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The influence of temperature and activity on certain cardiovascular and respiratory parameters in adult… Davis, John Christopher 1968

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THE INFLUENCE OF TEMPERATURE AND A C T I V I T Y ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS' I N ADULT SOCKEYE SALMON  by JOHN CHRISTOPHER DAVIS B.Sc,  University of Victoria,  1966  A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t h e Department of Zoology  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g required  to the  standard  THE UNIVERSITY OF B R I T I S H COLUMBIA February,  1968  In  presenting  for  an  that  advanced  thesis  shall  I further  agree  for scholarly  Department  o r by  publication  without  thesis  degree  the Library  study.  or  this  my  Department  in partial  at the U n i v e r s i t y make  i t freely  that  purposes  may  be  written  this  thesis  granted  of Columbia  by  requirements  Columbia,  t h e Head  shall  of  agree  and  copying  It i s understood gain  I  f o r reference  f o r extensive  for financial  permission.  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  of British  available  permission  his representatives.  of  f u l f i l m e n t o f the  of  this  my  that n o t be  copying allowed  i  ABSTRACT The i n f l u e n c e o f t e m p e r a t u r e a n d a c t i v i t y cardiovascular  and r e s p i r a t o r y parameters i n a d u l t  s a l m o n was s t u d i e d . 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 respirometer  until  Three groups o f f i s h were a c c l i m a t e d and 22°C r e s p e c t i v e l y .  d o r s a l a o r t a and b u c c a l heart  rate, blood  Pressures  they  fatigued.  and t e s t e d a t 5, recorded from t h e  c a v i t y gave i n f o r m a t i o n  pressure,  r a t e and p r e s s u r e s and  pulse  i n the buccal  the blood  c a v i t y before,  adult  allowed  fish,  rates of  t e m p e r a t u r e s and l e v e l s o f  c a l c u l a t i o n o f s t r o k e v o l u m e and c a r d i a c  output by t h e F i c k  principle.  During successively greater heart  Hematocrit  Knowledge o f t h e b l o o d  r a t e and t h e m e t a b o l i c  sockeye a t v a r i o u s  activity  during  oxygen c a p a c i t y o f these  t o b e a p p r o x i m a t e l y 9 v o l s %. oxygen c a p a c i t y , h e a r t  about  pressure, v e n t i l a t i o n  a f t e r t h e f i s h w e r e f a t i g u e d b y swimming.  data revealed  sockeye  Cannulae were i m p l a n t e d i n t h e d o r s a l  swim i n a t u n n e l - t y p e  15,  on c e r t a i n  r a t e and b l o o d  pressure  swimming  activity  rose i n a l l three  test  g r o u p s 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 . Calculated  s t r o k e v o l u m e and c a r d i a c o u t p u t  increased  m a r k e d l y and i t i s s u g g e s t e d t h a t t h e p e r i p h e r a l of the vascular  system diminished  The i n c r e a s e  i n heart  during  rate during  thought t o be r e l a t e d t o a r e l e a s e  resistance  exercise. exercise i s  of vagal  tone or p o s s i b l y ,  to the presence of c i r c u l a t i n g catecholamines. dorsal a o r t i c pressure during the  r e s u l t of elevated  a c t i v i t y was u n d o u b t a b l y  cardiac  output.  a o r t i c pressure d i d not increase increases is  Elevated  Since  dorsal  i n accordance w i t h the  i n oxygen u p t a k e o b s e r v e d d u r i n g  activity i t  suggested that p e r i p h e r a l r e s i s t a n c e decreases i nthe  face  of elevated  cardiac  Post-exercise  output.  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 buccal  p r e s s u r e remained above r e s t i n g l e v e l s .  