@prefix vivo: . @prefix edm: . @prefix ns0: . @prefix dcterms: . @prefix skos: . vivo:departmentOrSchool "Science, Faculty of"@en, "Zoology, Department of"@en ; edm:dataProvider "DSpace"@en ; ns0:degreeCampus "UBCV"@en ; dcterms:creator "Davis, John Christopher"@en ; dcterms:issued "2011-07-09T22:32:17Z"@en, "1968"@en ; vivo:relatedDegree "Master of Science - MSc"@en ; ns0:degreeGrantor "University of British Columbia"@en ; dcterms:description """The influence of temperature and activity on certain cardiovascular and respiratory parameters in adult sockeye salmon was studied. Cannulae were implanted in the dorsal aorta and buccal cavities of fish which were forced to swim in a tunnel-type respirometer until they fatigued. Three groups of fish were acclimated and tested at 5, 15, and 22°C respectively. Pressures recorded from the dorsal aorta and buccal cavity gave information about heart rate, blood pressure, pulse pressure, ventilation rate and pressures in the buccal cavity before, during and after the fish were fatigued by swimming. Hematocrit data revealed the blood oxygen capacity of these fish, to be approximately 9 vols %. Knowledge of the blood oxygen capacity, heart rate and the metabolic rates of adult sockeye at various temperatures and levels of activity allowed calculation of stroke volume and cardiac output by the Fick principle. During successively greater swimming activity heart rate and blood pressure rose in all three test groups while ventilation rate was highly variable. Calculated stroke volume and cardiac output increased markedly and it is suggested that the peripheral resistance of the vascular system diminished during exercise. The increase in heart rate during exercise is thought to be related to a release of vagal tone or possibly, to the presence of circulating catecholamines. Elevated dorsal aortic pressure during activity was undoubtably the result of elevated cardiac output. Since dorsal aortic pressure did not increase in accordance with the increases in oxygen uptake observed during activity it is suggested that peripheral resistance decreases in the face of elevated cardiac output. Post-exercise ventilation rate approached resting levels within one hour after fatigue but heart rate and buccal pressure remained above resting levels. High post-exercise heart rates and buccal pressures were believed to be evidence for the presence of an oxygen debt. Blood pressures fell below resting levels in the 15 and 22°C test groups following fatigue and remained low one hour after fatigue. These low pressures may indicate that vasodilation of peripheral vessels had occurred to facilitate flushing of the muscles with blood and aid in the elimination of oxygen debt. Temperature appeared to directly influence heart rate of both quiescent and active fish. Higher acclimation and test temperatures produced higher heart rates than lower acclimation and test temperatures. Presumably temperature influences heart rate by acting directly on membrane phenomena in the myocardium. No cardiac failure was observed in sockeye, even at 22°C during severe exercise. Routine and active oxygen uptake increased with temperature but the rate of increase of active oxygen uptake decreased with temperature - possibly because of the low availability of oxygen in warm water. Temperature appeared to directly influence the ventilation rate of quiescent fish. Higher temperatures were accompanied by high ventilation rates, undoubtably as a result of increased routine metabolic rate at high temperatures and scarcity of oxygen in warm water."""@en ; edm:aggregatedCHO "https://circle.library.ubc.ca/rest/handle/2429/35960?expand=metadata"@en ; skos:note "THE INFLUENCE OF TEMPERATURE AND ACTIVITY ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS' IN ADULT SOCKEYE SALMON by JOHN CHRISTOPHER DAVIS B . S c , U n i v e r s i t y o f V i c t o r i a , 1966 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t h e Department of Z oology We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA Fe b r u a r y , 1968 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i 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 an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, C a n a d a i ABSTRACT The i n f l u e n c e o f te m p e r a t u r e and a c t i v i t y on c e r t a i n c a r d i o v a s c u l a r and r e s p i r a t o r y parameters i n a d u l t sockeye salmon was s t u d i e d . Cannulae were i m p l a n t e d i n t h e d o r s a l a o r t a and b u c c a l c a v i t i e s o f f i s h w h i c h were f o r c e d t o swim i n a t u n n e l - t y p e r e s p i r o m e t e r u n t i l t h e y f a t i g u e d . Three groups o f f i s h were a c c l i m a t e d and t e s t e d a t 5, 15, and 22°C r e s p e c t i v e l y . P r e s s u r e s r e c o r d e d from t h e d o r s a l a o r t a and b u c c a l c a v i t y gave i n f o r m a t i o n about h e a r t r a t e , b l o o d p r e s s u r e , p u l s e p r e s s u r e , v e n t i l a t i o n r a t e and p r e s s u r e s i n t h e b u c c a l c a v i t y b e f o r e , d u r i n g and a f t e r t h e f i s h were f a t i g u e d by swimming. H e m a t o c r i t d a t a r e v e a l e d t h e b l o o d oxygen c a p a c i t y o f t h e s e f i s h , t o be a p p r o x i m a t e l y 9 v o l s %. Knowledge o f t h e b l o o d oxygen c a p a c i t y , h e a r t r a t e and the m e t a b o l i c r a t e s o f a d u l t sockeye a t v a r i o u s t e m p e r a t u r e s and l e v e l s o f a c t i v i t y a l l o w e d c a l c u l a t i o n o f s t r o k e volume and c a r d i a c o u t p u t by t h e F i c k p r i n c i p l e . D u r i n g s u c c e s s i v e l y g r e a t e r swimming a c t i v i t y h e a r t r a t e and b l o o d p r e s s u r e r o s e i n a l l t h r e e t e s t groups w h i l e v e n t i l a t i o n r a t e was h i g h l y v a r i a b l e . C a l c u l a t e d s t r o k e volume and c a r d i a c o u t p u t i n c r e a s e d m a r k edly and i t i s suggested t h a t the p e r i p h e r a l r e s i s t a n c e o f t h e v a s c u l a r system d i m i n i s h e d d u r i n g e x e r c i s e . The i n c r e a s e i n h e a r t r a t e d u r i n g e x e r c i s e i s thought t o be r e l a t e d t o a r e l e a s e of v a g a l tone o r p o s s i b l y , t o t h e pr e s e n c e o f c i r c u l a t i n g c a t e c h o l a m i n e s . E l e v a t e d d o r s a l a o r t i c p r e s s u r e d u r i n g a c t i v i t y was un d o u b t a b l y t h e r e s u l t o f e l e v a t e d c a r d i a c o u t p u t . S i n c e d o r s a l a o r t i c p r e s s u r e d i d n o t i n c r e a s e i n accordance w i t h t h e i n c r e a s e s i n oxygen u p t a k e o b s e r v e d d u r i n g a c t i v i t y i t i s s u g g e sted t h a t p e r i p h e r a l r e s i s t a n c e d e c r e a s e s i n t h e f a c e o f e l e v a t e d c a r d i a c o u t p u t . P o s t - e x e r c i s e v e n t i l a t i o n r a t e approached r e s t i n g l e v e l s w i t h i n one hour a f t e r f a t i g u e b u t h e a r t r a t e and b u c c a l p r e s s u r e remained above r e s t i n g l e v e l s . H i g h p o s t - e x e r c i s e h e a r t r a t e s and b u c c a l p r e s s u r e s were b e l i e v e d t o be e v i d e n c e f o r t h e pr e s e n c e of an oxygen debt . B l o o d p r e s s u r e s f e l l below r e s t i n g l e v e l s i n t h e 15 and 22°c t e s t groups f o l l o w i n g f a t i g u e and remained low one hour a f t e r f a t i g u e . These low p r e s s u r e s may i n d i c a t e t h a t v a s o d i l a t i o n o f p e r i p h e r a l v e s s e l s had o c c u r r e d t o f a c i l i t a t e f l u s h i n g o f t h e muscles w i t h b l o o d and a i d i n t h e e l i m i n a t i o n o f oxygen debt. Temperature appeared t o d i r e c t l y i n f l u e n c e h e a r t r a t e o f b o t h q u i e s c e n t and a c t i v e f i s h . H i g h e r a c c l i m a t i o n and t e s t t e m p e r a t u r e s produced h i g h e r h e a r t r a t e s than lower a c c l i m a t i o n and t e s t t e m p e r a t u r e s . Presumably t e m p e r a t u r e i n f l u e n c e s h e a r t r a t e by a c t i n g d i r e c t l y on membraneJphenomena i n t h e myocardium. No c a r d i a c f a i l u r e was o b s e r v e d i n sockeye, even a t 22°C d u r i n g s e v e r e e x e r c i s e . R o u t i n e and a c t i v e oxygen uptake i n c r e a s e d w i t h t emperature b u t t h e r a t e o f i n c r e a s e o f a c t i v e oxygen uptake d e c r e a s e d w i t h t e m p e r a t u r e - p o s s i b l y because o f t h e low a v a i l a b i l i t y o f oxygen i n warm w a t e r . Temperature appeared t o d i r e c t l y i n f l u e n c e t h e v e n t i l a t i o n r a t e o f q u i e s c e n t f i s h . H i g h e r t e m p e r a t u r e s were accompanied by h i g h v e n t i l a t i o n r a t e s , u n d o u b t a b l y as a r e s u l t o f i n c r e a s e d r o u t i n e m e t a b o l i c r a t e a t h i g h t e m p e r a t u r e s and s c a r c i t y o f oxygen i n warm wa t e r . i v TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS i v LIST OF TABLES v LIST OF FIGURES v i ACKNOWLEDGEMENT i x GENERAL INTRODUCTION 1 GENERAL METHODS 4 PART ONE - THE EFFECT OF SWIMMING ACTIVITY ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS IN SOCKEYE SALMON. A) I n t r o d u c t i o n I 17 B) Methods I 17 C) R e s u l t s and D i s c u s s i o n I 17 D) Summary I 52 PART TWO - THE EFFECT OF TEMPERATURE ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS IN QUIESCENT AND SWIMMING SOCKEYE SALMON. A) I n t r o d u c t i o n I I 54 B) Methods I I 5 7 C) R e s u l t s and D i s c u s s i o n I I 57 D) Summary I I 76 GENERAL DISCUSSION 78 REFERENCES 85 APPENDIX 91 V LIST OF TABLES F a c i n g Page I H e a r t r a t e b e f o r e , d u r i n g and a f t e r t h e t h r e e t e s t groups were f a t i g u e d by swimming. 92 I I S y s t o l i c and d i a s t o l i c p r e s s u r e s i n t h e d o r s a l a o r t a e o f t h e t h r e e t e s t groups. 95 I I I P u l s e p r e s s u r e i n t h e d o r s a l a o r t a e o f t h r e e groups o f f i s h b e f o r e , d u r i n g and a f t e r t h e f i s h were f a t i g u e d by swimming. 99 IV V e n t i l a t i o n r a t e i n t h e t h r e e groups o f t e s t f i s h b e f o r e , d u r i n g and a f t e r t h e f i s h were f a t i g u e d by swimming. 102 V Maximal p r e s s u r e r e c o r d e d i n t h e b u c c a l c a v i t y o f two groups o f f i s h a c c l i m a t e d and t e s t e d a t 5 and 22°C r e s p e c t i v e l y . 105 VI Standard and a c t i v e m e t a b o l i c r a t e s o f groups o f sockeye salmon t e s t e d a t d i f f e r e n t t e m p e r a t u r e s . 107 V I I R e s u l t s o f h e m a t o c r i t d e t e r m i n a t i o n s made on a group, o f a d u l t sockeye salmon a t t e m p e r a t u r e s o f 15-22°C. 107 V I I I A comparison o f t h e observ e d d o r s a l a o r t i c p r e s s u r e i n t h e t h r e e groups w i t h t h a t c a l c u l a t e d from oxygen uptake d a t a . 110 IX A summary o f c a r d i a c o u t p u t and s t r o k e volume e s t i m a t e s made on a v a r i e t y o f a n i m a l s . 112 v i LIST OF FIGURES F a c i n g Page 1 Cannulae a r e shown i m p l a n t e d i n t h e head o f a sockeye salmon. 9 2 D e t a i l s o f t h e r e s p i r o m e t e r used i n t h e s e e x p e r i m e n t s a r e i l l u s t r a t e d . 10 3 Changes i n h e a r t r a t e o f t h r e e groups o f sockeye b e f o r e , d u r i n g and a f t e r a c t i v i t y a r e i l l u s t r a t e d . 19 4 The e f f e c t o f w e i g h t on h e a r t r a t e o f r e s t i n g ( r o u t i n e ) and m o d e r a t e l y a c t i v e f i s h i s i l l u s t r a t e d . 20 5 T y p i c a l p r e s s u r e r e c o r d s . 22 6 T y p i c a l p r e s s u r e r e c o r d s . 23 7 Changes i n d o r s a l a o r t i c b l o o d p r e s s u r e b e f o r e , d u r i n g and a f t e r t h r e e groups o f f i s h had been f a t i g u e d by swimming. 28 8 A h y p o t h e t i c a l b l o o d p r e s s u r e r e c o r d t o i l l u s t r a t e what i s meant by t h e \" t r u e mean\" o r \"area mean\" o f a p u l s a t i l e p r e s s u r e . 30 9 Changes i n d o r s a l a o r t i c p u l s e p r e s s u r e b e f o r e , d u r i n g and a f t e r swimming a c t i v i t y i n t h r e e t e s t groups o f sockeye salmon. 35 10 Changes i n v e n t i l a t i o n r a t e i n t h r e e groups o f f i s h i n r e s p o n s e t o i n c r e a s i n g swimming a c t i v i t y and f o l l o w i n g f a t i g u e . 37 v i i 11 S e m i - l o g a r i t h m i c p l o t o f oxygen uptake and swimming e f f o r t . 3 9 12 Changes i n b u c c a l p r e s s u r e d u r i n g i n c r e a s e d swimming a c t i v i t y and f o l l o w i n g f a t i g u e a r e i l l u s t r a t e d . 40 13 The e f f e c t o f te m p e r a t u r e on c a r d i a c o u t p u t o f f u l l y a c t i v e and r e s t i n g sockeye salmon. 46 14 The e f f e c t o f t e m p e r a t u r e on s t r o k e volume o f f u l l y a c t i v e and r e s t i n g sockeye salmon. 47 15 Changes i n h e a r t r a t e d u r i n g i n c r e a s i n g ' swimming e f f o r t and d u r i n g r e c o v e r y from f a t i g u e . 58 16 H e a r t r a t e s o f a d u l t sockeye salmon a c c l i m a t e d and t e s t e d a t t h r e e t e m p e r a t u r e s . 5 9 17 A r e a mean b l o o d p r e s s u r e i n t h e d o r s a l a o r t a o f t h r e e groups o f a d u l t sockeye a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e s . 62 18 The i n f l u e n c e o f f i s h w e i g h t on r o u t i n e a r e a mean b l o o d p r e s s u r e i n t h e d o r s a l a o r t a o f a group o f a d u l t sockeye salmon a c c l i m a t e d and t e s t e d a t 22°C. 63 19 Oxygen consumption v a l u e s o f groups o f a d u l t sockeye salmon measured a t v a r i o u s a c c l i m a t i o n t e m p e r a t u r e s . 65 20 The e f f e c t o f te m p e r a t u r e on v e n t i l a t i o n r a t e o f a d u l t sockeye salmon. 73 The e f f e c t o f t e m p e r a t u r e on b u c c a l p r e s s u r e o f a d u l t sockeye salmon b e f o r e , d u r i n g and a f t e r t h e f i s h had been f a t i g u e d by swimming. i x ACKNOWLEDGEMENT The a u t h o r w i s h e s t o thank Dr. L.S. Smith and Dr. J.R. B r e t t f o r s u g g e s t i n g and s u p e r v i s i n g t h i s r e s e a r c h . Mr. D. S u t h e r l a n d ( B i o l o g i c a l S t a t i o n , Nanaimo, B.C.) p r o v i d e d v a l u a b l e t e c h n i c a l a s s i s t a n c e . Mr. D. Stevens and Mr. G. H o l e t o n made u s e f u l s u g g e s t i o n s and prompted v a l u a b l e d i s c u s s i o n s of t h i s work. The a s s i s t a n c e of Dr. D. R a n d a l l i n t h e p r e p a r a t i o n o f t h i s m a n u s c r i p t i s g r e a t l y a p p r e c i a t e d . GENERAL INTRODUCTION In 195 7 Mott r e v i e w e d t h e l i t e r a t u r e on the c a r d i o v a s c u l a r system o f f i s h and emphasized t h e p a u c i t y o f i n f o r m a t i o n a v a i l a b l e . Up t o t h a t time much o f t h e work had been c a r r i e d out on i m m o b i l i z e d , drugged, r e s t r a i n e d or o t h e r w i s e abnormal f i s h (Burger and B r a d l e y , 1951. Itazawa, 1957. Mott, 1950.). Rushmer, e t a l , (1960) and R a n d a l l and Smith (1967) s t r e s s e d t h e need f o r more complete a n a l y s i s on i n t a c t u n r e s t r a i n e d f i s h . W i t h t h e advent o f t e c h n i q u e s w h i c h a l l o w o p e r a t i o n and i m p l a n t a t i o n o f cannulae and t h e use o f p r e s s u r e t r a n s d u c e r d e v i c e s t h e scope o f e x p e r i m e n t a t i o n has v a s t l y i n c r e a s e d . Saunders (1961) d e s c r i b e d t e c h n i q u e s o f c a n n u l a t i n g t h e o r a l and o p e r c u l a r c a v i t i e s so t h a t p r e s s u r e r e c o r d s o r water samples c o u l d be t a k e n . Smith and B e l l (1964) d e v i s e d a d o r s a l a o r t i c c a n n u l a t i o n t e c h n i q u e w h i c h a l l o w e d p r e s s u r e r e c o r d i n g or b l o o d s a m p l i n g from w i t h i n t h e v a s c u l a r system o f free-swimming f i s h . Recent s t u d i e s have demonstrated t h e u s e f u l n e s s o f t h i s t e c h n i q u e ( R a n d a l l , e t a l , 1965. R a n d a l l and Smith, 1967.). H o l e t o n and R a n d a l l (1967 a,b) c a n n u l a t e d t h e v e n t r a l a o r t a as w e l l as t h e d o r s a l a o r t a , b u c c a l and o p e r c u l a r c a v i t i e s o f r a i n b o w t r o u t (Salmo g a i r d n e r i ) . U s i n g the same s p e c i e s and i d e n t i c a l t e c h n i q u e s Stevens and R a n d a l l (1967 a,b) r e c o r d e d r e s p i r a t o r y and c a r d i o v a s c u l a r changes d u r i n g moderate 2 short-term swimming a c t i v i t y . A s i m i l a r approach has been adopted here however, i n t h i s study salmon were exposed to severe and prolonged e x e r c i s e which r e s u l t e d e v e n t u a l l y i n f a t i g u e . Thus experimental c o n d i t i o n s would resemble those encountered by a f i s h moving upstream through t u r b u l e n t water d u r i n g i t s spawning m i g r a t i o n . Salmon are capable of swimming at a v a r i e t y of speeds and o f t e n must maintain moderate swimming speeds f o r long p e r i o d s of time as i s the case d u r i n g t h e i r e x t e n s i v e m i g r a t i o n s i n the sea. A l s o these f i s h may swim r a p i d l y at \"burst speeds\" f o r s h o r t p e r i o d s w h i l e c a t c h i n g prey, a v o i d i n g p r e d a t o r s or moving through t u r b u l e n t water. Burst speeds b r i n g about oxygen debt and f a t i g u e i n sockeye salmon (Brett, 1965). F a t i g u e i s c h a r a c t e r i z e d by a f i s h e s i n a b i l i t y t o swim f u r t h e r even a f t e r v i o l e n t s t i m u l a t i o n . Sustained swimming at h i g h v e l o c i t i e s w i l l e v e n t u a l l y r e s u l t i n f a t i g u e and the time r e q u i r e d b e f o r e f a t i g u e occurs i n f i s h of a given s i z e can be d i r e c t l y r e l a t e d to the s u s t a i n e d swimming speed (Brett, 1964). The o b j e c t of t h i s study was to examine c a r d i o v a s c u l a r and r e s p i r a t o r y changes o c c u r r i n g d u r i n g and a f t e r a d u l t sockeye salmon (Onchorynchus nerka) were f a t i g u e d by swimming. Thus changes i n the c i r c u l a t o r y and r e s p i r a t o r y systems i n response to a c t i v i t y c ould be s t u d i e d . The e f f e c t of temperature on the c a r d i o v a s c u l a r and r e s p i r a t o r y systems was a l s o examined. Some work 3 has a l r e a d y been done a t 15°C hence t h i s work was done a t 5° and 22°C. T h i s work was i n i t i a t e d i n 1964 by L.S. Smith. Smith's e x p e r i m e n t s were d e s i g n e d t o complement the oxygen uptake s t u d i e s o f J.R. B r e t t . In t h i s way a s p e c t s o f c i r c u l a t i o n r e l a t e d t o oxygen uptake c o u l d be examined. Smith's work was c a r r i e d out a t 15°C and has r e c e n t l y been p u b l i s h e d (Smith e t a l , 1967). In t h e summers of 1965 and 1966 t h e a u t h o r c o n t i n u e d Smith's s t u d i e s a t two d i f f e r e n t t e m p e r a t u r e s - 5 and 22°C. A l l 15°C d a t a r e f e r r e d t o i n t h i s paper i s e x t r a c t e d from Smith's work w i t h h i s p e r m i s s i o n . In o r d e r t o s t u d y c a r d i o v a s c u l a r and r e s p i r a t o r y changes a t v a r i o u s l e v e l s o f a c t i v i t y and t e m p e r a t u r e we measured d o r s a l a o r t i c b l o o d p r e s s u r e , h e a r t r a t e , r e s p i r a t o r y r a t e and p r e s s u r e i n t h e b u c c a l c a v i t y . I t was hoped t h a t measures o f d o r s a l a o r t i c b l o o d p r e s s u r e and h e a r t r a t e would i n d i c a t e what s o r t s o f changes o c c u r r e d i n t h e c i r c u l a t o r y system of sockeye a t d i f f e r e n t t e m p e r a t u r e s and l e v e l s o f a c t i v i t y . Such an approach s h o u l d p r o v i d e c l u e s as t o t h e f u n c t i o n and c o n t r o l o f v a r i o u s components o f t h e c i r c u l a t o r y system. Measurement o f r e s p i r a t o r y r a t e and b u c c a l p r e s s u r e s h o u l d i n d i c a t e some o f t h e changes o c c u r r i n g i n t h e r e s p i r a t o r y a p p a r a t u s d u r i n g a c t i v i t y and a t d i f f e r e n t t e m p e r a t u r e s . The use o f t h e s e d a t a a l o n g w i t h B r e t t ' s m e t a b o l i c r a t e d e t e r m i n a t i o n s s h o u l d a l l o w c o n s i d e r a t i o n o f c i r c u l a t i o n and r e s p i r a t i o n as i n t e g r a t e d p r o c e s s e s . The e x p e r i m e n t s 4 r e p o r t e d h e r e were i d e n t i c a l t o t h o s e o f B r e t t (1965) i n t h a t t h e same s p e c i e s o f f i s h were t e s t e d under i d e n t i c a l c o n d i t i o n s i n t h e same a p p a r a t u s . Thus we can use B r e t t ' s m e t a b o l i c r a t e d a t a t o c a l c u l a t e c a r d i a c o u t p u t by t h e F i c k p r i n c i p l e . I t i s then p o s s i b l e t o c o n s i d e r t h e i n t e r d e p e n d a n c e o f c i r c u l a t i o n and r e s p i r a t i o n i n terms o f b l o o d f l o w t h r o u g h t h e g i l l s , t h e exchange of gases a t t h e r e s p i r a t o r y i n t e r f a c e and t h e importance o f b o t h systems i n r e g u l a t i n g oxygen u p t a k e . The s t u d y o f c i r c u l a t i o n and r e s p i r a t i o n i n i n t a c t free-swimming f i s h a l l o w s a c l o s e comparison t o p h y s i o l o g i c a l c o n d i t i o n s o f f i s h swimming i n t h e i r n a t u r a l environment. Thus t h e p r e s e n t s t u d y had two b r o a d o b j e c t i v e s : 1) t o s t u d y t h e e f f e c t o f a c t i v i t y on c e r t a i n c i r c u l a t o r y and r e s p i r a t o r y parameters and 2) t o examine t h e e f f e c t o f t e m p e r a t u r e on t h e s e parameters. GENERAL METHODS 1) F i s h C o l l e c t i o n and A c c l i m a t i o n A l l e x p e r i m e n t a l work was c a r r i e d out on j a c k (premature 3 y e a r o l d males) and a d u l t sockeye salmon (Onchorynchus nerka) a t t h e F i s h e r i e s R e s e a r c h Board o f Canada B i o l o g i c a l S t a t i o n , Nanaimo, B.C. T e s t s were conducted from May 1 t o September 1 i n t h e summers o f 1965 and 1966. A d u l t sockeye salmon were t r a p p e d i n the Stamp R i v e r near A l b e r n i , B.C. d u r i n g May and e a r l y June. 5 These f i s h ranged from 115 0 t o 1750 g i n w e i g h t (x- S.E. = 1438-39. 