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The effects of epinephrine on bone blood flow in dogs and rabbits Shim, Sun Shik 1963

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THE EFFECTS OF EPINEPHRINE GN BONE BLOOD FLOW IN DOGS AND RABBITS by SUN SHIK SHIM M.D., Yo n s e i U n i v e r s i t y Severance M e d i c a l C o l l e g e , 1955 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in- the - Department, of P h y s i o l o g y We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA February, 1963 In presenting this thesis in p a r t i a l fulfilment of the requirements for an advanced degree at the University of Br i t i sh Columbia, I agree that the Library shal l make i t 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 representatives. It is understood that copying or publication of this thesis for f inancial gain shall not be alloxred without my written permission. Department The University of Br i t i sh Columbia, Vancouver 8, Canada. ABSTRACT This thesis i s a report of a study on bone blood flow i n adult dogs and rabbits. The ef f e c t s of epinephrine and some other factors were investigated: (1) by d i r e c t observation of bone bleeding through d r i l l holes and i n the medullary cavity; (2) by measurement of changes i n intramedullary pressure of long bones; and (3) by quanti-t a t i v e estimation of bone blood flow by the Fick p r i n c i p l e . A technique was developed for measurement of the i n i t i a l Sr clearance by bone by d i v i d i n g the bone uptake of Sr8-* by the integrated average concentration of S r 8 ^ i n the systemic a r t e r i a l blood. This clearance w i l l represent at least'a minimum bone blood flow. It should be equivalent to e f f e c t i v e bone blood flow on the assumption that bone clears S r 8 ^ ra p i d l y and almost completely from blood c i r c u l a t i n g through bone by exchange with calcium i n bone, just as PAH clearance gives a measure of e f f e c t i v e renal blood flow. The normal rate of bone blood flow i n adult rabbits by the rate of i n i t i a l S r 8 ^ clearance appeared to be at least 16 ml. per minute per 100 gm. of fresh bone which would represent about 5-10% of the rest i n g cardiac output. The average intramedullary pressure of the femur i n dogs was about 55 mm Hg, about 1/2 of the s y s t o l i c systemic a r t e r i a l blood pressure. Epinephrine caused a profound reduction i n bone Blood flow as indicated by reduced bone bleeding, a marked (65%) reduction i n intramedullary pressure of bone marrow i n the presence of p e r s i s t e n t l y increased systemic blood pressure, and a s i g n i f i c a n t (75%) reduction i n Sr^5 clearance by Q C bone. The changes i n intramedullary pressure and i n S r O J clearance by bone thus appear to correlate very well with changes i n bone blood flow. i . ACKNOWLEDGEMENTS The author would l i k e to express h i s appreciation to Dr. D. Harold Copp, Professor and Head of the Department of Physiology, for h i s p r o f i t a b l e encouragement, d i r e c t i o n , discussion and sponsorship of both t h i s research work and the author's graduate study; to Dr. Frank P. Patterson and to Dr. Kenneth S. Morton, i n the D i v i s i o n of Orthopedic Surgery, for t h e i r counsel and encouragement as well as for co-sponsorship of the author's graduate study; to Mr. Kurt Henze, Chief Technician of the Department of Physiology, for his expert and t i r e l e s s technical assistance and preparation of the photographs; to Mrs. D. Wilson for her technical assistance i n the study using the radioisotope; to Mrs. J . Archer and Mrs. B. Cheney for t h e i r assistance i n preparation of the manuscript; and to many other members of the Department of Physiology for t h e i r valuable suggestions and cooperation. The author would l i k e also to acknowledge the f i n a n c i a l support of the National Research Council of Canada and the Trauma Research Unit of the Department of Surgery which made t h i s work possible. i v TABLE OF CONTENTS Page CHAPTER I - INTRODUCTION AND PURPOSE OF THE STUDY 1 CHAPTER II - REVIEW OF THE LITERATURE 5 1. Anatomy of c i r c u l a t o r y system of bone 5 2. Vasomotor and sensory nerve suply of bone 10 3. Physiology of blood c i r c u l a t i o n of bone 11 A. Quantitative bone blood flow 12 B. Qualitative bone blood flow.. 13 CHAPTER I I I - MATERIALS AND METHODS OF STUDIES .. 22 1. Materials and General protocol.. 22 2. Methods of experiments 24 A. Qualitative study of bone blood flow 24 a) Direct observation of bone bleeding 24 b) Relationship of intramedullary and systemic blood pressures 24 B. Quantitative study of bone blood flow 25 a) Measurement of intramedullary and systemic blood pressures 25 b) Measurement of i n i t i a l Sr^5 clearance by bone 26 V TABLE OF CONTENTS (Cont'd.) Page (1) In normal rabbits 29 (2) Infusion of epinephrine.. 30 CHAPTER IV - RESULTS 31 A. Qualitative observations of bone blood flow 31 1. Direct observations of bone bleeding 31 2. Relationship of intramedullary and systemic pressures 32 B. Quantitative studies of bone blood flow 1. Intramedullary and systemic blood pressures 33 (a) Normal quantitative r e l a t i o n s 33 " (b) E f f e c t of epinephrine ... 34 (c) E f f e c t of acetylcholine.. 40 (d) E f f e c t of nor-epinephrine 40 (e) E f f e c t of p i t r e s s i n 40 2. S r 8 ^ clearance by bone and estimated bone blood flow.... 46 (a) In normal rabbits 46 -(b) E f f e c t of epinephrine . 46 CHAPTER V - DISCUSSION 52 A. Qualitative aspects of bone blood flow 52 B. Quantitative aspects of bone blood flow 57 v i TABLE OF CONTENTS (Contd) Page CHAPTER VI - SUMMARY 64 CHAPTER V I I - CONCLUSIONS 66 APPENDICES 69 BIBLIOGRAPHY 71 THE EFFECTS OF EPINEPHRINE ON BONE BLOOD FLOW IN DOGS AND RABBITS 2 CHAPTER I - INTRODUCTION AND THE PURPOSE OF THE STUDY L i t t l e i s known about the physiology of blood c i r c u l a -t i o n of bone. Despite the importance of bone blood flow, there i s l i t t l e quantitative data available on t h i s subject . either for man or animals. Extensive researches on anatomy, biochemistry, biophysics, physiology and pathology of bone have been carried out i n the past few decades. There has been growing recognition of the important roles of bone as an organ of the supportive and locomotor, hemopoietic and r e t i c u l o - e n d o t h e l i a l systems; as a mineral reservoir; involved i n ccatlon homeostasis. However, the modern medical and b i o l o g i c a l s c i e n t i s t s suffer from a lack of knowledge of the many b i o l o g i c a l - both ph y s i o l o g i c a l and pathological - phenomena which occur i n bone. The fundamental mechanisms of c a l c i f i c a t i o n and mineral exchan-ges are s t i l l not well understood. It can not be emphasized too strongly that a good knowledge of physiology of both quantitative and q u a l i t a -t i v e bone blood c i r c u l a t i o n and i t s co r r e l a t i o n with metabolism i s e s s e n t i a l for the better understanding of many unsolved problems. Unfortunately, i t appears from the l i t e r a t u r e that t h i s fact has been somewhat overlooked i n past research on bone. 3. I t i s now conceded t h a t bone i s not a permanent u n a l t e r a b l e s t r u c t u r e as one might suppose, but i s , on the co n t r a r y , a l a b i l e t i s s u e c h a r a c t e r i z e d by a continuous and r a p i d m e t a b o l i c turnover of i t s o r g a n i c and m i n e r a l c o n t e n t s . Blood flow of bone, as f o r other t i s s u e s and organs, i s a fundamental mediating f a c t o r of metabolism - the homeostatic t i e . R i g i d as i t i s , bone i s c h a r a c t e r i s t i c a l l y a h i g h l y v a s c u l a r and c a n a l i c u l a r t i s s u e . The l i f e of a bone t i s s u e i s dependent upon the metabolism of the o s t e o c y t e s and the l a t t e r i s depen-dent on bone blo o d flow and the c i r c u l a t i o n of the t i s s u e f l u i d - d i f f u s i n g through the c a n a l i c u l i and lacunae. I f f o r any reason, the bl o o d supply should be i n t e r r u p t e d s u f f i c i e n t l y l o n g f o r the o s t e o c y t e s t o d i e , the area undergoes a v a s c u l a r n e c r o s i s . A new v a s c u l a r i n v a s i o n i s the f i r s t and e s s e n t i a l step of r e g e n e r a t i o n and r e p a i r ; t h a t i s t o say r e s o r p t i o n of the dead bone t i s s u e and r e p l a c i n g by new bone. The two processes t o g e t h e r are known as c r e e p i n g s u b s t i t u t i o n . A l l of the processes of bone formation (matrix f o r m a t i o n and c a l c i f i c a t i o n ) , r e s o r p t i o n , r e p a i r i n g and r e m o d e l l i n g must be c l o s e l y r e l a t e d t o both q u a l i t a t i v e and q u a n t i t a t i v e bone b l o o d flow. The pH, pC>2 and pCC>2 i n bone must a l s o be dependent on bone b l o o d flow. 4 D e s p i t e the f a c t t h a t t h i s i s true , modern physiology-p r o v i d e s l i t t l e q u a n t i t a t i v e i n f o r m a t i o n on the r a t e o f bone b l o o d flow i n man or i n animals (except the r a t -v i d e i n f r a ) . L i t t l e i s known of the r a t e o f O2 consump-t i o n nor the r a t e of p r o d u c t i o n by bone, nor of the pH of the i n t r a o s s e o u s b l o o d and t h e i r q u a n t i t a t i v e c o r r e l a t i o n w i t h metabolism of bone. THE PURPOSE OF THE STUDY To s o l v e many unanswered problems r e l a t e d t o bone, i t i s important to understand p r o p e r l y both q u a n t i t a t i v e and q u a l i t a t i v e bone b l o o d flow and r e l a t i o n s h i p w i t h many other f a c t o r s a f f e c t i n g metabolism of bone. There were the f o l l o w i n g t h r e e o b j e c t i v e s i n t h i s study: 1. To i n v e s t i g a t e the f a c t o r s r e l a t e d t o bone b l o o d flow. 2. To develop a method f o r e s t i m a t i n g the q u a n t i -t a t i v e r a t e o f e f f e c t i v e bone b l o o d flow. 3. To study the changes i n bone hemodynamincs produced by i n f u s i o n of e p i n e p h r i n e . T h i s approach and the r e s u l t s should p r o v i d e a b r i d g e , connecting many q u a n t i t a t i v e m e t a b o l i c s t u d i e s o f bone, and l e a d i n g t o the b e t t e r understanding of many h i t h e r t o p o o r l y understood phenomena o c c u r r i n g i n bone. •5 Skeleton. Special Connective Tissue-Frame. Weighs = 15 % of fresh body weight Composed of 206 bones Bone: composed of Water 25 % Organics . . . . 25 % 95 % Collagen 5 % Mucopolysaccharides Inorganic Mineral.50 % Functions as organ of : 1. Supportive and Locomotor 2. Hemopoietic 3. Reticulo-endothelial 4. Mineral Reservoir containing 4s 9 9 % of total body Ca 9 0 % N P 8 0 % " Carbonate 7 0 % U Citrate 5 0 % II Mg 3 0 % H Na 8% II H 2 0 F i g . 1 - Bone i s a speci a l i z e d connective t i s s u e . The -skeleton i s an important organ with many functions. It i s also the p r i n c i p a l reservoir of mineral. 