i v e r m i t o c h o n d r i a by the general anaesthetic p r o p o f o l . B i o c h e m P h a r m a c o l 1992 ;44 :391-393 . 17. M u s a c c h i o E , R i z z o l i V , B i a n c h i M , B i n d o l i A , G a l z i g n a L . A n t i o x i d a n t action of p r o p o f o l on l iver m i c r o s o m e s , m i t o c h o n d r i a and b r a i n synaptosomes i n the rat. P h a r m a c o l T o x i c o l 1991;69 :75-77 . 18. A n s l e y D M , L e e J , G o d i n D V , Garnett M E , Q a y u m i A K . P r o p o f o l enhances red c e l l antioxidant capacity in swine and humans . C a n J A n a e s t h 1998;45 :233-239. 19. Feher J , C s o m o s G , V e r e c k e i A , eds. Free r a d i c a l reactions in m e d i c i n e . B e r l i n : S p r i n g - V e r l a g B e r l i n H e i d e l b e r g , 1987; 1-10. 20. G r i s h a m M B , M c C o r d J . C h e m i s t r y and cytotoxic i ty o f reactive o x y g e n metaboli tes . In : T a y l o r A E , M a t a l o n S, W a r d P A , eds. P h y s i o l o g y o f o x y g e n radica ls . A m e r i c a n p h y s i o l o g i c a l society , B a l t i m o r e : W a v e r l y Press , I n c , 1 9 8 6 ; l - 1 8 . 21. R i c e - E v a n s C . T h e effects of o x y g e n - d e r i v e d free radicals on l i p i d s , protein and their interact ions : p a t h o l o g i c a l i m p l i c a t i o n s . In : W i r t z K W A , Packer L , G u s t a f s s o n J A , E v a n g e l o p o u l o s A E , C h a n g e u s J P , eds. N e w developments i n l i p i d - p r o t e i n interactions and receptor f u n c t i o n . N e w Y o r k : P l e n u m Press , 1993;287-296. 22. F i s h e r A B . Intracel lular p r o d u c t i o n of o x y g e n - d e r i v e d free r a d i c a l s , oxygen radicals and tissue i n j u r y . Bethesda , U p j o h n ; 1988 ;34-39 . 80 23. Hess M L , M a n s o n N H . M o l e c u l a r o x y g e n : f r i e n d or foe : the role of the oxygen free r a d i c a l system i n the c a l c i u m paradox , the o x y g e n paradox and i s c h e m i a / r e p e r f u s i o n i n j u r y . J M o l C e l l C a r d i o l 1984 ;16 :969-985 . 24. B a b i o r B . T h e respiratory burst o f phagocytes . N E n g l J M e d 1978;298:659-668. 25. F e h e r J , C s o m o s G , V e r e c k e i A , eds. F r e e r a d i c a l reactions i n m e d i c i n e . B e r l i n : S p r i n g - V e r l a g B e r l i n H e i d e l b e r g , 1987; 18-39. 26. F e h e r J , C s o m o s G , V e r e c k e i A , eds. Free r a d i c a l reactions i n m e d i c i n e . B e r l i n : S p r i n g - V e r l a g B e r l i n H e i d e l b e r g , 1987;40-43. 27. A u t o r A P . Pathology of o x y g e n . N e w Y o r k : A c a d e m i c Press , 1982. 28. F r e i B . N a t u r a l antioxidants . San D i e g o , C a l i f o r n i a : A c a d e m i c Press , Inc, 1994. 29. M u l l a n e K M . M y o c a r d i a l i s c h e m i c - r e p e r f u s i o n i n j u r y : role of neutrophils and neutrophi l d e r i v e d mediators . In : M a r o n e G . H u m a n i n f l a m m a t o r y d i s e a s e x l i n i c a l i m m u n o l o g y , V o l 1. B u r l i n g t o n , O n t a r i o , C a n a d a , 1988;143-198. 30. M a n f r e d i J P , H o m e s E W . P u r i n e salvage pathways i n m y o c a r d i u m . A n n Rev P h y s i o l 1985 ;47 :691-705 . 31. Crastes de Paulet A , D o u s t e - B l a z y L , Paolet t i R . Free r a d i c a l s , l i p o p r o t e i n s , and membrane l i p i d s . N e w Y o r k : P l e n u m Press , 1 9 9 0 ; V . 32. M a z i e r e J C , S a l m o n S, Santus R , et a l . L i p i d p e r o x i d a t i o n and ce l lu lar funct ions : i n vi tro models and re la t ion to i n v i v o observat ions . In : Crastes de Paulet A , D o u s t e - B l a z y L , Paolet t i R . Free r a d i c a l s , l i p o p r o t e i n s , and membrane l i p i d s . N e w Y o r k : P l e n u m Press , 1990;327-342. 33. Benedett i A , C o m p o r t i M , Esterbauer H . I d e n t i f i c a t i o n of 4- h y d r o x y n o n e n a l as a cytotoxic product o r i g i n a t i n g f r o m the p e r o x i d a t i o n of l iver m i c r o s o m a l l i p i d s . B i o c h e m B i o p h y s A c t a 1980 ;620 :281-296 . 34. Panagamala R V , C o r n w e l l D G . T h e effects o f v i t a m i n E on a r a c h i d o n i c acid m e t a b o l i s m . N e w Y o r k : A n n N Y A c a d S c i 393 :376-390 . 35. Siems W G , Scherat T , B e h r e n d H , et a l . Influence of a l l i u m sat ivum linne on oxidat ive stress status- a c l i n i c a l inves t iga t ion . In : P a c k e r L , T r a b e r M G , X i n W , eds. Proceedings of the internat ional s y m p o s i u m on natural 81 antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996; 188-195. 36. D i n g c h a o H , Z h i d u a n Q , L i y e H , X i a o d o n g F . T h e protect ive effects of high-dose ascorbic acid on m y o c a r d i u m against r e p e r f u s i o n in jury d u r i n g and after c a r d i o p u l m o n a r y bypass . T h o r a c C a r d i o v a s c S u r g 1994 ;42 :276-278 . 37. Z h a n g J L , Shi Z X , S h i Y T . C l i n i c a l study of n a o x i n sutong i n the treatment of acute cerebral i n f a r c t i o n . C h u n g - K u o C h u n g H s i I C h i e h H o T s a C h i h 1994 ;14 :478-481 . 38. C l a u s e n J . A n i n vi tro system for e v a l u a t i o n of ox idat ive stress and effects of antioxidants . In: Packer L , T r a b e r M G , X i n W , eds. P r o c e e d i n g s of the internat ional s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996; 145-154. 39. G o d i n D V , K o K M , Q a y u m i A K , J a m i e s o n W R E . A method for m o n i t o r i n g the effect iveness of a l l o p u r i n o l pretreatment i n the p r e v e n t i o n of i s c h e m i a / r e p e r f u s i o n i n j u r y . J P h a r m a c o l M e t h 1989 ;22 :289-297 . 40. M a k I T , W e g l i c k i W B . Protec t ion by b e t a - b l o c k i n g agents against free r a d i c a l - m e d i a t e d s a r c o l e m m a l l i p i d p e r o x i d a t i o n . C i r Res 1988 ;63 :262-266 . 