post-exercise believed debt. 15 low  heart  rates  and b u c c a l  r a t e and High  p r e s s u r e s were  t o b e e v i d e n c e f o r t h e p r e s e n c e o f an o x y g e n  Blood pressures f e l l below r e s t i n g l e v e l s i n the  and 22°c t e s t g r o u p s f o l l o w i n g f a t i g u e a n d r e m a i n e d one h o u r a f t e r f a t i g u e .  T h e s e l o w 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 occurred and  to facilitate  f l u s h i n g o f the muscles w i t h  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  rate of both quiescent and  blood  and a c t i v e f i s h .  t e s t temperatures produced higher  lower a c c l i m a t i o n  influence Higher  heart  and t e s t t e m p e r a t u r e s .  temperature influences heart  heart  acclimation  rates  than  Presumably  r a t e b y a c t i n g d i r e c t l y on  membraneJphenomena i n t h e m y o c a r d i u m .  No c a r d i a c  was o b s e r v e d i n s o c k e y e , e v e n a t 22°C d u r i n g R o u t i n e and a c t i v e o x y g e n u p t a k e i n c r e a s e d  failure  severe  with  exercise.  temperature  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 w i t h temperature - 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 o x y g e n i n warm w a t e r .  Temperature  influence the ventilation  rate of quiescent f i s h .  t e m p e r a t u r e s were accompanied undoubtably  as a r e s u l t  appeared  to directly  by h i g h v e n t i l a t i o n  Higher rates,  of increased routine metabolic  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 water.  decreased  o f o x y g e n i n warm  iv  TABLE OF  CONTENTS Page  ABSTRACT  i  TABLE OF CONTENTS  iv  L I S T OF TABLES  v  L I S T OF FIGURES  v i  ACKNOWLEDGEMENT  ix  GENERAL INTRODUCTION  1  GENERAL METHODS  4  PART ONE - THE EFFECT OF SWIMMING A C T I V I T Y 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) M e t h o d s I  17  C) R e s u l t s a n d D i s c u s s i o n  I  D) Summary I PART TWO  17 52  - 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  II  54  B) M e t h o d s I I C) R e s u l t s and D i s c u s s i o n D) Summary I I  57 II  57 76  GENERAL DISCUSSION  78  REFERENCES  85  APPENDIX  91  V  L I S T OF TABLES Facing I  Heart r a t e before,  d u r i n g and a f t e r t h e  t h r e e t e s t g r o u p s w e r e f a t i g u e d b y swimming. II  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 the  d o r s a l aortae o f t h e three t e s t groups. III  Pulse pressure  95  i n the d o r s a l aortae of  three 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 w e r e f a t i g u e d b y swimming. IV  92  99  V e n t i l a t i o n r a t e i n the three 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 w e r e f a t i g u e d b y swimming.  V  Maximal pressure  recorded  i n the buccal  c a v i t y o f two g r o u p s o f f i s h and VI  acclimated  t e s t e d a t 5 a n d 22°C r e s p e c t i v e l y .  Standard  102  and a c t i v e m e t a b o l i c  105  rates of  groups o f sockeye salmon t e s t e d a t d i f f e r e n t temperatures. VII  Results of hematocrit  107 determinations  made on a group, o f a d u l t s o c k e y e s a l m o n at VIII  t e m p e r a t u r e s o f 15-22°C.  107  A comparison o f t h e observed  dorsal  a o r t i c pressure  groups  i n the three  w i t h t h a t c a l c u l a t e d from oxygen uptake data. IX  A summary o f c a r d i a c o u t p u t  110 and s t r o k e  v o l u m e e s t i m a t e s made on a v a r i e t y o f animals.  112  Page  vi L I S T OF 1  C a n n u l a e a r e shown  FIGURES  implanted  Facing i n t h e head  o f a sockeye salmon. 2  9  D e t a i l s of the respirometer  used i n these  experiments are i l l u s t r a t e d . 3  Changes i n h e a r t r a t e o f t h r e e g r o u p s o f sockeye before, are  4  10  d u r i n g and a f t e r  activity  illustrated.  