6 CHAPTER I I - REVIEW OF THE LITERATURE 1. ANATOMY OF CIRCULATORY SYSTEM OF BONE Compared wit h the meager p h y s i o l o g i c a l s t u d i e s of b l o o d c i r c u l a t i o n of bone, the anatomy of the c i r c u l a t o r y system of the s k e l e t o n has been e x t e n s i v e l y s t u d i e d . The b l o o d supply of bone has never been s e r i o u s l y con-s i d e r e d f o r study by o t h e r s than the o r t h o p e d i c surgeons. K e l l y e t _ a l . (25) and Peterson and K e l l y (37) have reviewed the s u b j e c t w e l l . Langer (28), as c i t e d by the above authors, d e s c r i b e d the c l a s s i c a l c i r c u l a t o r y anatomy of bone as e a r l y as 1876. I t appears from the l i t e r a t u r e t h a t the modern concepts on t h i s s u b j e c t i s almost i d e n t i c a l t o the d e s c r i p t i o n of Johnson (21) i n 1927. Recently,. T r u e t a and. h i s a s s o c i a t e s (44, 45) , H a l i b u r t o n e t a l . (17) and Nelson et al. (34) have r e p o r t e d e x c e l l e n t experiments u s i n g many s p e c i a l techniques i n c l u d i n g microangiography and microradiography. T h e i r r e p o r t s appear to r e p r e s e n t the most modern concepts of c i r c u l a t i o n i n both the compact and spongy bones. A. C i r c u l a t o r y system of long bone Although t h e r e e x i s t s some s p e c i e s d i f f e r e n c e s , the g e n e r a l p a t t e r n of the v a s c u l a r system of long bone i s w e l l e s t a b l i s h e d . There are t h r e e major a r t e r i a l i n l e t s ; 7 the n u t r i e n t , the epi-metaphyseal and the p e r i o s t e a l ( F i g . 2). They anastomose w i t h each other through m u l t i p l e a r t e r i o l e s and c a p i l l a r i e s i n the c o r t e x and medullary spaces. They d r a i n through the venules or s i n u s e s and e v e n t u a l l y to the venous o u t l e t s which are a s s o c i a t e d w i t h and p a r a l l e l t o a r t e r i e s . The n u t r i e n t a r t e r y , one l a r g e a r t e r y , except f o r two i n the femur, t u n n e l l i n g the c o r t e x o b l i q u e l y t o enter the marrow c a v i t y , d i v i d e s i n t o two or more main branches, immediately a f t e r g a i n i n g access to the medullary c a v i t y , toward each end o f the long bone. Nelson e_t _ a l . (34) observed t h a t s m a l l a r t e r i o l e s branch r a d i a l l y p a s s i n g i n a c e n t r i f u g a l d i r e c t i o n t o the c o r t i c a l bone i n the zone of spongy bone and i n the medullary c a v i t y . These v e s s e l s f u r t h e r d i v i d e i n t o f i n e branches as they enter the haver-s i a n c a n a l s . Many h a v e r s i a n canals c o n t a i n more than one c a p i l l a r y type of v e s s e l . These v e s s e l s i n the h a v e r s i a n canals make f i n e anastomoses w i t h the numerous p e r i o s t e a l a r t e r i e s , many of which p i e r c e the compact bone t o reach the i n t e r i o r through c r o s s channels termed volkmann's c a n a l s . Thus the l o n g i t u d i n a l (haversian) and t r a n s v e r s e (volkmann's) ca n a l s p r o v i d e m u l t i p l e r o u t e s f o r v a s c u l a r supply to the c o r t i c a l bone ( F i g . 3). 8 Bone Blood Supply. Periosteal System Nutrient System Epi - Metaphyseal System F i g . 2 - I l l u s t r a t i o n o f t h r e e s e t s of the b l o o d supply of long bone - diagrammatic. For t h e i r anastomoses, r e f e r t o F i g . 3. 9 The nutrient a r t e r i o l e s at each end of the long bone also send terminal twigs into the metaphyseal region where they anastomose with the metaphyseal a r t e r i e s . The c a p i l l a r i e s of the metaphyseal vessels run to the epiphyse plate i n long loops. The epiphyseal arteries, which arise from the j o i n t capsule, do not j o i n the metaphyseal ar t e r i e s across theepiphyseal plate u n t i l bony union i s complete. After the epiphyseal plate closes, they form a single unit of vessel which i s c a l l e d epi-metaphyseal a r t e r i e s . B. Circulatory system of cancellous bone The cancellous or spongy bone has received r e l a t i v e l y l i t t l e study. However, because of t h e i r c l i n i c a l s i g n i f i cances, p a r t i c u l a r l y related with fracture healing and avascular necrosis, the femoral head and the talus have been studied extensively by several workers. These two are representative examples of the cancellous bone. Recently, excellent studies have been reported by Trueta and Harrison (44) on the blood supply of the femoral head, and by Haliburton et a l . (17) on the extra- and i n t r a -osseous blood supply of the t a l u s . The blood supply to the femoral head i s , however, a rather special case and the talus i s the more appropriate one for the study on the 10 Diagrammatic Bone Blood Supply. Haversian Canal with Vessels and Nutrient Artery 3 - Diagrammatic i l l u s t r a t i o n o f anastomoses o f e x t r a -and i n t r a o s s e o u s b l o o d s u p p l y o f l o n g bone, i n c r o s s s e c t i o n o f d i a p h y s i s . 11 general pattern of blood c i r c u l a t i o n of the cancelleous bone. Several a r t e r i e s which enter the cancellous bone branch u n t i l they become oriented to each i n d i v i d u a l marrow space formed by trabeculae. K e l l y et a l . (25) showed that there are a r t e r i o l e s which have d e f i n i t e d muscular walls. F i n a l l y , t h i n walled c a p i l l a r i e s or sinuses are seen about the i n d i v i d u a l trabeculae; t h i s i s where the metabolic exchanges occur. The main intraosseous a r t e r i e s are associated with veins which progressively unite to form large veins and eventually leave the bone by routes which are almost i d e n t i c a l with the a r t e r i a l i n l e t s . 2. VASOMOTOR AND SENSORY NERVE SUPPLY OF BONE Less attention i s paid to the nervous system of bone and l i t t l e i s known about i t . It i s generally believed, however, that bone i s abundantly supplied by the sympathetic vasomotor (vasoconstrictor) f i b r e s along blood vessels i n bone. Ottolenghi (35) i n 1902, as cited by Drinker et a l . (13) made a good study of the nerves to the bone marrow of man, sheep, dog, rabbit, guinea pig and chicken. He concluded that: (1) the marrow i s r i c h l y supplied with medullated and non-medullated f i b r e s , (2) these nerves form fine plexuses i n the wall of the blood vessels, many ramifications reaching the c a p i l l a r i e s , (3) i n the marrow pulp there are many medullated and non-medullated f i b e r s passing eventually to distant vessls, (4) the existence of special nerve endings about independent marrow elements can not be d e f i n i t e l y determined. Myelinated f i b r e s i n t h i s region can only be afferent and suggest the p o s s i b i l i t y of specialized reflexes from the marrow, or are related to bone pain. Small nerve-like structures are often found i n the cross section of bone cl o s e l y associated with the vascular wall i n the haversian canals and medullary space (27). Peterson et. a l . (37) observed medullated nerve f i b r e s associated with the nutrient artery. The existence of sensory nerve f i b r e s i n the periosteum and endosteum has also been recorded (42). 3. PHYSIOLOGY OF BLOOD CIRCULATION OF BONE The physiology of blood c i r c u l a t i o n of any tissue or organ i s concerned l a r g e l y with hemodynamics - the 13. r e l a t i o n s h i p of blood flow (F), pressure (P) and resistance (R). The physiological as well as the pathological factors a f f e c t i n g the FPR re l a t i o n s h i p are multiple. The physiology of hemodynamics of bone may be conveniently divided into two aspects: the quantitative and the q u a l i -t a t i v e . A. Quantitative (rate of) bone blood flow No data of the rate of the bone blood flow i n man or animals, except the rat, i s available to date. 1) Measurement by d i r e c t method: Not available to date. 2) Measurement by i n d i r e c t method: Even the available i n d i r e c t method i s li m i t e d . Fredrickson, Honour and Copp (15) and Copp and Suiker (6) estimated the rate of bone blood flow by measure-ment of the i n i t i a l bone clearance of Ca 4^ i n the r a t . Their studies were based upon the Fick p r i n c i -ple which i s widely accepted for the blood flow measurement including cardiac output. The following equations are the bases of the Fick p r i n c i p l e (1, 10): X4-> i n which - F: Volume b l o o d flow per u n i t of time C a and C v: A r t e r i a l and venous c o n c e n t r a t i o n of X substance AC: G r a d i e n t between C a and C v Q: Amount of X substance added to or removed from the b l o o d i n p a s s i n g an organ s u b j e c t e d to study. B. Q u a l i t a t i v e ( c h a r a c t e r of) bone b l o o d flow Far more i n f o r m a t i o n i s a v a i l a b l e on the q u a l i t a t i v e aspect, or the c h a r a c t e r of bone blo o d flow although the q u a n t i t a t i v e data are l i m i t e d . 1) Vasomotor c o n t r o l o f bone b l o o d supply: Although i t i s known t h a t the a r t e r i e s and a r t e r i o l e s of bone are abundantly s u p p l i e d w i t h vaso-motor f i b r e s , the p h y s i o l o g i c a l s i g n i f i c a n c e i s not w e l l understood. D r i n k e r e t a l . (13, 14) were of the o p i n i o n i n t h e i r p e r f u s i o n s t u d i e s of the t i b i a o f the dog i n 1916 and 1922 t h a t these f i b r e s had a v a s o c o n s t r i c t o r f u n c t i o n . Recently, Weiss and Root (46) t r a c e d the v a s o c o n s t r i c t o r f i b r e s p a s s i n g t o the marrow c a v i t y of v a r i o u s bones of the cat, by c u t t i n g d i f f e r e n t s p e c i f i c nerves and s t i m u l a t i n g t h e i r p e r i p h e r a l ends. They have observed t h a t IS: s t i m u l a t i o n of the cut p e r i p h e r a l end caused a f a l l of i n t r a m e d u l l a r y p r e s s u r e which i m p l i e d v a s o c o n s t r i c t i o n . 