41. H i c k e y M J , K n i g h t K R , H u r l e y J V , L e p o r e D A . P h o s p h o e n o l p y r u v a t e / a d e n o s i n e tr iphosphate enhances p o s t - i s c h e m i c s u r v i v a l of skeletal m u s c l e . J Recons M i c r o s u r g 1995;11 :415-422. 42. X i n H B , Z h a n g B H , Shen H J . Protect ive effects o f cyproheptadine on m y o c a r d i a l r e p e r f u s i o n injury i n isolated rat hearts. A c t a P h a r m a c o l S i n i c a 1994 ;15 :253-257 . 43. K o l l e r P T , B e r g m a n n S R . R e d u c t i o n of l i p i d p e r o x i d a t i o n i n reperfused isolated rabbit hearts by d i l t i a z e m . C i r Res 1989 ;65 :838-846 . 44. G i r o n - C a l l e J , Z w i z i n s k i C W , S c h m i d H H . P e r o x i d a t i v e damage to cardiac m i t o c h o n d r i a . II. I m m u n o l o g i c a l analysis of m o d i f i e d adenine nucleot ide t ranslocase . A r c h B i o c h e m B i o p h y s 1994 ;315 :1-7 . 45. G r e e n T R , Bennett S R , N e l s o n V M . S p e c i f i c i t y and propert ies of p r o p o f o l as an antioxidant free radica l scavenger . T o x i c o l A p p l P h a r m a c o l 1994;129 :163-169. 46. Prasad K , K a l r a J , Bharadwaj B , C h a u d h a r y A K . Increased o x y g e n free radica l act ivi ty i n patients on c a r d i o p u l m o n a r y bypass u n d e r g o i n g aortocoronary bypass surgery . A m H e a r t J 1992 ;123 :37-45 . 82 47. Janssen M , K o s t e r J F , Bos E , de Jong J W . M a l o n d i a l d e h y d e and glutathione p r o d u c t i o n i n isolated perfused h u m a n and rat hearts . C i r Res 1993;73 :681-688. 48. P l u m m e r G F . I m p r o v e d method for the d e t e r m i n a t i o n of p r o p o f o l in b l o o d 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 w i t h f luorescence detect ion. J C h r o m a t o g r 1987;421:171-176. 49. W o n g S H J , K n i g h t J A , H o p f e r S M , Z a h a r i a O , L e a c h C N , S u n d e r m a n F W . L i p o p e r o x i d e s in plasma as measured by l i q u i d - c h r o m a t o g r a p h i c separation of m a l o n d i a l d e h y d e - t h i o b a r b i t u r i c ac id adduct . C l i n C h e m 1987;33 :214-220. 50. C h i p a u l t J R , Pr ivet t O S , M i z u n o G R , N i c k e l l E C , L u n d b e r g W O . E f f e c t of i o n i z i n g radiations on fatty acid esters. Ind E n g C h e m . 1957;49 :1713-20 . 51. R o m a s c h i n A D , R e b e y k a I, W i l s o n G J , M i c k l e D A G . C o n j u g a t e d dienes in i schemic and reperfused m y o c a r d i u m : an i n v i v o c h e m i c a l signature of oxygen free radica l mediated i n j u r y . J M o l l C e l l C a r d i o l 1987 ;19 :289-302 . 52. C a w o o d P , Iversen S A , D o r m a n d y T L . T h e nature of diene conjugat ion i n b i o l o g i c a l f l u i d s . In : Bors W , Sarn M , T a i t D , eds. O x y g e n radicals i n chemistry and b i o l o g y . B e r l i n : W a l t e r de G r u y t e r , 1984;355-358. 53. D a v i e s S W , D u f f y JP , W i c k e n s D G , et a l . T i m e - c o u r s e of free radica l activity d u r i n g coronary artery operations with c a r d i o p u l m o n a r y bypass . J T h o r a c C a r d i o v a s c Surg 1993;105 :979-987. 54. W i c k e n s D G , G r i f f i n JR , M a h e r E R , et a l . T h e effect of systemic hepar inisa t ion and haemodia lys is on plasma o c t a d e c a - 9 , 1 1 - d i e n o i c ac id (9 ,11- L A ' ) . Free R a d Res C o m m u 1987;3 :99-106. 55. Fantone J C , W a r d P A . R o l e of o x y g e n - d e r i v e d free radicals and metabolites i n leukocyte-dependent i n f l a m m a t o r y react ions . A m J Pathol 1982;107:397-418. 56. H a m m o n d B , H e s s M L . T h e o x y g e n - f r e e r a d i c a l sys tem: potential mediator o f m y o c a r d i a l i n j u r y . J A m C o l l C a r d i o l 1985 ;6 :215-220 . 57. G o d i n D V . R o l e of reactive o x y g e n d e r i v e d radicals i n i s c h e m i c heart disease. C a n J C a r d i o l 1989;5 :235-238. 58. S c h m i d - S c h o n b e i n G W . C a p i l l a r y p l u g g i n g by granulocytes and the no- ref low p h e n o m e n o n in the m i c r o c i r c u l a t i o n . F e d P r o c 1987 ;46 :2395-2433 . 83 59. M a r t i n R R . A l t e r a t i o n s in leukocyte structure and f u n c t i o n . In : H w a n g N H C , G r o s s D R , Patel D J , eds. Quanti tat ive c a r d i o v a s c u l a r studies : c l i n i c a l and research applicat ions of engineer ing p r i n c i p l e s . B a l t i m o r e : U n i v e r s i t y Park Press , 1979;419-454. 60. H a m m e r s c h m i d t D E , Stroncek D F , B o w e r s T k , et a l . C o m p l e m e n t ac t ivat ion and neutropenia o c c u r r i n g d u r i n g c a r d i o p u l m o n a r y bypass . J T h o r a c C a r d i o v a s c Surg 1981;81 :370-377. 61. Westaby S. N e u t r o p h i l protease enzymes and o x y g e n free radicals as mediators o f p u l m o n a r y membrane damage. P r o g C l i n B i o l Res 1 9 8 7 ; 2 3 6 A : 7 5 - 8 6 . 62. K i r k l i n J K , Westaby S, Blackstone E H , K i r k l i n J W , C h e n o w e t h D E , P a c i f i c o A D . C o m p l e m e n t and d a m a g i n g effects o f c a r d i o p u l m o n a r y bypass . J T h o r a c C a r d i o v a s c Surg 1983 ;86 :845-857 . 63. H o l l o w a y D S , S u m m a r i a L , Sandesara J , A l e x a n d e r J C . D e c r e a s e d platelet number and f u n c t i o n and increased f i b r i n o l y s i s contribute to postoperat ive b l e e d i n g i n c a r d i o p u l m o n a r y bypass patients . T h r o m Haemostat 1988 ;59 :62-67 . 64. A n t o n s e n S, B r a n d s l u n d I, C l e m a n s e n S, S o f e l D t , M a d s e T , A l s t r u P . N e u t r o p h i l l y s o s o m a l enzyme release and c o m p l e m e n t ac t ivat ion d u r i n g c a r d i o p u l m o n a r y bypass . Scand J T h o r a c C a r d i o v a s c S u r g 1987;21 :47-52 . 