19  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 resting fish  ( r o u t i n e ) and m o d e r a t e l y a c t i v e  is illustrated.  20  5  Typical pressure  records.  22  6  T y p i c a l pressure  records.  23  7  Changes i n d o r s a l a o r t i c b l o o d  pressure  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 h a d b e e n f a t i g u e d b y swimming. 8  A hypothetical blood  pressure  28  record to  i l l u s t r a t e w h a t i s meant b y t h e " t r u e mean" o r " a r e a mean" o f a p u l s a t i l e pressure. 9  30  Changes i n d o r s a l a o r t i c p u l s e before,  d u r i n g and a f t e r  pressure  swimming  activity  i n t h r e e t e s t groups o f sockeye salmon. 10  35  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 of f i s h  i n response 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  Page  vii  11  Semi-logarithmic  p l o t o f oxygen uptake and  swimming e f f o r t . 12  39  Changes i n b u c c a l  pressure  during  increased  swimming a c t i v i t y a n d f o l l o w i n g f a t i g u e a r e illustrated. 13  The e f f e c t o f t e m p e r a t u r e o n c a r d i a c of f u l l y  14  output  a c t i v e and r e s t i n g s o c k e y e salmon.  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 of f u l l y  15  40  volume  a c t i v e and r e s t i n g sockeye salmon.  Changes i n h e a r t  rate during  swimming e f f o r t a n d d u r i n g  recovery  from 58  Heart rates of adult and t e s t e d a t t h r e e  17  A r e a mean b l o o d  sockeye salmon  acclimated  temperatures.  pressure  59  i n the dorsal  a o r t a o f three groups o f a d u l t acclimated  sockeye  and t e s t e d a t t h e i n d i c a t e d  temperatures. 18  62  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  pressure  of a group o f a d u l t acclimated 19  47  increasing'  fatigue. 16  46  i n the dorsal  sockeye  aorta  salmon  a n d t e s t e d a t 22°C.  Oxygen c o n s u m p t i o n v a l u e s  63  o f groups o f  a d u l t sockeye salmon measured a t v a r i o u s acclimation 20  temperatures.  65  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 rate of adult  sockeye salmon.  73  The  e f f e c t o f t e m p e r a t u r e on  pressure during by  buccal  o f a d u l t sockeye salmon  before,  and a f t e r t h e f i s h h a d b e e n  swimming.  fatigued  ix  ACKNOWLEDGEMENT The  author  w i s h e s t o t h a n k D r . L . S . S m i t h 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  Mr.  D. S u t h e r l a n d  S t a t i o n , Nanaimo, B.C.)  provided and  (Biological  valuable technical assistance.  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  v a l u a b l e d i s c u s s i o n s o f t h i s work. Dr.  D. R a n d a l l  greatly  Mr. D.  research.  Stevens  and prompted  The a s s i s t a n c e o f  i n the preparation o f t h i s manuscript i s  appreciated.  GENERAL INTRODUCTION I n 195 7 M o t t r e v i e w e d cardiovascular of  system o f f i s h  information available.  t h e l i t e r a t u r e on t h e and e m p h a s i z e d t h e p a u c i t y  Up t o t h a t t i m e much o f t h e  w o r k h a d b e e n c a r r i e d o u t on i m m o b i l i z e d , or o t h e r w i s e Itazawa, and  abnormal f i s h  1957. M o t t ,  R a n d a l l and S m i t h  (Burger  1950.).  and B r a d l e y , 1951.  Rushmer, e t a l , (1960)  (1967) s t r e s s e d t h e n e e d f o r more  c o m p l e t e 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 With t h e advent o f techniques and  drugged, r e s t r a i n e d  fish.  which allow  operation  i m p l a n t a t i o n o f c a n n u l a e and t h e u s e o f p r e s s u r e  transducer increased.  