2) and were m i g r a t i n g upstream i n t o G r e a t C e n t r a l Lake. In a d d i t i o n a few j a c k s w e i g h i n g between 580 and 957 g were c o l l e c t e d (x+S.E. = 760.5+37.4). M o r p h o l o g i c a l changes a s s o c i a t e d w i t h spawning were n o t apparant i n any f i s h a t t h e time o f c o l l e c t i o n . E x p e r i m e n t a l f i s h were t r a n s p o r t e d t o t h e B i o l o g i c a l S t a t i o n i n i c e d , oxygenated 400 g a l l o n t a n k s . A d d i t i o n o f s m a l l amounts o f a n a e s t h e t i c (2 - phen o x y e t h a n o l , 100 ml/400 g a l . ) t o t h e water r e d u c e d a c t i v i t y and m i n i m i z e d d e a t h and i n j u r y t o t h e t r a n s p o r t e d f i s h . A t t h e B i o l o g i c a l S t a t i o n t h e sockeye were t r a n s f e r r e d t o 2 meter d i a m e t e r f i b r e g l a s s t a n k s f o r a c c l i m a t i o n . Tanks were equipped w i t h r e c i r c u l a t i o n pumps as w e l l as a c o n t i n u o u s s u p p l y o f f r e s h w a t e r . Such c o n d i t i o n s m a i n t a i n e d oxygen l e v e l s between 80 and 100% s a t u r a t i o n and k e p t t h e f i s h m o d e r a t e l y a c t i v e . Fungus growth was r e t a r d e d by r u n n i n g seawater i n t o t h e a c c l i m a t i o n t a n k s f o r a few hours a t l e a s t one weekly. F i s h were n o t f e d d u r i n g t h e h o l d i n g and a c c l i m a t i o n p e r i o d . S e p a r a t e s t o c k s o f f i s h o f s i m i l a r w e i g h t were a c c l i m a t e d t o 5 and 22°C. Temperature i n t h e 22°C a c c l i m a t i o n t a n k s was m a i n t a i n e d by r e c i r c u l a t i n g t h e water t h r o u g h a 15 cm p l a s t i c p i p e c o n t a i n i n g two 500 w a t t immersion h e a t e r s . The h e a t e r s were c o n t r o l l e d by Y SI te m p e r a t u r e c o n t r o l l e r s w h i c h m a i n t a i n e d a s t a b l e t e m p e r a t u r e w i t h i n l e s s than + 1°C. Temperature i n t h e 6 5°C a c c l i m a t i o n t a n k was c o n t r o l l e d by m i x i n g s u i t a b l e amounts o f r e f r i d g e r a t e d and \"normal\" f r e s h water i n the i n f l o w l i n e . The 5°C a c c l i m a t e d f i s h were g i v e n 1 week a t 10°C and 2 weeks a t 5°C b e f o r e t e s t i n g . The 22°c a c c l i m a t e d f i s h were h e l d a t 18°C f o r 5 days and a t l e a s t 5 days a t 22°C p r i o r t o e x p e r i m e n t a t i o n . I t was b e l i e v e d t h a t such a c c l i m a t i o n p e r i o d s p r o v i d e d c o m p l e t e l y a c c l i m a t e d f i s h ( B r e t t - p e r s o n a l communication). 2) C a n n u l a t i o n Techniques Sockeye were a n a e s t h e t i z e d w i t h . 1:10, 000 MS 222 a n a e s t h e t i c (Sandoz) and p l a c e d v e n t r a l s i d e up on an o p e r a t i n g t a b l e equipped w i t h a pump and n o z z l e s f o r p e r f u s i n g t h e g i l l s w i t h w a t e r . The t a b l e was so c o n s t r u c t e d t h a t a stream o f water c o n t a i n i n g a n a e s t h e t i c (MS 222 - 1:10,000) c o u l d be c o n t i n u a l l y pumped over t h e g i l l s t o f a c i l i t a t e r e s p i r a t i o n and m a i n t a i n a n a e s t h e t i c . To b r i n g t h e f i s h out o f a n a e s t h e s i a one m e r e l y s w i t c h e d over t o a water s u p p l y c o n t a i n i n g no a n a e s t h e t i c and w a i t e d f o r t h e f i r s t s i g n s o f r e c o v e r y ( t w i t c h i n g , f i n movements, e t c . ) . Smith and B e l l (1964, 1967) have d e s c r i b e d t h e o p e r a t i n g t a b l e and i t s f u n c t i o n i n d e t a i l . The D o r s a l A o r t i c C a n n u l a t i o n The d o r s a l a o r t a was c a n n u l a t e d a t i t s p o i n t o f i n t e r s e c t i o n w i t h t h e second e f f e r e n t b r a n c h i a l a r t e r i e s as d e s c i r b e d by Smith and B e l l (1964). The c a n n u l a c o n s i s t e d 7 of a 76 cm length, o f Clay-Adams P.E. 60 (0. 762 mm bore) p l a s t i c t u b i n g i n t o w h i c h a 3 cm #21 huber p o i n t C l a y -Adams n e e d l e had been i n s e r t e d . A h o l e was punched m i d - d o r s a l l y i n t h e snout o f t h e f i s h w i t h a l a r g e b o r e n e e d l e (#12), c a r e b e i n g t a k e n t o a v o i d t h e o l f a c t o r y l o b e s . A 3 cm l e n g t h o f Clay-Adams P.E. 200 p l a s t i c t u b i n g (1.397 mm bore) h e a t f l a r e d on one end was passed t h r o u g h the h o l e i n t h e snout from i n s i d e t h e mouth. The d o r s a l a o r t i c c a n n u l a f i t t e d s n u g l y i n s i d e t h i s s l e e v e . The s l e e v e was t i e d t i g h t l y t o t h e c a n n u l a a t t h e p o i n t where b o t h tubes emerged from t h e d o r s a l t i p o f t h e snout. I n s i d e t h e mouth t h e c a n n u l a was h e l d f l u s h a g a i n s t t h e p a l a t e w i t h a s i n g l e s t i t c h mid-way between t h e c a n n u l a t i o n p o i n t and t h e p l a c e where the t u b es passed t h r o u g h t h e snout. The c a n n u l a was f i l l e d w i t h h e p a r i n i z e d (10 I.U./ml) C o r t l a n d s a l i n e (Wolf, 1963) and plugged w i t h a t a p e r e d s t a i n l e s s s t e e l p i n when n o t i n use. Such a c a n n u l a t i o n was q u i t e s e c u r e and d u r a b l e and, i n many i n s t a n c e s , remained open f o r as l o n g as a week. D e t a i l s o f t h e d o r s a l a o r t i c c a n n u l a t i o n a r e shown i n f i g u r e 1. The B u c c a l C a n n u l a t i o n The b u c c a l c a v i t y was c a n n u l a t e d w i t h a 76 cm l e n g t h o f P.E. 60 t u b i n g h e a t f l a r e d on one end. The b u c c a l c a n n u l a passed t h r o u g h and was f i x e d t o a P.E. 200 s l e e v e i d e n t i c a l t o t h e one used f o r t h e d o r s a l 8 a o r t i c c a n n u l a . F i g u r e 1 i l l u s t r a t e s d e t a i l s o f c a n n u l a t i o n and shows t h e b u c c a l c a n n u l a l o c a t e d s l i g h t l y t o one s i d e o f t h e d o r s a l a o r t i c c a n n u l a . Saunders (1961) d e s c r i b e d a s i m i l a r c a n n u l a t i o n . 3) R e c o r d i n g Techniques H y d r o s t a t i c p r e s s u r e s were r e c o r d e d d i r e c t l y f rom b o t h c a n nulae u s i n g two t y p e s o f r e c o r d i n g d e v i c e s . Some o f t h e work was done u s i n g a Sanborn model 321, 2 c h a n n e l c a r r i e r a m p l i f i e r - r e c o r d e r and Sanborn s e r i e s 267 t r a n s d u c e r s . Frequency r e s p o n s e o f t h e e n t i r e system was 30 c y c l e s / s e c w i t h P.E. 60 cannulae (Smith - p e r s o n a l communication). A l t e r n a t e l y , p r e s s u r e s were r e c o r d e d u s i n g a Beckman t y p e R o f f n e r Dynograph. W i t h t h i s r e c o r d e r b u c c a l p r e s s u r e s were m o n i t o r e d w i t h a Statham P-23-BB p r e s s u r e t r a n s d u c e r ; d o r s a l a o r t i c p r e s s u r e s w i t h a Statham P-23-AA p r e s s u r e t r a n s d u c e r . A d d i t i o n o f one drop o f w e t t i n g agent (\"tween 80\") / 500 ml C o r t l a n d s a l i n e g r e a t l y deduced b u b b l e f o r m a t i o n i n th e t r a n s d u c e r s and f a c i l i t a t e d t r o u b l e - f r e e r e c o r d i n g . 4) R e s p i r o m e t e r C i r c u l a t o r y and r e s p i r a t o r y parameters o f swimming f i s h were s t u d i e d u s i n g a t u n n e l - t y p e r e s p i r o m e t e r d e s c r i b e d by B r e t t (1964, 1965). D e t a i l s o f t h e r e s p i r o m e t e r a r e shown i n f i g u r e 2. B a s i c a l l y t h e apparat u s c o n s i s t s o f a 1 1 % cm d i a m e t e r p l e x i g l a s tube connected t o a v a r i a b l e speed pump w h i c h r e c i r c u l a t e s t h e water t h r o u g h t h e 9 Legend f o r F i g u r e 1 Cannulae a r e shown i m p l a n t e d i n t h e head o f a sockeye salmon. The b u c c a l c a n n u l a opens i n t o the mouth c a v i t y w h i l e t h e d o r s a l a o r t i c c a n n u l a i s i n s e r t e d d i r e c t l y i n t o t h e lumen o f t h e d o r s a l a o r t a . D o r s a l a o r t a D o r s a l a o r t i c c a n n u l a I— B u c c a l c a n n u l a f r n R E . 2 0 0 s l e e v e tfit \\ t i e d t o c a n n u l a 10 Legend f o r F i g u r e 2 D e t a i l s o f t h e r e s p i r o m e t e r used i n t h e s e e x p e r i m e n t s a r e i l l u s t r a t e d . F i s h swam w i t h t h e i r heads beneath t h e black, p l a s t i c s u r r o u n d i n g t h e upstream end o f t h e tube. Temperature i n t h e r e s p i r o m e t e r c o u l d be c l o s e l y c o n t r o l l e d by t h e h e a t e r and r e f r i d g e r a t i o n j a c k e t . Charged Pump 1_ * i ^Heater •> L _ J Access port Cannulae to pressure transducer. 11 tube a t any v e l o c i t y d e s i r e d up t o 3.7 f t / s e c o n d . An i m p e l l e r - t y p e f l o w meter g i v e s c o n t i n u o u s r e a d o u t o f water v e l o c i t y . Temperature can be c o n t r o l l e d w i t h i n + 0.1°C by a system o f h e a t i n g and c o o l i n g c o n t r o l l e d by a r e l a y . The w o r k i n g t e m p e r a t u r e range o f t h e apparat u s i s r o u g h l y 2-30°C. Water can be made up t o any d e s i r e d t e m p e r a t u r e and oxygen s a t u r a t i o n i n \"header t a n k s \" a d j o i n i n g t h e r e s p i r o m e t e r . The system can be c l o s e d and used as a c o n v e n t i o n a l r e s p i r o m e t e r f o r swimming f i s h o r l e f t open, as i n t h i s work, so t h a t a c o n t i n u o u s s u p p l y o f oxygenated water f l o w s t h r o u g h the a p p a r a t u s . Oxygen l e v e l s w i t h i n t h e r e s p i r o m e t e r were m o n i t o r e d by c o l l e c t i n g w ater samples w i t h a, n e e d l e v a l v e and a p p l y i n g t h e u n m o d i f i e d W i n k l e r t e c h n i q u e (Stroganov, 1962). 5) H e m a t o c r i t D e t e r m i n a t i o n s In o r d e r t o o b t a i n a rough e s t i m a t e o f t h e oxygen c a p a c i t y o f sockeye b l o o d and t o d e t e r m i n e t h e c o n d i t i o n o f t h e group o f f i s h used i n t h e experiment i t was n e c e s s a r y t o c a r r y out h e m a t o c r i t d e t e r m i n a t i o n s . B l o o d was withdrawn w i t h a 2 cc s y r i n g e from t h e d o r s a l a o r t i c c a n n u l a o f f i v e f i s h h e l d a t t e m p e r a t u r e s o f 15-22°C. Samples o f 0.5 cc b l o o d were withdrawn and s m a l l amounts were t r a n s f e r r e d t o g l a s s m i c r o - h e m a t o c r i t t u b e s . These tubes were spun i n a m u l t i p l e - h e a d h e m o t o c r i t c e n t r i f u g e a t about 13,000 x g f o r 3 minute s . Three 12 s e p a r a t e d e t e r m i n a t i o n s were made on each b l o o d sample. H e m a t o c r i t d e t e r m i n a t i o n s were made w i t h a m i c r o - h e m a t o c r i t tube r e a d e r (Clay-Adams, I n c . ) . 6) A c t i v i t y T e s t s a) Ter m i n o l o g y In h i s comprehensive r e v i e w o f f i s h r e s p i r a t o r y m e t a b o l i s m B r e t t (1962) d e s c r i b e d v a r i o u s l e v e l s o f m e t a b o l i c r a t e w h i c h c o u l d be s t u d i e d i n t h e l a b o r a t o r y . A c t i v e m e t a b o l i s m i s \"the maximum r a t e c o n s i s t a n t w i t h t h e h i g h e s t c o n t i n u a l l e v e l o f a c t i v i t y \" . R o u t i n e m e t a b o l i s m i s t h e \"average oxygen consumption o f f i s h w h i c h a r e u n d e r g o i n g c o n t i n u o u s r e c o r d i n g d u r i n g \" f r e e \" a c t i v i t y i n a s e a l e d aquarium\". R o u t i n e m e t a b o l i c r a t e i s t h u s t h e oxygen consumption accompanying low l e v e l s o f a c t i v i t y o f f i s h i n t h e l a b o r a t o r y . I t i s d i s t i n c t from, and h i g h e r than b a s a l m e t a b o l i c r a t e w h i c h i s \"the minimum m e t a b o l i c r a t e accompanying t h e energy c o s t of m a i n t a i n a n c e \". In t h e p r e s e n t s t u d y c a r d i o v a s c u l a r and r e s p i r a t o r y p a rameters were measured a t l e v e l s o f a c t i v i t y whose upper and lower l i m i t s c o r r e s p o n d t o \" r o u t i n e \" and \" a c t i v e \" m e t a b o l i c r a t e . The h e a r t r a t e , r e s p i r a t o r y r a t e , b l o o d p r e s s u r e and b u c c a l p r e s s u r e o f u n d i s t u r b e d , q u i e s c e n t f i s h i n a q u a r i a c o v e r e d w i t h b l a c k p l a s t i c a r e t h u s termed \" r o u t i n e \" . I d e n t i c a l parameters i n f i s h swimming h a r d j u s t p r i o r t o f a t i g u e a r e termed 13 \" a c t i v e \" i n accordance w i t h a c t i v e m e t a b o l i c r a t e , b) A c t i v e Records Records o f c i r c u l a t o r y and r e s p i r a t o r y dynamics i n a c t i v e f i s h were o b t a i n e d i n t h e f o l l o w i n g manner. A f t e r c a n n u l a t i o n t h e f i s h were p l a c e d i n t h e r e s p i r o m e t e r a t t h e d e s i r e d t e m p e r a t u r e (5 or 22°C) and a l l o w e d t o r e c o v e r from t h e o p e r a t i o n . A r e c o v e r y p e r i o d o f a t l e a s t 3 h o u r s was a l l o w e d a l t h o u g h i n most i n s t a n c e s f i s h were c a n n u l a t e d i n t h e l a t e a f t e r n o o n or e v e n i n g and l e f t i n t h e r e s p i r o m e t e r o v e r n i g h t f o r r e c o v e r y . Records from o v e r n i g h t r e c o v e r y or 3 hour r e c o v e r y f i s h d i d n o t appear d i f f e r e n t . I t was found t h a t a water v e l o c i t y o f 0.6-1.0 f t / s e c f a c i l i t a t e d r e s p i r a t i o n and a l l o w e d t h e f i s h t o r e s t q u i e t l y and remain u p r i g h t i n t h e tube. A c t i v i t y t e s t s were as f o l l o w s : Water v e l o c i t y was r a i s e d u n t i l t h e f i s h s t a r t e d t o swim s t e a d i l y and c o n s i s t a n t l y a g a i n s t t h e c u r r e n t ( u s u a l l y about 1.3 f t / s e c w i t h a 1-1.5 Kg f i s h ) . Sockeye were encouraged t o swim by a p p l y i n g a l i g h t e l e c t r i c a l c u r r e n t (3-5 v o l t s A.C.) t o a w i r e g r i d l o c a t e d downstream from t h e swimming f i s h . Once s t e a d y swimming o c c u r r e d t h e i n i t i a l v e l o c i t y was m a i n t a i n e d f o r 30 minutes and was then r a i s e d by 0.3 f t / s e c f o r a n o t h e r 30 minut e s . Stepwise 30 minute i n c r e a s e s i n v e l o c i t y were m a i n t a i n e d u n t i l t h e f i s h f a t i g u e d i . e . - i t f e l l back on t h e e l e c t r i f i e d g r i d and would n o t swim a g a i n s t t h e water c u r r e n t . 14 Once f a t i g u e o c c u r r e d t h e water v e l o c i t y was r e d u c e d t o r e s t i n g l e v e l s (0.6-1.0 f t / s e c ) and t h e f i s h was a l l o w e d t o r e c o v e r f o r one hour. P r e s s u r e s i n t h e d o r s a l a o r t a and t h e b u c c a l c a v i t y were c o n t i n u a l l y r e c o r d e d d u r i n g t h e e n t i r e a c t i v i t y and r e c o v e r y p e r i o d . Records used f o r t h e d a t a d i s c u s s e d i n t h i s paper were o b t a i n e d by r e c o r d i n g c o n t i n u o u s l y f o r a few m i n u tes a t t h e b e g i n n i n g , m i d d l e , and end o f each 30 minute v e l o c i t y i n crement. S t r i p s o f r e c o r d o b t a i n e d 2, 5, 10, 20, 45 and 60 minutes a f t e r f a t i g u e p r o v i d e d i n f o r m a t i o n on r e c o v e r y from f a t i g u e . Water samples f o r oxygen d e t e r m i n a t i o n s were t a k e n r o u g h l y e v e r y 15 minutes d u r i n g the e n t i r e t e s t p e r i o d . Thus i t was p o s s i b l e t o d e t e r m i n e t h e oxygen c o n t e n t o f t h e water i n t h e r e s p i r o m e t e r d u r i n g each p a r t i c u l a r swimming v e l o c i t y . In a l l e x p e r i m e n t s oxygen l e v e l s were k e p t between 70% and 110% s a t u r a t i o n . C a r d i o v a s c u l a r dynamics are a f f e c t e d by b o t h h i g h and low e n v i r o n m e n t a l oxygen (Smith - p e r s o n a l communication). Thus any d a t a c o l l e c t e d when t h e oxygen l e v e l was o u t s i d e t h e 70-110% s a t u r a t i o n range was d i s c a r d e d . A p i e c e o f b l a c k p l a s t i c was p l a c e d over t h e upstream end o f t h e r e s p i r o m e t e r so t h a t t h e f i s h c o u l d swim w i t h i t s head i n t h e darkened end o f t h e tube. Thus t h e p o s s i b i l i t y o f f r i g h t e n i n g t h e f i s h was reduced. P o s i t i o n o f t h e swimming f i s h i n t h e tube i s shown i n f i g u r e 2. We found t h a t sockeye r a p i d l y l e a r n e d t o 15 a s s o c i a t e emergence o f t h e i r heads i n t o t h e l i g h t w i t h a shock i n t h e t a i l . Thus t h e f i s h u s u a l l y swam w e l l i n one p o s i t i o n w i t h t h e i r heads under t h e b l a c k p l a s t i c . The swimming e f f o r t o f f i s h a t each t e s t v e l o c i t y i n t h e r e s p i r o m e t e r tube was e v a l u a t e d by v i s u a l l y c o u n t i n g t h e f r e q u e n c y o f t a i l b e a t s (T.B.F. - t a i l b e a t f r e q u e n c y ) . B a i n b r i d g e (195 8) r e p o r t e d t h a t t h e swimming speed o f f i s h i s d i r e c t l y r e l a t e d t o t h e f r e q u e n c y and a m p l i t u d e o f t h e t a i l b e a t . O b v i o u s l y i n a 11% cm d i a m e t e r tube a d u l t salmon can a t t a i n o n l y a s m a l l p o r t i o n o f t h e i r n o r m a l t a i l b e a t a m p l i t u d e and hence must i n c r e a s e t h e f r e q u e n c y o f t a i l b e a t s . T h e r e f o r e t h e swimming e f f o r t f o r any one v e l o c i t y w i l l p r o b a b l y be h i g h e r than under n a t u r a l c o n d i t i o n s . S i n c e we are i n t e r e s t e d i n t h e e f f e c t o f l e v e l s o f a c t i v i t y on a group o f s i m i l a r s i z e d f i s h t h i s d i s p a r i t y i s n o t of g r e a t importance. What i s o f i n t e r e s t i s t h e changes b r o u g h t about by i n c r e a s e d a c t i v i t y . One must remember t h a t t h e s e changes a r e l i k e l y t o accompany g r e a t e r swimming speeds under n a t u r a l c o n d i t i o n s . c) \" R o u t i n e \" Records Records o f b u c c a l and d o r s a l a o r t i c p r e s s u r e i n r o u t i n e (low a c t i v i t y ) performance f i s h were o b t a i n e d i n two ways. F i s h were p l a c e d i n c o v e r e d , darkened a q u a r i a s u p p l i e d w i t h r u n n i n g water o f t h e d e s i r e d t e m p e r a t u r e (5 or 22°C). Oxygen l e v e l s were f o l l o w e d by s i p h o n i n g o f f samples o f water and a p p l y i n g the 16 u n m o d i f i e d W i n k l e r t e c h n i q u e (Stroganov, 1962). B u c c a l and d o r s a l a o r t i c c a n n ulae were l e d out o f t h e ta n k so t h a t p r e s s u r e s c o u l d be i n t e r m i t t a n t l y r e c o r d e d w i t h o u t d i s t r u b i n g t h e f i s h . G e n e r a l l y r e c o r d s were o b t a i n e d over a 24-48 hour p e r i o d . R a n d a l l , e t al, (1965) used s i m i l a r t e c h n i q u e s t o r e c o r d d o r s a l a o r t i c p r e s s u r e s from r a i n b o w t r o u t . In most cases t h e f i s h were v e r y q u i e s c e n t , h o l d i n g one p o s i t i o n w i t h o c c a s i o n a l p o s t u r a l movements o f t h e t a i l and f i n s . I f t h e f i s h was a t a l l a c t i v e , r e c o r d s were d i s c a r d e d . A l t e r n a t e l y , r e s t i n g r e c o r d s were o b t a i n e d from c a n n u l a t e d f i s h p l a c e d i n t h e r e s p i r o m e t e r o v e r n i g h t i n a g e n t l y moving stream o f water (0.6-1.0 f t / s e c ) . The r e s p i r o m e t e r was c o m p l e t e l y c o v e r e d w i t h b l a c k p l a s t i c and f i s h were g e n e r a l l y as q u i e s c e n t as t h o s e i n c o v e r e d a q u a r i a . R e s t i n g p r e s s u r e s and r a t e s i n b o t h t h e r e s p i r o m e t e r and c o v e r e d a q u a r i a were s i m i l a r (a t - t e s t showed t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n h e a r t r a t e a t t h e 5% l e v e l i n 5°C f i s h . Only a few 5°C a c c l i m a t e d f i s h were p l a c e d i n c o v e r e d a q u a r i a f o r r e c o r d i n g . A l l 22°C f i s h were t e s t e d i n t h e r e s p i r o m e t e r o n l y . ) . 