2) F l o w - p r e s s u r e - r e s i s t a n c e r e l a t i o n s h i p of bone b l o o d Bone does not l e n d i t s e l f e a s i l y t o a study of hemodynamics f o r many reasons: i t s r i g i d s t r u c t u r e , i t s many s m a l l a r t e r i e s and v e i n s ; the number of i n d i v i d u a l bones; and the deep l o c a t i o n , beneath the muscles and bound by ligaments through which the bone bl o o d supply passes. D i f f i c u l t t o study as i t i s , D r i n k e r e t _ a l . (13) i n v e s t i g a t e d the f l o w - p r e s s u r e -r e s i s t a n c e r e l a t i o n s h i p , d i r e c t l y and i n d i r e c t l y . They were the f i r s t group to study bone hemodynamics. They p e r f u s e d the t i b i a of the dog w i t h both pressure and i n f l o w of the p e r f u s i o n kept constant. By e l e c t r i c a l s t i m u l a t i o n s of nerves to the bone marrow and by i n f u s i o n of e p i n e p h r i n e they observed a decreased o u t f l o w from the p e r f u s i o n o u t l e t s . V a r i a -t i o n s i n the outflow under constant i n f l o w p r e s s u r e and r a t e can mean o n l y v a r i a t i o n s i n the c a l i b r e of the v e s s e l s - changes i n r e s i s t a n c e . The volume of r a t e of b l o o d flow to a g i v e n organ or t i s s u e s i s d e f i n i t e l y more i n f l u e n c e d by the r e s i s t a n c e of the v a s c u l a r beds than by the p r e s s u r e , 16 and the resistance i s greatly dependent on the size of the cal i b r e - the rad ius — of the vessels. This i s well i l l u s t r a t e d i n P o i s e u i l l e ' s experimental law (11). F = l = (Pl - P 2) x ( 7 L r 4 ) X R ( 8 L ) (V) i n which - F : Flow of f l u i d per unit of time P : P-[_ i s pressure at an upstream point, 1?2 at downstream point R : Resistance r : radius of the vessel 7L : 3.14 L : Length of the vessel V : V i s c o s i t y of the f l u i d Although t h i s law i s not s t r i c t l y applicable to hemodynamics i n the l i v i n g body, the underlying p r i n c i p l e i s s t i l l important for understanding the biophysics of hemodrynamics. The most important point of t h i s law i s that i f the pressure i s doubled, the blood flow also might double, but, doubling the mean cal i b r e of the vessel might Increase the blood flow some 16 times. Conversely, i f the mean ca l i b r e 17 of the b l o o d v e s s e l i s halved, then the blo'od flow might be reduced to some one s i x t e e n t h (1/16). 3) R e l a t i o n s h i p of i n t r a m e d u l l a r y p r e s s u r e and hemodynamics of bone. The i n t r a m e d u l l a r y pressure of bone has been s t u d i e d by few workers. Bloomenthal e t a l . (5) appear to be the f i r s t group to study i t i n 1952. S t e i n e t _ a l . (40, 41) advanced the study. Both groups measured the i n t r a m e d u l l a r y p r e s s u r e of bone of the dog and observed i t s changes by i n j e c t i n g v a r i o u s p r e s s o r and depressor drugs. The observa-t i o n s were s i m i l a r but i n t e r p r e t a t i o n s of the r e s u l t s were d i f f e r e n t i n c e r t a i n a s p e c t s . Bloomenthal et. a l . (5) thought t h a t r e d u c t i o n i n the i n t r a m e d u l l a r y p r e s s u r e by a d r e n a l i n was due to d i l a t a t i o n of a r t e -r i o l e s and c a p i l l a r i e s i n the marrow c a v i t y , such as t h a t found i n the v e s s e l s of the muscles. S t e i n e_t a l . (40), on the other hand, suggested t h a t i t i s probably due to v a s o c o n s t r i c t i o n . More r e c e n t l y , Weiss and Root (46), and H e r z i g and Root (20) a l s o showed a f a l l o f the i n t r a m e d u l l a r y p r e s s u r e d u r i n g and f o l l o w -i n g e p i n e p h r i n e i n j e c t i o n i n the cat, and as a r e s u l t 18 of s t i m u l a t i o n of the cut p e r i p h e r a l end of the sympathetic nerve f i b r e s i n the c a t . They a l s o were of the o p i n i o n t h a t t h i s f a c t s i g n i f i e s vaso-c o n s t r i c t i o n . The i n t r a m e d u l l a r y p r e s s u r e f e l l a f t e r i n j e c t i o n of a c e t y l c h o l i n e (5, 40) and f o l l o w -i n g s t i m u l a t i o n of the cut p e r i p h e r a l end of the vagus (20). The change of the i n t r a m e d u l l a r y p r e s s u r e can be independent of the changes i n the systemic b l o o d pressure, as i n the case of a d r e n a l i n i n j e c t i o n , or c o u l d be dependent on systemic b l o o d p r e s s u r e as i n the case of vagus s t i m u l a t i o n and i n j e c t i o n of a c e t y l c h o l i n e . 4) O b s e r v a t i o n of i n t r a o s s e o u s b l o o d flow Using v i t a l microscopy, Branemark (4) observed the b l o o d flow i n the marrow space as i t r e l a t e d t o the flow i n the c o r t e x of bone i n r a b b i t s . He observed t h a t t h e r e seemed t o be two types of c i r c u -l a t i o n i n the bone marrow; the one i s of the c a p i l l a r y type and the other i s of the s i n u s o i d a l type. He observed t h a t the bone marrow a r t e r i o l e s d i v i d e i n t o c a p i l l a r i e s which then enter e i t h e r s i n u s o i d s or venules d i r e c t l y . The s i n u s o i d s v a r y r h y t h m i c a l l y i n degree i n d i l a t a t i o n and consequently, the v e l o c i t y 19 of b l o o d flow v a r i e s w i t h i n them. The venules d r a i n i n t o the n u t r i e n t v e i n . The v e l o c i t y i n the s i n u s o i d s i s slower than e i t h e r t h a t i n the c a p i l l a r i e s or t h a t i n the h a v e r s i a n v e s s e l s . The v e l o c i t y of flow i n the h a v e r s i a n v e s s e l s i s f a s t e r than t h a t i n the c a p i l l a r i e s . The b l o o d flow i n the c o r t i c a l bone i s r a p i d and steady. K i n i s i t a e t a l . (26) s t a t e d t h a t the venules are • c o n t r a c t i l e and can r e g u l a t e the flow i n v a r i o u s p o r t i o n s of the s i n u s o i d a l network. 5) R e s p e c t i v e r o l e s of each s e t o f v e s s e l s i n bone b l o o d supply. The r e s p e c t i v e r o l e s or r e s p o n s i b l e areas of b l o o d supply of the n u t r i e n t , epi-metaphyseal and p e r i o s t e a l a r t e r i e s c o u l d be observed by i n j e c t i n g a dye such as I n d i a ink i n t o d i f f e r e n t v e s s e l s and then, o b s e r v i n g i t s d i s t r i b u t i o n . A l s o , i t can be s t u d i e d by l i g a t i n g d i f f e r e n t v e s s e l s and then, by s t u d y i n g h i s t o l o g i c a l s e c t i o n s determining the areas of bone which have d i e d due t o l o s s of b l o o d supply. Accord-i n g t o Johnson (21) the n u t r i e n t a r t e r i e s w i l l m a i n t a i n the l i f e of the marrow and the i n n e r two t h i r d of the c o r t e x of the s h a f t of the long bones. 20 Moreover, he showed t h a t there i s e x c e l l e n t c o l l a -t e r a l c i r c u l a t i o n between the branches of the n u t r i e n t a r t e r i e s and the metaphyseal v e s s e l s . The p e r i o s t e a l c i r c u l a t i o n alone would ma i n t a i n the l i f e of o n l y the outer one t h i r d or one h a l f of the c o r t e x . However, more r e c e n t s t u d i e s and c l i n i c a l i n v e s t i g a t i o n by v a r i o u s groups of workers i n d i f f e r e n t c e n t r e s such as the Mayo C l i n i c (24, 25, 36, 37) and the U n i v e r s i t y of Toronto (18, 19, 30) have i n d i c a t e d t h a t the b l o o d supply of bone i s more complex than was f o r m e r l y thought. 6) C o n d i t i o n s a s s o c i a t e d w i t h a l t e r e d hemodynamics and metabolism of bone. Although v a r i o u s c o n d i t i o n s - c l i n i c a l and experimental - which are a s s o c i a t e d w i t h a l t e r e d hemodynamics of bone are known, l i t t l e i n f o r m a t i o n i s a v a i l a b l e f o r the c o r r e l a t i o n of q u a n t i t a t i v e bone bl o o d flow and r a t e o f metabolism i n such c o n d i t i o n s . Hyperemia and ischemia of bone co u l d be e i t h e r l o c a l or d i f f u s e i n type, and co u l d be e i t h e r a c t i v e or p a s s i v e i n nature. A c t i v e hypermia i n acute inflamma-t o r y c o n d i t i o n s , i . e . acute o s t e o m y e l i t i s , i n the stage of a f r a c t u r e healing,, and i n Paget' s d i s e a s e ( o s t e i t i s 21 deformans) are well known. Passive hyperemia occurs i n a large arterio-venous f i s t u l a i n a limb (24), following c e r v i c a l or lumber sympathectomy and i n pulmonary osteoarthropathy. Trotman and Ke l l y (43) reported a 27% increase i n blood flow to the t i b i a i n the anesthetized dog on fourth day after lumbar sympathectomy. Their study was based upon the rate of uptake of radioactive rubidium ( R b 8 6 ) . Ischemic conditions are commonly associated with trauma of bones, blood vessels and i n neurogenic conditions, i . e . r e f l e x sympathetic dystrophy, as such. The investigations on alterations of uptake of the bone seeking radioisotopes i n various condi-tions have become an i n t e r e s t i n g subject for the studies of both bone blood supply and metabolism. Bauer (2), Copp et a l . (6) and McDonald (31), and many others have found an increased radioisotope uptake by bone i n many c l i n i c a l and experimental conditions. L i t t l e i s known about the changes i n bone blood flow with aging. 22 CHAPTER I I I - MATERIALS AND METHODS OF STUDIES 1. MATERIALS AND GENERAL PROTOCOL ANIMALS - A d u l t dogs and r a b b i t s were used. The weights of the dogs v a r i e d from 15 to 35 kg., and r a b b i t s weighed from 1.5 t o 2.5 kg. Both sexes were used. The animals were a l l a p p a r e n t l y normal i n h e a l t h . ANESTHESIA - For the a n e s t h e s i a of the dog, a s o l u -t i o n of 6% of nembutal (Sodium p e n t o b a r b i t a l ) i n 10% a l c o h o l was used. The i n i t i a l dose, 0.5 ml/kg was g i v e n i n t r a v e n o u s l y and the maintenance dose, 1.0 - 2.0 ml was repeated as r e q u i r e d . The r a b b i t s were a n e s t h e t i z e d by i n t r a p e r i t o n e a l i n j e c t i o n of a mixed s o l u t i o n of 30% urethane and 12% b a r b i t o n e , 1.5 m l / l b and 1.0 m l / l b r e s p e c t i v e l y . HEPARINIZATION - The dogs were h e p a r i n i z e d by intr a v e n o u s i n j e c t i o n of a dose of 1.0 - 2.0 mg/lb (about 0.5 - 1.0 mg/kg) whenever epi n e p h r i n e was used i n the experiment. Although e p i n e p h r i n e was i n f u s e d t o the r a b b i t s , i t was f o r a s h o r t p e r i o d and h e p a r i n i z a t i o n was not r e q u i r e d . EPINEPHRINE - E p i n e p h r i n e h y d r o c h l o r i d e was i n f u s e d i n t r a v e n o u s l y i n t o the dogs by standard method of d r i p 23 at an average r a t e of 4.0 y. gm/kg/min of 1:1000 epi n e p h r i n e h y d r o c h l o r i d e s o l u t i o n which was f u r t h e r d i l u t e d i n 100-150 ml of normal s a l i n e . In r a b b i t s , i t was i n f u s e d i n t o an ear v e i n by u s i n g a constant r a t e s y r i n g e pump a t the same dose r a t e . NOR-EPINEPHRINE - 2.0 mg of nor-e p i n e p h r i n e i n 250 ml of 5% dextrose i n water was i n f u s e d i n t o the dogs by the method of continuous intravenous d r i p . PITRESSIN - 10 u n i t s o f p i t r e s s i n i n 100 ml of 5% dextrose i n water was admin i s t e r e d to the dogs by the same r o u t e . ACETYLCHOLINE - 5.0 ml of 1:1000 a c e t y l c h o l i n e i n 100 ml of 5% dextrose i n water was administered t o the dogs by the same method. RADIOISOTOPE ( S r 8 5 ) - The c a r r i e r - f r e e r a d i o s t r o n t i u m ( S r 8 ^ C l 2 ) / 40.0 //c i n 0.5 ml i s o t o n i c s a l i n e , was i n j e c t e d i n t o an ear v e i n of the r a b b i t v e r y r a p i d l y ( i n l e s s than a second). SYSTEMIC BLOOD PRESSURE - In most of the cases, t h i s was measured i n the c a r o t i d a r t e r y , u s i n g a mercury manometer. INTRAMEDULLARY PRESSURE - T h i s was g e n e r a l l y determined i n the d i a p h y s i s of the femur, u s i n g a needle c a t h e t e r and• a mercury manometer. 