devices  t h e scope o f e x p e r i m e n t a t i o n  Saunders  (1961) d e s c r i b e d  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 records  allowed  techniques  cavities  o r water samples c o u l d be taken.  (1964) d e v i s e d  so t h a t  pressure  a d o r s a l a o r t i c cannulation technique  pressure  r e c o r d i n g or blood  have demonstrated t h e u s e f u l n e s s  sampling  a,b) c a n n u l a t e d  Recent  Holeton  studies (Randall,  and R a n d a l l  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 (Salmo g a i r d n e r i ) .  i d e n t i c a l techniques  which  from w i t h i n  o f t h i s technique  e t a l , 1965. R a n d a l l and S m i t h , 1 9 6 7 . ) .  trout  of  S m i t h and B e l l  the v a s c u l a r system o f free-swimming f i s h .  (1967  has v a s t l y  Using  c a v i t i e s of rainbow  t h e same s p e c i e s and  Stevens and R a n d a l l  (1967 a,b)  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 c h a n g e s d u r i n g  recorded  moderate  2 short-term  swimming a c t i v i t y .  b e e n a d o p t e d h e r e however, exposed t o  s e v e r e and  eventually  in fatigue.  A  s i m i l a r approach  in this  prolonged  study  e x e r c i s e which r e s u l t e d  w o u l d r e s e m b l e t h o s e e n c o u n t e r e d by  Salmon a r e s p e e d s and for  long  extensive  of  prey,  avoiding  is  Burst  time r e q u i r e d b e f o r e  a given  size  can  swimming s p e e d The  and  (Brett,  object  cardiovascular  and  after adult  were f a t i g u e d by and be and  be  The  Fatigue  Sustained result  swimming in fatigue in  fish  r e l a t e d to the  sustained  s t u d y was  to  examine  r e s p i r a t o r y changes o c c u r r i n g  s o c k e y e salmon swimming.  effect  debt  1964).  of t h i s  r e s p i r a t o r y systems studied.  through  t o swim f u r t h e r  f a t i g u e occurs  directly  may while  a b o u t oxygen  a fishes inability  and  their  periods  ( B r e t t , 1965).  eventually  speeds  these f i s h  or moving  speeds b r i n g  velocities will  of  Also  predators  even a f t e r v i o l e n t s t i m u l a t i o n .  the  case d u r i n g  speeds" f o r short  at high  upstream  migration.  m o d e r a t e swimming  sea.  f a t i g u e i n s o c k e y e salmon c h a r a c t e r i z e d by  a f i s h moving  swimming a t a v a r i e t y o f  i s the  in the  "burst  t u r b u l e n t water. and  t i m e as  migrations  swim r a p i d l y a t catching  capable of  conditions  i t s spawning  o f t e n must m a i n t a i n  periods  salmon were  Thus e x p e r i m e n t a l  through t u r b u l e n t water d u r i n g  has  (Onchorynchus n e r k a )  Thus c h a n g e s i n t h e  in response to a c t i v i t y o f t e m p e r a t u r e on  r e s p i r a t o r y s y s t e m s was  during  a l s o examined.  the  circulatory could  cardiovascular  Some work  3 has  a l r e a d y b e e n done a t 15°C  a t 5° and  h e n c e t h i s w o r k was  done  22°C.  T h i s w o r k was Smith's experiments  initiated  i n 1964  were d e s i g n e d  o x y g e n u p t a k e s t u d i e s o f J.R.  b y L.S.  Smith.  t o complement  Brett.  the  I n t h i s way  aspects  o f c i r c u l a t i o n r e l a t e d t o o x y g e n u p t a k e c o u l d be S m i t h ' s w o r k was been p u b l i s h e d o f 1965 a t two  and  c a r r i e d o u t a t 15°C (Smith e t a l , 1967).  1966  the author  continued  d i f f e r e n t temperatures  - 5 and  examined.  and h a s r e c e n t l y In t h e  summers  Smith's s t u d i e s 22°C.  A l l  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  15°C Smith's  work w i t h h i s p e r m i s s i o n . I n 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 changes at v a r i o u s l e v e l s of a c t i v i t y we  and  respiratory  temperature  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 e s p i r a t o r y r a t e and p r e s s u r e I t was  i n the b u c c a l  rate,  cavity.  