17 PART ONE THE EFFECT OF SWIMMING ACTIVITY ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS IN SOCKEYE SALMON INTRODUCTION I To a s s e s s t h e e f f e c t s o f a c t i v i t y on c a r d i o v a s c u l a r and r e s p i r a t o r y dynamics, f i s h were c a n n u l a t e d and t e s t e d as o u t l i n e d p r e v i o u s l y . Thus i t was p o s s i b l e t o o b t a i n \" r o u t i n e \" and \" a c t i v e \" r e c o r d s from f i s h b e f o r e , d u r i n g and a f t e r t h e f i s h was f a t i g u e d by swimming. METHODS I Methods a r e as o u t l i n e d i n t h e g e n e r a l i n t r o d u c t i o n . Most r e s u l t s f o r c i r c u l a t o r y or r e s p i r a t o r y parameters ar e e x p r e s s e d as \"% r o u t i n e \" so t h a t changes produced by a c t i v i t y can be r e l a t e d t o c o n d i t i o n s i n q u i e s c e n t f i s h . E x a c t n u m e r i c a l v a l u e s f o r t h e v a r i o u s parameters w i l l be g i v e n i n P a r t Two o f t h i s paper and i n accompanying t a b l e s . RESULTS AND DISCUSSION I Mean average h e a r t r a t e i n c r e a s e d d u r i n g a c t i v i t y i n b o t h groups o f f i s h t e s t e d (5 and 22°C). Smith's 18 15 C d a t a shows s i m i l a r i n c r e a s e s . A t h i g h e r swimming speeds h e a r t r a t e l e v e l e d o f f i n t h e 22°C t e s t group ( f i g . 3) . The h e a r t r a t e s o f 22°C a c c l i m a t e d j a c k s were c o r r e c t e d f o r s i z e . A p l o t o f w e i g h t v s . r o u t i n e h e a r t r a t e and m o d e r a t e l y a c t i v e h e a r t r a t e (T.B.F. = 132) shows t h a t a c o n s i d e r a b l e s i z e e f f e c t was p r e s e n t ( f i g . 4 ) . S m a l l e r f i s h had h i g h e r h e a r t r a t e s than l a r g e r ones. A t - t e s t o f mean r o u t i n e h e a r t r a t e o f j a c k and a d u l t groups showed t h a t a s i g n i f i c a n t d i f f e r e n c e e x i s t e d between t h e two means a t t h e 5% l e v e l o f s i g n i f i c a n c e . S i n c e mean a d u l t h e a r t r a t e a t 22°C was 0.85 t i m e s t h a t o f mean j a c k h e a r t r a t e t h e j a c k d a t a was m u l t i p l i e d by 0.85 and t h e d a t a from a d u l t and j a c k salmon combined. A s i m i l a r p l o t o f w e i g h t v s . r o u t i n e h e a r t r a t e and a t - t e s t were a p p l i e d t o t h e 5°C t e s t group t o d e t e r m i n e i f a w e i g h t f a c t o r was p r e s e n t . In t h i s case no s i g n i f i c a n t d i f f e r e n c e a t t h e 5% l e v e l was d e t e c t a b l e between mean r o u t i n e h e a r t r a t e s o f j a c k and a d u l t f i s h . C o n s e q u e n t l y t h e j a c k and a d u l t d a t a was combined w i t h no c o r r e c t i o n i n t h e 5°C t e s t group. Smith's 15°C d a t a c o n t a i n e d no j a c k s and hence r e q u i r e d no c o r r e c t i o n . There appeared t o be no p a r t i c u l a r p a t t e r n o f h e a r t r a t e change accompanying each i n c r e a s e i n water v e l o c i t y . In some cases h e a r t r a t e r o s e i n i t i a l l y a f t e r t h e v e l o c i t y i n c r e a s e d ; e s p e c i a l l y when t h e f i s h put 19 Legend f o r F i g u r e 3 Changes i n h e a r t r a t e o f t h r e e groups o f sockeye b e f o r e , d u r i n g and a f t e r a c t i v i t y a r e i l l u s t r a t e d . These groups were a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e s . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f the. mean. 0 100 120 S40 160 580 200 0 20 40 60 TAIL BEAT FREQUENCY (beots/mln) MINUTES. AFTER FATIGUE 20 Legend f o r F i g u r e 4 The e f f e c t o f w e i g h t on h e a r t r a t e o f r e s t i n g ( r o u t i n e ) and m o d e r a t e l y a c t i v e f i s h i s i l l u s t r a t e d . The f i s h were a c c l i m a t e d and t e s t e d a t 22°C. P o i n t s r e p r e s e n t d a t a f o r i n d i v i d u a l f i s h . L e a s t squares r e g r e s s i o n l i n e s and t h e i r e q u a t i o n s a r e i n c l u d e d . 21 on a b u r s t o f speed f o r a few seconds. In o t h e r i n s t a n c e s t h e r a t e remained s t e a d y or r o s e s l o w l y d u r i n g the 30 minutes i n w h i c h any one v e l o c i t y was a p p l i e d . The o v e r a l l e f f e c t o f s t e p w i s e v e l o c i t y i n c r e a s e s was a g e n e r a l r i s e i n h e a r t r a t e as n o t e d e a r l i e r . T y p i c a l segments o f p r e s s u r e r e c o r d s t a k e n d u r i n g a c t i v i t y a r e shown i n f i g u r e 5 and 6. There i s v e r y l i t t l e i n f o r m a t i o n on changes i n h e a r t r a t e o f f i s h e s i n r e s p o n s e t o a c t i v i t y . R a n d a l l and Smith (1967) r e p o r t e d t h a t h e a r t r a t e i n c r e a s e d i n g o l d f i s h as a r e s u l t o f v i o l e n t movements of t h e p o s t e r i o r p a r t o f t h e body. In t r o u t t h e r e was l i t t l e o r no change. Stevens and R a n d a l l (1967 a,b) o b s e r v e d a 1 5 % r i s e i n h e a r t r a t e i n m o d e r a t e l y a c t i v e r a i n b o w t r o u t (Salmo g a i r d n e r i ) swimming i n a tube f o r 10 minutes. F o l l o w i n g a c t i v i t y h e a r t r a t e o f t h e i r f i s h dropped back q u i c k l y t o p r e - e x e r c i s e l e v e l s . In t h e r e s t i n g s u c k e r (Catostomus m a c r o c h e i l u s ) t h e r e i s c o n s i d e r a b l e v a g a l tone w h i c h i n h i b i t s t h e h e a r t r a t e . D u r i n g a c t i v i t y t h e r e i s an apparent d e c r e a s e i n v a g a l tone w h i c h a l l o w s a 75% i n c r e a s e i n h e a r t r a t e . I n j e c t i o n o f a t r o p i n e b l o c k s t h e vagus and produces c a r d i o a c c e l e r a t i o n i n t h e r e s t i n g s u c k e r . In t h e r a i n b o w t r o u t however, t h e r e i s no v a g a l tone i n r e s t i n g f i s h and moderate swimming a c t i v i t y produces o n l y a 1 5 % r i s e i n h e a r t r a t e (Stevens and R a n d a l l ; 1967 a,b). R a n d a l l and Stevens (1967) found evidence. 22 Legend f o r F i g u r e 5 - t y p i c a l p r e s s u r e r e c o r d s A) Segments o f d o r s a l a o r t i c and b u c c a l p r e s s u r e r e c o r d s o f a 1440 g a d u l t sockeye r e s t i n g q u i e t l y i n an aquarium. These a r e t y p i c a l p r e s s u r e r e c o r d s from a q u i e s c e n t f i s h a c c l i m a t e d and t e s t e d a t 15°C. B) A t y p i c a l p r e s s u r e r e c o r d from an a c t i v e f i s h swimming i n t h e r e s p i r o m e t e r . The r e c o r d i s from a 778 g j a c k swimming a g a i n s t a water c u r r e n t o f 1.8 f t / s e c (T.B.F. = 176 b e a t s / m i n ) . The f i g u r e shows t h a t s t r u g g l i n g produces an e l e v a t e d d o r s a l a o r t i c b l o o d p r e s s u r e f o r about 30 seconds. Temperature = 15°C. PRESSURE (mm Hg) 23 Legend f o r F i g u r e 6 - t y p i c a l p r e s s u r e r e c o r d s A) Record o f d o r s a l a o r t i c p r e s s u r e o f a 1425 g a d u l t sockeye i n t h e r e s p i r o m e t e r a t 15°C. The water v e l o c i t y was r a i s e d from 1.0 f t / s e c t o 1.3 f t / s e c t o s t i m u l a t e t h e f i s h t o swim. A r a p i d r i s e i n b l o o d p r e s s u r e accompanies t h e onset o f swimming. P r e s s u r e s a r e i n mm Hg. B) Record t a k e n from a 1506 g a d u l t sockeye a t 22°c d u r i n g r e c o v e r y from f a t i g u e . The graph shows t h a t v e n t i l a t i o n r a t e and h e a r t r a t e d e c r e a s e w i t h t i m e . D o r s a l a o r t i c p r e s s u r e drops and d o r s a l a o r t i c and b u c c a l p u l s e p r e s s u r e d e m i n i s h w i t h t i m e . P r e s s u r e s a r e i n mm Hg. 40 r 30 20 T water velocity up ¥ 1 2 0 sees. 6 3 0 [ WIIKilllSSIIIBi IHBitflll mmmmm Buccal pressure Fatigue +2 mins. +10 mins. + 45 mins. 40 30 20 «-Dorsal aortic pressure Fatigue + 2 mins. + IO mins. +45 mins. + 1 2 0 mins. 8 sees. I 1 + 1 2 0 mins. 24 o f v a g a l t o n e i n r e s t i n g coho salmon, Onchorynchus k i s u t c h , as a t r o p i n e i n j e c t i o n caused c a r d i o a c c e l e r a t i o n i n r e s t i n g f i s h . Thus t h e r e appear t o be two t y p e s o f c a r d i o a c c e l e r a t o r y mechanisms p r e s e n t i n t h e f i s h s t u d i e d . One o f t h e s e i s a n e u r a l mechanism i n v o l v i n g t h e vagus, t h e o t h e r appears a n e u r a l i n n a t u r e . I f t h e r e i s no v a g a l tone i n f i s h , as i s t h e case i n t h e t r o u t , then c a r d i o a c c e l e r a t i o n cannot be produced by r e l e a s e o f v a g a l t one i n r e s p o n s e t o a c t i v i t y . An a n e u r a l mechanism must speed t h e h e a r t s i n c e no s y m p a t h e t i c n e r v e s s e r v e t h e f i s h h e a r t (Couteaux and L a u r e n t , 1957. Mott, 1957). C a r d i a c o u t p u t goes up i n t r o u t d u r i n g a c t i v i t y as does s t r o k e volume and venous r e t u r n (Stevens and R a n d a l l , 1967 b ) . Johansen (1962) r e p o r t e d t h a t c a r d i o a c c e l e r a t i o n d i d n o t o c c u r i n r e s p o n s e t o i n c r e a s e d venous r e t u r n i n t h e r e s t r a i n e d b u t u n a n a e s t h e t i z e d cod (Gadus morhua) bu t t h a t s t r o k e volume almost d o u b l e d . He s u g g ested t h a t b l o o d f l o w i n t h e r e s t r a i n e d cod can be i n c r e a s e d o n l y by e l e v a t i n g t h e s t r o k e volume. I t might be t h a t c a r d i o a c c e l e r a t i o n o c c u r s i n t h e cod b u t was n o t o b s e r v e d due t o t h e somewhat u n n a t u r a l c o n d i t i o n s o f h i s e xperiment. The s i t u a t i o n c o u l d be q u i t e d i f f e r e n t i n an u n r e s t r a i n e d free-swimming cod. T a c h y c a r d i a f o l l o w e d i n c r e a s e d venous r e t u r n i n t h e c a t f i s h (Amerius n e b u l o s u s ) a c c o r d i n g t o t h e s t u d y o f L a b a t et a l . (1961) . They c o n c l u d e d t h a t c a r d i o a c c e l e r a t i o n r e s u l t e d from t h e d i r e c t a c t i o n o f 25 p r e s s u r e on t h e myocardium. Thus t h e r e may be a v a r i e t y o f c o n t r o l mechanisms g o v e r n i n g h e a r t r a t e i n f i s h . N e u r a l c o n t r o l may be p r e s e n t t h r o u g h t h e a c t i o n o f t h e vagus n e r v e or a n e u r a l c o n t r o l may be b r o u g h t about t h r o u g h t h e d i r e c t i n f l u e n c e o f p r e s s u r e on t h e myocardium. I t i s a l s o p o s s i b l e t h a t c a r d i o a c c e l e r a t o r y s u b s t a n c e s may be p r e s e n t w h i c h a c t on t h e myocardium. There i s some e v i d e n c e t h a t an endogenous s u p p l y o f a c a r d i o a c c e l e r a t o r s u b s t a n c e may be p r e s e n t i n t h e h e a r t . Shepherd (1965) r e p o r t e d c a r d i o a c c e l e r a t i o n i n dogs t h a t was n o t r e l a t e d t o c i r c u l a t i n g c a t e c h o l a m i n e s . B r e t o n e t a l (1964) o b s e r v e d e l e v a t i o n o f h e a r t r a t e f o l l o w i n g e l e c t r i c a l s t i m u l a t i o n o f t h e t e l e o s t h e a r t . Jensen (1963) r e p o r t e d t h a t i t was p o s s i b l e t o i s o l a t e a c a r d i o a c c e l e r a t o r s u b s t a n c e from th e h a g f i s h b r a n c h i a l h e a r t t h a t was n o t a c a t e c h o l a m i n e . I f an endogenous s u p p l y o f c a r d i o a c c e l e r a t o r i s p r e s e n t i n t h e h e a r t t h e r e must be a mechanism m e d i a t i n g i t s r e l e a s e . More s t u d y i s r e q u i r e d t o d e t e r m i n e i f an endogenous mechanism o f c a r d i o a c c e l e r a t i o n i s p r e s e n t and i n what manner i t o p e r a t e s . C e r t a i n l y such a mechanism c o u l d e x p l a i n t h e c a r d i o a c c e l e r a t i o n o f t h e c a t f i s h h e a r t i n r e s p o n s e t o i n c r e a s i n g venous r e t u r n . Another more p l a u s i b l e e x p l a n a t i o n f o r c a r d i o a c c e l e r a t i o n d u r i n g e x e r c i s e r e l a t e s t o t h e p r e s e n c e o f a c c e l e r a t o r s u b s t a n c e s i n t h e b l o o d i t s e l f . These s u b s t a n c e s c o u l d be r e l e a s e d i n t o t h e b l o o d i n r e s p o n s e 26 t o a c t i v i t y and thus produce changes i n t h e c a r d i o v a s c u l a r system. Nakano and Thomlinson (1967) have measured i n c r e a s e d l e v e l s o f c a t e c h o l a m i n e s i n t h e b l o o d o f swimming t r o u t (Salmo g a i r d n e r i ) . R a n d a l l and Stevens (1967) o b s e r v e d i n c r e a s e d h e a r t r a t e and b l o o d p r e s s u r e f o l l o w i n g i n j e c t i v e o f 2-7 ug e p i n e p h r i n e i n t o t h e s u b i n t e s t i n a l v e i n o f sockeye and coho salmon a t 15°C. Less than 1 ug o f e p i n e p h r i n e i n j e c t e d i n salmon a p p a r e n t l y slowed t h e h e a r t b u t caused c a r d i o a c c e l e r a t i o n i n a t r o p i n i z e d f i s h . I t appears t h e n t h a t e p i n e p h r i n e can a c t as a c a r d i o a c c e l e r a t o r i n salmon and t h a t t h e e f f e c t s o f low e p i n e p h r i n e c o n c e n t r a t i o n can be masked by a c t i o n o f the vagus. Thus i n t h e salmon t h e r e may be two mechanisms by w h i c h t h e h e a r t r a t e i s i n c r e a s e d d u r i n g a c t i v i t y . The f i r s t may be n e u r a l and i n v o l v e r e l e a s e o f v a g a l tone d u r i n g a c t i v i t y w h i l e t h e second may be a n e u r a l and be a s s o c i a t e d w i t h t h e a c t i o n o f blo o d - b o u r n e c a t e c h o l a m i n e s a c t i n g on t h e h e a r t . F u r t h e r s t u d y i s r e q u i r e d t o e l u c i d a t e t h e r e l a t i v e importance o f t h e s e two mechanisms i n salmon. The p r e s e n c e o f c a t e c h o l a m i n e s i n t h e b l o o d d u r i n g a c t i v i t y i n t r o u t i n d i c a t e s t h a t t h e r e must be some s i t e f o r p r o d u c t i o n and r e l e a s e o f t h e s e s u b s t a n c e s i n t o t h e b l o o d . C a t e c h o l a m i n e - c o n t a i n i n g t i s s u e has been found s c a t t e r e d t h r o u g h o u t t h e body o f t e l e o s t s , much o f i t i n t h e r e g i o n o f t h e head k i d n e y (Bern, 1967. von E u l e r , 1953, 1961. von E u l e r and Fange, 1961. O s t l u n d , 1954). 27 E p i n e p h r i n e u s u a l l y makes up 5 0 % o f t h e t o t a l c a t e c h o l a m i n e s o f t e l e o s t s . Thus t h e r e appear t o be adequate s u p p l i e s o f e p i n e p h r i n e i n t h e b o d i e s o f t e l e o s t s w h i c h c o u l d be m o b i l i z e d t o f u n c t i o n as c a r d i o a c c e l e r a t o r s d u r i n g a c t i v i t y . The i n c r e a s e s i n h e a r t r a t e w i t h s u c c e s s i v e l y h i g h e r swimming speeds shown i n f i g u r e 3 c o u l d be r e l a t e d t o t h e c o n c e n t r a t i o n o f c i r c u l a t i n g c a t e c h o l a m i n e s . P o s s i b l y g r e a t e r amounts o f c a r d i o a c c e l e r a t o r y s u b s t a n c e a r e r e l e a s e d i n t o t h e b l o o d as swimming e f f o r t i n c r e a s e s . Average b l o o d p r e s s u r e changes d u r i n g t h e t e s t p r o c e d u r e a r e i l l u s t r a t e d i n f i g u r e 7. S i n c e b l o o d p r e s s u r e s r e c o r d e d i n t h e d o r s a l a o r t a a r e p u l s a t i l e and o s c i l l a t e between a maximal ( s y s t o l i c ) and m i n i m a l ( d i a s t o l i c ) p r e s s u r e , mean b l o o d p r e s s u r e s i n t h e v e s s e l were c a l c u l a t e d . I n t h i s way b l o o d p r e s s u r e s o f t h e t h r e e t e s t groups c o u l d be most e a s i l y compared. Mean b l o o d p r e s s u r e s were c a l c u l a t e d u s i n g t h e f o l l o w i n g f o r m u l a : Average b l o o d p r e s s u r e = S y s t o l i c P r e s s u r e + 2 ( D i a s t o l i c P r e s s u r e ) 3 B u r t o n (1966) suggested t h a t t h i s f o r m u l a gave t h e \" t r u e \" o r \"area mean\" o f a p u l s a t i l e p r e s s u r e i n an a r t e r y . Such a t r u e mean p r e s s u r e i s n o t e q u a l t o the a r i t h m e t i c mean o f t h e s y s t o l i c and d i a s t o l i c p r e s s u r e s b u t r e p r e s e n t s t h e t r u e mean p r e s s u r e d u r i n g the time 28 Legend f o r F i g u r e 7 F i g u r e 7 shows changes i n d o r s a l a o r t i c b l o o d p r e s s u r e b e f o r e , d u r i n g and a f t e r t h r e e groups o f f i s h had been f a t i g u e d by swimming. F i s h were a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e s . P o i n t s a r e mean averages + 1 s t a n d a r d e r r o r o f t h e mean. A R E A M E A N BLOOD P R E S S U R E ( % r o u t i n e ) 29 c o u r s e o f a p r e s s u r e o s c i l l a t i o n w i t h i n t h e v e s s e l . F i g u r e 8 i l l u s t r a t e s what i s meant by a \" t r u e \" or \"area mean\" p r e s s u r e . A t a l l t h r e e t e s t temperatures p r e s s u r e s showed l i t t l e change d u r i n g t h e i n i t i a l swimming p e r i o d and then r o s e above r o u t i n e l e v e l s i n re s p o n s e t o i n c r e a s i n g swimming e f f o r t . F i s h a c c l i m a t e d and t e s t e d a t 22°C and 15°C showed e s s e n t i a l l y t h e same p r e s s u r e changes i n r e s p o n s e t o a c t i v i t y . In t h e same f a s h i o n as w i t h t h e h e a r t r a t e d a t a , a s i g n i f i c a n t d i s p a r i t y i n r o u t i n e average b l o o d p r e s s u r e was apparent between mean average b l o o d p r e s s u r e o f j a c k s and a d u l t s a t 22°C ( s i g . w i t h t - t e s t a t t h e 0.01 l e v e l ) . A r e a mean a d u l t b l o o d p r e s s u r e was h i g h e r t h a n t h a n o f j a c k s . J a c k d a t a was m u l t i p l i e d by 1.1 t o a d j u s t i t t o a d u l t l e v e l s . There was no s i g n i f i c a n t d i f f e r e n c e i n j a c k and a d u l t average p r e s s u r e s a t 5°C ( t - t e s t , .05 l e v e l ) . Mott (195 7) summarized t h e a v a i l a b l e b l o o d p r e s s u r e e s t i m a t e s t a k e n from a v a r i e t y o f f i s h and showed t h a t t h e r e was c o n s i d e r a b l e v a r i a t i o n w i t h i n and between d i f f e r e n t s p e c i e s o f f i s h . She r e p o r t e d no i n f o r m a t i o n on p r e s s u r e changes i n a c t i v e , u n r e s t r a i n e d f i s h e s . Lyon (1926) r e p o r t e d t h a t b l o o d p r e s s u r e i n s h a r k s r o s e as h i g h as 50 mm Hg d u r i n g s t r u g g l i n g o r swimming. R e c e n t l y , Stevens and R a n d a l l (1967 a) r e p o r t e d a 16% r i s e i n s y s t o l i c p r e s s u r e and a 2 1 % r i s e i n d i a s t o l i c 30 Legend f o r F i g u r e 8 F i g u r e 8 shows a h y p o t h e t i c a l b l o o d p r e s s u r e r e c o r d t o i l l u s t r a t e what i s meant by the \" t r u e mean\" or \"area mean\" o f a p u l s a t i l e p r e s s u r e . The a r e a o f t h e c u r v e above t h e s o l i d l i n e must e q u a l t h e sum o f t h e two a r e a s below t h e s o l i d l i n e . The f o r m u l a f o r computing a r e a mean b l o o d p r e s s u r e i s i n c l u d e d and a sample c a l c u l a t i o n i s shown. 