24 2. METHODS OF EXPERIMENTS A. Q u a l i t a t i v e study of bone bloo d flow 1) Observations o f bone b l e e d i n g (a) Through d r i l l h o l e s i n bone: In 7 dogs, v a r i o u s long bones and other bones were exposed w i t h a m i n i -mum trauma. Many e l e c t r i c d r i l l h o l e s were made through the c o r t e x i n t o the medullary c a v i t y . The ch a r a c t e r of bone b l e e d i n g from these h o l e s was observed d i r e c t l y w i t h and without i n f u s i o n of epine-p h r i n e to the dogs i n t r a v e n o u s l y . (b) In the medullary c a v i t y o f long bone^: In 4 dogs, the a n t e r o - l a t e r a l aspect o f a femur was exposed through the muscular septum w i t h minimum trauma. Since the two l a r g e n u t r i e n t a r t e r i e s enter the femur at the p o s t e r i o r aspect on the l i n e a aspera, they were un d i s t u r b e d by t h i s approach. Using an e l e c t r i c saw, a l o n g square p a r t o f the c o r t e x was removed and v a r i o u s o r i g i n s and the nature of b l e e d i n g , and t h e i r changes b e f o r e , d u r i n g and a f t e r the i n t r a -venous i n f u s i o n of e p i n e p h r i n e were observed. 2V) O b s e r v a t i o n of r e l a t i o n s h i p between i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e s . In 5 dogs, the r e l a t i o n s h i p of the i n t r a m e d u l l a r y 25 pr e s s u r e of bone and the systemic b l o o d p r e s s u r e were observed. T h e i r c h a r a c t e r , i n t e r r e l a t i o n s h i p and changes d u r i n g and a f t e r intravenous i n f u s i o n o f epi n e p h r i n e were recorded on the smoked drum o f a ky-mograph. The d e t a i l e d method o f r e c o r d i n g of these p r e s s u r e s w i l l be d e s c r i b e d i n the next s e c t i o n . B. Q u a n t i t a t i v e study o f bone b l o o d flow For q u a n t i t a t i v e s t u d i e s of b l o o d flow of bone, the f o l l o w i n g two methods were developed: a) Measurement" of the marrow pr e s s u r e 85 b) Sr c l e a r a n c e by bone. a) Measurement of i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e In 6 dogs, i n order t o determine q u a n t i t a t i v e v a l u e s and t h e i r r e l a t i o n s h i p s r e f l e c t i n g the r e l a -t i v e changes of bone b l o o d flow, the i n t r a m e d u l l a r y p r e s s u r e i n the femur marrow c a v i t y and the ..systemic b l o o d p r e s s u r e i n the c a r o t i d a r t e r y were measured si m u l t a n e o u s l y and recorded on the smoked drum of a kymograph. Through a s m a l l s k i n i n c i s i o n , 2 - 3 inches long, the a n t e r i o - l a t e r a l aspect of the femur or humerus was exposed by s p l i t t i n g the muscular septum. Then, a s m a l l e l e c t r i c d r i l l h o l e was made i n the c o r t e x . A 15 gauge needle was t i g h t l y i n s e r t e d i n t o the i n t r a m e d u l l a r y c a v i t y i n order to t r a n s m i t the p r e s s u r e from i t without b l o o d l e a k i n g . B l e e d i n g can be n o t i c e d i n a rhythmic p u l s a t i n g p a t t e r n through the needle. The needle was connected to a mercury manometer u s i n g a t r a n s l u c e n t p l a s t i c tube. The c a r o t i d a r t e r y or femoral a r t e r y was cannulated and connected i n the same way to a mercury manometer, r e c o r d i n g on the kymograph ( F i g . 4 ) . A s i g n a l time was a l s o r e c o r d e d . A f t e r a time i n t e r v a l s u f f i c i e n t t o e s t a b l i s h and r e c o r d a s t a b l e c o n t r o l l e v e l , the e f f e c t s of intravenous e p i n e p h r i n e i n f u s i o n and i n f u s i o n s of the other drugs such as nor- e p i n e p h r i n e , p i t r e s s i n - and a c e t y l c h o l i n e were e v a l u a t e d . D u r a t i o n of i n f u s i o n s was v a r i e d from a few minutes t o one hour. b) Measurement of S r 8 5 c l e a r a n c e by bone f o r q u a n t i -t a t i v e e s t i m a t i o n of bone b l o o d flow i n r a b b i t s . A technique was developed f o r e s t i m a t i n g bone , b l o o d flow by measurement of S r 8 ^ c l e a r a n c e by bone from b l o o d d u r i n g the i n i t i a l 5 minute p e r i o d f o l l o w i n g 27 Fig.4 - Apparatus f o r measuring and r e c o r d i n g s i m u l t a -neously the i n t r a m e d u l l a r y pressure of bone and the systemic b l o o d p r e s s u r e i n v a r i o u s c o n d i t i o n s . 28 i n t r a v e n o u s i n j e c t i o n of the i s o t o p e . The bone 0 85 uptake of Sr was d i v i d e d by the i n t e g r a t e d average c o n c e n t r a t i o n of Sr i n b l o o d d u r i n g t h i s p e r i o d . The c l e a r a n c e was determined i n 10 c o n t r o l r a b b i t s f o r the normal bone blood flow and i n 10 r a b b i t s which were r e c e i v i n g s i m u l t a n e o u s l y e p i n e -p h r i n e i n f u s i o n . D e t e r m i n a t i o n of average S r 8 ^ c o n c e n t r a t i o n i n b l o o d was made by the f o l l o w i n g method. The r a d i o -a c t i v i t y of b l o o d a t each minute of the i n i t i a l 5 minute p e r i o d was determined and p l o t t e d a g a i n s t time. An average dose of 40.0 m i c r o - c u r i e s of the r a d i o a c t i v e s t r o n t i u m ( S r ^ ) was r a p i d l y i n j e c t e d i n t o an ear v e i n i n l e s s than one second. . A systemic a r t e r i a l b l o o d sample was withdrawn at a constant r a t e of 1.0 ml i n each minute through a f i n e p o l y -e t h y l e n e tube i n the c a r o t i d a r t e r y which was cannulated p r i o r t o the i n j e c t i o n of the i s o t o p e . The r a d i o a c t i v i t i e s of these whole b l o o d samples were counted i n the f r e s h s t a t e w i t h a s c i n t i l l a t i o n d e t e c t o r , and the i n t e g r a t e d average c o n c e n t r a t i o n (count per minute per ml whole blood) was determined. 29 85 (1) Measurement of Sr c l e a r a n c e by bone i n normal r a b b i t s . In 10 normal r a b b i t s , the q u a n t i t a t i v e bone bloo d flow was estimated by the measurement of the i n i t i a l 85 5 minute Sr c l e a r a n c e by bone as f o l l o w s : The animals were a n e s t h e r i z e d w i t h b a r b i t o n e -urethane and weighed. A c a r o t i d a r t e r y was exposed and cannulated toward the h e a r t w i t h a f i n e p o l y e t h y l e n e tube. F o l l o w i n g r a p i d i n j e c t i o n of 40.0 m i c r o c u r i e s 85 of Sr i n t o an ear v e i n , the c a r o t i d a r t e r i a l b l o o d was withdrawn c o n t i n u o u s l y , immediately a f t e r the i n j e c t i o n , f o r 5 minutes of the r a t e of 1.0 ml. per minute. At the end of 5 minute, the animals were s a c r i f i c e d by i n d u c i n g acute c a r d i a c a r r e s t by i n j e c t i o n of nembutal i n t o the h e a r t through the c a r o t i d a r t e r y . Then, the t i b i a - f i b u l a on one s i d e and the humerus of the o p p o s i t e s i d e were q u i c k l y removed. The bones were then weighed a f t e r complete removal of tendons and muscles attached to them. The average r a d i o a c t i v i t y per ml of the f r e s h b l o o d samples of the 5 minutes was determined as d e s c r i b e d p r e v i o u s l y . The uptake of the i s o t o p e by each bone d u r i n g the 5 minute c l e a r a n c e p e r i o d was 30 determined on the b a s i s of 5 minutes counting of the a c t i v i t y i n the f r e s h whole bone ( i n c l u d i n g marrow). T h i s was then expressed as CPM uptake per minute. The l a t t e r was d i v i d e d by the former, g i v i n g the c l e a r a n c e per minute by each bone. T h i s c l e a r a n c e was again d i v i d e d by the weight (grams) of each bone, and expressed as c l e a r a n c e per minute per gm. of f r e s h bone. 85 (2) Measurement of Sr c l e a r a n c e by bone d u r i n g e p i n e p h r i n e i n f u s i o n i n r a b b i t s In 10 r a b b i t s , the e f f e c t s of e p i n e p h r i n e on the 85 r a t e of Sr c l e a r a n c e by bone was s t u d i e d . The technique used i n t h i s study was e s s e n t i a l l y i d e n t i c a l t o t h a t used f o r the normal r a b b i t s mentioned i n the p r e v i o u s s e c t i o n . Epinephrine, at an average r a t e of 4.0 micro gm/kg/min was i n f u s e d i n t o the other ear v e i n c o n t i n u o u s l y , u s i n g a constant r a t e s y r i n g e pump from 5 minutes p r i o r t o i n j e c t i o n of s t r o n t i u m u n t i l the animals were s a c r i f i c e d ( i . e . a t o t a l of 10 minutes). 31 CHAPTER IV - RESULTS A. QUALITATIVE OBSERVATIONS ON BONE BLOOD FLOW 1. D i r e c t o b s e r v a t i o n s of bone b l e e d i n g (a) From d r i l l h o l e s i n bone: In the 7 dogs s t u d i e d , b l e e d i n g from the d r i l l h o l e s i n t o the medullary c a v i t y through the c o r t e x was a constant f i n d i n g . The i n t e n s i t y of b l e e d i n g and the c o l o u r of b l o o d v a r i e d , and seemed dependent on the s i t e of the h o l e s , the sizle of the bone and on the v e s s e l s i n j u r e d by the d r i l l . The femur always showed more a c t i v e b l e e d i n g . Sometimes b l e e d i n g was g r e a t e r from the h o l e s made i n the s h a f t and a t other times, i t was more prof u s e from the metaphysis. A l l animals were w e l l h e p a r i n i z e d . E p i n e p h r i n e i n f u s i o n reduced and e v e n t u a l l y stopped bone b l e e d i n g , w h i l e muscular b l e e d i n g was i n c r e a s e d . The r e d u c t i o n and c e s s a t i o n of the b l e e d i n g c o u l d be maintained as long as the i n f u s i o n of e p i n e p h r i n e was maintained. B l e e d i n g r e c u r r e d when the i n f u s i o n was stopped. (b) In the medullary c a v i t y : In 4 dogs, when a long square area of the a n t e r o - l a t e r a l aspect of the femur was cut by an e l e c t r i c saw and removed, there was p r o f u s e b l e e d i n g from m u l t i p l e sources and the area was soon f l o o d e d w i t h b l o o d . Many p o i n t s o f b l e e d i n g c o u l d be observed by g e n t l e sponging. The i n t e n s i t y of b l e e d i n g was v a r i e d from oozi n g t o p u l s a t i n g i n type. The c o l o u r of the bl o o d was w e l l d i f f e r e n t i a t e d from the a r t e r i a l and venous o r i g i n s . On i n f u s i o n of epin e p h r i n e , the f l o o d i n g w i t h b l o o d r a p i d l y disappeared and the area was completely dry w i t h i n a few minutes. When the i n f u s i o n was stopped, the d e f e c t i n the c o r t e x soon f l o o d e d again w i t h b l o o