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  and h e a r t r a t e w o u l d i n d i c a t e w h a t s o r t s o f occurred  changes  i n the c i r c u l a t o r y system of sockeye at  temperatures  and  levels of a c t i v i t y .  S u c h an  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 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  pressure  different  approach  control  system.  M e a s u r e m e n t 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 i n d i c a t e some o f t h e c h a n g e s o c c u r r i n g i n t h e apparatus  during a c t i v i t y  The  use  respiration  at d i f f e r e n t  respiratory  temperatures.  of these data along w i t h B r e t t ' s metabolic  rate determinations and  and  should  should allow c o n s i d e r a t i o n of  as i n t e g r a t e d p r o c e s s e s .  The  circulation  experiments  4 reported in that  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 t h e same s p e c i e s  identical conditions  o f f i s h were t e s t e d  i n t h e same a p p a r a t u s .  (1965)  under Thus we  can u s e 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 output by t h e F i c k p r i n c i p l e . consider  through the g i l l s ,  of gases a t t h e r e s p i r a t o r y of b o t h systems  i n regulating  fish  a close  t h e exchange  i n t e r f a c e and t h e i m p o r t a n c e oxygen u p t a k e .  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  f i s h allows of  I t i s then p o s s i b l e t o  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  of  cardiac  The s t u d y  free-swimming  comparison t o p h y s i o l o g i c a l  swimming i n t h e i r n a t u r a l  conditions  environment.  Thus t h e p r e s e n t s t u d y h a d two b r o a d  objectives:  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 p a r a m e t e r s a n d 2) t o e x a m i n e 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 p a r a m e t e r s . GENERAL METHODS 1) F i s h C o l l e c t i o n a n d All  Acclimation  e x p e r i m e n t a l w o r k was c a r r i e d o u t on  (premature 3 y e a r o l d males) (Onchorynchus of  and a d u l t  sockeye  nerka) a t t h e F i s h e r i e s Research  Canada B i o l o g i c a l S t a t i o n , Nanaimo, B.C.  jack  salmon Board  T e s t s were  c o n d u c t e d f r o m May 1 t o S e p t e m b e r 1 i n t h e summers o f 1965  and 1966. A d u l t s o c k e y e s a l m o n w e r e t r a p p e d i n t h e Stamp  River  near A l b e r n i ,  B.C. d u r i n g  May a n d e a r l y  June.  5 These f i s h ranged (x-  f r o m 115 0 t o 1750 g i n w e i g h t  S.E. = 1438-39. 2) a n d w e r e m i g r a t i n g u p s t r e a m  Great C e n t r a l Lake.  I n a d d i t i o n a few j a c k s w e i g h i n g  b e t w e e n 580 and 957 g w e r e 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 apparant  into  were n o t  i n any f i s h a t t h e t i m e 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  Biological  Station  i n iced, 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 - p h e n o x y e t h a n o l , 100 m l / 4 0 0 g a l . ) t o t h e w a t e r 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  fish.  At the B i o l o g i c a l to  S t a t i o n t h e sockeye were  transferred  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 .  T a n k s w e r e e q u i p p e d w i t h r e c i r c u l a t i o n pumps a s 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  conditions  m a i n t a i n e d o x y g e n l e v e l s b e t w e e n 80 and 1 0 0 % 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 . was r e t a r d e d b y r u n n i n g s e a w a t e r  Fungus  growth  into the acclimation  t a n k s f o r a f e w h o u r s a t l e a s t one w e e k l y . 