31 p r e s s u r e i n t h e d o r s a l a o r t a o f m o d e r a t e l y a c t i v e r a i n b o w t r o u t . In t h e i r e x p e r i m e n t s v e n t r a l a o r t i c d i a s t o l i c and s y s t o l i c p r e s s u r e s r o s e by about 40%. The s u b i n t e s t i n a l v e i n showed no p u l s e p r e s s u r e b u t t h e r e were i r r e g u l a r r a p i d i n c r e a s e s i n b l o o d p r e s s u r e i n t h e v e s s e l d u r i n g a c t i v i t y . The changes i n d o r s a l a o r t i c p r e s s u r e i n f i g u r e 7 appear c o m p a r i b l e w i t h t h o s e o f Stevens and R a n d a l l . The i n c r e a s e i n b l o o d p r e s s u r e o b s e r v e d d u r i n g a c t i v i t y c o u l d r e s u l t from 1) i n c r e a s e d h e a r t r a t e , 2) i n c r e a s e d s t r o k e volume and 3) i n c r e a s e d p e r i p h e r a l r e s i s t a n c e or some c o m b i n a t i o n o f t h e s e f a c t o r s . Our d a t a show t h a t h e a r t r a t e i n c r e a s e d d u r i n g a c t i v i t y and t h a t s t r o k e volume appeared t o i n c r e a s e . S i n c e s t r o k e volume i s c a l c u l a t e d and n o t measured d i r e c t l y we can say n o t h i n g o f t h e importance o f s t r o k e volume i n c r e a s e i n p r o d u c i n g e l e v a t e d b l o o d p r e s s u r e . C e r t a i n l y t h e e l e v a t e d h e a r t r a t e d u r i n g a c t i v i t y s u g g e s t s t h a t c a r d i a c o u t p u t has i n c r e a s e d . I f r e s i s t a n c e o f t h e c i r c u l a t o r y system d i d n o t change i n t h e f a c e o f i n c r e a s e d c a r d i a c o u t p u t then one would e x p e c t an i n c r e a s e i n b l o o d p r e s s u r e t o r e s u l t . The c r u x o f t h e problem then appears r e l a t e d t o r e s i s t a n c e i n t h e c i r c u l a t o r y system. R a n d a l l and Stevens (1967) i n j e c t e d e p i n e p h r i n e i n t r a v e n o u s l y i n t o r e s t i n g coho salmon (Onchorynchus k i s u t c h ) and o b s e r v e d e l e v a t e d d o r s a l a o r t i c b l o o d p r e s s u r e a f t e r i n j e c t i o n . I n j e c t i o n o f an ec-adrenergic 32 b l o c k i n g agent, phenoxybenzamine, a b o l i s h e d t h e r i s e i n b l o o d p r e s s u r e produced by e p i n e p h r i n e . They c o n c l u d e d t h a t t h e r e a r e oC-adrengergic r e c e p t o r s p r e s e n t i n t h e g i l l s and g e n e r a l body c i r c u l a t i o n o f salmon. These w o r k e r s a l s o found t h a t phenoxybenzamine a b o l i s h e d r i s e s o f b l o o d p r e s s u r e t h a t o c c u r r e d w h i l e t h e f i s h were swimming. Thus i t appeared t h a t v a s o c o n s t r i c t o r y o C - a d r e n e r g i c r e c e p t o r s might be p a r t l y r e s p o n s i b l e f o r b l o o d p r e s s u r e i n c r e a s e s a s s o c i a t e d w i t h swimming. The b l o o d p r e s s u r e changes i n t h e d o r s a l a o r t a c o u l d be due t o v a s o d i l a t i o n o f t h e g i l l s . Indeed a v a s o d i l a t o r y a c t i o n o f a d r e n a l i n e on t h e g i l l s has been demonstrated (Keyes and Bateman, 1932. Krawkow 1931. Steen and K r u y s s e , 1964.). The v a s o d i l a t i o n c o u l d be due t o t h e a c t i o n o f <£ and r e c e p t o r s on t h e g i l l s . The work of R a n d a l l and Stevens has demonstrated th e p r e s e n c e o f oc r e c e p t o r s and s u b s e q u e n t l y Baumgarten and R a n d a l l ( p e r s o n a l communication) demonstrated t h e p r e s e n c e of b o t h oC and A r e c e p t o r s i n t h e g i l l s o f r ainbow t r o u t . In a swimming f i s h t h e o v e r a l l r e s i s t a n c e o f t h e p e r i p h e r a l c i r c u l a t i o n d i m i n i s h e s ( R a n d a l l and Stevens, 1967) i n d i c a t i n g t h a t v a s o d i l a t i o n or opening o f a d d i t i o n a l v e s s e l s has o c c u r r e d . One c o u l d h y p o t h e s i z e t h a t d u r i n g a c t i v i t y t h e r e i s some p o w e r f u l c o n t r o l mechanism o p e r a t i n g w h i c h i s c a p a b l e o f o v e r r i d i n g the v a s o c o n s t r i c t o r y a c t i o n o f e p i n e p h e r i n e or a d r e n e r g i c 33 r e c e p t o r s . Such v a s o d i l a t i o n c o u l d r e s u l t from e p i n e p h r i n e a c t i n g on v a s o d i l a t o r y a d r e n e r g i c r e c e p t o r s w h i c h may be p r e s e n t i n t h e p e r i p h e r a l c i r c u l a t i o n ( R a n d a l l - p e r s o n a l communication). A v a s o d i l a t o r y mechanism would be i m p o r t a n t as i t would p r e v e n t l a r g e changes i n b l o o d p r e s s u r e o c c u r r i n g i n t h e f a c e o f l a r g e i n c r e a s e s i n c a r d i a c o u t p u t . We a r e thus u n a b l e t o say e x a c t l y what f a c t o r s produce e l e v a t e d b l o o d p r e s s u r e d u r i n g a c t i v i t y . P r o b a b l y i n c r e a s e d c a r d i a c o u t p u t i s a major c a u s i t i v e f a c t o r however t h e r e s i s t a n c e o f the c i r c u l a t o r y system i s u n d o u b t a b l y o f c o n s i d e r a b l e importance. The e f f e c t s o f c i r c u l a t i n g c a t e c h o l a m i n e s and t h e p r e s e n c e o f «c and >B r e c e p t o r s i n f i s h r e q u i r e f u r t h e r a t t e n t i o n . The p r e s e n t s t u d y s u p p o r t s t h e o b s e r v a t i o n s o f R a n d a l l and Stevens (1967) t h a t t h e r e s i s t a n c e o f t h e v a s c u l a r system d r o p s d u r i n g a c t i v i t y . Assuming t h a t a r t e r i o - v e n o u s oxygen l e v e l s do n o t change, f o r a d o u b l i n g o f oxygen u p t a k e one s h o u l d o b s e r v e a d o u b l i n g o f b l o o d p r e s s u r e i f t h e v a s c u l a r r e s i s t a n c e remains u n a l t e r e d . S i n c e a c t i v e oxygen consumption i s 5-10 t i m e s r o u t i n e l e v e l s ( f i g u r e 11) one might e x p e c t v e r y h i g h b l o o d p r e s s u r e s t o accompany s e v e r e e x e r c i s e i f i n c r e a s e s i n c a r d i a c o u t p u t a l o n e f a c i l i t a t e e l e v a t e d oxygen upta k e . O b v i o u s l y t h i s i s n o t t h e case ( f i g u r e 7, t a b l e V I I I ) . A l t e r n a t e l y , e l e v a t e d a c t i v e oxygen uptake c o u l d r e s u l t from changes i n a r t e r i o - v e n o u s oxygen d i f f e r e n c e s . 34 However, i n o r d e r t o account f o r e l e v a t e d oxygen uptakes o f 5-10 t i m e s r o u t i n e l e v e l s by i n c r e a s e d a r t e r i o - v e n o u s oxygen d i f f e r e n c e a l o n e , t h i s d i f f e r e n c e a t r o u t i n e l e v e l s would have t o be e x t r e m e l y s m a l l - i . e . 1/5 t o 1/10 t h a t o f f u l l y a c t i v e f i s h . S i n c e we have no d a t a on A-V oxygen d i f f e r e n c e s and we have c a l c u l a t e d c a r d i a c o u t p u t d a t a from oxygen up t a k e we a r e u n a b l e t o c o n c l u d e whether i n c r e a s e d c a r d i a c o u t p u t or i n c r e a s e d a r t e r i o - v e n o u s oxygen d i f f e r e n c e s account f o r e l e v a t e d a c t i v e oxygen uptake. S i n c e t h e r e p o r t e d A-V oxygen d i f f e r e n c e s i n r e s t i n g t r o u t are q u i t e l a r g e ( v e n t r a l a o r t i c b l o o d 38% s a t u r a t e d , Stevens and R a n d a l l , 1967 b; v e n t r a l a o r t i c b l o o d 70% s a t u r a t e d , H o l e t o n and R a n d a l l , 1966 b; and d o r s a l a o r t i c b l o o d 100% s a t u r a t e d i n b o t h cases) then i t would be i m p o s s i b l e t o account f o r even a 5 - f o l d i n c r e a s e i n oxygen uptake by i n c r e a s i n g t h e A-V oxygen d i f f e r e n c e a l o n e . I t f o l l o w s t h e n t h a t c a r d i a c o u t p u t must i n c r e a s e m a r kedly and i n t h e f a c e o f t h i s i n c r e a s e one might e x p e c t an i n c r e a s e i n t h e oxygen t r a n s f e r f a c t o r o f t h e g i l l s . P r o b a b l y b o t h o f t h e s e mechanisms a r e a s s o c i a t e d w i t h t h e i n c r e a s e d oxygen up t a k e . As b l o o d p r e s s u r e does n o t i n c r e a s e p r o p o r t i o n a t e l y w i t h c a r d i a c o u t p u t t h e r e must be d e c r e a s e s i n p e r i p h e r a l r e s i s t a n c e o f t h e c i r c u l a t o r y system w h i c h accompany e l e v a t e d c a r d i a c o u t p u t d u r i n g swimming. F i g u r e 9 shows t h a t p u l s e p r e s s u r e i n t h e d o r s a l 35 Legend f o r F i g u r e 9 T h i s f i g u r e shows changes i n d o r s a l a o r t i c p u l s e p r e s s u r e s b e f o r e , d u r i n g and a f t e r swimming a c t i v i t y i n t h r e e t e s t groups o f sockeye salmon. V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean. No s t a n d a r d e r r o r s a r e a v a i l a b l e f o r t h e 15°C d a t a . 36 a o r t a r o s e d u r i n g swimming i n t h e 5 and 15°C groups and f e l l below r o u t i n e l e v e l s i n t h e 22°C group. The s i g n i f i c a n c e o f t h e s e r e s u l t s i s d i s c u s s e d i n P a r t Two o f t h i s paper (p.64). R e s p i r a t i o n r a t e d a t a showed c o n s i d e r a b l e v a r i a b i l i t y ( f i g u r e 10). F i s h i n t h e 5°C t e s t group showed l a r g e i n c r e a s e s i n r e s p i r a t o r y r a t e d u r i n g a c t i v i t y . Changes were s l i g h t i n t h e 22°C group and t h e r a t e dropped below r o u t i n e l e v e l s i n t h e 15°C t e s t f i s h . Smith e t a l (1967) r e p o r t e d t h a t t h i s drop a t 15°C was due t o t h e f i s h s t o p p i n g v e n t i l a t i o n movements and swimming w i t h t h e i r mouths h e l d open. B r e t t (1964, 1967) r e p o r t e d s i m i l a r c e s s a t i o n o f r e s p i r a t o r y movements i n swimming sockeye salmon. F r y (1957) p o i n t e d out t h a t c e s s a t i o n o f v e n t i l a t i o n was a common phenomenon i n a number o f d i f f e r e n t s p e c i e s o f f i s h . S i n c e t h e mean r o u t i n e r e s p i r a t o r y r a t e o f j a c k s was h i g h e r than a d u l t sockeye a t 22°C ( s i g . a t 5% l e v e l , t - t e s t ) i t was n e c e s s a r y t o make a p p r o p r i a t e c o r r e c t i o n s . The r e s p i r a t o r y r a t e d a t a o f t h e j a c k s were t h e r e f o r e m u l t i p l i e d by 0.784 t o c o r r e c t them t o a d u l t l e v e l s and t h e d a t a from b o t h j a c k s and a d u l t s combined. There was no s i g n i f i c a n t d i f f e r e n c e between mean j a c k and a d u l t r e s p i r a t o r y r a t e s a t 5°C ( t - t e s t , 5% l e v e l o f s i g n i f i c a n c e ) hence no c o r r e c t i o n was n e c e s s a r y . A c t i v e , s t a n d a r d and r o u t i n e oxygen consumption 37 Legend f o r F i g u r e 10 F i g u r e 10 shows changes i n v e n t i l a t i o n r a t e i n res p o n s e t o i n c r e a s i n g swimming a c t i v i t y and f o l l o w i n g f a t i g u e . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean and a r e t a k e n from t h r e e groups o f f i s h a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e . L arge v a r i a b i l i t y i s e v i d e n t s i n c e some f i s h c o n t i n u e d t o v e n t i l a t e d u r i n g t h e e n t i r e a c t i v i t y p e r i o d w h i l e o t h e r s ceased v e n t i l a t i o n and swam i n t o t h e water c u r r e n t w i t h t h e i r mouths open. VENTILATION R A T E (mouth closures/min) k \" (% routine) g\\D INJ CJ W OJ O Ol O Oi O «r> o 0 0 0 0 0 o o r 1 — — - — r ~ ' — ~ 1 ' M 0 © ro — ro 01 01 C O © 0 0 0 38 v a l u e s a r e shown i n f i g u r e 11 and t a b l e V I . These d a t a were e x t r a c t e d from B r e t t ' s work. R o u t i n e oxygen uptake v a l u e s were o n l y measured i n a group o f j a c k s a t 15°C and a l l o t h e r r o u t i n e v a l u e s have been o b t a i n e d by p r o j e c t i n g t h i s a c t i v i t y l e v e l on d i f f e r e n t c u r v e s i n f i g u r e 11. Such a p r o c e d u r e may be s l i g h t l y i n a c c u r a t e as i t assumes t h a t r o u t i n e oxygen consumption o c c u r s a t t h e same a c t i v i t y a t a l l t e m p e r a t u r e s . Indeed, spontaneous a c t i v i t y i s t e m p e r a t u r e dependent ( B r e t t -p e r s o n a l communication). B r e t t ' s measure o f r o u t i n e m e t a b o l i c r a t e a t 15°C i s p r o b a b l y a good e s t i m a t e o f r o u t i n e m e t a b o l i c r a t e t o use as a b a s i s f o r c a l c u l a t i o n i n t h e p r e s e n t s t u d y s i n c e h i s f i s h were s t u d i e d under v i r t u a l l y i d e n t i c a l c o n d i t i o n s i n t h e same r e s p i r o m e t e r ( B r e t t , 1965). B u c c a l p r e s s u r e s i n c r e a s e d markedly d u r i n g swimming i n t h e 5 and 22°C t e s t groups ( f i g u r e 12). Smith (1967) r e p o r t e d no d a t a on b u c c a l p r e s s u r e s i n f i s h a c c l i m a t e d and t e s t e d a t 15°C. I t i s apparent from f i g u r e 11 t h a t oxygen consumption r i s e s markedly d u r i n g a c t i v i t y n e c e s s i t a t i n g an i n c r e a s e i n r e s p i r a t o r y gas exchange. I t i s thus n o t s u r p r i s i n g t h a t r e s p i r a t i o n r a t e and b u c c a l p r e s s u r e r i s e d u r i n g a c t i v i t y . The l a r g e v a r i a b i l i t y i n r e c o r d e d r e s p i r a t o r y r a t e s and the drop i n r a t e a t h i g h e r swimming speeds a t 15°C i s r e l a t e d t o d i f f e r e n c e s i n b e h a v i o r . Some 39 Legend f o r F i g u r e 11 F i g u r e 11 i s a s e m i - l o g a r i t h m i c p l o t o f oxygen uptake and swimming e f f o r t . V a l u e s f o r v a r i o u s t e s t groups a r e i l l u s t r a t e d ; p o i n t s r e p r e s e n t means f o r each group. S t a n d a r d e r r o r s a r e g i v e n i n t a b l e V I s i n c e t h e y a r e t o o s m a l l t o be i n c l u d e d a c c u r a t e l y i n t h i s p l o t . R o u t i n e oxygen uptake was o n l y measured i n a group of j a c k sockeye a t 15°C. The r o u t i n e oxygen uptake f o r t h e s e j a c k s was p r o j e c t e d onto t h e d a t a f o r o t h e r groups, as shown by t h e arrow, so that an e s t i m a t e o f r o u t i n e m e t a b o l i c r a t e c o u l d be made f o r t h e s e groups. The l i n e f o r 22°C a d u l t s was o b t a i n e d by e x t r a p o l a t i n g t h e v a l u e s o f f i g u r e 19. 40 Legend f o r F i g u r e 12 Changes i n b u c c a l p r e s s u r e d u r i n g i n c r e a s e d swimming a c t i v i t y and f o l l o w i n g f a t i g u e a r e i l l u s t r a t e d . B u c c a l p r e s s u r e i s t h e maximum p r e s s u r e r e c o r d e d i n the mouth c a v i t y d u r i n g v e n t i l a t i o n . V a l u e s a r e mean averages + 1 s t a n d a r d e r r o r o f t h e mean and a r e t a k e n from groups o f f i s h a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e . No d a t a i s a v a i l a b l e on b u c c a l p r e s s u r e s a t 15°C. H i g h v a r i a n c e s r e s u l t e d s i n c e some f i s h ceased v e n t i l a t i o n o r slowed t h e i r v e n t i l a t i o n r a t e a t h i g h swimming speeds w h i l e o t h e r s c o n t i n u e d t o v e n t i l a t e r a p i d l y . 41 f i s h h a l t e d r e s p i r a t o r y movements and swam i n t o t h e c u r r e n t w i t h t h e i r mouths open. Others c o n t i n u e d v e n t i l a t i o n movements at a l l a c t i v i t y l e v e l s . In g e n e r a l l a r g e r f i s h tended t o h a l t r e s p i r a t o r y movements a t lower v e l o c i t i e s t han t h e s m a l l e r f i s h hence Smith's 15°C d a t a , w h i c h c o n t a i n s no j a c k s , r e f l e c t a r a p i d c e s s a t i o n o f r e s p i r a t o r y movements. The a b i l i t y o f swimming f i s h t o s t o p v e n t i l a t i o n movements would be a v a l u a b l e means o f c o n s e r v i n g energy. S i n c e pumping such a dense medium as water over t h e g i l l s r e q u i r e s a l a r g e component of t h e r e s t i n g oxygen consumption (Schumann and P i i p e r , 1966) any means o f s h u t t i n g down t h i s energy-consuming mechanism would be o f v a l u e t o swimming f i s h . Once t h e f i s h has a t t a i n e d a s u f f i c i e n t f o r w a r d motion or i s r e m a i n i n g s t a t i o n a r y i n a water c u r r e n t o f moderate v e l o c i t y i t c o u l d s t o p v e n t i l a t i n g and a l l o w t h e s t r e a m o f water r u s h i n g p a s t t o f l u s h t h e g i l l s . We have f r e q u e n t l y o b s e r v e d l a r g e salmon whose swimming and r e s p i r a t o r y movements suggest t h e p r e s e n c e o f some s o r t o f r e f l e x . L a r g e f i s h p l a c e d i n t h e r e s p i r o m e t e r i n a moderate water c u r r e n t o f t e n swim s l o w l y f o r w a r d i n t o t h e c u r r e n t w i t h mouth h e l d open and no v e n t i l a t o r y movements. As soon as swimming movements cease and t h e f i s h d r i f t s back i n the water c u r r e n t r e s p i r a t o r y movements a r e i n i t i a t e d - o n l y t o s t o p a g a i n when t h e f i s h resumes swimming. A t h i g h water v e l o c i t i e s t h e r e 42 i s no c e s s a t i o n o f swimming and t h e f i s h swims w i t h mouth h e l d open. I t appears t h e n , t h a t swimming and v e n t i l a t i o n a r e l i n k e d i n some way as a means o f s a v i n g energy i n swimming f i s h . B e f o r e p r o c e e d i n g w i t h t h e d i s c u s s i o n t h e r e s u l t s w i l l be summarized. Both h e a r t r a t e and b l o o d p r e s s u r e i n c r e a s e d u r i n g swimming i n sockeye salmon. E l e v a t e d b l o o d p r e s s u r e appeared t o be accompanied by a drop i n p e r i p h e r a l r e s i s t a n c e . I t seems l i k e l y t h a t c a r d i a c o u t p u t would i n c r e a s e m a r kedly d u r i n g e x e r c i s e . Indeed, oxygen consumption r i s e s 5-10 t i m e s r o u t i n e l e v e l s d u r i n g s e v e r e e x e r c i s e and we have shown t h a t such an i n c r e a s e cannot be f a c i l i t a t e d by i n c r e a s e d a r t e r i o -venous oxygen d i f f e r e n c e s a l o n e . I t i s t h e r e f o r e i m p o r t a n t t o have some i d e a o f what changes i n c a r d i a c o u t p u t accompany e x e r c i s e i n salmon. U n f o r t u n a t e l y we d i d n o t measure c a r d i a c o u t p u t d i r e c t l y hence we must c a l c u l a t e i t u s i n g t h e F i c k p r i n c i p l e . S i n c e d a t a were a v a i l a b l e on h e a r t r a t e and oxygen consumption i t was p o s s i b l e t o c a l c u l a t e c a r d i a c o u t p u t and s t r o k e volume a t r o u t i n e and a c t i v e l e v e l s o f performance f o r a l l t h r e e t e m p e r a t u r e groups. These c a l c u l a t i o n s were made i n t h e f o l l o w i n g manner: - 5°C a c c l i m a t e d f i s h ; mean r o u t i n e oxygen uptake from f i g u r e 11 i s 48 mg 0 2/Kg/hr - Assuming t h e f i s h weigh 1 Kg and t h a t a r t e r i o -venous oxygen l e v e l s remain c o n s t a n t 43 - Assuming v e n t r a l a o r t i c b l o o d PO^ = z e r o 48 mg 0 2/Kg/hr = 0.8 mg 0 2/Kg/min. a t h e a r t r a t e = 31 b e a t s / m i n . 