65. R i e g e l W , S p i l l n e r G , Schlosser V , H o r l W H . P l a s m a levels of m a i n granulocyte components d u r i n g c a r d i o p u l m o n a r y b y p a s s . J T h o r a c C a r d i o v a s c Surg 1988 ;95 :1014-9 . 66. But ler J , P i l l a i R , R o c k e r G M , Westaby S, P a r k e r D , Shale D J . E f f e c t of c a r d i o p u l m o n a r y bypass on systemic release of n e u t r o p h i l elastase and tumor necrosis factor . J T h o r a c C a r d i o v a s c S u r g 1993 ;105 :25-30 . 67. C o l l e t t B , A l h a q A , A b d u l l a h N B , et a l . Pathways to complement ac t ivat ion d u r i n g c a r d i o p u l m o n a r y bypass . B r M e d J 1984 ;289 :1251 . 68. K i r k l i n J K , Westaby S, Blackstone E H , K i r k l i n J W , C h e n o u s e t h D E , P a c i f i c o A D . C o m p l e m e n t and the damaging effects of c a r d i o p u l m o n a r y bypass . J T h o r a c C a r d i o v a s c Surg 1983;86 :845-857. 69. C a v a r o c c h i N C , P l u t h JR , S c h a f f H V , et a l . C o m p l e m e n t ac t ivat ion d u r i n g c a r d i o p u l m o n a r y bypass : c o m p a r i s o n of bubble and membranous oxygenators . J T h o r a c C a r d i o v a s c S u r g 1986;91 :252 . 84 70. Fosse E , M o l l n e r s T E , Ingraldsen B . C o m p l e m e n t ac t ivat ion d u r i n g major operations with or without c a r d i o p u l m o n a r y b y p a s s . J T h o r a c C a r d i o v a s c S u r g 1987;93 :860. 71. Jones H M , Matthews N , V a u g h a n R S , Stark J M . C a r d i o p u l m o n a r y bypass and complement ac t ivat ion . Anaesthes ia 1982 ;37 :629 . 72. Q a y u m i A K , Jamieson W R E . P a t h o p h y s i o l o g y o f r e p e r f u s i o n in jury i n organ transplantat ion. In: Das D K , e d . P a t h o p h y s i o l o g y of r e p e r f u s i o n i n j u r y . B o c a R a t o n , F l o r i d a : C R C Press Inc, 1993;325-362. 73. H a n d l e y D A , Sanders R N , H o u l i h a n W J , T o m e s c h J C , eds. Platelet- act ivating factor , in endotoxin and immune diseases . M a r c e l D e k k e r , N e w Y o r k , 1990; chapters 1 , 2 , 3 , a n d 27. 74. L i m H W . T h e complement system: ac t iva t ion , m o d u l a t i o n , and c l i n i c a l re levance . D e r m a t o l C l i n 1990 ;8 :609 . 75. D w o r k i n G H , A n w a r S, A b d - e l f a t t a h , Y e h T , W e c h s l e r A S . E f f i c a c y of r e c o m b i n a n t - d e r i v e d h u m a n superoxide dismutase on p o r c i n e left vent r i cular contract i l i ty after n o r m o t h e r m i c g l o b a l m y o c a r d i a l i s c h e m i a and h y p o t h e r m i c c a r d i o p l e g i c arrest. C i r c u l a t i o n 1990(suppl I V ) ; 3 5 9 . 76. F r e e m a n B A , C r a p o J D . B i o l o g y of disease, free radicals and tissue i n j u r y . L a b Invest 1982;47 :412-426. 77. M c C o r d J M . Free radicals and m y o c a r d i a l i s c h e m i a : o v e r v i e w and out look. F r e e R a d B i o l M e d 1988;4 :9-14 . 78. F e r r a r i R , C e c o n i C , C u r e l l o S, et a l . Int racel lular effects of m y o c a r d i a l i s c h e m i a and r e p e r f u s i o n : role of c a l c i u m and o x y g e n . E u r H e a r t J 1986;7 :3-12 . 79. B o l l i R , Z h u W X , T h o r n b y J l , O ' N e i l l P G , Roberts R . T i m e - c o u r s e and determinants o f recovery of f u n c t i o n after revers ible i s c h e m i a i n conscious dogs. A m J P h y s i o l 1988 ;254 :H102-114 . 80. F e r r a r i R , C e c o n i C , C u r e l l o S, C a r g n o n i A , A l f i e r i O , P a r d i n i A . O x y g e n free radicals and m y o c a r d i a l damage: protect ive role o f t h i o l - containing agents. A m J M e d 1991 ; 9 1 ( S u p p l 3 C ) : 9 5 3 - 1 0 5 5 . 81. K o r t h u i s R J , G r a n g e r D N . React ive o x y g e n metabol i tes , n e u t r o p h i l s , and the pathogenesis of i s c h e m i a - t i s s u e / r e p e r f u s i o n . C l i n C a r d i o l 1993 ;16(Suppl I) :I19-I26. 85 82. R o m s o n J T , J o l l y S R , L u c c h e s i B R . P r o t e c t i o n of i s c h e m i c m y o c a r d i u m by p h a r m a c o l o g i c m a n i p u l a t i o n of leukocyte f u n c t i o n . C a r d i o v a s c Res Rep 1984;5 :690-709 . 83. H a l l i w e l l B . H o w to characterize a b i o l o g i c a l ant ioxidant . F r e e R a d Res C o m m 1990;9 :1-32 . 84. F r e i B , Stocker R , A m e s B . A n t i o x i d a n t defences and l i p i d p e r o x i d a t i o n in h u m a n b l o o d p l a s m a . Proc N a t l A c a d S c i 1989 ;85 :9748-9752 . 85. Ja in U , B o d y S C , B e l l o w s W , et a l . M u l t i c e n t e r study of target c o n t r o l l e d i n f u s i o n of p r o p o f o l - s u f e n t a n i l or s u f e n t a n i l - m i d a z o l a m for coronary artery bypass graft surgery . M u l t i c e n t e r study of per iopera t ive i schemia ( M c S P I ) research g r o u p . A n e s t h e s i o l o g y 1996 ;85 :522-535 . 86. F e r r a r i R , V i s i o l i O , C a l d a r e r a C M , N a y l e r W G . V i t a m i n E and the heart: poss ible role as antioxidants . A c t a V i t a m i n et E n z y m o l 1982 ;5 :11-22 . 87. F e r r a r i R , C a r g n o n i A , C e c o n i C , C u r e l l o S, A l g e r t i n i A , V i s i o l i O . R o l e of o x y g e n i n m y o c a r d i a l i schemia and r e p e r f u s i o n damage : protect ive effects of v i t a m i n E . In : H a y a i s h i O , M i n o M eds. C l i n i c a l and nutr i t ional aspects of v i t a m i n E . A m s t e r d a m : E l s e r v i e r , 1987;209-226. 88. O l s o n J A . P r o v i t a m i n A f u n c t i o n of carotenoids : the c o n v e r s i o n of P- carotene into v i t a m i n A . J N u t r 1989;119:105-108. 89. K e n n e d y T A , L e i b l e r D C . P e r o x y l r a d i c a l o x i d a t i o n of beta-carotene: f o r m a t i o n of p-carotene epoxides . C h e m Res T o x i c o l 1991 ;4 :290-295 . 90. M c C o r d J M , F r i d o v i c h I. Superoxide dismutase : an e n z y m a t i c f u n c t i o n for e r y t h r o c u p r e i n . J B i o l C h e m 1969;24 :6049-55 . 