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  F i s h were period.  Separate 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 b y r e c i r c u l a t i n g t h e w a t e r 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 watt  immersion h e a t e r s .  The h e a t e r s w e r e  controlled  by Y S I temperature 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 temperature w i t h i n  l e s s t h a n + 1°C.  Temperature  i n the  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 b y m i x i n g amounts o f r e f r i d g e r a t e d and the  inflow line.  "normal" f r e s h water i n  The 5°C a c c l i m a t e d  f i s h were  1 week a t 10°C and 2 weeks a t 5°C b e f o r e 22°c a c c l i m a t e d  suitable  given  testing.  The  f i s h w e r e h e l d a t 18°C f o r 5 d a y s and  a t l e a s t 5 d a y s 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 . was b e l i e v e d t h a t s u c h a c c l i m a t i o n p e r i o d s completely  acclimated  2) C a n n u l a t i o n  fish  It  provided  (Brett - personal  communication).  Techniques  S o c k e y e w e r e a n a e s t h e t i z e d w i t h . 1:10, 000 222 a n a e s t h e t i c  MS  (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 e q u i p p e d w i t h a pump and n o z z l e s for  p e r f u s i n g the g i l l s w i t h water.  constructed  t h a t a stream o f water c o n t a i n i n g  (MS 222 - 1:10,000) the g i l l s  over t o a water supply  a n a e s t h e t i c and w a i t e d (twitching,  anaesthetic  maintain  To b r i n g t h e f i s h o u t o f a n a e s t h e s i a  merely switched  f o r the f i r s t  f i n movements,  1967) h a v e d e s c r i b e d  so  c o u l d b e c o n t i n u a l l y pumped o v e r  t o f a c i l i t a t e r e s p i r a t i o n and  anaesthetic.  in  The t a b l e was  etc.) .  one  c o n t a i n i n g no  signs of  recovery  S m i t h and B e l l  (1964,  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  detail. The D o r s a l A o r t i c  Cannulation  The d o r s a l a o r t a was c a n n u l a t e d  at i t s point of  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 as d e s c i r b e d b y S m i t h and B e l l  (1964).  arteries  The c a n n u l a  consisted  7  o f a 76 cm l e n g t h , o f C l a y - A d a m s P.E. 60 (0. 762 mm b o r e ) plastic  tubing  i n t o w h i c h a 3 cm #21 h u b e r p o i n t  Adams n e e d l e h a d b e e n i n s e r t e d . mid-dorsally bore needle olfactory  A h o l e was p u n c h e d  i n t h e snout of t h e f i s h w i t h a l a r g e (#12), c a r e b e i n g  lobes.  taken  t o avoid the  A 3 cm l e n g t h o f C l a y - A d a m s P.E.  200  p l a s t i c tubing  end  was p a s s e d t h r o u g h t h e h o l e  (1.397 mm b o r e ) h e a t f l a r e d on one i n t h e snout from  t h e mouth.  The d o r s a l a o r t i c c a n n u l a  inside this  sleeve.  cannula  fitted  inside  snugly  The s l e e v e was t i e d t i g h t l y  tothe  a t t h e p o i n t w h e r e b o t h t u b e s emerged f r o m t h e  d o r s a l t i p o f t h e snout. was  Clay-  I n s i d e t h e mouth t h e c a n n u l a  held flush against the palate with a single  stitch  mid-way b e t w e e n t h e c a n n u l a t i o n p o i n t a n d t h e p l a c e w h e r e the tubes passed through t h e snout. f i l l e d with heparinized (Wolf,  as  (10 I.U./ml) C o r t l a n d  1963) and p l u g g e d w i t h a t a p e r e d  p i n when n o t i n u s e . and  The c a n n u l a  durable  saline  stainless  S u c h a c a n n u l a t i o n was q u i t e  Details of the dorsal  200  a r e shown i n f i g u r e 1.  