0.8 = 0.0258 mg 0 /Kg/beat, 0.0258 x .7 31 = 0.01806 ml 0 2/Kg/beat - i f t h e b l o o d oxygen c a p a c i t y i s 9 v o l s % then 0.08106 = 0.2007 ml b l o o d - s t r o k e volume. 0. 09 - i f s t r o k e volume i s 0.2007 m i s / s t r o k e then c a r d i a c o u t p u t = s t r o k e volume x h e a r t r a t e = 0.2007 x 31 = 6.22 ml/min c a r d i a c o u t p u t . The above c a l c u l a t i o n s a r e based on a b l o o d oxygen c a p a c i t y o f 9 v o l s %. H o l e t o n and R a n d a l l (1967 b) p r e s e n t e d a graph i n w h i c h h e m a t o c r i t was compared w i t h t h e b l o o d oxygen c a p a c i t y o f r a i n b o w t r o u t . They measured b l o o d oxygen l e v e l s w i t h a van S l y k e a p p a r a t u s u s i n g b l o o d samples o f v a r y i n g h e m a t o c r i t . In t h e p r e s e n t s t u d y t h e mean h e m a t o c r i t o f 5 f i s h a t 15°C was 23.4 +1.36%. A h e m a t o c r i t o f 23 c o r r e s p o n d s t o a b l o o d oxygen c a p a c i t y o f 8.5 v o l s % on H o l e t o n and R a n d a l l ' s graph. Smith (1966) measured t h e h e m a t o c r i t o f 8 sockeye salmon a t 11-16°C and found a mean v a l u e o f 26+3.8%. Smith's v a l u e c o r r e s p o n d s t o a b l o o d oxygen c a p a c i t y o f 9.5 v o l s % a c c o r d i n g t o H o l e t o n and R a n d a l l ' s graph. S i n c e t h e mean v a l u e o f Smith's and t h e p r e s e n t s t u d y were n o t s i g n i f i c a n t l y d i f f e r e n t ( t - t e s t , 0.05 l e v e l o f s i g n i f i c a n c e ) t h e m i d - p o i n t o f t h e b l o o d oxygen c a p a c i t y range, 8.5 - 9.5 v o l s %, was t a k e n t o be an e s t i m a t e o f t h e b l o o d oxygen c a p a c i t y o f t h e sockeye salmon used i n t h i s s t u d y - i . e . 9 v o l s %. Such a p r o c e d u r e o f c o u r s e , assumes t h a t r a i n b o w t r o u t b l o o d and sockeye salmon b l o o d have s i m i l a r oxygen c a p a c i t i e s w h i c h may n o t n e c e s s a r i l y be t h e case. S i n c e t h e r e i s no d a t a a v a i l a b l e f o r t h e oxygen c a p a c i t y o f sockeye salmon b l o o d i t i s n e c e s s a r y t o adopt t h e above p r o c e d u r e B l a c k e t j a l (1966) found t h a t t h e b l o o d oxygen c a p a c i t y o f A t l a n t i c salmon i n t h e summer was 8.3+0.67 v o l s % and t h e h e m a t o c r i t was 23.2+1.70%. S i n c e a h e m a t o c r i t o f 23 c o r r e s p o n d s t o a b l o o d oxygen c a p a c i t y o f 8.5 v o l s % on H o l e t o n and R a n d a l l ' s graph and t h e a c t u a l oxygen c a p a c i t y o f A t l a n t i c salmon b l o o d a c c o r d i n g t o B l a c k e t a l (1966) was 8.3+0.67 v o l s % i t appears t h a t t h e use o f such a graph p r o v i d e s a good e s t i m a t e o f t h e oxygen c a p a c i t y o f salmon b l o o d . The p r e v i o u s c a l c u l a t i o n s o f c a r d i a c o u t p u t were based on t h e assumption t h a t v e n t r a l a o r t i c b l o o d c o n t a i n s no oxygen (Ferguson and B l a c k , 1941) and t h a t d o r s a l a o r t i c b l o o d i s f u l l y s a t u r a t e d as r e p o r t e d by H o l e t o n and R a n d a l l (1967 b ) . The l a t t e r i n v e s t i g a t o r s however, found t h e v e n t r a l a o r t i c b l o o d o f q u i e s c e n t r a i n b o w t r o u t t o be a p p r o x i m a t e l y 70% s a t u r a t e d w h i l e Stevens and R a n d a l l (1967 b) found i t t o be 38% s a t u r a t e d Stevens and R a n d a l l suggest t h a t t h e i r lower v e n t r a l a o r t i c oxygen s a t u r a t i o n f i g u r e s r e s u l t from h i g h e r 45 b l o o d PCC>2 l e v e l s than t h o s e o f H o l e t o n and R a n d a l l . I t was t h u s n e c e s s a r y t o c a r r y out f u r t h e r c a l c u l a t i o n s b a sed on v e n t r a l a o r t i c oxygen l e v e l s o f 38 and 70% s a t u r a t i o n r e s p e c t i v e l y . R e s u l t s a r e shown i n f i g u r e s 13 and 14. There i s a marked i n c r e a s e i n c a r d i a c o u t p u t and s t r o k e volume produced by a c t i v i t y . I t i s d i f f i c u l t t o d e c i d e w h i c h o f t h e c a l c u l a t e d f i g u r e s can be b e s t a p p l i e d t o t h i s s t u d y . I t seems u n l i k e l y t h a t t h e v e n t r a l a o r t i c b l o o d i s c o m p l e t e l y u n s a t u r a t e d w i t h oxygen a t r o u t i n e a c t i v i t y l e v e l s i n t h e l i g h t o f s t u d i e s by H o l e t o n and R a n d a l l (1967 b) and Stevens and R a n d a l l (1967 b ) . W i t h no knowledge o f v e n t r a l a o r t i c PCO-j w e c a n deduce n o t h i n g o f t h e p o s s i b l e i n h i b i t i n g e f f e c t o f CO^ upon the c o m b i n a t i o n o f oxygen w i t h hemoglobin. I t seems u n l i k e l y t h a t v e n t r a l a o r t i c b l o o d oxygen remains a t a c o n s t a n t l e v e l o f s a t u r a t i o n as swimming e f f o r t i n c r e a s e s . One might e x p e c t t h a t v e n t r a l a o r t i c oxygen l e v e l s would be q u i t e low d u r i n g maximal a c t i v i t y . B e a r i n g t h e s e f a c t s i n mind we may then suggest t h a t t h e shaded p o r t i o n o f f i g u r e s 13 and 14 most l i k e l y r e p r e s e n t s t h e a c t u a l scope o f c a r d i a c o u t p u t and s t r o k e volume f i g u r e s t h a t c o u l d be c a l c u l a t e d f o r a d u l t sockeye salmon. What i s t h e s i g n i f i c a n c e o f t h e c a l c u l a t e d changes i n c a r d i a c o u t p u t and s t r o k e volume produced by a c t i v i t y ? I n c r e a s e d oxygen d e l i v e r y t o t h e t i s s u e s d u r i n g e x e r c i s e c o u l d be f a c i l i t a t e d i n 3 ways: (1) t a c h y c a r d i a , 46 Legend f o r F i g u r e 13 T h i s f i g u r e i l l u s t r a t e s t h e e f f e c t o f t e m p e r a t u r e on c a r d i a c o u t p u t o f f u l l y a c t i v e ( j u s t p r i o r t o f a t i g u e ) and r e s t i n g ( r o u t i n e ) sockeye salmon. C a r d i a c o u t p u t v a l u e s were c a l c u l a t e d by t h e F i c k p r i n c i p l e u s i n g t h r e e d i f f e r e n t l e v e l s o f v e n t r a l a o r t i c b l o o d oxygen s a t u r a t i o n . The shaded p o r t i o n o f t h e graph r e p r e s e n t s t h e range o f s t r o k e volumes thought t o be most r e p r e s e n t a t i v e o f t r u e c a r d i a c o u t p u t l e v e l s i n sockeye salmon. rouV\\ne c b\\ood © ventral 0% sat'd. blood 38 % sen v,. ventral aorYic blood = 70% sat'd. 47 Legend f o r F i g u r e 14 T h i s f i g u r e i l l u s t r a t e s t h e e f f e c t o f t e m p e r a t u r e on s t r o k e volume o f f u l l y a c t i v e ( j u s t p r i o r t o f a t i g u e ) and r e s t i n g ( r o u t i n e ) sockeye salmon. S t r o k e volumes were c a l c u l a t e d by the F i c k p r i n c i p l e u s i n g t h r e e d i f f e r e n t l e v e l s o f v e n t r a l a o r t i c b l o o d oxygen s a t u r a t i o n . The shaded p o r t i o n o f t h e graph r e p r e s e n t s t h e range o f s t r o k e volume v a l u e s thought t o be most r e p r e s e n t a t i v e o f t r u e s t r o k e volume o u t p u t l e v e l s i n sockeye salmon. fuliy acfivo . routin© I © ventral aortic blood = 0% sat'd-x ventral aortic blood = 3 0 % sat'd. o ventral aortic blood ° 7 0 % sat'd. 48 (2) i n c r e a s e d s t r o k e volume and (3) i n c r e a s e d a r t e r i o -venous oxygen l e v e l d i f f e r e n c e s . In-humans and dogs c a r d i o a c c e l e r a t i o n and i n c r e a s e d oxygen e x t r a c t i o n a r e the normal mechanisms t h a t i n c r e a s e oxygen d e l i v e r y d u r i n g moderate e x e r c i s e . Only i n t r a i n e d a t h l e t e s does s t r o k e volume i n c r e a s e d u r i n g moderate e x e r c i s e (Rushmer, 1962). The s i t u a t i o n appears somewhat d i f f e r e n t i n f i s h . Stevens and R a n d a l l (1967 b) r e p o r t e d a 15% r i s e i n h e a r t r a t e , an almost 5 - f o l d i n c r e a s e i n c a l c u l a t e d s t r o k e volume and o n l y s l i g h t changes i n a r t e r i o - v e n o u s oxygen l e v e l s i n m o d e r a t e l y a c t i v e t r o u t . Our s t u d y i n d i c a t e s t h a t s i m i l a r s o r t s o f h e a r t r a t e changes o c c u r d u r i n g a c t i v i t y i n salmon. We have assumed i n our c a r d i a c o u t p u t c a l c u l a t i o n s t h a t a r t e r i o - v e n o u s oxygen d i f f e r e n c e does not change d u r i n g a c t i v i t y . I n Stevens and R a n d a l l ' s s t u d y such changes were n o t o b s e r v e d , u n d o u b t a b l y because t h e i r f i s h were swimming f o r o n l y 10 minutes a t moderate v e l o c i t i e s . I t seems l i k e l y t h a t A-V oxygen d i f f e r e n c e i n c r e a s e s a t h i g h l e v e l s o f a c t i v i t y s i n c e t h e t i s s u e demand f o r oxygen would i n c r e a s e d i r e c t l y w i t h t h e a c t i v i t y l e v e l and t h e d u r a t i o n o f heavy e x e r c i s e . C o n s e q u e n t l y our i n t e r p r e t a t i o n o f t h e c a r d i a c o u t p u t and s t r o k e volume d a t a must be n e c e s s a r i l y c a u t i o u s as we do n o t know what changes i n A-V l e v e l s may accompany s e v e r e e x e r c i s e . I t appears t h a t changes i n s t r o k e volume 49 do accompany e x e r c i s e however t h e magnitude of t h e s e changes i s not known. I t appears t h a t t r o u t , and p r o b a b l y salmon, ar e a b l e t o u t i l i z e t h r e e mechanisms o f i n c r e a s i n g oxygen uptake d u r i n g e x e r c i s e ; t a c h y c a r d i a , e l e v a t e d s t r o k e volume and p o s s i b l y i n c r e a s e d a r t e r i o - v e n o u s oxygen l e v e l d i f f e r e n c e s . F a c t o r s i n f l u e n c i n g t h e s t r o k e volume o f t h e f i s h h e a r t w i l l be d i s c u s s e d more f u l l y i n t h e second p a r t o f t h i s paper (p. 71) . U n t i l now we have c o n f i n e d our d i s c u s s i o n t o changes i n c a r d i o v a s c u l a r and r e s p i r a t o r y parameters w h i c h accompany e x e r c i s e . We s h a l l now c o n s i d e r t h e s e parameters i n f i s h i n t h e t i m e p e r i o d a f t e r t h e f i s h were f a t i g u e d by swimming. At v e r y h i g h l e v e l s o f a c t i v i t y w h i c h approach f a t i g u e l e v e l s , a n i m a l s may expend over 20 t i m e s t h e i r b a s a l m e t a b o l i c r a t e w i t h accompanying use of a n a e r o b i c energy r e s e r v e s ( B r e t t , 1962). Under t h e s e c o n d i t i o n s t h e a n i m a l goes i n t o oxygen debt. Oxygen debt i s a s s o c i a t e d w i t h t h e p r e s e n c e o f a n a e r o b i c m e t a b o l i t e s i n t h e b l o o d such as l a c t i c and p y r u v i c a c i d s and w i t h t h e e x p e n d i t u r e o f muscle g l y c o g e n and h i g h energy phosphorus compounds. F o l l o w i n g e x e r c i s e i n t r o u t , b l o o d l a c t a t e remains e l e v a t e d f o r about 8 hours ( B l a c k e t a l , 1961, 1962. B r e t t , 1962. Stevens and B a l c k , 1966). Thus oxygen debt may be p r e s e n t i n f i s h f o r some t i m e a f t e r a c t i v i t y . 50 I t seems l i k e l y t h a t c o n s i d e r a b l e oxygen debt was p r e s e n t i n our f i s h d u r i n g t h e one hour p o s t - e x e r c i s e p e r i o d . H e a r t r a t e d e c r e a s e d b u t d i d n o t r e a c h r o u t i n e l e v e l s a f t e r one hour ( f i g u r e 3) w h i l e b l o o d p r e s s u r e approached or f e l l below r o u t i n e l e v e l s ( f i g u r e 7 ) . D u r i n g r e c o v e r y p u l s e p r e s s u r e i n t h e d o r s a l a o r t a o f th e 22°C group remained below r o u t i n e l e v e l s . P u l s e p r e s s u r e was v a r i a b l e and tended t o remain above r o u t i n e l e v e l s i n t h e 15°C t e s t group w h i l e i n t h e 5°C t e s t group i t approximated r o u t i n e l e v e l s d u r i n g r e c o v e r y ( f i g u r e 9 ) . In t h e 15°C t e s t group v e n t i l a t i o n r a t e r e a c h e d r o u t i n e l e v e l s w i t h i n one hour. V e n t i l a t i o n r a t e d e c l i n e d d u r i n g r e c o v e r y i n t h e 5 and 22°C a c c l i m a t i o n groups b u t f a i l e d t o r e a c h r o u t i n e l e v e l s w i t h i n one hour ( f i g u r e 10). In t h e 5 and 22°C groups b u c c a l p r e s s u r e remained h i g h d u r i n g t h e r e c o v e r y p e r i o d ( f i g u r e 12) . These o b s e r v a t i o n s suggest t h a t c o n s i d e r a b l e oxygen debt was s t i l l p r e s e n t one hour a f t e r f a t i g u e and t h a t compensatory mechanisms were o p e r a t i n g t o e l i m i n a t e t h e debt. E l e v a t e d h e a r t r a t e and b u c c a l p r e s s u r e i n d i c a t e t h a t more water and b l o o d were b e i n g pumped than a t p r e - e x e r c i s e r o u t i n e a c t i v i t y l e v e l s . U n f o r t u n a t e l y , no oxygen consumption d a t a i s a v a i l a b l e t o s u b s t a n t i a t e t h i s c o n c l u s i o n or t o a l l o w t h e c a l c u l a t i o n o f b l o o d f l o w . Low b l o o d p r e s s u r e s d u r i n g r e c o v e r y c o u l d be a s s o c i a t e d w i t h a drop i n v a s c u l a r r e s i s t a n c e o f t h e p e r i p h e r a l c i r c u l a t i o n . V a s o d i l a t i o n o f v e s s e l s s e r v i n g 51 t h e muscles or opening o f a d d i t i o n a l v e s s e l s c o u l d speed r e m o v a l o f a n a e r o b i c m e t a b o l i t e s and h a s t e n a b o l i t i o n o f oxygen debt. Such a mechanism would be u s e f u l t o f i s h w h i c h a p p a r e n t l y a r e f a r more p o o r l y v a s c u l a r i z e d t h a n mammals (Stevens - p e r s o n a l communication). 52 SUMMARY 1) The h e a r t r a t e o f sockeye salmon r o s e s u b s t a n t i a l l y d u r i n g s u c c e s s i v e l y g r e a t e r swimming a c t i v i t y . 2) C a r d i o a c c e l e r a t i o n d u r i n g a c t i v i t y may be due i n p a r t t o a r e l e a s e o f v a g a l t one i n sockeye. I t i s s u g g e s t e d t h a t c i r c u l a t i n g c a t e c h o l a m i n e s and/or an endogenous c a r d i o a c c e l e r a t o r s u b s t a n c e may a l s o produce e l e v a t e d h e a r t r a t e d u r i n g e x e r c i s e . 3) D o r s a l a o r t i c b l o o d p r e s s u r e i n c r e a s e d d u r i n g swimming, p r o b a b l y as a r e s u l t o f i n c r e a s e d c a r d i a c o u t p u t produced by e l e v a t e d h e a r t r a t e and s t r o k e volume. 4) The p e r i p h e r a l r e s i s t a n c e o f t h e c i r c u l a t o r y system p r o b a b l y d e c r e a s e s d u r i n g a c t i v i t y . 5) A l t e r a t i o n s i n v e n t i l a t i o n r a t e i n r e s p o n s e t o a c t i v i t y were v a r i a b l e , i n d i c a t i n g t h a t t h e r e are d i f f e r e n c e s i n v e n t i l a t i o n movements between d i f f e r e n t f i s h . In g e n e r a l , f i s h tended t o swim w i t h t h e i r mouths h e l d open a t h i g h v e l o c i t i e s , u n d o u b t a b l y w i t h c o n s i d e r a b l e s a v i n g o f energy. The p o s s i b i l i t y o f a r e f l e x c o n n e c t i o n o f swimming and v e n t i l a t i o n i s d i s c u s s e d . 6) In t h o s e f i s h w h i c h d i d v e n t i l a t e d u r i n g a c t i v i t y b u c c a l p r e s s u r e s r o s e markedly w i t h a c t i v i t y , i n d i c a t i n g t h a t i n c r e a s e d water movements was o c c u r r i n g a c r o s s t h e g i l l s . 53 7) St-r.oke volume and c a r d i a c o u t p u t , c a l c u l a t e d by t h e F i c k p r i n c i p l e , r o s e markedly w i t h a c t i v i t y . The a c c u r a c y o f t h e s e c a l c u l a t i o n s i n p r e d i c t i n g a c t u a l c a r d i a c o u t p u t and s t r o k e volumes i n i n t a c t f i s h i s q u e s t i o n a b l e . 8) E l e v a t e d oxygen uptake d u r i n g a c t i v i t y i n sockeye appears f a c i l i t a t e d by i n c r e a s e d water f l o w over t h e g i l l s , t a c h y c a r d i a , i n c r e a s e d c a r d i a c o u t p u t and p o s s i b l y by i n c r e a s e d a r t e r i o - v e n o u s oxygen d i f f e r e n c e s . 9) H e m a t o c r i t d a t a i n d i c a t e d t h a t t h e b l o o d oxygen c a p a c i t y o f t h e sockeye salmon used i n t h i s s t u d y was a p p r o x i m a t e l y 9 v o l s %. 10) A f t e r f a t i g u e v e n t i l a t i o n r a t e and b l o o d p r e s s u r e approached or f e l l below p r e - e x e r c i s e l e v e l s a f t e r one hour b u t h e a r t r a t e and b u c c a l p r e s s u r e remained e l e v a t e d . H i g h p o s t - e x e r c i s e f l o w s o f b l o o d and water suggest t h e p r e s e n c e o f a c o n s i d e r a b l e oxygen debt. 11) F o l l o w i n g e x e r c i s e , e l e v a t e d f l u s h i n g o f t h e m uscles w i t h b l o o d (as suggested by a drop i n b l o o d p r e s s u r e i n comparison t o r o u t i n e l e v e l s ) may h a s t e n e l i m i n a t i o n o f oxygen debt and removal o f a n a e r o b i c m e t a b o l i t e s . 