91. A g a r N S , Sadrzadeh S M H , H a l l a w a y P E , E a t o n J W . E r y t h r o c y t e catalase: a somatic oxidant defense? J C l i n Invest 1986 ;77 :319-321 . 92. B r o w n J M , G r o s s o M A , T e r a d a L S , et a l . E r y t h r o c y t e s decrease m y o c a r d i a l h y d r o g e n peroxide levels and r e p e r f u s i o n i n j u r y . A m J P h y s i o l 1 9 8 9 ; 2 5 6 : H 5 8 4 - H 5 8 8 . 93. Patterson B H , B l o c k G , Rosenberger W F , Pee D , K a h l e U . F r u i t and vegetable i n the A m e r i c a n diet : data f r o m the N H A N E S II s u r v e y . A m J P u b l i c H e a l t h 1990 ;80 :1443-9 . 94. B u r t o n G W , Joyce A , Ingold K U . Is v i t a m i n E the only l i p i d - s o l u b l e , c h a i n - b r e a k i n g antioxidant in h u m a n b l o o d plasma and erythrocyte membranes . A r c h B i o c h e m B i o p h y s 1983;221:281-290. 86 95. C o g h l a n J G , F l i t ter W D , C l u t t o n S M , et a l . L i p i d p e r o x i d a t i o n and changes i n v i t a m i n E levels d u r i n g coronary artery bypass g r a f t i n g . J T h o r a c C a r d i o v a s c S u r g 1993 ;40 :245-260 . 96. W e s t h u y z e n J W , C o c h r a n e A D , Tesar P J , et a l . E f f e c t of preoperat ive supplementat ion with a - t o c o p h e r o l and ascorbic a c i d on m y o c a r d i a l injury in patients u n d e r g o i n g cardiac o p e r a t i o n . J T h o r a c C a r d i o v a s c S u r g 1997; 113: 942-948. 97. S i m k o L C , W a l k e r J H . Preoperat ive antioxidant and a l l o p u r i n o l therapy for r e d u c i n g r e p e r f u s i o n - i n d u c e d injury i n patients u n d e r g o i n g c a r d i o t h o r a c i c surgery . C r i t C N u r s e 1996 ;16 :69-73 . 98. K e n n e d y K A . D i e t a r y antioxidants i n the p r e v e n t i o n of o x y g e n - i n d u c e d i n j u r y . S e m i n P e r i n a t o l 1989 ;13 :97-103 . 99. M e n a s c h e P , P i w n i c a A . Free radials and m y o c a r d i a l p r o t e c t i o n : a surgica l v i e w p o i n t . A n n T h o r a c S u r g 1989 ;47 :939-945 . 100. A z e n S P , Q i a n D , M a c k W J , et a l . E f f e c t o f supplementary antioxidant v i t a m i n intake on carot id arterial w a l l i n t i m a - m e d i a thickness i n a c o n t r o l l e d c l i n i c a l t r ial of choles terol l o w e r i n g . C i r c u l a t i o n 1996 ;94 :2369-72 . 101. H o d i s H N , M a c k W J , L a B r e e L , et a l . S e r i a l c o r o n a r y angiographic evidence that antioxidant v i t a m i n intake reduces p r o g r e s s i o n of coronary artery a therosc lerosis . J A M A 1995;273:1849-54 . 102. D r i e u K . P r e p a r a t i o n et d e f i n i t i o n de l 'extrai t de g i n k g o b i l o b a . Presse M e d 1986 ;15 :1455-57 . 103. W i l l e t K , D e t r y D , E v e n s A , D r o y - L e f a i x M T , Sluse F E . M i t o c h o n d r i a l o x i d a t i v e - p h o s p h o r y l a t i o n i n vi tro and i n si tu: effects o f E G b 761. In: Packer L , T r a b e r M G , X i n W , eds. Proceedings of the internat ional s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;417-423. 104. Das D K , E n g e l m a n R M , C l e m e n t R , et a l . R o l e of xanthine oxidase inhibi tor as free r a d i c a l scavenger : a n o v e l m e c h a n i s m of ac t ion of a l l o p u r i n o l and o x y p u r i n o l i n m y o c a r d i a l salvage. B i o c h e m B i o p h y s Res C o m m u n 1987;148 :314-319. 105. G r i s h a m M B , H e r n a n d e z L A , G r a n g e r D N . X a n t h i n e oxidase and neutrophi l i n f i l t r a t i o n i n intestinal i s c h e m i a . A m J P h y s i o l 1986;251 : G 5 6 7 - G 5 7 4 . 87 106. M i k u l i t k o v a D , B o s m a n s k y , Bosak V , O n d r a s i k M . T h e effect of a l l o p u r i n o l on l y s o s o m a l enzyme release. Z e i t F u r R h e u m a t o l 1989 ;48 :26-29 . 107. Peterson D A , K e l l y B , G e r r a r d J M . A l l o p u r i n o l can act as an elec t ron transfer agent. B i o c h e m B i o p h y s Res C o m m u n 1986 ;137 :76-79 . 108. G o d i n D V , K o K M , Garnett M E . A l t e r e d antioxidant status i n the i s c h e m i c / r e p e r f u s e d rabbit m y o c a r d i u m : effects of a l l o p u r i n o l . C a n J C a r d i o l 1989 ;5 :365-371 . 109. D e W a l l R A , V a s c o L A , Stanley E L , K e z d i P . Response of the i s c h e m i c m y o c a r d i u m to a l l o p u r i n o l . A m Hear t J 1971 ;82 :362-370 . 110. C h a m b e r s D J , B r a i m b r i d g e M V , Hearse D J . F r e e radicals and c a r d i o p l e g i a : the absence of an addit ive effect wi th a l l o p u r i n o l pretreatment and the use of antioxidant enzymes i n the rat. E u r J C a r d i o - T h o r a c S u r g 1987;1 :80-90. 111. Sisto T , Paajanen H , M e t s a - K e t e l a T , H a r m o i n e n A , N o r d a c k I, T a r k k a M . Pretreatment wi th antioxidants and a l l o p u r i n o l d i m i n i s h e s cardiac onset events i n c o r o n a r y artery bypass g r a f t i n g . A n n T h o r a c S u r g 1995;59 :1519- 23. 112. E m e r i t I, F a b i a n i J N , P o n z i o O , M u r d a y A , L u n e l F , C a r p e n t i e r A . C l a s t o g e n i c effect i n i s c h e m i a r e p e r f u s i o n injury d u r i n g open-heart surgery : protect ive effect of a l l o p u r i n o l . A n n T h o r a c Surg 1988 ;46 :619-624 . 113. G i m p e l J A , L a h p o r J R , van der M o l e n A J , D a m e n J , H i t c h c o c k J F . R e d u c t i o n of r e p e r f u s i o n injury of h u m a n m y o c a r d i u m by a l l o p u r i n o l : a c l i n i c a l s tudy. F ree R a d B i o l M e d 1995 ;19 :251-255 . 114. T a b a y a s h i K , S u z u k i Y , N u g a m i n e S, et a l . A c l i n i c a l t r ial of a l l o p u r i n o l ( z y l o r i c ) for m y o c a r d i a l p r o t e c t i o n . J T h o r a c C a r d i o v a s c Surg 1991;101:713-718. 115. B u l k l e y G B . Free radicals and other reactive o x y g e n metaboli tes : c l i n i c a l re levance and the therapeutic e f f i cacy of antioxidant therapy. Surgery 1993;113 :479-483. 