d . These f i n d i n g s were constant i n a l l 4 dogs. 2. Observations of r e l a t i o n s h i p of i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e s . Without accurate measurement, the i n t e r - r e l a t i o n s h i p of the i n t r e m e d u l l a r y p r e s s u r e and the systemic b l o o d p r e s s u r e was observed i n 5 dogs by r e c o r d i n g them on the kymograph drum. Both p r e s s u r e s were q u i t e s t a b l e under normal c o n d i t i o n s . On i n f u s i o n o f epinephrine, the systemic b l o o d p r e s s u r e was r a p i d l y e l e v a t e d and p e r s i s t e d , but the i n t r a m e d u l l a r y p r e s s u r e ( i n most cases, of the femur) f e l l and remained low as long as the i n f u s i o n was maintained. When the i n f u s i o n was stopped, the systemic b l o o d p r e s s u r e soon r e t u r n e d t o the o r i g i n a l l e v e l , where-as the i n t r a m e d u l l a r y p r e s s u r e rose slowly, r e t u r n i n g t o 33 the o r i g i n a l l e v e l much l a t e r . I t was a constant f i n d i n g t h a t these two p r e s s u r e s always moved i n o p p o s i t e d i r e c -t i o n s w i t h e p i n e p h r i n e i n f u s i o n i n a l l 5 dogs; the i n t r a -m edullary p r e s s u r e f e l l as the systemic b l o o d p r e s s u r e rose, and v i c e v e r s a when epi n e p h r i n e i n f u s i o n was stopped. However, w i t h i n j e c t i o n of a mixed s o l u t i o n of nembutal-a l c o h o l , or of a c e t y l c h o l i n e , and w i t h massive hemorrhage, both p r e s s u r e s s i m u l t a n e o u s l y f e l l . B. RESULTS OF QUANTITATIVE STUDIES OF BONE BLOOD FLOW 1. Measurements of i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e . (a) Normal q u a n t i t a t i v e r e l a t i o n s : The approximate average normal i n t r a m e d u l l a r y p r e s s u r e i n the femur i n 11 dogs was 55 mm Hg, (range from 43 - 80 mm Hg) w h i l e the average systemic b l o o d p r e s s u r e i n the c a r o t i d a r t e r y was 134 mm Hg (range: 120 - 160) as shown i n Table I . As shown i n Table I, the i n t r a m e d u l l a r y p r e s s u r e of the femur i s about h a l f t h a t i n the c a r o t i d p r e s s u r e . 34 TABLE I. Normal r e l a t i o n of i n t r a m e d u l l a r y and systemic b l o o d pressure i n 11 dogs. C a r o t i d B.P. I.M.P. ( s y s t o l i c ) i n femur (mm Hg) Average 134 ± 13* 55 .+ 1.2* * t S . D . (b) E f f e c t of e p i n e p h r i n e on both p r e s s u r e s : There was always a r i s e i n the systemic p r e s s u r e and a f a l l i n the i n t r a m e d u l l a r y p r e s s u r e by the i n f u s i o n of e p i n e p h r i n e i n 6 dogs s t u d i e d . The r e d u c t i o n i n the i n t r a m e d u l l a r y p r e s s u r e p e r s i s t e d (even f o r 40 to 60 minutes) as long as the i n f u s i o n of e p i n e p h r i n e was maintained. In most cases the i n t r a m e d u l l a r y p r e s s u r e f e l l a t l e a s t 60% from the o r i g i n a l pressure.. The r a t e of i n c r e a s e s of the systemic b l o o d p r e s s u r e was r a t h e r i n c o n s t a n t although i t u s u a l l y rose at l e a s t twice as h i g h as d u r i n g the c o n t r o l p e r i o d as shown i n Tables I I - IV, and F i g u r e s 4 and 5. 35 TABLE I I . E f f e c t o f ep i n e p h r i n e on bone marrow pre s s u r e i n dogs. Systemic B.P. M.P. No. of dogs Average c o n t r o l .1.34 55 11 E p i n e p h r i n e i n f u s i o n + (50-^/100%) - (50~65%) . 6 36 TABLE I I I . Q u a n t i t a t i v e changes of two p r e s s u r e s (mm Hg) w i t h e p i n e p h r i n e i n f u s i o n Measurement B.P. ( c a r o t i d ) ** I.M.P. (Femur) C o n t r o l p e r i o d (^  hr.) 140 55 * E p i n e p h r i n e .1 170 25 ( i n f u s i o n f o r a # 2 180 22 b r i e f p e riod) # 3 220 20 # 4 230 20 # 5 240 20 # 6 240 22 E f f e c t s were measured r e p e a t e d l y a f t e r both p r e s s u r e s s t a b i l i z e d at c o n t r o l l e v e l . Note t h a t each time i n t r a m e d u l l a r y p r e s s u r e f e l l 50% or more d e s p i t e systemic b l o o d p r e s s u r e r i s e s . I n t r a m e d u l l a r y p r e s s u r e . 37 TABLE IV. E f f e c t s of continuous e p i n e p h r i n e i n f u s i o n f o r 1 hour Time B.P. ( c a r o t i d ) mm Hg I.M.P. (Femur) mm Hg C o n t r o l p e r i o d 20 min. E p i n e p h r i n e Immediately-A f t e r 3 min. 10 min. 20 min. 30 min. 40 min. 50 min. 60 min. Stopped e p i n e p h r i n e 160 300 250 250 250 250 250 250 250 Rapid r e t u r n t o c o n t r o l l e v e l w i t h i n 3 minutes 65 50 35 25 25 25 25 25 25 Gradual r e t u r n to c o n t r o l l e v e l w i t h i n 20 minutes Note p e r s i s t e n t r e d u c t i o n of i n t r a m e d u l l a r y p r e s s u r e d e s p i t e systemic b l o o d p r e s s u r e i n c r e a s e d . Note marked f a l l of i n t r a m e d u l l a r y p r e s s u r e w h i l e systemic b l o o d p r e s s u r e r i s e s d u r i n g e p i n e p h r i n e i n f u s i o n f o r a b r i e f p e r i o d . Marrow pressure r e t u r n s t o normal much more g r a d u a l l y a f t e r the i n f u s i o n was stopped. 39 \ I - i r — i r — ^ r 1 r r — i r 1 »—? 1 r — T — 1 r~ F i g . 5 a - I n t r a m e d u l l a r y p r e s s u r e f e l l from 53 mm Hg to 12 w h i l e systemic b l o o d p r e s s u r e rose from 130 mm Hg t o 180 as a r e s u l t of e p i n e p h r i n e i n f u s i o n . A f t e r i n f u s i o n was stopped, the former r e t u r n e d to the o r i g i n a l p r e s s u r e much slower than the l a t t e r . 40 (c) E f f e c t o f a c e t y l c h o l i n e on i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e s : With i n f u s i o n of a c e t y l c h o l i n e i n 4 dogs, both i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e f e l l s i m u l taneously, u n l i k e i n c o n t r a s t t o the response to e p i n e p h r i n e i n f u s i o n , as shown i n F i g u r e s 6 and 7. (d) E f f e c t o f no r - e p i n e p h r i n e on i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e s : In the 3 dogs, the e f f e c t s o f nor- e p i n e p h r i n e were observed. The e f f e c t s were q u i t e s i m i l a r t o those due t o e p i n e p h r i n e , as shown i n F i g u r e 8. The comparative e f f e c t s of nor- e p i n e p h r i n e and a c e t y l c h o l i n e are shown i n F i g u r e 9. (e) E f f e c t s of p i t r e s s i n r on i n t r a m e d u l l a r y and systemic p r e s s u r e s : In the 3 dogs, the e f f e c t s of p i t r e s s i n were a l s o observed. These e f f e c t s were s i m i l a r t o those observed w i t h e p i n e p h r i n e and nor- e p i n e p h r i n e but the r i s e i n systemic b l o o d p r e s s u r e was much sm a l l e r and the r e c o v e r y o f the c o n t r o l p r e s s u r e a f t e r s t o p p i n g the i n f u s i o n of p i t r e s s i n was much slower as shown i n F i g u r e 10. 41 F i g . 6 - E f f e c t of a c e t y l c h o l i n e on i n t r a m e d u l l a r y and systemic b l o o d p r e s s u r e . Note t h a t both p r e s s u r e s f e l l s i m u l t a n e o u s l y (see a l s o F i g . 7). 42 F i g . 7 - I l l u s t r a t i o n s of the s t a b i l i t y of systemic b l o o d p r e s s u r e and i n t r a m e d u l l a r y p r e s s u r e , and the comparative e f f e c t s of a c e t y l c h o l i n e and e p i n e -p h r i n e i n a dog. 43 F i g . 8 - The e f f e c t s of nor-epinephrine are i d e n t i c a l t o t h a t of e p i n e p h r i n e . Note remarkable d i s s o c i a t i o n of two p r e s s u r e s . 44 F i g . 9 - Comparison of e f f e c t s o f n o r - e p i n e p h r i n e and a c e t y l -c h o l i n e (compare w i t h F i g . 7). 45 F i g . 10 - E f f e c t s of p i t r e s s i n . Recovery of c o n t r o l p r e s s u r e i s much slower. Note the s m a l l systemic p u l s e p r e s s u r e i n c r e a s e . Compare wit h F i g . 9. (the same dog.) 46 85 2. Sr c l e a r a n c e r a t e and bone b l o o d flow 85 The time c o n c e n t r a t i o n curves of Sr and the i n t e -g r a t e d average concentration?- i n 5 r a b b i t s are g i v e n i n F i g u r e 11. 85 (a) Sr c l e a r a n c e r a t e by bone i n normal r a b b i t s : The r a t e of i n i t i a l S r 8 ^ c l e a r a n c e by bones, based on the humerus and t i b i a - f i b u l a , i n 10 normal r a b b i t s are g i v e n i n Table ::v and F i g u r e 12. On the b a s i s of the r a t e of c l e a r a n c e by the humerus, i t was 16.95 - 1.43 ml blood/min/100 gm f r e s h bone. . For the t i b i a - f i b u l a , i t was 15.91 + 1.41. The average f o r both bones was 16.43 i 1.42 ml blood/min/ 100 gm f r e s h bone (see a l s o Appendix 1 ) . (b) E f f e c t o f e p i n e p h r i n e on Sr c l e a r a n c e by bone i n r a b b i t s : E p i n e p h r i n e reduced the S r 8 5 c l e a r a n c e by 75% i n i n 10 r a b b i t s w i t h simultaneous i n f u s i o n , as shown i n Table VI, and compared w i t h those of the c o n t r o l s i n Table VII and F i g u r e 12 (see a l s o Appendix 2). The average c l e a r a n c e r a t e on the b a s i s of the humerus was 4.42 t 0.49 ml blood/min/100 gm f r e s h bone, and 2.96 t 0.51 f o r the t i b i a - f i b u l a . The average f o r both bones -j-was 3.69 - 0.50 ml blood/min/100 gm f r e s h bone which i s o n l y 1/4 of the c o n t r o l r a t e , as shown i n Table V. 47 85 Time - Concentrat ion Curve for Sr Disappearance from Blood. 5000-4 0 0 0 3000-2000 -1000-0 I Time in Min Injection. F i g . 11 - Tim e - c o n c e n t r a t i o n curve o f Sr i n b l o o d and i n t e g r a t e d average c o n c e n t r a t i o n f o r i n i t i a l 5 minute p e r i o d f o l l o w i n g intravenous i n j e c t i o n ; o f -'the i s o TABLE V. Sr c l e a r a n c e by bone i n normal r a b b i t s (ml blood/min/100 gm f r e s h bone) Ra b b i t No. Clearance r a t e s Humerus T i b i a - f i b u l a 12 18.40 15.20 14 14.41 14.44 15 12.22 9.83 19 18.12 18.52 21 16.92 12.92 22 18.22 15.58 23 20.64 22.97 24 24.39 23.19 25 18.31 17.48 41 7.91 8.97 16.95 15.91 +1.43 ±1.41 Average f o r 10 r a b b i t s 1 6 . 4 3 t l Standard e r r o r 49 85 TABLE VI. Sr. c l e a r a n c e by bone (ml blood/min/100 gm f r e s h bone) i n r a b b i t s w i t h e p i n e p h r i n e i n f u s i o n . Rabbit No. Clearance r a t e s Humerus T i b i a - f i b u l a 26 3.79 2.18 27 6.52 4.22 28 6.28 4.00 29 3.27 2.41 30 3.67 3.02 31 4.30 2.76 33 6.53 4.27 38 3.35 1.54 39 1.93 1.02 40 4.69 .4.16 4.42 2.96 ±0.49 ±0.51 Average f o r 10 r a b b i t s 3.69± i Standard e r r o r 50 TABLE V I I . I n i t i a l 5 minute S r 8 5 c l e a r a n c e by bone (ml blood/min/100 gm f r e s h bone) Bone No. of r a b b i t s (a) C o n t r o l Av.± S.E, (b) D i f f e r e n c e E p i n e p h r i n e a - b x ]_00% Av.