54 PART TWO THE EFFECTS OF TEMPERATURE ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS OF QUIESCENT AND SWIMMING SALMON INTRODUCTION P r o b a b l y a l l l i v i n g t h i n g s e x p e r i e n c e some te m p e r a t u r e v a r i a t i o n s i n t h e c o u r s e o f t h e i r l i f e t i m e s . In g e n e r a l , t e m p e r a t u r e f l u c t u a t i o n s a r e l e s s r a p i d and extreme i n t h e sea than i n f r e s h w ater o r on t h e l a n d . Hence, most marine f i s h would be e x p e c t e d t o be l e s s t o l e r a n t o f r a p i d o r e x c e s s i v e t e m p e r a t u r e change than t h e i r f r e s h w a t e r r e l a t i v e s . Anadromous f i s h , such as t h e salmon, spend p a r t o f t h e i r l i v e s i n f r e s h w ater and p a r t i n t h e sea, r e t u r n i n g t o f r e s h w a t e r t o spawn. A d u l t sockeye salmon must be a b l e t o t o l e r a t e f a i r l y r a p i d t e m p e r a t u r e changes as t h e y move from t h e sea t o f r e s h w a t e r . These a n i m a l s must th e n be a b l e t o o p e r a t e a t a v a r i e t y o f t e m p e r a t u r e s . In t h i s i n v e s t i g a t i o n t h e e f f e c t o f t e m p e r a t u r e on some c a r d i o v a s c u l a r and r e s p i r a t o r y changes t h a t o c c u r d u r i n g e x e r c i s e were s t u d i e d . A l t h o u g h t h e r e i s c o n s i d e r a b l e i n f o r m a t i o n a v a i l a b l e on t h e e f f e c t s o f t e m p e r a t u r e upon p h y s i o l o g i c a l p r o c e s s e s i n a v a r i e t y o f organisms (Giese, 1962. P r o s s e r and Brown, 55 1961) l i t t l e has been done on t h e e f f e c t s o f t e m p e r a t u r e on c i r c u l a t i o n i n f i s h . Lyon (1926) r e p o r t e d t h a t t h e r m a l s t i m u l i a p p l i e d t o t h e s k i n o f s h a r k s produced c a r d i a c i n h i b i t i o n . G r o d z i n s k i (1950) o b s e r v e d t h a t t h e r a t e o f t h e embryonic sea t r o u t h e a r t (Salmo t r u t t a ) v a r i e d d i r e c t l y w i t h t e m p e r a t u r e . S i m i l a r l y , t h e r a t e s o f i s o l a t e d h e a r t s o f g l a s s e e l s ( A n g u i l l a a n g u i l l a ) show a d i r e c t v a r i a n c e w i t h t e m p e r a t u r e up t o a t e m p e r a t u r e c h a r a c t e r i s t i c o f t h e s p e c i e s ; a t h i g h e r t e m p e r a t u r e s t h e r a t e s t a r t s t o drop ( G r o d z i n s k i , 1954) . _In s i t u e x p e r i m e n t s on h a g f i s h showed t h a t t h e h e a r t r a t e almost d o u b l e d f o r a 13°C r i s e i n t e m p e r a t u r e (Jensen, 1961). I t i s g e n e r a l l y b e l i e v e d t h a t temperature a c t s d i r e c t l y on t h e myocardium t o e l e v a t e h e a r t r a t e (Labat, e t a l , 1961. Jensen, 1961). In a d d i t i o n , t e m p e r a t u r e may have o t h e r e f f e c t s on c i r c u l a t i o n . Mott (195 7) s u g g e s t e d t h a t \" c o n d i t i o n s i n e x p e r i m e n t s w i t h i n t a c t a n i m a l s a r e v e r y complex and changes o f t e m p e r a t u r e may cause changes i n t h e v a s c u l a r r e s i s t a n c e o f t h e g i l l and s y s t e m i c c a p i l l a r i e s as w e l l as t h e a c t i v i t y o f t h e myocardium\". Indeed, L a f f o n t and Labat (1966) have demonstrated a r e v e r s a l o f t h e e f f e c t s o f e p i n e p h r i n e on h e a r t r a t e i n c a r p w h i c h was a p p a r e n t l y produced by t e m p e r a t u r e . C o n s i d e r a b l y more i s known o f t h e e f f e c t s o f t e m p e r a t u r e on r e s p i r a t i o n and m e t a b o l i c r a t e . Numerous measures o f m e t a b o l i c r a t e have been made a t d i f f e r e n t t e m p e r a t u r e s ( B r e t t , 1964. F r y , 1957. F r y and H a r t , 1948. P r o s s e r and Brown, 1961). In g e n e r a l , a c t i v e and s t a n d a r d m e t a b o l i s m i n c r e a s e w i t h t e m p e r a t u r e a l t h o u g h B r e t t (1964) r e p o r t e d a sh a r p c u t - o f f i n a c t i v e m e t a b o l i c r a t e above 15°C i n y e a r l i n g sockeye salmon. B r e t t s u g g e s t s t h a t t h i s c u t - o f f i s a r e s u l t o f oxygen becoming l i m i t i n g as warmer water h o l d s p r o p o r t i o n a t e l y l e s s oxygen than c o l d water. I r v i n g et_ al_, (1941) s t u d i e d t h e e f f e c t o f temperature upon t h e c o m b i n a t i o n o f oxygen w i t h t r o u t b l o o d . They r e p o r t e d t h a t t h e b l o o d of f o u r t r o u t s p e c i e s c o u l d be c o m p l e t e l y s a t u r a t e d w i t h oxygen a t e n v i r o n m e n t a l t e n s i o n s a t t e m p e r a t u r e s below 25°C. Complete s a t u r a t i o n o f t h e b l o o d was p o s s i b l e below 25°C even when t h e PC0 2 o f t h e b l o o d was 10 mm Hg -i . e . a t t h i s CO^ t e n s i o n t h e r e was no r o o t e f f e c t . B l a c k e t a l (1966) found t h a t t h e b l o o d o f t h e l a n d l o c k e d salmon (Salmo s a l a r ) c o u l d be c o m p l e t e l y s a t u r a t e d i f t h e PC0 2 was 0-1 mm Hg a t 25°C. A PCC>2 o f 10 mm Hg however, produced a marked r o o t e f f e c t a t 25°C Recent s t u d i e s (Beaumont and R a n d a l l - p e r s o n a l communication) on rainbow t r o u t (SaImp g a i r d n e r i ) have a l s o demonstrated a r o o t e f f e c t i n t h e presence o f low C 0 2 l e v e l s . I t th u s appears t h a t as l o n g as t h e PCC>2 o f s a l m o n i d b l o o d i s v e r y low i t can s t i l l be f u l l y s a t u r a t e d a t t e m p e r a t u r e s below 25°C. The o b j e c t o f t h i s s t u d y was t o a s s e s s t h e e f f e c t o f temperature upon some c a r d i o v a s c u l a r and 57 r e s p i r a t o r y ' p a r a m e t e r s i n q u i e s c e n t and swimming f i s h . Thus comparisons t o t h e e n v i r o n m e n t a l t e m p e r a t u r e s encountered by f i s h under n a t u r a l c o n d i t i o n s c o u l d be made and t h e e f f e c t s o f t e m p e r a t u r e on gas exchange and c i r c u l a t o r y c o n t r o l examined. In a d d i t i o n , any p o s s i b l e l i m i t i n g e f f e c t s o f t e m p e r a t u r e upon c i r c u l a t i o n o r r e s p i r a t i o n c o u l d be e l u c i d a t e d . METHODS The methods u t i l i z e d i n t h i s s t u d y were i d e n t i c a l t o t h o s e used i n P a r t One o f t h i s t h e s i s and a r e n o t r e p e a t e d h e r e . Indeed, t h i s s e c t i o n d e s c r i b e s e x a c t l y t h e same r e s u l t s as P a r t One b u t d e a l s w i t h a b s o l u t e n u m e r i c a l v a l u e s r a t h e r than r e l a t i v e v a l u e s - i . e . r e s u l t s a r e e x p r e s s e d as a c t u a l p r e s s u r e s and r a t e s r a t h e r than as \"% o f r o u t i n e l e v e l s \" as i n P a r t One. I t i s hoped t h a t t h i s approach w i l l c l a r i f y t h e p r e s e n t a t i o n somewhat by h e l p i n g s e p a r a t e t h e t e s t r e s u l t s - i . e . t h e e f f e c t s o f a c t i v i t y and t e m p e r a t u r e on c i r c u l a t i o n and r e s p i r a t i o n . On t h i s b a s i s P a r t Two d e a l s w i t h two c o n c e p t s : 1) t h e e f f e c t o f t e m p e r a t u r e on r o u t i n e c a r d i o v a s c u l a r and r e s p i r a t o r y parameters and 2) t h e e f f e c t o f t e m p e r a t u r e upon a c t i v e c a r d i o v a s c u l a r and r e s p i r a t o r y parameters. RESULTS AND DISCUSSION F i g u r e 15 and t a b l e I show changes i n h e a r t r a t e b e f o r e , d u r i n g and a f t e r a c t i v i t y i n groups o f 58 Legend f o r F i g u r e 15 T h i s f i g u r e i l l u s t r a t e s changes i n h e a r t r a t e d u r i n g i n c r e a s i n g swimming e f f o r t and d u r i n g r e c o v e r y from f a t i g u e . V a l u e s a re means + 1 s t a n d a r d e r r o r o f the mean. 59 Legend f o r F i g u r e 16 F i g u r e 16 shows t h e h e a r t r a t e s o f a d u l t sockeye salmon a c c l i m a t e d and t e s t e d a t t h r e e t e m p e r a t u r e s . Maximal r e c o r d e d h e a r t r a t e was o b t a i n e d from swimming f i s h j u s t p r i o r t o f a t i g u e . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean. The number o f f i s h used t o c a l c u l a t e each i s shown i n b r a c k e t s a d j a c e n t t o each p o i n t . 60 f i s h a t t h e t h r e e a c c l i m a t i o n and t e s t t e m p e r a t u r e s -5, 15 and 22°C. A g e n e r a l r i s e i n r a t e o c c u r r e d a t a l l t h r e e t e m p e r a t u r e s i n r e s p o n s e t o a c t i v i t y . In a l l groups h e a r t r a t e dropped back towards r o u t i n e l e v e l s d u r i n g r e c o v e r y . F i g u r e 16 i l l u s t r a t e s t h e e f f e c t o f t e m p e r a t u r e on maximal r e c o r d e d a c t i v e h e a r t r a t e and r o u t i n e h e a r t r a t e . B oth a c t i v e and r o u t i n e h e a r t r a t e showed a n e a r l y l i n e a r r e l a t i o n s h i p t o t e m p e r a t u r e . I t i s r e a s o n a b l e t o c o n c l u d e t h a t t e m p e r a t u r e a c t s d i r e c t l y on t h e myocardium t o e l e v a t e h e a r t r a t e as s u g g e s t e d by Labat e t a l , (1961) and Jensen (1961). Temperature p r o b a b l y has some e f f e c t on membrane phenomena i n c a r d i a c muscle and t h u s a f f e c t s t h e r a t e o f b e a t i n g . Hence t h e l i n e a r r e l a t i o n s h i p between tem p e r a t u r e and h e a r t r a t e can be e x p l a i n e d as a d i r e c t i n f l u e n c e o f t e m p e r a t u r e on membrane phenomena i n t h e h e a r t muscle i t s e l f . The v a l u e s i n f i g u r e 16 do n o t show a p e r f e c t l i n e a r i t y w i t h t e m p e r a t u r e b u t t h i s c o u l d be due t o t h e s m a l l s i z e . In a d d i t i o n , spontaneous a c t i v i t y l e v e l s a r e p r o b a b l y t e m p e r a t u r e dependent ( B r e t t -p e r s o n a l communication) hence a c t i v i t y c o u l d i n f l u e n c e r o u t i n e h e a r t r a t e a t d i f f e r e n t t e m p e r a t u r e s . Temperature a p p a r e n t l y e x e r t e d no d r a s t i c l i m i t i n g e f f e c t on h e a r t r a t e i n t h e 5-22°C temperature range. The h e a r t d i d not cease t o b e a t a t h i g h or low 61 t e m p e r a t u r e s nor was t h e r e any r e p e a t a b l e p a t t e r n o f a b n o r m a l i t y i n t h e h e a r t r a t e . The e f f e c t o f te m p e r a t u r e on r o u t i n e and maximum r e c o r d e d a r e a mean b l o o d p r e s s u r e i s shown i n f i g u r e 17, s y s t o l i c and d i a s t o l i c p r e s s u r e s a r e g i v e n i n t a b l e I I . I t i s e v i d e n t t h a t t h e g r e a t e s t d o r s a l a o r t i c p r e s s u r e s , b o t h r o u t i n e and a c t i v e , o c c u r r e d a t 15°C. R o u t i n e and a c t i v e b l o o d p r e s s u r e s a t 5 and 22°c were e s s e n t i a l l y s i m i l a r . The change i n a r e a mean b l o o d p r e s s u r e produced by a c t i v i t y was about 6 mm Hg a t a l l t h r e e t e s t t e m p e r a t u r e s . A number o f e x p l a n a t i o n s f o r t h e h i g h e r p r e s s u r e s r e c o r d e d i n t h e 15°C t e s t group a r e p o s s i b l e . A s i z e e f f e c t may be i n v o l v e d s i n c e t h e 15°C t e s t group had a mean w e i g h t o f 165 2 g+129 as compared t o w e i g h t s o f 1230 g+137 (5°test group) and 1080 g+113 (22° te§st g r o u p ) . Large f i s h a r e b e l i e v e d t o have h i g h e r b l o o d p r e s s u r e s than s m a l l f i s h (Burger and B r a d l e y , 1951. Greene, 1904. H a r t , 1943). A p l o t o f w e i g h t v s . b l o o d p r e s s u r e a t 22°C showed t h a t t h e r e was a s i g n i f i c a n t s i z e e f f e c t p r e s e n t b u t a 500 g d i f f e r e n c e i n w e i g h t produced o n l y a 17% r i s e i n s y s t o l i c b l o o d p r e s s u r e ( f i g u r e 18). I f t h e w e i g h t e f f e c t a t 15°C were comparable w i t h t h a t a t 22°C then t h e 15°C t e s t group would be ex p e c t e d t o have about a 17% h i g h e r a r e a mean b l o o d p r e s s u r e than t h e 5 or 22°C t e s t groups due t o i t s g r e a t e r mean w e i g h t . S i n c e r o u t i n e and a c t i v e b l o o d p r e s s u r e s a t 15°c a r e a l m o s t 5 0 % h i g h e r than t h o s e 62 Legend f o r F i g u r e 17 A r e a mean b l o o d p r e s s u r e i n t h e d o r s a l a o r t a o f t h r e e groups o f a d u l t sockeye salmon a c c l i m a t e d and t e s t e d a t t h e i n d i c a t e d t e m p e r a t u r e s . Maximum r e c o r d e d b l o o d p r e s s u r e was o b t a i n e d from swimming f i s h j u s t p r i o r t o f a t i g u e . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean. The number o f f i s h used t o c a l c u l a t e each mean i s shown i n b r a c k e t s a d j a c e n t t o each p o i n t . 63 Legend f o r F i g u r e 18 T h i s f i g u r e shows t h e i n f l u e n c e o f f i s h w e i g h t on r o u t i n e a r e a mean b l o o d p r e s s u r e i n t h e d o r s a l a o r t a o f a group o f a d u l t sockeye salmon a c c l i m a t e d and t e s t e d a t 22°C. V a l u e s r e p r e s e n t d a t a f o r i n d i v i d u a l f i s h . The l a s t squares r e g r e s s i o n l i n e o f Y on X i s i l l u s t r a t e d and t h e e q u a t i o n g i v e n . 64 o f t h e o t h e r t e m p e r a t u r e groups then some o t h e r f a c t o r t h a n s i z e may be p r o d u c i n g t h e h i g h e r p r e s s u r e s . The n a t u r e o f t h i s f a c t o r i s unknown a t t h i s t i m e . P u l s e p r e s s u r e i n t h e d o r s a l a o r t a r o s e d u r i n g a c t i v i t y i n 5°C a c c l i m a t e d f i s h . In t h e 15°C a c c l i m a t e d group p u l s e p r e s s u r e s dropped below r o u t i n e l e v e l s d u r i n g a c t i v i t y b u t approximated r o u t i n e l e v e l s f o l l o w i n g f a t i g u e . A s i m i l a r s l i g h t drop i n p u l s e p r e s s u r e was e v i d e n t i n t h e 22°C t e s t group and i n t h i s group i t remained below r o u t i n e l e v e l s d u r i n g t h e e n t i r e p o s t -e x e r c i s e p e r i o d ( f i g u r e 9 ) . S i n c e h e a r t r a t e i n c r e a s e s w i t h t e m p e r a t u r e t h e s e r e s u l t s suggest t h a t l e s s b l o o d i s pumped per h e a r t b e a t i n t h e 15 and 22°C t e s t groups t h a n i n t h e 5°C t e s t group. F i g u r e 13 shows t h a t c a r d i a c o u t p u t tends t o l e v e l o f f a t te m p e r a t u r e s above 15°c. Such r e s u l t s s u ggest t h a t a c t i v e s t r o k e volume may be d r o p p i n g a t s u c c e s s i v e l y h i g h e r t e m p e r a t u r e s . F i g u r e 19 shows r o u t i n e and a c t i v e oxygen consumption a t d i f f e r e n t t e m p e r a t u r e s . I t i s apparent t h a t t e m p e r a t u r e e l e v a t e s m e t a b o l i c r a t e and t h a t f i s h can e x t r a c t more oxygen a t h i g h e r t e m p e r a t u r e s i n res p o n s e t o i n c r e a s e d m e t a b o l i c demand. The s l o p e o f t h e a c t i v e m e t a b o l i c r a t e c u r v e i s i n t e r e s t i n g as i t appears t o d e c l i n e a t h i g h e r t e m p e r a t u r e s . Warm water c o n t a i n s l e s s oxygen t h a n c o l d w ater hence f i s h must expend more energy t o e x t r a c t oxygen a t h i g h e r t e m p e r a t u r e s . To do t h i s t h e y must pump more water over t h e g i l l s e i t h e r by i n c r e a s i n g 65 Legend f o r F i g u r e 19 F i g u r e 19 shows oxygen consumption v a l u e s o f groups o f a d u l t sockeye salmon measured a t v a r i o u s a c c l i m a t i o n t e m p e r a t u r e s . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean. Sta n d a r d e r r o r s a r e o m i t t e d f o r t h e s t a n d a r d and r o u t i n e m e t a b o l i c r a t e d a t a s i n c e t h e y a r e too s m a l l t o be p l o t t e d a c c u r a t e l y . T a b l e V I I shows a l l t h e d a t a and i n c l u d e s s t a n d a r d e r r o r s . 66 t h e r a t e o f t h e i r b u c c a l pump or by swimming and a l l o w i n g t h e water c u r r e n t t o f l u s h t h e g i l l s . Thus th e oxygen c o n t e n t o f t h e water a t h i g h t e m p e r a t u r e c o u l d p o s s i b l y l i m i t a c t i v e m e tabolism. I t i s t h e r e f o r e i n t e r e s t i n g t o c o n s i d e r i f c i r c u l a t o r y a d j u s t m e n t s would o p e r a t e t o i n c r e a s e t h e e f f e c t i v e n e s s o f oxygen uptake and d e l i v e r y a t h i g h t e m p e r a t u r e s . To do t h i s we s h a l l have t o c o n s i d e r c a r d i a c o u t p u t , s t r o k e volume and e f f i c i e n c y o f exchange a t t h e g i l l s . The e f f e c t o f t e m p e r a t u r e on c a r d i a c o u t p u t i s shown i n f i g u r e 13. As p r e v i o u s l y d i s c u s s e d t h e shaded a r e a o f f i g u r e 13 seems most r e p r e s e n t a t i v e o f the a c t u a l range o f c a r d i a c o u t p u t f i g u r e s p o s s i b l e f o r sockeye salmon. I t i s p o s s i b l e t h a t t e m p e r a t u r e i n f l u e n c e s venous s a t u r a t i o n and, i f t h a t i s t h e case, i t may be e r r o n e o u s t o use a s i n g l e venous s a t u r a t i o n v a l u e f o r c a r d i a c o u t p u t c a l c u l a t i o n s over a range o f d i f f e r e n t t e m p e r a t u r e s - i . e . t h e venous b l o o d may be more s a t u r a t e d a t low t e m p e r a t u r e s than a t h i g h ones. More work would be n e c e s s a r y t o see i f t e m p e r a t u r e d i d i n f l u e n c e venous s a t u r a t i o n . In any case t h e o n l y d a t a a v a i l a b l e t o us i s t h a t o f f i g u r e 13 and c o n s i d e r a t i o n o f i t s v a l u e s s h o u l d be n e c e s s a r i l y c a u t i o u s . I t appeared t h a t c a r d i a c o u t p u t i n c r e a s e d o n l y s l i g h t l y w i t h t e m p e r a t u r e a t r o u t i n e 1 l e v e l s o f a c t i v i t y . A c t i v e c a r d i a c o u t p u t however, i n c r e a s e d markedly from 5 t o 15°C and t h e n showed a tendency t o l e v e l o f f a t 67 t e m p e r a t u r e s h i g h e r than 15°C. F i g u r e 14 shows t h a t s t r o k e volume a t r o u t i n e a c t i v i t y l e v e l s changed v e r y l i t t l e a t t h e d i f f e r e n t t e m p e r a t u r e s b u t t h a t a c t i v e s t r o k e volume d e c r e a s e d a t t h e h i g h e r t e m p e r a t u r e s . I t must be remembered t h a t c a r d i a c o u t p u t was c a l c u l a t e d from oxygen uptake v a l u e s . As a c t i v e h e a r t r a t e i n c r e a s e s d i r e c t l y w i t h t e m p e r a t u r e and a c t i v e osygen uptake does n o t , c a l c u l a t e d a c t i v e s t r o k e volumes n a t u r a l l y drop a t h i g h e r t e m p e r a t u r e s . S i m i l a r l y , c a l c u l a t e d a c t i v e c a r d i a c o u t p u t v a l u e s ( f i g u r e 13) show t h e same n o n - l i n e a r i t y w i t h t e m p e r a t u r e as do oxygen consumption v a l u e s ( f i g u r e 19). I t i s d i f f i c u l t t o say whether t h e s t r o k e volume and c a r d i a c o u t p u t c u r v e s o f f i g u r e s 13 and 14 a r e r e a l owing t o t h e b a s i s o f t h e i r c a l c u l a t i o n . A number o f f a c t o r s must be c o n s i d e r e d w h i c h were n o t t a k e n i n t o account i n t h e c a l c u l a t i o n s . We know t h a t a c t i v e h e a r t r a t e shows a l i n e a r r e l a t i o n s h i p w i t h t e m p e r a t u r e due t o t h e d i r e c t e f f e c t s o f t e m p e r a t u r e a c t i n g on t h e myocardium. D u r i n g a c t i v i t y b l o o d p r e s s u r e i n c r e a s e s s u g g e s t i n g a p o s s i b l e i n c r e a s e i n c a r d i a c o u t p u t has o c c u r r e d . The r a t e o f oxygen upt a k e however, d e c r e a s e s a t h i g h e r t e m p e r a t u r e s . Such a d e c r e a s e c o u l d be due t o t h r e e f a c t o r s ; 1) i n s u f f i c i e n t oxygen i n t h e w a t e r , 2) i n a b i l i t y o f t h e g i l l s t o t r a n s f e r oxygen i n t o t h e b l o o d , and 3) i n s u f f i c i e n t c a r d i a c o u t p u t . L e t us c o n s i d e r each o f t h e s e t h r e e p o s s i b i l i t i e s . 