116. B u r n a k i s T G . A l l o p u r i n o l for m i n i m i z i n g m y o c a r d i a l r e p e r f u s i o n i n j u r y . H o s p P h a r m 1993;28 :996-999. 117. Sastre J , P l a R , Juan G , et a l . P r e v e n t i o n by g i n k g o b i l o b a extract of age-associated impairment of b r a i n m i t o c h o n d r i a . In : Packer L , T r a b e r M G , X i n W , eds. Proceedings of the international s y m p o s i u m on natural 88 antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;434-443. 118. W e l t K , F i t z l F , S c h a f f r a n i e t z . G i n k g o b i l o b a extract protects ultrastructure of h y p o x i c o l d rat 's m y o c a r d i u m . In: P a c k e r L , T r a b e r M G , X i n W , eds. Proceedings of the internat ional s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;424-433. 119. H u a n g P L , Z e n g Z H . S c a v e n g i n g effects of g i n k g o b i l o b a L and H a w t h o r n leaves on o x y g e n free radicals and their ant ioxidant ac t ion . In : Packer L , T r a b e r M G , X i n W , eds. Proceedings of the internat ional s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;499-505. 120. N i Y , Z h a o B , H o u J , X i n W . G i n k g o b i l o b a extract pro tec t ion of b r a i n neurons f r o m damage i n d u c e d by free radica ls . In: Packer L , T r a b e r M G , X i n W , eds. P r o c e e d i n g s of the international s y m p o s i u m o n natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;506-512. 121. P i e t r i S, S e g u i n J R , d ' A r b i g n y P , D r i e u K , C u l c a s i M . G i n k g o b i l o b a extract ( E G b 761) pretreatment l imits free r a d i c a l - i n d u c e d oxidat ive stress in patients u n d e r g o i n g c o r o n a r y bypass surgery . C a r d i o v a s c D r u g s T h e r 1997;11 :121-131. 122. Pasquier C , B a b i n - C h e v a y e C , M a r q u e t t y C . E G b 761 i n h i b i t i o n of neutrophi l funct ions and adhesion to e n d o t h e l i u m activated by o x y g e n free radica ls . In: Packer L , T r a b e r M G , X i n W , eds. P r o c e e d i n g s of the international s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;488-498. 123. D r o y - L e f a i x M T , M e n e r a t h J M , S z a b o - T o s a k i E , B o n h o m m e B , D o l y M . E G b 761 and r e p e r f u s i o n injury of ret ina . In: P a c k e r L , T r a b e r M G , X i n W , eds. P r o c e e d i n g s of the internat ional s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;413-416. 124. C l o s t r e F . E f f e c t of g i n k g o b i l o b a extract ( E G b 761) on free r a d i c a l - induced damage i n the b r a i n . In : Packer L , T r a b e r M G , X i n W , eds. Proceedings of the international s y m p o s i u m on natural antioxidants m o l e c u l a r mechanisms and health effects . C h a m p a i g n , I l l i n o i s : A O C S Press , 1996;444- 452. 89 125. E g g e r t s e n R , Siver tsson R, A n d r e n L , H a n s s o n L . H a e m o d y n a m i c effects of c a r v e d i l o l , a beta-adrenoceptor b l o c k e r and p r e c a p i l l a r y vasodi la tor i n essential h y p e r t e n s i o n . J H y p e r t e n s 1984;2 :529-534. 126. E g g e r t s e n R , S iver tsson R , A n d r e n L , H a n s s o n L . A c u t e and l o n g - t e r m h e m o d y n a m i c effects of c a r v e d i l o l , a c o m b i n e d beta-adrenoceptor b l o c k i n g and p r e - c a p i l l a r y vasodi la t ing agent i n h y p e r t e n s i o n patients . J C a r d i o v a s c P h a r m a c o l 1987 ;S97-S100 . 127. S u n d b e r g S, T i h o n e n K , G o r d i n A . V a s o d i l a t o r y effects o f c a r v e d i l o l and p i n d o l o l . J C a r d i o v a s c P h a r m a c o l 1987 ;10 :976-980 . 128. Y u e T L , C h e n g H Y , L y s k o P , et a l . C a r v e d i l o l , a new vasodi la tor and beta-adrenoceptor b l o c k e r antagonist is an antioxidant and free r a d i c a l scavenger . J P h a r m a c o l E x p T h e r 1990;263:92-98 . 129. Y u e T L , L i u T , Feuers te in G . C a r v e d i l o l , a new vasodi la tor and (3- adrenoceptor antagonist , inhibits o x y g e n r a d i c a l mediated l i p i d p e r o x i d a t i o n i n swine ventr i cular membranes . P h a r m a c o l C o m m 1992 ;1 :27-35 . 130. Y u e T L , M c K e n n a P J , L y s k o P G , R u f f o l o R R Jr , F e u e r s t e i n G Z . C a r v e d i l o l , a new ant ihyper tensive , prevents o x i d a t i o n o f h u m a n low density l i p o p r o t e i n by macrophages and copper . A t h e r o s c l e r o s i s 1992 ;92 :209-216 . 131. H a m b u r g e r S A , Barone F C , F e u e r s t e i n G , R u f f o l o R R . C a r v e d i l o l (kredex) reduces infarct size i n a canine m o d e l o f acute m y o c a r d i a l i n f a r c t i o n . P h a r m a c o l o g y 1991;43 :113-120. 132. F e u e r s t e i n G Z , Y u e T L , C h e n g H Y , R u f f o l o R R . M y o c a r d i a l protec t ion by the n o v e l vasodi la t ing beta b l o c k e r c a r v e d i l o l : potential re levance of antioxidant ac t iv i ty . J H y p e r t e n s 1993 ;4(suppl 4 ) :541-549 . 133. B r i l A , S l i v j a k M , D i M a r t i n o M , et a l . C a r d i a l protect ive effects of c a r v e d i l o l , a new beta-adrenoceptor antagonist w i t h v a s o d i l a t i n g proper t ies , i n anesthetized m i n i p i g s . C a r d i v a s c Res 1992 ;26 :515-528 . 134. F e u e r s t e i n G Z , R u f f o l o R R Jr. C a r v e d i l o l , a n o v e l m u l t i p l e ac t ion antihypertensive agent wi th antioxidant act ivity and the potential for m y o c a r d i a l and vascular protec t ion . E u r Hear t J 1995; 16(suppl F ) : 3 8 - 4 2 . 135. B a i l e y J M , M o r a C T , Shafer S L . P h a r m a c o k i n e t i c s o f p r o p o f o l i n adult patients u n d e r g o i n g c o r o n a r y r e v a s c u l a r i z a t i o n . A n e s t h e s i o l o g y 1996;84 :1288-97 . 