± S.E. a Humerus T i b i a and f i b u l a 10 10 16.95 t 1.43 4.42 t 0.49 15.91 t 1.41 2.96 t 0.51 - 74% - 81% Average f o r both groups ± S.E. 16.43 i 1.42 3.69 t 0.50 - 78% D i f f e r e n c e " F i s h e r " t e s t r a t i o P r o b a b i l i t y t h a t d i f f e r e n c e was due to chance v a r i a t i o n A a - b = 12.74 ± 1.51 12.74 t = 1.51 = 8.44 p < 0.001 (See a l s o F i g u r e 12) 51 85 Initial 5 Minutes Bone Clearance of Sr in Rabbits ( ml. blood /min./IOOgm. bone ) ml./min./IOOgm. 30 20 • io -o J 1 Control 16.43 + 1.42 T Epinephrine 3.69 ± 0.50 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Rabbits. F i g . 12 - E s t i m a t i o n o f bone b l o o d flow from i n i t i a l c l e a r a n c e of Sr from b l o o d i n t i b i a - f 1'bula and humerus i n c o n t r o l and epi n e p h r i n e i n f u s e d r a b b i t s . The l a t t e r reduced the c l e a r a n c e by 75%. CHAPTER V - DISCUSSION The s e r i e s of o b s e r v a t i o n s and data presented i n d i c a t e c l e a r l y t h a t e p i n e p h r i n e reduces bone b l e e d i n g , bone b l o o d flow and i n t r a m e d u l l a r y p r e s s u r e o f bone su g g e s t i n g t h a t i t causes a profound v a s o c o n s t r i c t i o n . By measuring 85 the i n i t i a l Sr c l e a r a n c e by bone, based on the F i c k p r i n c i p l e , and assuming t h a t the s r 8 ^ i s c l e a r e d completely by bone m i n e r a l , the estimated bone blo o d flow appears t o be at l e a s t 16 ml per minute per 100 gm of f r e s h bone i n normal a d u l t r a b b i t s . T h i s v a l u e would r e p r e s e n t s about 5 - 10% of the r e s t i n g c a r d i a c out. The average normal i n t r a m e d u l l a r y p r e s s u r e of the femur of normal a d u l t dogs appeared t o be about 55 mm Hg, about 1/2 of the systemic b l o o d p r e s s u r e . E p i n e p h r i n e i n f u s i o n caused a 75% reduc-t i o n of the normal bone b l o o d flow, and reduced the i n t r a -m edullary p r e s s u r e by at l e a s t 60%. A. DISCUSSION ON THE QUALITATIVE ASPECTS OF' BONE BLOOD FLOW I t has been known f o r many years t h a t the v e s s e l s o f the bone marrow are abundantly s u p p l i e d w i t h medullated and non-medullated nerve f i b r e s i n man and animals as s t u d i e d i n 1901 by O t t o l e n g h i (35). D r i n k e r e t _ a l . (13) demonstrated t h a t these f i b r e s must have a v a s o c o n s t r i c t o r f u n c t i o n i n the dog. They observed i n t h e i r p e r f u s i o n study of the dog's t i b i a t h a t the p e r f u s i o n o u t f l o w was decreased by e l e c t r i c a l s t i m u l a t i o n of the nerve f i b r e s o f the marrow and by e p i n e p h r i n e i n f u s i o n w h i l e the i n f l o w p r e s s u r e was kept c o n s t a n t . Recently, Weiss and Root (46) supported t h i s view by t r a c i n g the v a s o c o n s t r i c t o r f i b r e s , by c u t t i n g s p e c i f i c nerves and by s t i m u l a t i n g t h e i r p e r i p h e r a l ends i n the c a t . The o b s e r v a t i o n s presented i n t h i s t h e s i s i n d i c a t i n g t h a t e p i n e p h r i n e caused a marked r e d u c t i o n and c e s s a t i o n of bone b l e e d i n g d e s p i t e a r i s e i n the systemic b l o o d p r e s s u r e suggests t h a t these f i b r e s are a d r e n e r g i c . The f a c t t h a t e p i n e p h r i n e causes a marked (60%) and p e r s i s t e n t f a l l o f the i n t r a m e d u l l a r y p r e s s u r e of bone wh i l e i t e l e v a t e s p e r s i s t e n t l y the systemic p r e s s u r e i s evidence t h a t the b l o o d c i r c u l a t i o n of bone i s under c o n t r o l of a d r e n e r g i c v a s o c o n s t r i c t o r f i b r e s . As has been w e l l demonstrated i n Tables I I - IV, and F i g u r e s 4, 5 and 7, t h e r e i s always d i s s o c i a t i o n of the two p r e s s u r e s d u r i n g e p i n e p h r i n e i n f u s i o n . The same i s t r u e w i t h nor-epine-p h r i n e , as shown i n F i g u r e s 8 and 9. These f a c t s were p r e v i o u s l y observed by Bloomenthal e t a l . (5) i n 1952 and by S t e i n e t a l . (40) i n 1958. H e r z i g and Root (20) i n 54 1958 and Weiss and Root (46) i n 1959 a l s o observed t h a t t h e r e was a f a l l of i n t r a m e d u l l a r y pressure d u r i n g stimu-l a t i o n of the p e r i p h e r a l cut end of the sympathetic nerve and e p i n e p h r i n e i n j e c t i o n i n the c a t . As shown i n Table IV, i t was p o s s i b l e to m a i n t a i n a markedly lowered i n t r a m e d u l l a r y p r e s s u r e f o r 40 to 60 minutes by a constant d r i p of e p i n e -p h r i n e . T h e r e f o r e i t i s not a t r a n s i t o r y r e f l e x phenomena but a p e r s i s t e n t v a s o c o n s t r i c t o r a c t i o n . In a sense the bone i s an unexpandible, r i g i d l y s e a l e d tube or box. As i s shown i n diagrammatic p r e s e n t a t i o n i n F i g u r e 13, t h e r e are b a s i c a l l y two e f f e c t i v e p r e s s u r e f a c t o r s i n the marrow cavity, 1 the one i s a s t a t i c f a c t o r , and the other i s a dynamic f a c t o r . The s t a t i c f a c t o r i s the r e l a t i v e l y s t a b l e marrow contents and w i l l have minimum e f f e c t s on the i n t r a m e d u l l a r y p r e s s u r e . The dynamic f a c t o r i s the bone b l o o d flow. The more the b l o o d i n f l o w the h i g h e r the i n t r a m e d u l l a r y pressure, and v i c e v e r s a . A f a l l i n the i n t r a m e d u l l a r y p r e s s u r e thus s i g n i f i e s a reduced i n f l o w which i s o b v i o u s l y c o n t r o l l e d by the vaso-motor system. As P o i s e u i l l e ' s experimental law i l l u s t r a t e s , the most important f a c t o r i n hemodynamics i s the r a d i u s of the v e s s e l . I f p r e s s u r e of i n f l o w i s doubled, then the flow might be a l s o doubled. But d o u b l i n g or r e d u c i n g 55 to one h a l f the r a d i u s of the v e s s e l i s f o l l o w e d by an i n c r e a s e b l o o d flow t o some 16 times or reduced t o 1/16 r e s p e c t i v e l y . Thus, o b v i o u s l y , a f a l l i n t r a m e d u l l a r y p r e s s u r e d e s p i t e a r i s e i n the systemic p r e s s u r e s i g n i f i e s a marked r e d u c t i o n of bone b l o o d f l o w due to a profound v a s o c o n s t r i c t i o n . The o p i n i o n of Bloomenthal e t al. (5) t h a t the f a l l o f i n t r a m e d u l l a r y p r e s s u r e i s due t o vaso-d i l a t i o n i s not i n agreement w i t h these r e s u l t s . Impaire-ment of a venous drainage might i n c r e a s e the i n t r a m e d u l l a r y pressure but the f a c t t h a t i t f e l l i n such c o n d i t i o n s w i t h epinephrine i n f u s i o n suggests t h a t the f a l l o f the i n t r a -m edullary p r e s s u r e i s due t o p r i m a r i l y a r e d u c t i o n of bone b l o o d i n f l o w by v a s o c o n s t r i c t i o n of the a r t e r i o l e s . The other drugs such as n o r - e p i n e p h r i n e and p i t r e s s i n have s i m i l a r e f f e c t s t o epinephrine (Figures 8 - 10). However, a c e t y l c h o l i n e caused a simultaneous f a l l o f both p r e s s u r e s as shown i n F i g u r e s 6 and 7. T h i s e f f e c t i s s i m i l a r t o t h a t o b t a i n e d s t i m u l a t i n g the cut p e r i p h e r a l end of the vagus nerve as was observed by H e r z i g and Root (20). Thus, the i n t r a m e d u l l a r y p r e s s u r e of bone i s a good index of changes i n the bone b l o o d flow. I t can be inde-pendent of and a l s o dependent on the systemic b l o o d p r e s s u r e . 56 Diagrammatic Relationship of Bone Blood Flow and Intramedullary Pressure. Medullary Cavity Blood Flow Med. pressure Blood Flow Med. pressure Stable pressure factor (Marrow Contents) Normal dynamic pressure factor ( Blood Flow ) Modified dynamic factor by Epinephrine. ( even systemic B.P f ) F i g . 13 - I n t r a m e d u l l a r y p r e s s u r e of bone i s a good index" of changes i n bone hemodynamics. The more the b l o o d i n f l o w , the h i g h e r the i n t r a m e d u l l a r y p r e s s u r e , and v i c e v e r s a . I t can be independent of the systemic b l o o d p r e s s u r e . E p i n e p h r i n e causes a f a l l because of v a s o c o n s t r i c t i o n and r e d u c t i o n of bone b l o o d flow. A c e t y l c h o l i n e causes a f a l l because systemic pressure f a l l s . B. DISCUSSION ON THE QUANTITATIVE ASPECTS OF BONE BLOOD FLOW. I t i s unfortunate t h a t no q u a n t i t a t i v e data on volume b l o o d flow i n bone i s a v a i l a b l e i n man and most animals t o date. . F r e d e r i c k s o n , Honour and Copp (15) and Copp and Suiker (6) estimated bone b l o o d flow t o be about 5% of the r e s t i n g c a r d i a c output i n the r a t . They measured the i n i t i a l C a ^ c l e a r a n c e of bone, and a p p l i e d the F i c k p r i n c i p l e . In work r e p o r t e d i n t h i s t h e s i s , the same technique and r e a t i o n a l e were used t o study the bone b l o o d f l o w i n r a b b i t s . The r e s u l t s are g i v e n i n Table V - VII, and F i g u r e 12 (a l s o i n Appendix 1 ) . The c l e a r a n c e ranged from 8.5 to 24.0 ml blood/min/100 gm f r e s h bone w i t h the average, i n 10 normal r a b b i t s , .16.43 - 1.42 ml blood/min/100 gm f r e s h bone based on the t i b i a - f i b u l a and humerus. Copp (7) found i n h i s study t h a t the estimated bone b l o o d flow i n the rat- ranged from 10 - 30 ml/min/100 gm f r e s h weight of bone which i s q u i t e s i m i l a r t o t h a t i n r a b b i t s . The va l u e of e f f e c t i v e bone b l o o d flow i n r a b b i t s o b t a i n e d i n t h i s work was, a t l e a s t , 16.0 ml/min/100 gm of f r e s h bone, and would r e p r e s e n t about 8% of the r e s t i n g c a r d i a c output of the r a b b i t , s i n c e 58 the average c a r d i a c output i n the white a d u l t r a b b i t s i s r e p o r t e d to be approximately 450 ml/min (39), and assuming the f r e s h bone weight i s about 10 - 15% of the body weight. The average weight of the r a b b i t s used i n these s t u d i e s was about 2.00 kg. The r a t i o n a l e of t h i s i n d i r e c t method of bone bloo d flow e s t i m a t i o n i s based upon the c l e a r a n c e of a bone-seek i n g r a d i o i s o t o p e by bone from the b l o o d c i r c u l a t i n g through bone. T h i s c l e a r a n c e r a t e then would r e p r e s e n t a t l e a s t minimum bone blood flow. T h i s method of r a d i o -i s o t o p e c l e a r a n c e f o r e s t i m a t i o n of bone bloo d flow i s then a c t u a l l y based upon the F i c k p r i n c i p l e . I t i s assumed t h a t C a 4 5 or S r 8 ^ i s r a p i d l y and almost completely taken up by the bone through i o n exchange w i t h the l a r g e excess of exchangeable c a l c i u m i n the bone d u r i n g the i n i t i a l p e r i o d of 5 - 10 minutes, a f t e r i n j e c t i o n o f the r a d i o i s o t o p e b e f o r e s i g n i f i c a n t amount of Sr 0-" have b u i l t up i n bone. The Sr c o n c e n t r a t i o n i n b l o o d l e a v i n g bone would thus be an e s s e n t i a l l y z e r o . The c l e a r a n c e , which i s ob t a i n e d by d i v i d i n g the bone uptake by the i n t e -g r a t e d average c o n c e n t r a t i o n i n b l o o d d u r i n g the p e r i o d would be, by F i c k p r i n c i p l e , e i t h e r e q u i v a l e n t t o e f f e c t i v e bone b l o o d flow or at l e a s t minimum b l o o d flow. T h i s i s 59 CRYSTALS OF BONE SALT \ / \ / 83 REMOVAL OF Sr BY EXCHANGE. > Ca F i g . 