68 I t i s known t h a t t h e oxygen c o n t e n t o f water d e c r e a s e s w i t h i n c r e a s i n g t e m p e r a t u r e . I t thus seems l i k e l y t h a t l a c k o f oxygen c o u l d l i m i t a c t i v e metabolism. Indeed, B r e t t (1964) demonstrated t h a t a c t i v e oxygen consumption o f y e a r l i n g sockeye salmon i n c r e a s e d when th e oxygen c o n t e n t o f t h e water was r a i s e d t o 15 0% a i r s a t u r a t i o n . B r e t t o n l y c a r r i e d out p r e l i m i n a r y e x p e r i m e n t s and f u r t h e r work i s n e c e s s a r y i n t h i s a r e a . S econdly, a c t i v e oxygen uptake a t h i g h t e m p e r a t u r e s may be l i m i t e d by t h e i n a b i l i t y o f t h e g i l l s t o t r a n s f e r oxygen i n t o t h e b l o o d . The exchange o f gases w i l l be i n f l u e n c e d by t h e s u r f a c e a r e a o f t h e g i l l s a v a i l a b l e f o r gas exchange and by t h e d i f f u s i o n d i s t a n c e between water and b l o o d . These r e l a t i o n s h i p s can be e x p r e s s e d as a \" t r a n s f e r f a c t o r \" w h ich, a c c o r d i n g t o R a n d a l l , e t a l , (1967), i s \"a measure o f t h e r e l a t i v e a b i l i t y o f t h e r e s p i r a t o r y s u r f a c e t o exchange gases, and i s a f f e c t e d by changes i n s u r f a c e a r e a a v a i l a b l e f o r exchange, as w e l l as t h e d i f f u s i o n d i s t a n c e between b l o o d and wa t e r \" . The oxygen t r a n s f e r f a c t o r , TO^, i s d e f i n e d a s : T O = Y 0 2 1 U 2 M P i 0 2 + Pe0 2) - h(P^02 + Pv0 2) where: VC>2= oxygen u p t a k e / u n i t t i m e P = p a r t i a l p r e s s u r e o f gas: i = r e f e r s t o water i n t h e b u c c a l c a v i t y -i . e . i n s p i r e d water e = r e f e r s t o water i n t h e o p e r c u l a r c a v i t y -i . e . e x p i r e d w ater a = a r t e r i a l b l o o d l e a v i n g g i l l s 69 v = venous b l o o d e n t e r i n g g i l l s = m o l e c u l a r oxygen I f t h e t r a n s f e r f a c t o r i n c r e a s e s t h e r e w i l l be a more e f f e c t i v e u ptake o f oxygen by t h e g i l l s . Indeed, R a n d a l l , et a l , (1967) demonstrated t h a t t h e t r a n s f e r f a c t o r i n c r e a s e d a l m o s t f i v e - f o l d d u r i n g moderate e x e r c i s e i n ra i n b o w t r o u t (Salmo g a i r d n e r i ) . Presumably, t h i s i n c r e a s e was a r e s u l t o f s h u n t i n g t h e b l o o d c l o s e r t o t h e s u r f a c e o f t h e g i l l s , d e c r e a s e d t h i c k n e s s o f g i l l l a m e l l a e , i n c r e a s e d b l o o d volume i n t h e r e s p i r a t o r y c i r c u l a t i o n o r a c o m b i n a t i o n of, t h e s e f a c t o r s . I t t h u s appears t h a t r a i n b o w t r o u t a r e c a p a b l e o f markedly i n c r e a s i n g t h e e f f e c t i v e n e s s o f 0^ uptake by t h e g i l l s d u r i n g a c t i v i t y . P r o b a b l y salmon can do the same. I t i s p o s s i b l e t h a t a t h i g h e r t e m p e r a t u r e s salmon a r e n o t c a p a b l e o f i n c r e a s i n g t h e i r t r a n s f e r f a c t o r s u f f i c i e n t l y t o meet t h e r e q u i r e m e n t s o f a c t i v e m e t a b o l i s m . I t might be p o s s i b l e t o i n c r e a s e v e n t i l a t i o n and t h u s s u p p l y more oxygen t o t h e g i l l s however, v e n t i l a t i o n i s a c o s t l y energy-consuming p r o c e s s i n water (Schumann and P i i p e r , 1966) hence l a r g e i n c r e a s e s i n v e n t i l a t i o n would n o t be an e f f i c i e n t means o f i n c r e a s i n g t h e t r a n s f e r f a c t o r . Our s t u d y d i d not a l l o w us t o c a l c u l a t e t r a n s f e r f a c t o r as we d i d n o t measure oxygen l e v e l s i n b l o o d and water a f f e r e n t and e f f e r e n t t o t h e g i l l s . F r y (195 7) summarized t h e r e s u l t s o f o t h e r workers and showed t h a t t h e s u r f a c e a r e a o f t h e g i l l s o f 34 t r o p i c a l marine s p e c i e s was much lower t h a n t h e l o w e s t v a l u e r e p o r t e d f o r temperate marine s p e c i e s ( t o a d f i s h ) . I f i n d e e d , t h e r e s p i r a t o r y s u r f a c e a r e a l i m i t s a c t i v e m e t a b o l i s m i t seems add t h a t t r o p i c a l s p e c i e s , l i v i n g i n w a ter c o n t a i n i n g l e s s oxygen than temperate r e g i o n s , s h o u l d have s m a l l e r g i l l a r e a s than temperate s p e c i e s . Such o b s e r v a t i o n s suggest t h a t t h e r e s p i r a t o r y s u r f a c e a r e a o f f i s h may not be as i m p o r t a n t as t h e r a t e o f d e l i v e r y o f oxygen t o t h e g i l l s i n l i m i t i n g oxygen u p t a k e a t h i g h t e m p e r a t u r e s . A t h i r d f a c t o r l i m i t i n g a c t i v e oxygen uptake might be t h e a b i l i t y o f t h e c a r d i o v a s c u l a r system t o d e l i v e r oxygen t o t h e t i s s u e s . We know t h a t a c t i v e h e a r t r a t e i n c r e a s e s l i n e a r l y w i t h t e m p e r a t u r e ; however i f s t r o k e volume d e c r e a s e d o r a r t e r i o - v e n o u s oxygen l e v e l d i f f e r e n c e s dropped t h e n oxygen d e l i v e r y t o t h e t i s s u e s c o u l d become i n a d e q u a t e . Indeed, i f ina d e q u a t e l e v e l s o f oxygen r e a c h t h e g i l l s a t h i g h t e m p e r a t u r e s t h e n d o r s a l a o r t i c b l o o d would n ot be f u l l y s a t u r a t e d and a r t e r i o - v e n o u s oxygen l e v e l d i f f e r e n c e would f a i l . T h i s would n ot be a s i g n o f c a r d i a c i n s u f f i c i e n c y b u t would m e r e l y be a r e f l e c t i o n o f low a v a i l a b i l i t y o f oxygen i n t h e i n s p i r e d w a t e r . I t seems l i k e l y t h en, t h a t t h e e x p l a n a t i o n f o r d i m i n i s h e d a c t i v e oxygen uptake a t h i g h t e m p e r a t u r e s r e l a t e s t o t h e s c a r c i t y o f oxygen i n t h e w a t e r . B r e t t ' e x p e r i m e n t s i n w h i c h a c t i v e m e t a b o l i c r a t e was shown 71 t o be dependent on oxygen l e v e l s i n t h e water s u p p o r t t h i s c o n c l u s i o n . P u l s e p r e s s u r e drops a t 15+22°C i n d i c a t i n g t h a t a p o s s i b l e d e c r e a s e i n s t r o k e volume has o c c u r r e d . I f indeed a r e d u c t i o n i n s t r o k e volume a t h i g h e r t e m p e r a t u r e s does o c c u r i t appears t h a t t h e r e s u l t a n t d e c r e a s e i n c a r d i a c o u t p u t would be p a r t i a l l y o f f s e t by i n c r e a s e d h e a r t r a t e . Thus t h e a b i l i t y o f t h e h e a r t t o i n c r e a s e i t s r a t e o f c o n t r a c t i o n i n t h e f a c e o f d e c r e a s e d s t r o k e volume might s e r v e as a means o f k e e p i n g c a r d i a c o u t p u t as h i g h as p o s s i b l e . I f a d e c r e a s e i n s t r o k e volume does oc c u r a t h i g h t e m p e r a t u r e s i n a c t i v e f i s h . w h a t c o u l d be t h e cause o f t h i s d e c r e a s e ? S t a r l i n g ' s law o f t h e h e a r t h o l d s t h a t s t r o k e volume o u t p u t o f t h e h e a r t i s d i r e c t l y r e l a t e d t o t h e m e c h a n i c a l e f f e c t s o f r e t u r n i n g venous b l o o d . A c c o r d i n g l y , i f t h e i n i t i a l l e n g t h o f c a r d i a c muscle f i b r e s i s i n c r e a s e d by s t r e t c h i n g t h e h e a r t responds by c o n t r a c t i n g more f o r c e f u l l y and c o m p l e t e l y , e x p e l l i n g a c o n s e q u e n t l y l a r g e r amount o f b l o o d . In mammals i t i s known t h a t S t a r l i n g ' s law can be m o d i f i e d by t h e a c t i o n o f c i r c u l a t i n g c a t e c h o l a m i n e s (Rushmer, 1962. S a r n o f f and M i t c h e l l , 1962). Substances such as a d r e n a l i n e and n o r a d r e n a l i n e can a l t e r m y o c a r d i a l c o n t r a c t i l i t y and thus can a l t e r c a r d i a c o u t p u t by p r o d u c i n g a change i n s t r o k e volume. I f h i g h e r t e m p e r a t u r e s d e c r e a s 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 o r i n t e r f e r e d w i t h 72 t h e e f f e c t s o f c i r c u l a t i n g c a t e c h o l a m i n e s a d e c r e a s e i n s t r o k e volume c o u l d r e s u l t . F i g u r e 20 shows t h e e f f e c t o f t e m p e r a t u r e on r o u t i n e and maximal r e c o r d e d r e s p i r a t o r y r a t e . R o u t i n e r e s p i r a t o r y r a t e appeared t o show a g e n e r a l i n c r e a s e i n r e s p o n s e t o e l e v a t e d t e m p e r a t u r e b u t maximal r e c o r d e d r e s p i r a t o r y r a t e d i d n o t appear r e l a t e d t o t e m p e r a t u r e . V a r i a t i o n s i n a c t i v e r e s p i r a t o r y r a t e r e s u l t e d as some f i s h c o n t i n u e d t o v e n t i l a t e d u r i n g t h e e n t i r e t e s t p e r i o d w h i l e o t h e r s ceased r e s p i r a t o r y movements and swam w i t h mouths h e l d open as d i s c u s s e d p r e v i o u s l y . I n c r e a s e d v e n t i l a t i o n a t h i g h e r t e m p e r a t u r e s a t r o u t i n e a c t i v i t y l e v e l s would be e x p e c t e d as m e t a b o l i c r a t e i n c r e a s e s w i t h t e m p e r a t u r e ( f i g u r e 19) . B o th r o u t i n e and maximal r e c o r d e d b u c c a l p r e s s u r e s were h i g h e r i n 22°C a c c l i m a t e d f i s h than i n t h e 5°C t e s t group ( f i g u r e 21). Thus t h e amount of water pumped over t h e g i l l s i n c r e a s e d w i t h b o t h a c t i v i t y and e l e v a t e d t e m p e r a t u r e . Such r e s u l t s i n d i c a t e t h a t r e s p i r a t o r y a d justment f a c i l i t a t e s i n c r e a s e d oxygen uptake a t h i g h t e m p e r a t u r e s or d u r i n g a c t i v i t y . In P a r t One i t was p o i n t e d out t h a t s i z e s i g n i f i c a n t l y i n f l u e n c e d h e a r t r a t e , d o r s a l a o r t i c b l o o d p r e s s u r e and r e s p i r a t o r y r a t e i n t h e 22°C t e s t group. No s i g n i f i c a n t s i z e e f f e c t s were a p p a r e n t l y p r e s e n t i n t h e 5°C t e s t group. I t appears t h e n , t h a t t h e s i z e e f f e c t on c i r c u l a t o r y and r e s p i r a t o r y parameters was 73 Legend f o r F i g u r e 20 The e f f e c t o f t e m p e r a t u r e on v e n t i l a t i o n r a t e o f a d u l t sockeye salmon i s i l l u s t r a t e d . Maximal r e c o r d e d v e n t i l a t i o n r a t e d i d n o t n e c e s s a r i l y o c c u r j u s t b e f o r e f a t i g u e as some f i s h slowed o r ceased v e n t i l a t i o n movements a t t h e h i g h e r water v e l o c i t i e s . V a l u e s a r e means + 1 s t a n d a r d e r r o r o f t h e mean and t h e number o f f i s h used f o r each average i s i n d i c a t e d i n a b r a c k e t a d j a c e n t t o each p o i n t . ACCLIMATION TEMPERATURE (°C) 74 Legend f o r F i g u r e 21 The e f f e c t o f t e m p e r a t u r e on b u c c a l p r e s s u r e o f a d u l t sockeye salmon b e f o r e , d u r i n g and a f t e r t h e f i s h had been f a t i g u e d by swimming i s i l l u s t r a t e d . V a l u e s a r e mean averages + 1 s t a n d a r d e r r o r o f t h e mean. B u c c a l p r e s s u r e s a r e t h e maximum p r e s s u r e r e c o r d e d i n th e mouth c a v i t y d u r i n g v e n t i l a t i o n . 5 O 5 10 15 20 25 ACCLIMATION TEMPERATURE (°C) 75 enhanced by te m p e r a t u r e . Why t h e r e s h o u l d be such an enhancement o f t h e s i z e e f f e c t a t 22°C and not a t 5°C cannot be e x p l a i n e d a t t h i s t i m e . Temperature i n f l u e n c e s a g r e a t number o f p r o c e s s e s w i t h i n t h e a n i m a l body hence a number o f f a c t o r s c o u l d be r e s p o n s i b l e f o r t h e s i g n i f i c a n t s i z e e f f e c t a t 22°C. In c o n c l u s i o n we can say t h a t a l l t h e c a r d i o v a s c u l a r and r e s p i r a t o r y parameters s t u d i e d i n t h e s e e x p e r i m e n t s were shown t o be a t l e a s t i n p a r t t e m p e r a t u r e dependent. Undoubtably, t h e fundamental e x p l a n a t i o n o f t h i s dependance can be r e l a t e d t o t h e d i r e c t i n f l u e n c e o f t e m p e r a t u r e on t h e r a t e s o f c h e m i c a l r e a c t i o n s . In a d d i t i o n , t h e c i r c u l a t o r y system d i d no t show any d r a s t i c l o s s o f f u n c t i o n over t h e t e m p e r a t u r e range o f 5-22°C, even though t h e upper boundary o f t h i s range i s near t h e upper l e t h a l t e m p e r a t u r e f o r salmon (25°C - B r e t t , 195 2 ) . The f u n c t i o n i n g o f t h e c i r c u l a t o r y system then, s h o u l d i n no way i n h i b i t t h e a b i l i t y o f sockeye salmon t o o p e r a t e i n water o f t e m p e r a t u r e s r a n g i n g between 5 and 22°C. The f a c t t h a t oxygen l e v e l s i n t h e water may l i m i t a c t i v e m e t a b o l i s m a t h i g h t e m p e r a t u r e s suggests t h a t t h e performance o f t h e s e f i s h may be l i m i t e d a t h i g h t e m p e r a t u r e s i f t h e oxygen c o n t e n t o f t h e water i s low. 76 SUMMARY 1) I n c r e a s e s i n h e a r t r a t e produced by a c t i v i t y appeared o f t h e same o r d e r o f magnitude i n groups o f f i s h a c c l i m a t e d t o 5, 15 t o 22°C. 2) R o u t i n e and a c t i v e h e a r t r a t e appeared t o be d i r e c t l y i n f l u e n c e d by te m p e r a t u r e , p r o b a b l y due t o a d i r e c t i n f l u e n c e o f te m p e r a t u r e on t h e myocardium. 3) In no case d i d t h e h e a r t cease t o b e a t nor were t h e r e any r e p e a t a b l e p a t t e r n s o f c a r d i a c a b n o r m a l i t y produced by t h e te m p e r a t u r e range t e s t e d . 4) A l t h o u g h t h e b l o o d p r e s s u r e r i s e produced by a c t i v i t y was s i m i l a r a t a l l t h r e e t e s t t e m p e r a t u r e s , b o t h r o u t i n e and a c t i v e b l o o d p r e s s u r e s were g r e a t e s t a t 15°C. 5) D o r s a l a o r t i c p u l s e p r e s s u r e r o s e d u r i n g a c t i v i t y a t 5°c b u t remained unchanged i n 22°C a c c l i m a t e d f i s h . T h i s l a c k o f change a t 22°C may be r e l a t e d t o a d e c r e a s e d s t r o k e volume a t h i g h e r t e m p e r a t u r e s . 6) R o u t i n e and a c t i v e oxygen uptake i n c r e a s e d w i t h t e m p e r a t u r e b u t t h e r a t e o f i n c r e a s e o f a c t i v e oxygen upt a k e d e c r e a s e d w i t h t e m p e r a t u r e . 7) The r a t e o f a c t i v e oxygen uptake d i m i n i s h e s w i t h i n c r e a s i n g t e m p e r a t u r e , p r o b a b l y as a r e s u l t o f low a v a i l a b i l i t y o f oxygen i n t h e water. 8) A d e c r e a s e i n s t r o k e volume, a r t e r i o - v e n o u s oxygen l e v e l d i f f e r e n c e , o r a c o m b i n a t i o n o f t h e s e f a c t o r s may be a s s o c i a t e d w i t h t h e d i m i n i s h e d r a t e o f oxygen uptake w i t h i n c r e a s i n g t e m p e r a t u r e . 9) R o u t i n e r e s p i r a t o r y r a t e seemed d i r e c t l y i n f l u e n c e d by t e m p e r a t u r e . 78 GENERAL DISCUSSION T h i s s t u d y has g i v e n us some i n f o r m a t i o n about c e r t a i n c a r d i o v a s c u l a r and r e s p i r a t o r y a d j u s t m e n t s w h i c h accompany s e v e r e e x e r c i s e i n sockeye salmon. In a d d i t i o n , some o f t h e e f f e c t s o f te m p e r a t u r e on t h e s e p r o c e s s e s have been r e c o r d e d . A g r e a t advantage o f t h i s s t u d y over much o f t h e p r e v i o u s work was t h a t i n t a c t , u n r e s t r a i n e d and u n a n a e s t h e t i z e d f i s h were used. C o n s i d e r a b l e work has been done on c i r c u l a t o r y changes w h i c h accompany e x e r c i s e i n mammals and r e c e n t l y , upon some f i s h . We s h a l l c o n s i d e r how c l o s e l y our r e s u l t s may be compared w i t h t h o s e o f o t h e r w o r k e r s . Chapman and M i t c h e l l (1965) have r e v i e w e d t h e p h y s i o l o g y o f e x e r c i s e i n humans, They suggest t h a t t h e c h i e f mechanisms e n a b l i n g a human t o p e r f o r m s t r e n u o u s e x e r c i s e a r e ; 1) t h e a b i l i t y t o i n c r e a s e c a r d i a c o u t p u t d u r i n g a c t i v i t y , 2) t h e a b i l i t y t o i n c u r and t o l e r a t e an oxygen debt, 3) t h e pr e s e n c e os hemoglobin w h i c h e n a b l e s t h e b l o o d t o c a r r y c o n s i d e r a b l e oxygen, and 4) mechanisms w h i c h a l t e r t h e p a t t e r n o f b l o o d f l o w t o t h e body d u r i n g e x e r c i s e . The p r e s e n t s t u d y e n a b l e s us t o say something o f t h e s e mechanisms i n salmon. In a young man t h e c a r d i a c o u t p u t i n c r e a s e s from 5.5 l i t r e s o f bl o o d / m i n a t r e s t t o n e a r l y 5 ti m e s t h i s volume d u r i n g maximal e x e r t i o n . The i n c r e a s e i n 79 c a r d i a c o u t p u t i s a c c o m p l i s h e d by i n c r e a s i n g the h e a r t r a t e and/or t h e s t r o k e volume. In g e n e r a l o n l y t r a i n e d human a t h l e t e s show i n c r e a s e d s t r o k e volume d u r i n g a c t i v i t y (Rushmer, 1962). Chapman and M i t c h e l l p o i n t out t h a t t h e v a s t r e s p i r a t o r y s u r f a c e o f the l u n g s does not l i m i t maximal oxygen uptake b u t t h a t t h e pumping c a p a c i t y o f t h e h e a r t i s t h e s o l e l i m i t i n g f a c t o r t o a c t i v e oxygen uptake. T h e r e f o r e t h e maximal oxygen uptake s e r v e s as \"a f a i r i n d e x o f c i r c u l a t o r y c a p a c i t y \" i n humans. Humans a r e c a p a b l e o f i n c r e a s i n g t h e i r oxygen u p t a k e 15-20 t i m e s t h e i r r e s t i n g r a t e d u r i n g maximal a c t i v i t y ( P r o s s e r and Brown, 1961) w h i l e some i n s e c t s may show a 50-200 f o l d i n c r e a s e w i t h e x e r c i s e . F i s h on t h e o t h e r hand, can i n c r e a s e t h e i r r e s t i n g m e t a b o l i c r a t e o n l y 4-8 t i m e s d u r i n g a c t i v i t y ( B r e t t , 1962) . I t would appear then t h a t some a i r - b r e a t h e r s show l a r g e r i n c r e a s e s o f m e t a b o l i c r a t e w i t h a c t i v i t y t han f i s h do. Undoubtably such a d i s p a r i t y i n a b i l i t y t o i n c r e a s e t h e r e s t i n g m e t a b o l i c r a t e between f i s h and mammals i s r e l a t e d i n p a r t t o t h e d i f f e r e n c e s between the a q u a t i c and t e r r e s t r i a l e n vironments. Water i s f a r denser than a i r hence r e s p i r a t i o n i n water i s more c o s t l y , i n terms o f energy expended, than i t i s i n a i r (Schumann and P i i p e r , 1966). Thus a f i s h may expend a l a r g e p a r t o f i t s r e s t i n g oxygen uptake t h r o u g h i t s 80 v e n t i l a t o r y movements. C o n s e q u e n t l y , t h e r e s t i n g oxygen r e q u i r e m e n t s o f f i s h would be r e l a t i v e l y h i g h e r than t h o s e o f a i r - b r e a t h i n g mammals and t h e scope f o r i n c r e a s i n g oxygen uptake somewhat lower i n f i s h than i n mammals. S i m i l a r l y , water h o l d s f a r l e s s oxygen than a i r hence th e c o s t o f removing g r e a t amounts o f oxygen t o s u p p o r t v e r y h i g h m e t a b o l i c r a t e s becomes p r o h i b i t i v e i n water . In a d d i t i o n , t h e r e s p i r a t o r y s u r f a c e a r e a o f the g i l l s may l i m i t maximal m e t a b o l i c r a t e i n f i s h . Grey (1954) s t u d i e d t h e s u r f a c e a r e a o f t h e g i l l s o f a v a r i e t y o f f i s h and found a good c o r r e l a t i o n between a c t i v i t y and s u r f a c e a r e a . An a c t i v e f i s h such as t h e m a c k e r a l (Scomber scombrus) had t h r e e t i m e s as many g i l l lamellae/mm o f f i l a m e n t as t h e s l u g g i s h t o a d f i s h (Opsanus tau) and t h e s u r f a c e a r e a o f t h e m a c k e r a l g i l l was al m o s t s i x t i m e s t h a t o f t h e t o a d f i s h . F r y (1957) r e p o r t e d t h a t t h e r e i s a s i m i l a r v a r i a t i o n i n the development o f t h e b r a n c h i a l pump amongst d i f f e r e n t f i s h e s and t h a t q u a n t i t i e s o f r e s p i r a t o r y pigments i n t h e b l o o d v e r y from s p e c i e s t o s p e c i e s . Thus, amongst t h e f i s h e s t h e r e i s a g r e a t v a r i a t i o n i n a b i l i t y t o e x t r a c t oxygen from t h e w a t e r . In c o n c l u s i o n t h e n , th e maximal oxygen consumption o f f i s h , u n l i k e t h a t o f humans, does n o t s e r v e as a good i n d e x o f c i r c u l a t o r y c a p a c i t y as a v a r i e t y o f r e s p i r a t o r y f a c t o r s a r e i n v o l v e d . I t i s t h e low a v a i l a b i l i t y o f oxygen i n the water and the d i f f i c u l t i e s e n c o u n t e r e d i n e x t r a c t i n g oxygen from 81 t h e water w h i c h p r o b a b l y l i m i t a c t i v e m e t a b o l i s m i n f i s h , r a t h e r than any c i r c u l a t o r y i n a d e q u a c i e s . The c a r d i a c o u t p u t and s t r o k e volume d a t e r e p o r t e d h e r e i s compared w i t h t h a t o f o t h e r a n i m a l s ( t a b l e I X ) . The a c t i v e c a r d i a c o u t p u t v a l u e s agree w i t h t h o s e o f H o l e t o n (1966) f o r t h e r a i n b o w t r o u t but a r e h i g h e r than t h o s e o f Stevens and R a n d a l l (1967 b) f o r t h e same s p e c i e s . We s h o u l d not attempt t o o c l o s e a comparison of t h e s e v a l u e s however, s i n c e a l l t h e v a l u e s f o r s a l m o n i d s were c a l c u l a t e d by t h e F i c k p r i n c i p l e and a r e based on a number o f assumptions w h i c h may n o t always h o l d . More work i s n e c e s s a r y i n w h i c h c a r d i a c o u t p u t and s t r o k e volume d a t a can be measured d i r e c t l y w i t h i m p l a n t e d f l o w probes or s i m i l a r d e v i c e s . Only then w i l l we be a b l e t o say c o n c l u s i v e l y what s o r t o f b l o o d f l o w accompanies a c t i v i t y i n v a r i o u s f i s h . In comparing t h e b l o o d f l o w d a t a o f t h e v a r i o u s s p e c i e s a g a i n we must be c a r e f u l o f comparing t h e t a b u l a t e d v a l u e s t o o e x a c t l y as p h y s i o l o g i c a l v a r i a t i o n , methods of measurement, and degree o f a c t i v i t y o f t h e a n i m a l s w i l l a l l a f f e c t t h e v a l u e s . In g e n e r a l however, t h e more a c t i v e a n i m a l s show h i g h e r c a r d i a c o u t p u t s than s l u g g i s h forms as might be expected. S t r o k e volume e s t i m a t e s t e n d t o be q u i t e u n i f o r m f o r a l l groups o f a n i m a l s . The t o t a l range i s 0.25-2.0 m l / s t r o k e / k g . In most cases s t r o k