90 136. M u r p h y P G , M y e r s D S , D a v i e s M J , Webster N R , Jones J G . T h e antioxidant potential of p r o p o f o l ( 2 , 6 - d i i s o p r o p y l p h e n o l ) . B r J A n e s t h 1992;68 :613-618. 137. Stoel t ing R K . P h a r m a c o l o g y & p h y s i o l o g y i n anesthetic prac t i ce , 2nd e d . P h i l a d e l p h i a : J . B . L i p p i n c o t t c o m p a n y , 1991; 143-147. 138. S e r v i n F , D e s m o n d s J M , H a b e r e r JP , C o c k s h o t t I D , P l u m m e r G F , F a r i n o t t i R . P h a r m a c o k i n e t i c s and prote in b i n d i n g of p r o p o f o l i n patients with c i r r h o s i s . A n e s t h e s i o l o g y 1988 ;69 :887-891 . 139. T a r r T J , K e n t A P . Sequestrat ion of p r o p o f o l i n an ex t racorporeal c i r c u i t . J C a r d i o t h o r a c A n e s t h 1989 ;3(suppl 1):75. 140. Ffynynen M , H a m m a r e n E , R o s e n b e r g P H . P r o p o f o l sequestration w i t h i n the ex t racorporeal c i r c u i t . C a n J A n e s t h 1994 ;41 :583-588 . 141. H a m m a r e n E , Y l i - H a n k a l a A , R o s e n b e r g P H , H y n y n e n M . C a r d i o p u l m o n a r y b y p a s s - i n d u c e d changes i n plasma concentrat ions of p r o p o f o l and i n auditory e v o k e d potentials . B r J A n e s t h 1996 ;77 :360-364 . 142. R u s s e l l G N , W r i g h t E L , F o x M A , D o u g l a s E J , C o c k s h o t t I D . P r o p o f o l - fentanyl anesthesia for coronary artery surgery and c a r d i o p u l m o n a r y bypass . Anaesthesia 1989;44 :205-208. 143. Gar tner S L , V a h o u n y G V . H e p a r i n ac t iva t ion of soluble heart l i p o p r o t e i n l ipase . A m J P h y s i o l 1966;211 :1063-1068. 144. W o o d M . P l a s m a d r u g b i n d i n g : i m p l i c a t i o n for anesthesiologists . A n e s t h A n a l g 1986;65 :786-804. 145. Boer F , Ros P , B o v i l l J G , B r u m m e l e n P V , v a n der K r o g t J . E f f e c t of p r o p o f o l on p e r i p h e r a l vascular resistance d u r i n g c a r d i o p u l m o n a r y bypass . Br J A n e s t h 1990 ;65 :184-189 . 146. U b e r W , Stegmann H B . M a g n e t i c propert ies o f free r a d i c a l s . V o l 9, part C 2 . B e r l i n : S p r i n g e r V e r l a g , 1979;29-214. 147. M a s o n R P , M o r e h o u s e K M . S p i n - t r a p p i n g - t h e ideal method for measur ing o x y g e n radica l formation? In: R i c e - E v a n s C , H a l l i w e l l B eds. Free radica ls : m e t h o d o l o g y and concepts . L o n d o n : T h e R i c h e l i e u Press , 1988; 157- 168. 148. H u y s m a n s W G B , Water W A . A r y l o x y - r a d i c a l s . Part I V . M e a s u r e m e n t of the e lec t ron spin resonance spectra of s h o r t - l i v e d substituted p h e n o x y - radicals i n benzene s o l u t i o n . J C h e m Soc B 1966 ;679 :1047-1049 . 91 149. K o n g Y , L e s n e f s k y E J , Y e J , H o r w i t z L D . P r e v e n t i o n of l i p i d p e r o x i d a t i o n does not prevent o x i d a n t - i n d u c e d m y o c a r d i a l contract i le d y s f u n c t i o n . A m J P h y s i o l 1 9 9 4 ; 2 6 7 : H 2 3 7 1 - 7 . 150. L e s n e f s k y E J , D a u b e r I M , H o r w i t z L D . M y o c a r d i a l s u l f h y d r y l p o o l alterations occur d u r i n g r e p e r f u s i o n after b r i e f and p r o l o n g e d m y o c a r d i a l i schemia i n v i v o . C i r Res 1991;68 :605-613. 151. C h a n e y M A . P r o p o f o l and early extubation after cardiac surgery . A n e s t h A n a l g 1997 ;85 :227-231 . 152. M y l e s P S , B u c k l a n d M R , Weeks A M , et a l . H e m o d y n a m i c effects , m y o c a r d i a l i s c h e m i a , and t i m i n g of tracheal extubation with p r o p o f o l - b a s e d anesthesia for cardiac surgery . A n e s t h A n a l g 1997 ;84 :12-19 . 153. B a r v a i s L , R a u s i n I, G l e n J B , et a l . A d m i n i s t r a t i o n o f p r o p o f o l by target -control led i n f u s i o n in patients u n d e r g o i n g c o r o n a r y artery surgery . J C a r d i o t h o r a c A n e s t h 1996;10 :877-883. 154. D e a k i n C D . C o n v e c t i v e w a r m i n g after C A B G . B r J A n e s t h 1996;77 :298-299. 155. L e e H S , K h o o Y M , C h u a B C , N g A S , T a n S S , C h e w S L . P h a r m a c o k i n e t i c s of p r o p o f o l i n f u s i o n i n A s i a n patients u n d e r g o i n g coronary artery bypass g r a f t i n g . T h e r D r u g M o n i t . 1995 ;17 :336-341 . 156. Roekaerts P M , G e r r i e s H J , T i m m e r m a n B E , de L a n g e S. C o n t i n o u s infusions of a l fentani l and p r o p o f o l for c o r o n a r y artery surgery . J C a r d i o t h o r a c A n e s t h 1995;9 :362-367. 157. Sorbara C , Pi t tarel lo D , R i z z o l i G , et a l . P r o p o f o l - f e n t a n y l versus i s o f l u r a n e - f e n t a n y l anesthesia for coronary artery bypass g r a f t i n g : effect on m y o c a r d i a l contract i l i ty and per iphera l h e m o d y n a m i c s . J C a r d i o t h o r a c A n e s t h 1995 ;9 :18-23 . 158. P h i l l i p s A S , M c M u r r a y T J , M i r a k h u r R K , G i b s o n F M , E l l i o t t P . P r o p o f o l - f e n t a n y l anesthesia: a c o m p a r i s o n with i s o f l u r a n e - f e n t a n y l anesthesia i n c o r o n a r y artery bypass graf t ing and valve replacement surgery . J C a r d i o t h o r a c A n e s t h 1994;8 :289-296. 159. G o r d o n P C , M o r r e l l D F , P a m m J D . T o t a l intravenous anesthesia us ing p r o p o f o l and alfentani l for coronary artery bypass s u r g e r y . J C a r d i o t h o r a c A n e s t h 1994 ;8 :284-288 . 92 160. P h i l l i p s A S , M c M u r r a y T J , M i r a k h u r R K , G i b s o n F M , E l l i o t t P . P r o p o f o l - f e n t a n y l anesthesia in cardiac surgery : a c o m p a r i s o n i n patients with good and i m p a i r e d ventr icular f u n c t i o n . A n e s t h e s i a 1993 ;48 :661-663 . 