The  Buccal  The  b u c c a l c a v i t y was c a n n u l a t e d  cannula  sleeve  secure  aortic  Cannulation 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 e n d . buccal  steel  a n d , i n many i n s t a n c e s , r e m a i n e d open f o r  l o n g a s a week.  cannulation  was  The  p a s s e d t h r o u g h a n d was f i x e d t o a P.E.  i d e n t i c a l t o t h e one u s e d f o r t h e d o r s a l  8 a o r t i c cannula.  Figure 1 i l l u s t r a t e s details of  c a n n u l a t i o n a n d shows t h e b u c c a l c a n n u l a  located  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 . (1961) d e s c r i b e d a s i m i l a r 3) R e c o r d i n g  Saunders  cannulation.  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 from both  slightly  c a n n u l a e u s i n g two t y p e s  directly  of recording devices.  Some o f t h e w o r k was done u s i n g a S a n b o r n m o d e l 3 2 1 , 2 channel  carrier  267 t r a n s d u c e r s .  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 Frequency response o f t h e e n t i r e  was 30 c y c l e s / s e c w i t h P.E. 60 c a n n u l a e communication).  Alternately,  (Smith - p e r s o n a l  p r e s s u r e s were  u s i n g a Beckman t y p e R o f f n e r D y n o g r a p h . r e c o r d e r b u c c a l p r e s s u r e s were monitored P-23-BB p r e s s u r e  transducer;  o f one d r o p o f w e t t i n g a g e n t Cortland  this  w i t h a Statham  transducer.  pressures Addition  ("tween 80") / 500 m l  s a l i n e g r e a t l y deduced bubble f o r m a t i o n i n  the transducers 4)  recorded  With  dorsal aortic  w i t h a S t a t h a m P-23-AA p r e s s u r e  system  and f a c i l i t a t e d  trouble-free recording.  Respirometer C i r c u l a t o r y a n d r e s p i r a t o r y p a r a m e t e r s 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 by  Brett  (1964, 1 9 6 5 ) .  shown i n f i g u r e 2. a 1 1 % cm d i a m e t e r  described  D e t a i l s of the respirometer are  B a s i c a l l y t h e apparatus  consists of  p l e x i g l a s tube connected t o a v a r i a b l e  s p e e d pump w h i c h r e c i r c u l a t e s t h e w a t e r t h r o u g h t h e  9  Legend f o r F i g u r e  1  C a n n u l a e a r e shown i m p l a n t e d sockeye salmon. cavity while  The b u c c a l  i n t h e head o f a  c a n n u l a o p e n s i n t o t h e mouth  the d o r s a l a o r t i c cannula i s inserted  i n t o t h e lumen o f t h e d o r s a l  aorta.  directly  Dorsal  aorta  Dorsal aortic cannula I—  Buccal  cannula  f r n R E . 200 sleeve tfit \ tied to c a n n u l a  10  Legend  f o r Figure  2  D e t a i l s of the respirometer experiments are i l l u s t r a t e d .  F i s h swam w i t h  heads b e n e a t h t h e black, p l a s t i c u p s t r e a m end o f t h e t u b e . respirometer heater  used i n these  surrounding  Temperature  jacket.  the  i n the  c o u l d be c l o s e l y c o n t r o l l e d b y  and r e f r i d g e r a t i o n  their  the  Charged Pump 1_  * i ^Heater •> L _ J  Access port  Cannulae to pressure transducer.  11 t u b e a t a n y 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 . i m p e l l e r - t y p e f l o w meter g i v e s continuous water v e l o c i t y .  An  readout o f  Temperature can be c o n t r o l l e d w i t h i n  + 0.1°C b y a s y s t e m o f h e a t i n g a n d c o o l i n g c o n t r o l l e d by  a relay.  is roughly temperature  The w o r k i n g 2-30°C.  temperature  W a t e r c a n b e made up t o a n y d e s i r e d  a n d o x y g e n s a t u r a t i o n i n "header  adjoining the respirometer. and  range o f t h e apparatus  The s y s t e m c a n b e c l o s e d  u s e d a s 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, a s i n t h i s w o r k , s o t h a t a supply o f oxygenated water flows through  continuous  the apparatus.  