14 - R a d i o a c t i v e s t r o n t i u m ( S r 8 5 ) i s one of the known c r i t i c a l bone seeking r a d i o i s o t o p e s . I t s uptake by bone i s presumably through i o n exchange. 60 Sr Clearance by Bone F i g . 15 - R a t i o n a l e of the i n d i r e c t method of bone b l o o d flow e s t i m a t i o n by the r a t e of S r 8 5 c l e a r a n c e by bone. T h i s i s ob t a i n e d by d i v i d i n g bone uptake by i n t e -g r a t e d average a r t e r i a l c o n c e n t r a t i o n i n blood, based on F i c k p r i n c i p l e and the assumption t h a t bone c l e a r s S r 8 5 almost completely from bone b l o o d d u r i n g the f i r s t 5 - 1 0 minutes a f t e r i n j e c t i o n of the i s o t o p e . 61 based upon a s i m i l a r p r i n c i p l e t o t h a t used to measure e f f e c t i v e r e n a l b l o o d flow by d i o d r a s t c l e a r a n c e by the k i d n e y . I t would be more i d e a l and a c t u a l l y d e s i r a b l e to o b t a i n the b l o o d from the n u t r i e n t a r t e r y and v e i n f o r d e t e r m i n a t i o n of the d i f f e r e n c e of the i s o t o p e c o n c e n t r a t i o n i n order t o o c t e s t the assumption t h a t the venous c o n c e n t r a t i o n o f S r O J i s z e r o . U n f o r t u n a t e l y , i t i s n e i t h e r easy nor p h y s i o l o -g i c a l l y p r a c t i c a b l e , though not i m p o s s i b l e , to draw the b l o o d from the n u t r i e n t a r t e r y and v e i n under p h y s i o l o g i c a l c o n d i -t i o n without d i s t u r b i n g bone b l o o d c i r c u l a t i o n . T h i s i s l a r g e l y due t o the f a c t t h a t they are v e r y s m a l l i n s i z e and l o c a t e d deeply, and p a s s i n g through deep muscles. I t i s v e r y u n f o r t u n a t e t h a t there i s n e i t h e r a d i r e c t method nor s a t i s f a c t o r y and p r a c t i c a b l e i n d i r e c t method to measure bone bl o o d flow i n man (and, a c t u a l l y i n animals, t o o ) . I t i s t h e r e f o r e not s u r p r i s i n g t h a t no data on t h i s s u b j e c t has been r e p o r t e d y e t . One can c a l c u l a t e the bone b l o o d flow i n man r o u g h l y by s u b s t r a c t i n g the known bloo d flow of the other organs of the body from the t o t a l c a r d i a c output. I f one r e a l i z e s the f a c t t h a t the t o t a l b l o o d volume i s d i f f e r e n t i n s p e c i e s , i n i n d i v i d u a l s , from time to time even i n the same i n d i v i d u a l . 62 and the methods measuring b l o o d flow of other organs are by no means e n t i r e l y s a t i s f a c t o r y and the r e s u l t s , t h e r e f o r e , are not always a c c u r a t e ; i t i s not s u r p r i s i n g t h a t t h e r e i s a wide range of d i f f e r e n c e i n r e p o r t e d data of b l o o d flow through other organs. The f o l l o w i n g data were o b t a i n e d from two r e c o g n i z e d textbooks of p h y s i o l o g y (3, 12). The v a l u e s were estimated by v a r i o u s workers but u s u a l l y were ad j u s t e d t o a man wighing about 60 - 65 kg. In Table V I I I , the b l o o d flow of the other remaining organs, ayerate 629 ml/min would be of flows to bones, t h y r o i d s , adrenals, e t c . I f one accounts f o r 300-400 ml/min of t h i s by bone b l o o d flow t h i s would be 5-8% of the c a r d i a c output i n man. F i n a l l y , the f a c t t h a t e p i n e p h r i n e caused 75% r e d u c t i o n 85 of Sr c l e a r a n c e i n 10 r a b b i t s s t u d i e d a l s o s t r o n g l y i n d i c a t e s a marked r e d u c t i o n of bone b l o o d flow and profound vasocons-t r i c t i o n . The s i g n i f i c a n t 75% r e d u c t i o n of the r a d i o i s o t o p e c l e a r a n c e by bone d u r i n g simultaneous e p i n e p h r i n e i n f u s i o n i n 10 r a b b i t s emphasizes s e v e r a l important p o i n t s . I t causes r e d u c t i o n of bone b l o o d flow by marked v a s o c o n s t r i c t i o n . Since S r 8 5 uptake by bone i s by i o n i c exchange w i t h bone m i n e r a l , as f a r as we know, the l a t t e r must have c l o s e q u a n t i t a t i v e r e l a t i o n s h i p 63 w i t h bone blo o d flow. A l s o , s i n c e e p i n e p h r i n e i s a naturally-o c c u r r i n g hormone i n the body and a c t s as a sympathomimetic v a s o c o n s t r i c t o r on bone, i t i s q u i t e p o s s i b l e t h a t there i s c l o s e r e l a t i o n s h i p between bone m i n e r a l metabolism and sympathetic vasomotor c o n t r o l o f bone, as the l a t t e r i s c l o s e l y r e l a t e d t o the hemodynamics of bone. 63(a) TABLE V I I I . Known b l o o d flow of v a r i o u s organs i n man. Organs Blood flow (ml/min) S e r i e s 1 S e r i e s 2 C a r d i a c output H e p a t o - p o r t a l Kidney (both) Muscles ( s k e l e t a l ) B r a i n Heart Sk i n Others 5400 1500 1260 815 750 250 460 340 5470 1450 1100 840 757 210 220 918 Average 629 64 CHAPTER VI - SUMMARY L i t t l e i s known about the hemodynamics of bone and the q u a n t i t a t i v e r e l a t i o n s h i p of bone blo o d flow and metabolism of bone. The c u r r e n t concepts of anatomy and p h y s i o l o g y of bone b l o o d c i r c u l a t i o n have been reviewed. A s e r i e s of e xperimental s t u d i e s on bone blo o d flow i n a d u l t dogs and r a b b i t s were c a r r i e d out i n c l u d i n g the e f f e c t s of epin e p h r i n e and some other drugs which a f f e c t vasomotor tone. The s i g n i f i c a n c e o f the changes o f the i n t r a m e d u l l a r y p r e s s u r e o f bone i n r e l a t i o n s h i p t o bone hemodynamics was q u a l i t a t i v e l y and q u a n t i t a t i v e l y s t u d i e d u s i n g a d u l t dogs. A technique was developed t o estimate i n d i r e c t l y bone 85 b l o o d flow i n animals by the r a t e of Sr c l e a r a n c e by bone. Since the r a d i o i s o t o p e i s known as a c r i t i c a l bone seeking substance, the i n i t i a l c l e a r a n c e r a t e by bone would r e p r e s e n t a t l e a s t minimum bone b l o o d flow, and may be e q u i v a l e n t t o the e f f e c t i v e bone b l o o d flow. The average v a l u e o b t a i n e d by t h i s method i n 10 normal r a b b i t s was 16.0 ml blood/min/100 gm f r e s h weight bone. Ep i n e p h r i n e caused r e d u c t i o n (and c e s s a t i o n ) of bone' b l e e d i n g , i n t r a m e d u l l a r y p r e s s u r e (60%), bone blo o d f l o w and Sr c l e a r a n c e (75%) which suggests marked vasocons-t r i c t i o n o f bone v e s s e l s . Since bone i s such an important m i n e r a l r e s e r v o i r , i t must have an important r o l e i n the r e g u l a t i o n of the c a t i o n l e v e l s - and e s p e c i a l l y of C a + + - i n body f l u i d s . The t i n y c r y s t a l s of bone m i n e r a l are l i k e the r e s i n p a r t i c l e s of an i o n exchange r e s i n . L i k e the kidneys, bone i s i n v o l v e d i n homeostatic c o n t r o l , and t h i s may e x p l a i n the enormous b l o o d flow through bone r e l a t i v e t o i t s m e t a b o l i c needs. I t i s i n t e r e s t i n g t h a t bone b l o o d i s g r e a t l y reduced by ep i n e p h r i n e j u s t as i s r e n a l b l o o d flow. CHAPTER VII - CONCLUSIONS 66 The s e r i e s of o b s e r v a t i o n s and data presented i n t h i s t h e s i s l e a d t o the f o l l o w i n g c o n c l u s i o n s . 1. The changes i n the i n t r a m e d u l l a r y p r e s s u r e o f 85 bone and i n Sr c l e a r a n c e by bone appear t o c o r r e l a t e v e r y w e l l w i t h the changes i n the bone blo o d flow. 2. An i n d i r e c t method of e s t i m a t i n g the bone b l o o d 85 flow was developed by measuring an i n i t i a l Sr c l e a r a n c e o f bone, based upon the F i c k p r i n c i p l e . 3. The average volume of the bone b l o o d flow 85 estimated by i n i t i a l Sr c l e a r a n c e of the humerus and t i b i a - f i b u l a i n 10 normal a d u l t white r a b b i t s appears t o be at l e a s t 16 ml/min/100 gm f r e s h bone or about 5 - 10% of the r e s t i n g c a r d i a c output. 4. In a d u l t r a b b i t s average r a t e o f the bone blo o d flow, (per gram o f f r e s h bone) of the humerus and t i b i a - f i b u l a are about e q u a l . 5. Continuous e p i n e p h r i n e i n f u s i o n appears t o reduce s i g n i f i c a n t l y (to 1/4 c o n t r o l value) the bone b l o o d flow i n a d u l t r a b b i t s as estimated on the b a s i s of i n i t i a l S r 8 ^ c l e a r a n c e of t h e i r bones. Epi n e -p h r i n e a d m i n i s t r a t i o n i n 10 r a b b i t s reduced the 67 cl e a r a n c e t o 3.7 ml/min/100 gm of f r e s h bone. Ep i n e p h r i n e i n f u s i o n reduces and stops bone b l e e d i n g . The normal i n t r a m e d u l l a r y p r e s s u r e of the femur i n 11 a d u l t dogs ranged from 40 to 80 mm Hg w i t h an average value of 55 mm Hg, approximately 1/2 of the systemic b l o o d p r e s s u r e . On a d m i n i s t r a t i o n of e p i n e p h r i n e the i n t r a -m edullary p r e s s u r e of bone f a l l s p e r s i s t e n t l y d e s p i t e a r i s e i n the systemic b l o o d p r e s s u r e . T h i s suggests s t r o n g l y t h a t e p i n e p h r i n e causes a profound v a s o c o n s t r c t i o n and r e d u c t i o n i n bone b l o o d flow. . A l s o , i t i n d i c a t e s t h a t the i n t r a m e d u l l a r y p r e s s u r e can be independent of the systemic b l o o d p r e s s u r e . Nor-epinephrine and p i t r e s s i n appear to have s i m i l a r , i f not i d e n t i c a l , e f f e c t on the hemodynamics o f bone t o t h a t of e p i n e p h r i n e . A c e t y l c h o l i n e causes simultaneous f a l l i n the i n t r a m e d u l l a r y and the systemic b l o o d p r e s s u r e s . I t s i g n i f i e s t h a t the former can be a l s o dependent on the systemic b l o o d p r e s s u r e . The bone b l o o d flow appears to be r e g u l a t e d by the a d r e n e r g i c vasomotor system. The f a c t o r s a f f e c t i n g bone hemodynamics appear t o be m u l t i p l e . 69 APPENDICES Appendix 1: Data of i n i t i a l 5 minute S r 8 ^ c l e a r a n c e by bones i n a d u l t r a b b i t s . (See a l s o Tables IV, V and F i g . 