161. H a e s s l e r R , Schwender D , L e p p m e i e r U , K l a s i n g S, R i n d f l e i s c h F , Peter K . Anaes thes ia for coronary artery bypass g r a f t i n g : o p i o i d - a n a l g e s i a c o m b i n e d with either f l u n i t r a z e p a m , p r o p o f o l or i s o f l u r a n e . A c t a A n a e s t h Scand 1993 ;37 :532-540 . 162. M o k k e n F C , H e n n y C P , G e l b A W . T h e effects of p r o p o f o l c o m p a r e d to high-dose fentanyl anesthesia on r h e o l o g i c parameters i n c o r o n a r y artery surgery . J C a r d i o t h o r a c A n e s t h 1993;7 :10-16 . 163. U n d e r w o o d S M , D a v i e s S W , F e n e c k R O , W a l e s b y R K . A n a e s t h e s i a for m y o c a r d i a l r e v a s c u l a r i s a t i o n . A c o m p a r i s o n of f e n t a n y l / p r o p o f o l with f e n t a n y l / e n f l u r a n e . Anaes thes ia 1992;47 :939-945. 164. P a g n i n A , C e r i a n a P , M a u r e l l i M , et a l . C o m p a r i s o n between p r o p o f o l and isof lurane i n patients u n d e r g o i n g aor to -coronary bypass . E f f e c t on systemic and c o r o n a r y c i r c u l a t i o n . M i n e r v a A n e s t e s i o l o g i c a 1992 ;58 :361-367 . 165. H a e s s l e r R , K e l l e r I, M a d l e r C . Induct ion of anaesthesia in patients u n d e r g o i n g aor tocoronary bypass surgery : p r o p o f o l versus etomidate . J C a r d i o t h o r a c A n e s t h 1989;3(5 suppl 1):28. 166. H a l l R I , M u r p h y J T , M o f f i t t E A , L a n d y m o r e R , P o l l a k P T , P o o l e L . A c o m p a r i s o n of the m y o c a r d i a l metabol ic and h a e m o d y n a m i c changes p r o d u c e d by p r o p o f o l - s u f e n t a n i l and enf lurane-sufentani l anaesthesia for patients h a v i n g c o r o n a r y artery bypass graf t ing surgery . C a n J A n e s t h 1991 ;38 :996- 1004. 167. Boer F . B o v i l l J G , Ros P , van O m m e n H . E f f e c t of thiopentone, etomidate and p r o p o f o l on systemic vascular resistance d u r i n g c a r d i o p u l m o n a r y bypass . B r J A n a e s t h 1991 ;67 :69-72 . 168. V e r m e y e n K M , D e H e r t S G , E r p e l s F A , A d r i a e s e n H F . M y o c a r d i a l metabol ism d u r i n g anaesthesia wi th p r o p o f o l - l o w dose fentanyl for c o r o n a r y artery bypass surgery . B r J Anaes th 1991;66 :504-8 . 169. L a n g e H , Stephan H , R i e k e H , K e l l e r m a n n M , Sonntag H , B i r c h e r J . Hepat ic and extrahepatic d i s p o s i t i o n of p r o p o f o l i n patients u n d e r g o i n g coronary bypass surgery . B r J A n a e s t h 1990 ;64 :563-570 . 170. K l i n g D , B a c h m a n n B , M o o s d o r f R , H e m p e l m a n n G . H e m o d y n a m i c act ion p r o f i l e of p r o p o f o l in c o m p a r i s o n with m i d a z o l a m . A study i n c o r o n a r y surgical patients. Anaesthesis t 1987;36 :640-645. 93 171. R i c h a r d s o n J . P r o p o f o l i n f u s i o n for coronary artery bypass surgery i n a patient wi th suspected malignant h y p e r p y r e x i a . A n a e s t h e s i a 1987 ;42 :1125 . 172. V e r m e y e n K M , E r p e l s F A , Janssen L A , B e e c k m a n C P , H a n e g r e e f s G H . P r o p o f o l - f e n t a n y l anaesthesia for c o r o n a r y bypass surgery i n patients with good left vent r i cular f u n c t i o n . B r J A n a e s t h 1987 ;59 :1115-20 . 173. H a m m a r e n E , H y n y n e n M . H a e m o d y n a m i c effects of p r o p o f o l i n f u s i o n for sedation after coronary artery surgery . B r J A n a e s t h 1995 ;75 :47-50 . 174. H i g g i n s T L , Y a r e d J P , Estafanous F G , C o y l e J P , K o H K , G o o d a l e D B . P r o p o f o l versus m i d a z o l a m for intensive care unit sedation after coronary artery bypass g r a f t i n g . C r i t i c a l C a r e M e d i c i n e 1994 ;22 :1415-23 . 175. Roekaerts P M , H u y g e n F J , de L a n g e S. I n f u s i o n of p r o p o f o l versus m i d a z o l a m for sedation in the intensive care unit f o l l o w i n g c o r o n a r y artery surgery . J C a r d i o t h o r a c A n e s t h 1993;7 :412-147 . 176. E w a r t M C , Y a u K W , M o r g a n M . 2% P r o p o f o l for sedation i n the intensive care uni t . A feas ibi l i ty study. Anaes thes ia 1992 ;47 :146-148 . 177. C h a u d h r i S, K e n n y G N . Sedat ion after cardiac bypass surgery : c o m p a r i s o n of p r o p o f o l and m i d a z o l a m i n the presence of a c o m p u t e r i z e d c losed loop arterial pressure c o n t r o l l e r . B r J A n a e s t h 1992 ;68 :98-99 . 178. F e r r e i r a R , B u r g o s M , M i l e i J , et a l . E f f e c t o f supplement ing c a r d i o p l e g i c so lut ion with deferoxamine on reperfused h u m a n m y o c a r d i u m . J T h o r a c C a r d i o v a s c Surg 1990;100:708-714. 179. F a h y L T , v a n M o u r i c k G A , U t t i n g J E . A c o m p a r i s o n of the i n d u c t i o n characterist ics of thiopentone and p r o p o f o l ( 2 , 6 - d i - i s o p r o p y l p h e n o l ) . Anaesthes ia 1985;40 :939-944. 180. Pensado A , M o l i n s N , A l v a r e z J . H a e m o d y n a m i c effects o f p r o p o f o l d u r i n g c o r o n a r y artery bypass surgery . B r J A n a e s t h 1993 ;71 :586-588 . 181. L i p p m a n M , Paic ius R , G i n g e r i c h S, et a l . A c o n t r o l l e d study of the h e m o d y n a m i c effects of p r o p o f o l vs thiopental d u r i n g anesthesia i n d u c t i o n . A n e s t h A n a l g 1986 ;65 :S89 . 182. Stephan H , Sonntag H , Schenk H D , Ket t ler D , K h a m b a t t a . E f f e c t s of p r o p o f o l on c a r d i o v a s c u l a r d y n a m i c s , m y o c a r d i a l b l o o d f l o w and m y o c a r d i a l metabol ism i n patients wi th coronary artery disease . B r J A n a e s t h 1986;58 :969-975. 94 183. P r y s - R o b e r t C , D a v i e s J R , C a l v e r l e y R K , G o o d m a n N W . H a e m o d y n a m i c effects of infusions of d i - i s o p r o p y l p h e n o l d u r i n g nitrous oxide anaesthesia i n m a n . Br J A n a e s t h 1983 ;55 :105 . 