e volume i n c r e a s e s accompany a c t i v i t y o r e x p e r i m e n t a l p e r f u s i o n 82 o f t h e h e a r t . The l a r g e d i f f e r e n c e s i n c a r d i a c o u t p u t among t h e d i f f e r e n t a n i m a l s i n t h e pr e s e n c e o f f a i r l y u n i f o r m s t r o k e volume v a l u e s suggests t h a t t h e r e i s a wide v a r i a t i o n i n t h e a b i l i t y o f t h e d i f f e r e n t s p e c i e s t o i n c r e a s e t h e i r h e a r t r a t e s . Undoubtably such v a r i a t i o n s a r e r e l a t e d t o d i f f e r e n t mechanisms o f c a r d i a c c o n t r o l . I f we examine t h e p h y s i o l o g i c a l mechanisms wh i c h p e r m i t e x e r c i s e i n humans and f i s h we f i n d a number of s i m i l a r i t i e s . Both humans and f i s h a r e c a p a b l e o f markedly i n c r e a s i n g t h e i r c a r d i a c o u t p u t d u r i n g e x e r c i s e t o f a c i l i t a t e e l e v a t e d m e t a b o l i c r a t e . L i k e man, f i s h can i n c u r an oxygen debt, a l t h o u g h r e c o v e r y from t h i s debt may t a k e some ti m e as f i s h a r e p o o r l y v a s c u l a r i z e d i n comparison t o man (Stevens, 1968). M y o g l o b i n i s p r e s e n t i n f i s h muscle and p r o b a b l y s e r v e s as an oxygen s o u r c e f o r emergency use. F i s h b l o o d c o n t a i n s hemoglobin a l t h o u g h t h e oxygen c a p a c i t y o f f i s h b l o o d i s s i g n i f i c a n t l y lower than t h a t o f mammals ( P r o s s e r and Brown, 1961). In salmon a t l e a s t , changes i n t h e p a t t e r n o f b l o o d f l o w p r o b a b l y o c c u r d u r i n g e x e r c i s e a l t h o u g h more work i s r e q u i r e d t o e l u c i d a t e t h e s e changes. Thus b o t h f i s h and humans appear t o po s s e s s e s s e n t i a l l y t h e same s e t o f mechanisms w h i c h f a c i l i t a t e e l e v a t e d m e t a b o l i c r a t e d u r i n g s t r e n u o u s e x e r c i s e . The l e v e l s o f performance r e a c h e d and t h e amount by whi c h a f i s h can i n c r e a s e i t s m e t a b o l i c r a t e a r e l i m i t e d by t h e dense water medium wh i c h i s b o t h d i f f i c u l t t o move t h r o u g h and c o n t a i n s 83 l i t t l e oxygen i n comparison t o a i r . S t u d i e s o f t h e e f f e c t o f te m p e r a t u r e on c a r d i o v a s c u l a r and r e s p i r a t o r y parameters i n sockeye salmon r e v e a l e d t h a t i n most i n s t a n c e s a tem p e r a t u r e e f f e c t was p r e s e n t . R o u t i n e and a c t i v e h e a r t r a t e i n c r e a s e d w i t h t e m p e r a t u r e as d i d r o u t i n e r e s p i r a t o r y r a t e . In no case d i d f a i l u r e o f any p a r t o f t h e c i r c u l a t o r y system o c c u r i n t h e t e m p e r a t u r e range t e s t e d (5-22°C). These r e s u l t s suggest t h a t t h e sockeye salmon c i r c u l a t o r y system would o p e r a t e s u c c e s s f u l l y w h i l e t h e f i s h were swimming t h r o u g h water between 5 and 22°C. I t must be remembered t h a t t h e f i s h were a c c l i m a t e d t o t h e t e s t t e m p e r a t u r e s and presumably t h e i r r a t e f u n c t i o n s had s t a b i l i z e d o r become a d j u s t e d t o t h e a c c l i m a t i o n t e m p e r a t u r e . T h i s s t u d y has p r o v i d e d no i n f o r m a t i o n on t h e e f f e c t o f r a p i d t e m p e r a t u r e changes on c i r c u l a t o r y parameters as might be encountered when spawning f i s h , l e a v e t h e sea and e n t e r r i v e r s . P o s s i b l y a r a p i d t e m p e r a t u r e change c o u l d have some d r a s t i c e f f e c t on c i r c u l a t i o n t h a t was n o t demonstrated h e r e . T h i s s t u d y has p r o v i d e d some i n f o r m a t i o n on c i r c u l a t o r y and r e s p i r a t o r y parameters i n u n r e s t r a i n e d , free-swimming f i s h s u b j e c t e d t o v a r i o u s l e v e l s o f a c t i v i t y . C o n s i d e r a b l e a d j u s t m e n t s i n some o f t h e parameters examined t a k e p l a c e i n response t o a c t i v i t y or a t d i f f e r e n t a c c l i m a t i o n t e m p e r a t u r e s . Many o f t h e f a c t o r s d i s c u s s e d remain l a r g e l y u n e x p l a i n e d and f a r 84 more work i s r e q u i r e d i n t h i s f i e l d b e f o r e a l l o f t h e d e t a i l s o f c a r d i o v a s c u l a r and r e s p i r a t o r y mechanisms i n f i s h can be d e s c r i b e d . 85 REFERENCES B a i n b r i d g e , R. (1958) . 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Stevens , E.D. and D.J. R a n d a l l . (1967 a ) . Changes i n b l o o d p r e s s u r e , h e a r t r a t e and b r e a t h i n g r a t e d u r i n g moderate swimming a c t i v i t y i n rainbow t r o u t . J . Expt. B i o l . , 46:307-315. Stevens , E.D. and D.J. R a n d a l l . (1967 b ) . Changes o f gas c o n c e n t r a t i o n s i n b l o o d and water d u r i n g moderate swimming a c t i v i t y i n r a i n b o w t r o u t . I b i d . , 46:329-337. Stroganov, N.S. (1962). Methods o f s t u d y o f r e s p i r a t i o n i n f i s h . In Techniques f o r t h e I n v e s t i g a t i o n o f F i s h P h y s i o l o g y , Oldbourne P r e s s , London. Wolf, K. (1963). P h y s i o l o g i c a l s a l i n e s f o r f r e s h w a t e r t e l e o s t s . P r o g r e s s i v e F i s h C u l t u r i s t , 25:135-140. 91 APPENDIX (Tables) The d a t a o b t a i n e d i n t h i s s t u d y i s summarized i n t a b u l a r f a s h i o n . In t h e f o l l o w i n g t a b l e s t h e s e symbols a r e used: x = mean average +S.D. = + 1 s t a n d a r d d e v i a t i o n +S.E. =. + 1 s t a n d a r d e r r o r o f t h e mean n = t h e number o f v a l u e s used t o c a l c u l a t e each mean average. Each v a l u e r e p r e s e n t s a d i f f e r e n t f i s h . T.B.F. = t a i l b e a t f r e q u e n c y i n b e a t s / m i n u t e . R o u t i n e t a i l b e a t f r e q u e n c y c o r r e s p o n d s t o t h e m i n i m a l a c t i v i t y l e v e l t h a t c o u l d be o b t a i n e d i n t h e l a b o r a t o r y . 92 Legend f o r T a b l e I H e a r t r a t e d a t a b e f o r e , d u r i n g and a f t e r t h e t h r e e t e s t groups were f a t i g u e d by swimming. TABLE I a) 5°C H e a r t Rate (beats/minute) T.B.F. Minut e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 128 140 15 0 165 2 5 10 20 45 60 X 1220 48.5 31.3 34. 2 37.5 40. 7 43. 7 45. 0 42. 0 41.1 37. 9 39. 0 42.0 +S.D. 409 4. 9 5.9 8. 7 6.2 7.2 3.3 3. 5 6. 6 8.2 7.2 4.8 4. 2 +S.E. 136 1.6 2.0 3.5 2.5 2.7 1.3 1. 3 2. 5 3.1 2.7 2.0 2.1 n 9 9 9 6 6 7 6 7 7 7 7 6 4 b) 15°C H e a r t Rate (beats/minute) T.B.F • M i n u t e s a f t e r F a t i g u e w e i g h t (g) Length+ R o u t i n e 95 125 153 182 2 7 14 30 50 x 1652 55. 9 52.0 62. 0 69. 0 80.0 83. 0 83. 0 73. 0 75.0 77. 0 72.0 +S.E. 129 19. 0 2.5 5.0 4.0 3.0 1.5 2.0 4.5 4.0 5.0 4.0 n 6 6 6 6 6 6 6 6 6 6 6 6 l e n g t h * - f o r k l e n g t h (cm) le n g t h + - t o t a l l e n g t h (cm) TABLE I (Cont'd) c) 22°c H e a r t Rate (beats/minute) T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 120 132 140 150 160 2 5 10 20 45 60 x 1100 48.7 86.2 101 100 105 105 105 103 99.9 107 104 101 88.8 +S.D. 310 5.1 5.6 8.8 8.8 3.2 3.3 7.1 15.0 16.5 11.9 10.3 9.6 10.9 +S.E. 93.5 1.6 2.3 3.9 2.9 1.2 1.5 3.2 5.7 6.3 4.9 4.2 3.9 4.4 n 11 10 6 5 9 7 5 5 7 7 6 6 6 6 l e n g t h * - f o r k l e n g t h (cm) 95 Legend f o r T a b l e I I S y s t o l i c and d i a s t o l i c p r e s s u r e s i n t h e d o r s a l a o r t a e o f t h e t h r e e t e s t groups. Data shows p r e s s u r e s b e f o r e , d u r i n g and a f t e r t h e f i s h were f a t i g u e d by swimming. TABLE I I a) S y s t o l i c B l o o d P r e s s u r e - 5°C, (mm Hg) T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n q t h * r o u t i n e 128 140 15 0 165 2 5 10 20 45 60 X 1230 48. 7 31.8 37. 0 37.0 38. 0 42. 0 38. 0 37. 0 34.0 34. 0 34.0 33.0 +S.D. 411 5.0 3.1 3.3 2.9 2.1 6.8 4. 8 8. 4 5.7 4. 9 3.8 3.0 +S.E. 137 1.7 1.1 1.4 1.2 0.9 3.4 1. 4 3. 2 2.2 1.9 1.6 1.5 n 9 9 8 6 6 5 4 6 7 7 7 6 4 b) D i a s t o l i c B l o o d P r e s s u r e - 5°C (mm Hg) T.B.F. Mi n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 128 140 15 0 165 2 5 10 20 45 60 X 1230 48. 7 27.5 31.0 31.0 33. 0 34. 0 34. 0 33. 0 30. 0 30. 0 29. 0 30.0 +S.D. 411 5.0 3.1 3.5 3.2 1.9 4. 2 2. 9 3. 5 4.5 3.8 2.4 2.5 +S.E. 137 1.7 1.1 1.6 1.3 0.9 2.1 1. 9 1. 3 1.7 1.4 1.0 1.3 n 9 9 8 5 6 5 4 6 7 7 7 6 4 l e n g t h * - f o r k l e n g t h (cm) TABLE I I (Cont'd) c) S y s t o l i c B l o o d P r e s s u r e - 15°C (mm Hg) T.B.F M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 100 125 150 185 4 7 15 30 50 x 1652 55. 9 48. 0 46. 0 45. 0 46. 0 55. 0 43. 0 44.5 40. 0 43. 0 41. 0 +S.E. 129 19. 0 1.2 1. 0 1.8 2. 7 1.3 2. 1 2.3 2.2 2.3 3.0 n 6 6 6 6 6 6 6 6 6 6 6 6 d) D i a s t o l i c B l o o d P r e s s u r e - 15°C (mm Hg) T.B.F i M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 100 125 150 185 4 7 15 30 50 x 1652 55. 9 42. 0 41.0 40. 0 42. 0 49. 0 40. 0 38. 0 35. 0 37.0 36. +S.E. 129 19. 0 1.0 1.4 1. 7 3.3 1.3 3. 4 1.5 2.0 2.3 3. n 6 6 6 6 6 6 6 6 6 6 6 6 l e n g t h * - t o t a l l e n g t h (cm) no s t a n d a r d d e v i a t i o n s a v a i l a b l e f o r means TABLE I I (Cont'd) e) S y s t o l i c B l o o d P r e s s u r e - 22°C (mm Hg) T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 132 148 160 180 2 5 10 20 45 60 x 1080 47. 3 33.8 32. 3 34. 2 35.5 39.2 30. 7 30. 3 31. 7 32.7 30. 7 30.0 +S.D. 340 5.5 4.7 6.7 6.8 6. 3 6.0 4. 5 4.5 5.5 5.0 3.8 4.6 +S.E. 113 1.8 1.4 2.8 3.1 2.6 2.7 2. 6 2.6 3.2 2.9 2.2 2.5 n 9 9 12 6 5 6 5 3 3 3 3 3 3 f ) D i a s t o l i c B l o o d P r e s s u r e - 22°C (mm Hg) T.B. F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 132 148 160 180 2 5 10 20 45 60 x 1080 47. 3 30. 2 31. 3 30.4 31. 8 36. 0 28. 7 28. 3 29.0 30.0 28. 7 28. 0 +S.D. 340 5.5 4. 3 5.1 6.8 6.8 5.2 4. 5 4.5 5.6 4.6 3.8 4.6 +S.E. 113 1.8 1.3 2.1 3.0 2.8 2.3 2. 6 2.6 3.2 2.7 2.2 2. 7 n 9 9 12 6 5 6 5 3 3 3 3 3 3 l e n g t h * - f o r k l e n g t h (cm) 99 Legend f o r T a b l e I I I P u l s e p r e s s u r e i n t h e d o r s a l a o r t a o f t h r e e groups o f f i s h b e f o r e , d u r i n g and a f t e r the f i s h were f a t i g u e d by swimming. TABLE I I I a) D o r s a l A o r t i c P u l s e P r e s s u r e (mm Hg) - 5°C T.B.F. Mi n u t e s A f t e r F a t i g u e w e i g h t (q) l e n g t h * r o u t i n e 128 140 150 165 2 5 10 20 45 60 X 1230 48. 7 4. 3 4.6 6.3 5.2 7.5 4.7 4. 9 4.1 4.2 4.3 3.0 +S.D. 411 5.0 1.4 1.1 4. 7 4.0 3.7 2.1 2.7 1.7 1. 3 2.1 0. 8 +S.E. 137 1. 7 0.5 0.5 1.9 1.8 1.9 0.8 1.0 0.6 0.5 0.8 0.5 n 9 9 8 5 6 5 4 6 7 7 6 6 4 b) D o r s a l A o r t i c P u l s e P r e s s u r e (mm Hg) - 15°C T.B.F. Mi n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h + r o u t i n e 100 125 150 185 4 7 15 30 50 x 1652 55.9 6.0 5.0 5.0 4.0 6.0 3.0 6.5 5.0 6.0 5.0 +S.E. 129 19.0 ( s t a n d a r d e r r o r s n ot a v a i l a b l e ) h 6 6 6 6 6 6 6 6 6 6 6 6 l e n g t h * - f o r k l e n g t h (cm) length+ - t o t a l l e n g t h (cm) TABLE I I I (Cont'd) c) D o r s a l A o r t i c P u l s e P r e s s u r e (mm Hg) - 22 C T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 132 148 160 180 10 20 45 60 X 1080 47. 3 3.8 3.8 3.8 4.3 3.2 2.7 2.0 2.0 1.7 +S.D. 340 •5.5 2.1 1.9 1.6 1.8 1.6 1.5 1.0 1.0 0.6 +S.E. 113 1.8 0.6 0.8 0.7 0.8 0. 7 0. 9 0.6 0. 6 0.3 n 9 9 12 6 5 6 5 3 3 3 3 l e n g t h * - f o r k l e n g t h (cm) 102 Legend f o r Table IV V e n t i l a t i o n r a t e i n t h e t h r e e groups o f t e s t f i s h b e f o r e , d u r i n g and a f t e r t h e f i s h were f a t i g u e d by swimming. TABLE IV a) V e n t i l a t i o n Rate (mouth c l o s u r e s / m i n u t e ) - 5°C T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 139 147 155 2 5 10 20 45 60 x 1108. 3 48.0 40. 0 93.4 105.0 115.0 79. 0 75. 0 67. 0 58. 0 65. 0 67. 0 +S.D. 383. 9 5.6 9. 8 11. 6 25. 0 33.4 5. 6 7. 2 8. 7 7. 7 14. 0 5. 4 +S.E. 145. 1 2.1 3.5 5.2 11. 2 19.3 2. 1 2. 7 3. 3 2: 9 5. 7 2. 7 n 7 7 8 5 5 3 7 7 7 7 6 4 b) V e n t i l a t i o n Rate (mouth c l o s u r e s / m i n u t e ) - 15°C T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) le n g t h + r o u t i n e 100 125 153 .4 7 15 30 50 x 1652 55. 9 65. 0 78. 0 34. 0 17.0 93. 0 77. 0 62. 0 62. 0 60. 0 +S.D. 315. 9 46.5 12. 3 15. 9 56. 3 39. 2 24. 5 24. 5 17. 1 19. 6 46. 5 +S.E. 129. 0 19.0 5.0 6.5 23. 0 16. 0 10. 0 10. 0 7. 0 8. 0 19. 0 n 6 6 6 6 6 6 6 6 6 6 6 l e n g t h * - f o r k l e n g t h (cm) le n g t h + - t o t a l l e n g t h (cm) TABLE IV (Cont'd) c) V e n t i l a t i o n Rate (mouth c l o s u r e s / m i n u t e ) - 22°C T.B.F. M i n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 120 132 154 165 178 2 5 10 20 45 60 x 1040 47.1 77.4 115 122 119 127 138 113 114 111 106 101 96.7 +S.D. 295 4.8 17.3 12.5 16.0 14.4 9.0 25.4 14.1 13.2 11.2 11.6 16.4 22.4 +S.E. 98.5 1.6 5.8 7.2 6.5 6.5 4.5 12.7 5.3 4.7 4.2 4.4 6.2 9.1 n 9 9 9 . 3 6 5 4 4 7 8 7 7 7 6 l e n g t h * - f o r k l e n g t h (cm) 105 Legend f o r T a b l e V Maximal p r e s s u r e r e c o r d e d i n t h e b u c c a l c a v i t y o f two groups o f f i s h a c c l i m a t e d and t e s t e d a t 5 and 22°C r e s p e c t i v e l y . In t h i s case o n l y d a t a f o r a d u l t s i s g i v e n as j a c k d a t a was h i g h l y v a r i a b l e and c o u l d n ot be c o r r e c t e d t o a d u l t l e v e l s . TABLE V ( A d u l t d a t a o n l y ) a) Maximum P r e s s u r e i n B u c c a l C a v i t y (mm Hg) - 5 C w e i g h t (g) l e n g t h * r o u t i n e 132 142 T.B.F. 147 150 167 M i n u t e s 2 5 A f t e r 10 F a t i g u e 20 45 60 X 1470 51.6 0. 7 1.1 1. 7 1.4 1.6 1.2 2.1 2.0 1.7 1.5 1.5 1.2 +S.D. 209 2.1 0.5 0. 7 0.8 0. 6 0.8 0.6 0.3 0.4 0.4 0.6 0.5 0. 7 +S.E. 93.5 0.9 0.2 0.5 0.4 0.4 0.5 0.4 0. 2 0.2 0.2 0.3 0.3 0.4 n 5 5 5 2 4 3 3 2 3 3 4 4 3 3 (no 15 C d a t a a v a i l a b l e ) b) Maximum P r e s s u r e i n B u c c a l C a v i t y (mm Hg ) - 22 C T.B.F. Mi n u t e s A f t e r F a t i g u e w e i g h t (g) l e n g t h * r o u t i n e 115 126 147 163 2 5 10 20 45 60 X 1312 51. 7 2.2 3.7 3.8 3.7 3.8 4.7 4. 7 3.9 2.9 3.1 3.5 +S.D. 178 1.1 0. 7 1.5 1.4 1.3 1.4 1.6 1.6 1.1 1.0 0.8 1.3 +S.E. 103 0.6 0.4 0.8 0.8 1. 0 1. 0 0. 9 0.9 0.6 0.6 0.5 0.7 n 3 3 3 3 3 2 2 3 3 3 3 3 3 l e n g t h * - f o r k l e n g t h (cm) 107 Legend f o r T a b l e V I T a b l e V I i l l u s t r a t e s s t a n d a r d and a c t i v e m e t a b o l i c r a t e s o f groups o f sockeye salmon t e s t e d a t d i f f e r e n t t e m p e r a t u r e s . P r i o r t o t e s t i n g , t h e f i s h were a c c l i m a t e d t o t h e t e m p e r a t u r e a t w h i c h t h e t e s t was t o be c a r r i e d o u t . Legend f o r T a b l e V I I T h i s t a b l e g i v e s t h e r e s u l t s of h e m a t o c r i t d e t e r m i n a t i o n s made on a group o f a d u l t sockeye salmon a t t e m p e r a t u r e s o f 15-22°C. TABLE V I ( a l l C>2 Uptake d a t a i n Mg 0 2/Kg/hr) M e t a b o l i c Rate - 5.5°C ( A d u l t s , x w e i g h t - 1510g+124) Standard A c t i v e Source x 30.45 502.0 +S.D. 2.98 136.5 B r e t t , u n p u b l i s h e d +S.E. 0.84 43.17 n 11 10 M e t a b o l i c Rate - 15°C (J a c k s , x w e i g h t - 745g+8.97) Standard A c t i v e Source x 70.7 730.0 +S.D. 7.9 90.2 B r e t t , u n p u b l i s h e d +S.E. 3.9 45.1 n 4 4 M e t a b o l i c Rate - 15°C ( A d u l t s , x w e i g h t - 1431.8g+40.6) Stan d a r d A c t i v e Source x 44.0 717.0 +S.D. 12.9 73.8 B r e t t , 1965 +S.E. 5.8 24.6 n 5 9 TABLE V I (Cont 'd) ( a l l 0 Uptake d a t a i n Mg 0 /Kg/hr) M e t a b o l i c Rate - 20 C ( A d u l t s , x w e i g h t - 1730g+219) x +S.D. +S.E. n M e t a b o l i c Rate x Sta n d a r d 76. 9 19. 0 7.2 7 - 22°C A c t i v e 786. 0 94. 9 28. 6 11 ( A d u l t s ) S t andard A c t i v e 145.0 800. 0 Source B r e t t , u n p u b l i s h e d Source e x t r a p o l a t e d from f i g u r e 19. TABLE V I I H e m a t o c r i t d a t a (Temp. . = 15-22°Cj Weight (g) F o r k l e n g t h (cm) H e m a t o c r i t x 1460.0 53.9 23.4 +S.D. 183.0 2.4 3.1 +S.E. 81.9 1.1 1.4 n 5 5 5 110 Legend f o r T a b l e V I I I T h i s t a b l e compares the o b s e r v e d d o r s a l a o r t i c p r e s s u r e i n t h e t h r e e t e s t groups w i t h t h a t c a l c u l a t e d from oxygen uptake d a t a . For example i f oxygen uptake d o u b l e s then d o r s a l a o r t i c b l o o d p r e s s u r e s h o u l d d o u b l e i f t h e i n c r e a s e i n oxygen u p t a k e i s s o l e l y due t o a d o u b l e d c a r d i a c o u t p u t . The t a b l e shows t h a t o b s e r v e d b l o o d p r e s s u r e i s f a r lower than would be e x p e c t e d on t h e b a s i s o f oxygen uptake d a t a . S i n c e c a r d i a c o u t p u t p r o b a b l y i n c r e a s e s m a r kedly w i t h e x e r c i s e t h e r e must be changes i n t h e r e s i s t a n c e o f t h e v a s c u l a r system accompanying e x e r c i s e . TABLE V I I I Oxygen Uptake ( f i g . 11) (Mg 0 2/Kg/hr) R o u t i n e A c t i v e 5.5 x 48.0 502.0 +S.E. — 43.2 n — 10 15.0 x 72.0 717.0 +S.E. — 24.6 n — 9 22.0 x 145.0 800.0 +S.E. Temperature (°C) A r e a Mean D o r s a l A o r t i c P r e s s u r e (mm Hg) Observed Expected R o u t i n e A c t i v e R o u t i n e A c t i v e 29.3 37.0 29.3 304.5 1.1 2.8 8 4 - - — 44.0 51.0 44.0 438.2 1.0 1.0 6 6 — — 31.3 37.0 31.3 172.8 1.4 2.5 12 5 112 Legend f o r T a b l e IX T h i s t a b l e p r o v i d e s a summary o f c a r d i a c o u t p u t and s t r o k e volume e s t i m a t e s made on a v a r i e t y o f a n i m a l s . TABLE IX C a r d i a c Output and S t r o k e Volumes of a V a r i e t y o f A n i m a l s A n i m a l Temperature S t r o k e Volume C a r d i a c Output Method R e f e r e n c e m l / s t r o k e / k g ml/min/kg man dog c a t f r o g octopus 20 7-9 1.0 (approx.) 0.31-2.01* 60.0-100.0 139. 0 690. 0 57.0 5.0-32.2 V e n t r i c u l a r d i s p l a c e m e n t F i c k p r i n c i p l e P r o s s e r and Brown, 1962 I b i d . I b i d . S heIton and Jones, 1965 Johansen, 1965 Opsanus t a u ( t o a d f i s h ) T e t rodon m a c u l a t u s ( p u f f e r ) Stenotomus c h r y s o p s (scup) Gadus morhua (cod) 0.31 - d o u b l e s w i t h i n c r e a s e d venous r e t u r n . 10.1 15.5 13. 7 9. 3 F i c k p r i n c i p l e , minimum v a l u e s As above As above Mott, 1957 I b i d . I b i d . E l e c t r o m a g n e t i c Johansen, flowmeter 1962 * c a l c u l a t e d from a h e a r t r a t e o f 16 b t s / m i n TABLE IX (Cont'd) C a r d i a c Output and S t r o k e Volumes of a V a r i e t y o f A n i m a l s A n i m a l Temperature S t r o k e Volume C a r d i a c Output Method R e f e r e n c e m l / s t r o k e / k g ml/min/kg Myoxocephalus s c o r p i u s ( s c u l p i n ) Squalus a c e n t h i a s ( d o g f i s h ) Salmo g a i r d n e r i (rainbow t r o u t ) Onchorynchus n e r k a (sockeye salmon) 15-18 11-17 12-18 4-8 5 15 20 22 0. 25-.94 -t o 1,88 when v e n t r i c l e p e r f u s e d . 0.85-2.0 0.15 ( r e s t i n g ) 0.7 (moderately a c t i v e ) 27. 75 9.0-24.8 F i c k p r i n c i p l e G o l d s t e i n , e t a l 1964 + L i g a t i o n and w e i g h i n g o f h e a r t . Flow from 1951 v e n t r a l a o r t a . Burger and B r a d l e y , 65.0-100.0 F i c k p r i n c i p l e 7.5 ( r e s t i n g ) 38.0 (mod- As above e r a t e l y a c t i v e ) r e s t i n g - f u l l y a c t i v e r e s t i n g - f u l l y a c t i v e 0.67-1.39 H o l e t o n , 1966 Stevens and R a n d a l l 1967 b. P r e s e n t s t u d y 0.60-1.12 0.65-1.04 0.73-0.99 20.74-65.07 F i c k p r i n c i p l e -r e s t i n g - VA 70% s a t d . 31.08-92.94 a c t i v e - VA 0% s a t d . 49.65-101.89 62.65-103.7 c a l c u l a t e d from a h e a r t r a t e o f 36 b t s / m i n "@en ; edm:hasType "Thesis/Dissertation"@en ; edm:isShownAt "10.14288/1.0104286"@en ; dcterms:language "eng"@en ; ns0:degreeDiscipline "Zoology"@en ; edm:provider "Vancouver : University of British Columbia Library"@en ; dcterms:publisher "University of British Columbia"@en ; dcterms:rights "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en ; ns0:scholarLevel "Graduate"@en ; dcterms:title "The influence of temperature and activity on certain cardiovascular and respiratory parameters in adult sockeye salmon"@en ; dcterms:type "Text"@en ; ns0:identifierURI "http://hdl.handle.net/2429/35960"@en .