12) Rabbits Average concent. Humerus T i b i a - f i b u l a No. Wt/gm i n ml b l o o d per minute Bone wt/gm Uptake CPM C S r 8 5 * Bone wt/gm Uptake CPM C S r 8 5 * CONTROL 12 2,134 2367 4.5 1963 18.40 7.5 2698 15.20 14 2, 100 2983 4.3 1845 14.41 7.1 3059 14.44 15 2,455 2567 5.6 1757 12.22 8.8 2221 9.83 19 1, 745 1405 3.4 866 18.12 6.1 1593 18.52 21 1, 540 10968 3.8 7052 16.92 5.9 8362 12.92 22 1,400 9874 3.7 6657 18.22 6.2 9538 15.58 23 1, 660 7521 4.0 6211 20.64 6.7 11555 22.97 24 1, 810 7533 4.6 8388 24.39 7.1 12311 23.19 25 1, 650 8447 4.2 6495 18.31 7.1 10480 17.48 41 2,150 12539 6.4 6356 7.91 10.0 11254 8.97 Av. 1, 864 4.4 16.95 + 1.43** 7.2 15.91 + 1.41** MEAN CONTROL Sr°° CLEARANCE 16.43 Z 1.42 BY BONE IN 10 ADULT RABBITS * Clearance ml blood/min/100 gm f r e s h bone ± Standard e r r o r NOTE: The data of the i n i t i a l 5 minute S r b 5 c l e a r a n c e by bone i n 10 r a b b i t s which r e c e i v e d e p i n e p h r i n e i n f u s i o n s i m u l -t a n e o u s l y are shown i n Appendix 2. 70 85 Appendix 2: The data of i n i t i a l Sr c l e a r a n c e r a t e s of bone of 10 r a b b i t s which r e c e i v e d simultaneous epine-p h r i n e i n f u s i o n . R a b b i t s Average concent. No. Wt/gm i n ml b l o o d per minute WITH SIMULTANEOUS EPINEPHRINE INFUSION 26 2, 050 12434 5.4 2496 3.79 8.9 2417 2.18 27 1,470 12011 3.3 2584 6.52 6.4 3248 4.22 28 1, 750 10036 3.5 2206 6.28 6.9 2769 4.00 29 2,150 9012 4.5 1322 3.27 7.9 1713 2.41 30 1, 580 10347 4.1 1556 3.67 6.0 1874 3.02 31 2, 150 7547 4.8 1579 4.30 8.2 1730 2.76 33 1, 710 2271 3.7 549 6.53 6.7 650 4.27 38 2, 150 20705 4.2 • 2989 3.35 7.7 2458 1.54 39 2, 250 25749 4.2 2296 1.93 8.1 2133 1.02 40 2, 250 20601 4.7 4550 4.69 8.6 7384 . 4.1.6 Av. 1,951 4.2 + 4.42 0.49** 7.5 + 2.96 , ** 0.51 or. MEAN Sr° CLEARANCE RATE IN 10 3.69 t 0.50 ADULT RABBITS RECEIVED SIMULTANEOUS EPINEPHRINE * S r 8 5 c l e a r a n c e ml blood/min/100 gm f r e s h bone ** ± standard e r r o r Humerus T i b i a - f i b u l a Bone Uptake Bone Uptake wt/gm CPM C S r 8 5 wt/gm CPM C S r 8 5 ' 71 BIBLIOGRAPHY 1. B a r c r o f t , H.: C i r c u l a t i o n . The h e a r t and the flow o f blood, through the v e s s e l s , _in Human Physiology, by Winton & B a y l i s s , pp.16-42, 4th Ed. J . & A. C h u r c h i l l L t d . , London, 1955. 2. . Bauer, G.C.H.: K i n e t i c s of c a l c i u m and s t r o n t i u m metabolism i n man, i n Bone as a T i s s u e , 118, McGraw-Hill Book Co., New York, Toronto, London, 1960. 3. Bazett, H.C. and Bard, P.: The bl o o d supply of s p e c i a l r e g i o n s , _in M e d i c a l Physiology, by Bard, pp. 220-243, 10th Ed., C C . Mosby Co., S t . L o u i s , 1956. 4. Branemark, P.I.: V i t a l microscopy of bone marrow i n r a b b i t s , Scandinav. J . C l i n . & Lab. In v e s t . 11 ( s u p p l . 38): 82, 1959. 5. Bloomenthal, E.D., Olson, W.H., and Necheles, H.: S t u d i e s on the bone marrow c a v i t y of the dog: F a t embolism 0 and marrow pr e s s u r e , Surg. Gyne. & Obst., 94:215-222, 1952. 6. Copp, D.H. and Suiker, A.P.: St u d i e s of c a l c i u m k i n e t i c s i n c a l c i u m - and p h o s p h o r u s - d e f i c i e n t r a t s w i t h the a i d of r a d i o c a l c i u m , _in R a d i o i s o t o p e s i n Bone, ed. by McLean, L a c r o i x and Budy, 1-6, 1962, B l a c k w e l l S c i . Pub. Oxford. 72 7. Copp, D.H.: I n i t i a l c l e a r a n c e o f C a 4 5 and P^2 Q f bone from b l o o d i n the r a t , P e r s o n a l Communication. 8. Copp, D.H.: Time-Concentration curves f o r disappearance of 45 39 Ca and P from b l o o d of the r a t , P e r s o n a l Communication. 9. Copp, D.H. and Shimm, S.S.: E f f e c t of e p i n e p h r i n e on bone bl o o d flow ( s t u d i e d by i v i n f u s i o n of Ca and EDTA), Proc. Can. Fed. B i o l . Soc. 5:22, June, 1962. 10 Cregg, D.E.: E s t i m a t i o n of volume of b l o o d flow, v e l o c i t y of b l o o d flow, volume of organ, v e s s e l s , c a v i t i e s and r e g i o n s : C i r c u l a t i o n time, _in P h y s i o l o g i c a l B a s i s of M e d i c a l P r a c t i c e , by Best and T a y l o r , pp. 205-230, 7th Ed. Wm. & W i l k i n s Co., Baltimore, 1961. 11. Cregg, D.E.: F u n c t i o n a l c h a r a c t e r i s t i c s of the systemic and pulmonary c i r c u l a t i o n , i n P h y s i o l o g i c a l B a s i s of M e d i c a l P r a c t i c e , by Best and T a y l o r , p.151, Wm. & W i l k i n s Co., Baltimore, 1961. 12. Davson, H. and Eggleton, M.G.: S t a r l i n g ' s Human Physiology, pp.202-224, 13th Ed., Lea & F e b i g e r , P h i l a d e l p h i a , 1962. 73 13. D r i n k e r , C.K. and D r i n k e r , K.R.: A method f o r m a i n t a i n i n g an a r t i f i c i a l c i r c u l a t i o n through the t i b i a of the dog, w i t h a demonstration of the vasomotor c o n t r o l of the marrow vessels,. Am. J . P h y s i o l . 40:514, 1916. 14. D r i n k e r , C.K. and D r i n k e r , K.R. and Lund, C.C.: C i r c u l a t i o n i n mammalian bone marrow, Am. J . P h y s i o l . 62:1, 1922. 15. F r e d r i c k s o n , J.M., Honour, A . J . and Copp, D.H.: Measurement 45 of i n i t i a l bone c l e a r a n c e o f Ca from b l o o d i n the rat,. #157, Fed. Proceedings, V o l . 14, No.l, March, 1955. 16. Green, H.D.: C i r c u l a t i o n ; P h y s i c a l p r i n c i p l e s , _in M e d i c a l P h y s i c s , Ed. by G l a s s e r , v o l . 2, Chicago, Year Book Pub., 1955. 17. H a l i b u r t o n , R.A., S u l l i v a n , CR., K e l l y , P.J. and Peterson, L.F.A.: The extraosseous and i n t r a o s s e o u s b l o o d supply of the t a l u s , J . Bone and J o i n t Surg. 40-A: 1115, 1958. 18. Ham, A.W. : H i s t o l o g y , 3rd Ed.. J.B. L i p p i n c o t t Co. ,. P h i l a d e l p h i a & Montreal, 1957. 19. H a r r i s , W.R. and Ham, A.W.: The mechanism of n u t r i t i o n i n bone and how i t a f f e c t s i t s s t r u c t u r e , r e p a i r and f a t e on t r a n s p l a n t a t i o n , _in Bone S t r u c t u r e and Metabolism, CIBA Symposium, 135-147, L i t t l e , Brown & Co., Boston, 1956. 20. H e r z i g , E. and Root, W.S.: R e l a t i o n of sympathetic nervous system t o b l o o d p r e s s u r e of bone marrow, Am. J . P h y s i o l . , 196(5):1053-1056, 1959. 21. Johnson, R.W.: A p h y s i o l o g i c a l study of the b l o o d supply of the d i a p h y s i s , J . Bone & J o i n t Surg. 9:153, 1927. 22. Jowsey, J . : Age changes i n human bone, C l i n i c a l O rthopedics, 17:210, 1960. 23. K e l l y , P.J., Peterson, L.F.A. and Janes, J.M.: A method of u s i n g s e c t i o n s of bone prepared f o r microangio-graphy f o r subsequent h i s t o l o g i c study,. Proceedings, The Mayo C l i n i c , 34 (11) :247, May, 1959. 24. K e l l y , P.J., Janes, J.M. and Peterson, L.F.A.: The e f f e c t of a r t e r i o v e n o u s f i s t u l a e i n the v a s c u l a r , p a t t e r n o f the femora o f immature dogs, A m i c r o a n g i o g r a p h i c study,. J . Bone & J o i n t Surg. 41A: 1101, 1959. 25. Kelly,. P.J., Peterson, L.F.A., Pease, D.C. and Zamboni, L. : C i r c u l a t i o n of bone, _in Blood v e s s e l s and lymphatics, pp.531, Ed. by Abramson, Academic Press, New York and London, 1962. 26. K i n o s i t a , R., Ohno, S. and Bierman, H.R.: Observations on r e g e n e r a t i n g bone marrow t i s s u e jLn s i t u (abst.) Proc. Am. Assoc. Cancer Res. 2:125, 1956. 75 27. Lockhart, R.D., Hamilton, G.F. and Fyfe,. F.W.: Anatomy of the Human Body, J.B. L i p p i n c o t Co., P h i l a d e l p h i a , 1959. 28. Langer, K.: Uber das Gafasssystem der Rohrenknochen, mit B e i t r a g e n zur Kenntniss des Baues und der Entwicklung des Knochengewebes. Denkschr.D.K.Akad. der Wissen. Mathemat. Naturw.-shaft. C l a s s e , .Wien,. 36 (abthj.) : 1-40, 1876. 29. L i s c o , H.: Bone as a c r i t i c a l organ f o r the d e p o s i t i o n of r a d i o a c t i v e m a t e r i a l s , in Bone S t r u c t u r e and Metabolism, CIBA Symposium, 272-283, L i t t l e , Brown & Co.,. Boston, 1956. 30. Macnab, I . : Blood c i r c u l a t i o n of long bone, J . Bone & J o i n t Surg. 40A-.1433, 1958. 31. McDonald, N.E.: The r a d i o i s o t o p e osteogram; k i n e t i c s t u d i e s of s k e l e t a l d i s o r d e r s i n humans, C l i n i c a l Orthope-d i c s , 17:154, 1960. 32. Misrahy, G.A., Hardwick, D.F., Brooks, C.J., Garwood, V.P. and H a l l , W.P.: Bone, bone marrow and b r a i n oxygen Am. J . P h y s i o l . 202(2): 225-231, 1962. 33. Morgan, J.D.: Blood supply o f growing r a b b i t ' s t i b i a , J.Bone & J o i n t Surg. 41B: 185, 1959. 76 34. Nelson, G.E. J r . , Kelly,. P.J., Peterson, L.F.A. and Janes, J.M.: Blood supply of the human t i b i a . J . Bone & J o i n t Surg. 42-A: 625, I960.. 35. O t t o l e n g h i , D.: Sur l e s n e r f s de molle des os, A r c h . I t a l . B i o l . , 37:73-80, 1902. 36. Peterson, L.F.A., K e l l y , P.J., and Janes, J.M.: U l t r a s t r u c t u r e of Bone: Technic of microangiography as a p p l i e d t o the study of bone, Proceedings, The Mayo C l i n i c , 32(24):681, 1957. 37. Peterson, L.F.A. and K e l l y , P.J.: S u r g i c a l aspect of b l o o d supply of bone, I n s t r u c t . Course L e c t u r e s , Am. Acad. Orthopedic Surg. 18:221-233, C.V. Mosby, S t . L o u i s , 1961. 38. Rut i s h a u s e r , E.: V a s c u l a r i t y of bone in:,.relation to p a t h o l o -g i c a l s t u d i e s , jLn Bone S t r u c t u r e and Metabolism, CIBA Symposium, 239-248, L i t t l e , Brown & Co., Boston, 1956. 39. Spector, W.S.(Ed.): C a r d i a c output, _in Handbook of B i o l o g i c a l Data, The D i v i s i o n of B i o l o g y and A g r i c u l t u r e , The N a t i o n a l Academy of Sciences, The N a t i o n a l Research C o u n c i l , Wright A i r Development Center, Report #56-273, p.279, October, 1956. 77 40. S t e i n , A.H. J r . , Morgan, H.C. and Porras, R.F.: The e f f e c t of p r e s s o r and depressor drugs i n i n t r a m e d u l l a r y bone marrow pr e s s u r e , J . Bone & J o i n t Surg. 40A: 1103-1110, 1958. 41. S t e i n , A.H. J r . , Morgan, H.C. and Reynolds, F.C.: V a r i a t i o n s i n normal bone marrow p r e s s u r e s , J.. Bone & J o i n t Surg. 39A:1129-1134, 1957. 42. S t e i n , I., S t e i n , R.O. and B e l l e r , M.L.: L i v i n g Bone i n the He a l t h and Disease, 2nd Ed. J.B. L i p p i n c o t t Co., P h i l a d e l p h i a and Montreal, 1955. 43. Trotman, N.M. and K e l l y , W.D.: The e f f e c t of sympathectomy on b l o o d f l o w t o bone, J A M A , 183(2):121, Jan,12, 1963. 44. Tr u e t a , J . and H a r r i s o n , M.J.M.: The normal v a s c u l a r anatomy of the femoral head i n a d u l t man, J . Bone & J o i n t Surg. 35B: 442, 1953. 45. Trueta, J . and Morgan,. J.D.: The v a s c u l a r c o n t r i b u t i o n s t o os t e o g e n e s i s , s t u d i e s by the i n j e c t i o n method. . J . Bone & J o i n t Surg. 42B:97, 1960. 46. Weiss, R.A. and Root, W.S.: I n n e r v a t i o n of the v e s s e l s of the marrow c a v i t y of c e r t a i n bones. Am. J . P h y s i o l . 197(6):1255-1257, 1959. 

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