184. J a y a k u m a r i N , K u m a r i K S , A m b i k a k u m a r i V , et a l . E n h a n c e d l i p i d p e r o x i d a t i o n i n patients d u r i n g coronary artery bypass g r a f t i n g . Ind H e a r t J 1993;45 :489-491. 185. G i m p e l J A , L a h p o r J R , van der M o l e n A J , D a m e n J , H i t c h c o c k J F . R e d u c t i o n of r e p e r f u s i o n injury of h u m a n m y o c a r d i u m by a l l o p u r i n o l : a c l i n i c a l s tudy. F ree R a d B i o l M e d 1995 ;19 :251-255 . 186. D e m e n t ' e v a II, M i l ' c h a k o v V I , D z m e s h k e v i c h S L , I a v o r o v s k i i A G , A n d r i a n o v a M I u . Assessment of r e p e r f u s i o n damage to the m y o c a r d i u m by oxygen free radicals i n patients with i s c h e m i c heart disease subjected to surgery wi th a r t i f i c i a l b l o o d c i r c u l a t i o n . A n e s t e z i o l o g i i a i R e a n i m a t o l o g i i a 1993;3 :14-18. 187. V r e e T B , Baars A M , de G r o o d P M . H i g h - p e r f o r m a n c e l i q u i d chromatographic determinat ion and p r e l i m i n a r y p h a r m a c o k i n e t i c s of p r o p o f o l and its metabolites i n h u m a n plasma and u r i n e . J C h r o m a t o g r 1987 417 :458- 464. 188. F a n S Z , Y u H Y , C h e n Y L , L i u C C . P r o p o f o l c o n c e n t r a t i o n m o n i t o r i n g in plasma or whole b l o o d by gas chromatography 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 . A n e s t h A n a l g 1995;81 :175-178 . 189. Y u H Y , L i a u J K . Quat i ta t ion of p r o p o f o l i n p l a s m a by c a p i l l a r y gas c h r o m a t o g r a p h y . J C h r o m a t o g r 1987;421:171-176. 190. T o t h K M , C l i f f o r d D P , Berger E M , W h i t e C W , R e p i n e J E . Intact human erythrocytes prevent h y d r o g e n p e r o x i d e - m e d i a t e d damage to isolated perfused rat lungs and cul tured bovine p u l m o n a r y artery endothel ia l c e l l s . J C l i n Invest 1984 ;74 :292-295 . 191. A s b e c k V , H o i d a l B S J , V e r c e l l o t t i G M , S c h w a r t z B A , M o l d o w C F , Jacob H S . P r o t e c t i o n against lethal h y p e r o x i a by tracheal i n s u f f l a t i o n of erythrocytes : role of red c e l l glutathione. Sc ience ( W a s h . D C ) 1985;227 :756- 759. 192. G o d i n D V , W o h a i e b S A , Garnett M E , G o u m e n i o u k A D . A n t i o x i d a n t enzyme alterations i n experimental and c l i n i c a l diabetes . M o l l C e l l B i o c h e m 1988:84 ;223-231. 193. C a r r e a F P , L e s n e f s k y E J , R e p i n e J E , Shikes R H , H o r w i t z L D . R e d u c t i o n of canine m y o c a r d i a l infarct size by a d i f f u s i b l e reactive o x y g e n 95 metabolic scavenger: efficacy of dimethythiourea given at the onset of reperfusion. Cir Res 1991;68:1652-59. 194. Entman M L , Youker L E , Shoji T, et al. Neutrophil induced oxidative injury of cardiac myocytes. A compartmental system requiring CD 116/ CD 18-1 CAM-1 adherence. J Clin Invest 1992;90:1335-45. 195. Lesnefsky EJ, Dauber IM, Horwitz L D . Myocardial sulfhydryl pool alterations occur during reperfusion after brief and prolonged myocardial ischemia in vivo. Cir Res 1991;68:605-613. 196. Loeb L A , James E A , Watersdorph A M , Klebanoff SJ. Mutagenesis by the auto-oxidation of iron with isolated dDNA. Proc Natl Acad Sci, USA 1988;85:3918-22. 197. Carrea FP, Lesnefsky EJ, Kaniser D G , Horwitz L D . The lazaroid U74006F, a 21-aminosteroid inhibitor of lipid peroxidation, attenuates myocardial injury from ischemia and reperfusion. J Cardivasc Pharmacol 1992;20:230-235. 198. Giacomini K M , Swezey SE, Giacomini JC, Blaschke T F . Administration of heparin causes in vitro release of nonesterified fatty acids in human plasma. Life Sci 1980;27:771-780. 199. Bolli R. Oxygen-derived free radicals and postischemic myocardial dysfunction ("stunned Myocardium"). J Am Coll Cardiol 1988;12:239-249. 200. Bull AW, Marnett LJ. Determination of malondialdehyde by ion-pairing high-performance liquid chromatography. Anal Biochem 1985;149:284-290. 201. Gutteridge JMC. Thiobarbituric-acid reactivity following iron-dependent free-radical damage to amino acid and carbohydrates. FEBS Lett 1981;128:343-346. 202. Janero DR, Burghardt B. Analysis of cardiac membrane phospholipid peroxidation kinetics as malondialdehyde: nonspecificity of thiobarbituric acid-reactivity. Lipids 1988;23:452-458. 203. Ceconi C, Cargnoni A, Pasini E, Condorelli E, Curello S, Ferrari R. Evaluation of phospholipid peroxidation as malondialdehyde during myocardial ischemia and reperfusion injury. Am J Physiol 1991 ;260:H1057- H1061. 204. Beuge JA, Aust SD. Microsomal lipid peroxidation. In: Fleisher and Packer L , eds. Methods in enzymology: biomembranes. Vol 52, Part C. New York: Academic Press, 1978;302-310. 96 205. Warren L . The thiobarbituric acid assay of sialic acid. J Biol Chem 1959;234:1971-1975. 206. Gutteridge JMC, Stocks T L , Dormandy T L . Thiobarbituric acid reacting substances derived from autooxidazing linoleic and linolenic acids. Anal Acta 1974;70:107-111. 207. Yagi K. Assay for serum lipid peroxide level and its clinical significance. In: Yagi K,ed. Lipid peroxides in biology and medicine. New York: Academic Press. 1982;223-241. 208. Gilbert HS, Stump D D , Roth EF JR. A method to correct for errors caused by generation of interfering compounds during erythrocyte lipid peroxidation. Anal Biochem 1984;137:282-286. 209. Rubis LJ . Heart: acquired disease. In: Davis JH, ed. Clinical surgery. Missouri.the C V . Mosby company, 1987; 1987-2093. 210. Guyton A C . Text book of medical physiology. Chapter 73 Body temperature, temperature regulation, and fever. Philadelphia:W.B. Sandners Company, 1991 ;797-808. 211. Zhen R, Ding WX, Su ZK, et al. Mechanisms of brain injury with deep hypothermic circulatory arrest and protective effects of coenzyme Q10. J Thorac Cardivasc Surg 1994;108:126-133. 97

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