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 w e r e by  tanks"  monitored  c o l l e c t i n g w a t e r s a m p l e s w i t h a, n e e d l e v a l v e and  applying the unmodified  Winkler technique  (Stroganov,  1962). 5) H e m a t o c r i t In  Determinations  order t o o b t a i n a rough estimate of t h e  o x y g e n c a p a c i t y o f s o c k e y e 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 carry out hematocrit  determinations.  B l o o d was w i t h d r a w n w i t h a 2 c c s y r i n g e f r o m t h e d o r s a l aortic  cannula o f f i v e f i s h h e l d a t temperatures  15-22°C.  S a m p l e s o f 0.5 c c b l o o d w e r e w i t h d r a w n a n d  s m a l l amounts w e r e t r a n s f e r r e d t o g l a s s tubes.  of  micro-hematocrit  These t u b e s were spun i n a m u l t i p l e - h e a d  c e n t r i f u g e a t a b o u t 13,000 x g f o r 3 m i n u t e s .  hemotocrit  Three  12 s e p a r a t e d e t e r m i n a t i o n s w e r e made on e a c h b l o o d Hematocrit  d e t e r m i n a t i o n s w e r e made w i t h a m i c r o - h e m a t o c r i t  tube reader  (Clay-Adams,  6) A c t i v i t y  Tests  a)  sample.  Inc.).  Terminology  In h i s c o m p r e h e n s i v e r e v i e w o f f i s h  respiratory  metabolism  Brett  (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 which  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 .  metabolism  i s " t h e maximum r a t e c o n s i s t a n t w i t h t h e  highest continual level metabolism which  Routine  i s t h e "average oxygen consumption o f f i s h  are undergoing  activity  of a c t i v i t y " .  Active  continuous recording during  i n a s e a l e d aquarium".  "free"  Routine metabolic r a t e  i s thus t h e oxygen consumption accompanying low l e v e l s of  activity  from,  of fish  i n the laboratory.  It i s distinct  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  " t h e minimum m e t a b o l i c r a t e a c c o m p a n y i n g t h e e n e r g y of  cost  m a i n t a i n a n c e ". In  parameters  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 were measured a t l e v e l s o f a c t i v i t y  upper and lower  limits  correspond  "active" metabolic rate.  whose  t o " r o u t i n e " and  The h e a r t r a t e ,  respiratory  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 , quiescent f i s h are thus termed  i n aquaria covered w i t h b l a c k "routine".  plastic  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 t e r m e d  13  " a c t i v e " i n accordance w i t h a c t i v e metabolic  rate,  b) A c t i v e R e c o r d s R e c o r d s 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 i n a c t i v e f i s h were o b t a i n e d  i n the following  dynamics 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 at  the d e s i r e d temperature  recover least  from the o p e r a t i o n .  A recovery period of at  3 h o u r s was a l l o w e d a l t h o u g h  f i s h were c a n n u l a t e d and  (5 o r 22°C) and a l l o w e d t o  left  i n most  instances  i n the l a t e afternoon or  i n the respirometer  evening  overnight f o r recovery.  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 did  n o t appear d i f f e r e n t .  I t was f o u n d  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 and  fish  t h a t a water respiration  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 r e m a i n u p r i g h t  i n the tube. A c t i v i t y t e s t s w e r e as f o l l o w s : was r a i s e d u n t i l  the f i s h  f t / s e c w i t h a 1-1.5 K g f i s h ) . swim b y a p p l y i n g a l i g h t  v o l t s A.C.)  to a wire grid  swimming f i s h .  by  ( u s u a l l y about  Sockeye were encouraged  electrical  c u r r e n t (3-5  swimming o c c u r r e d t h e  initial  f o r 30 m i n u t e s and was t h e n  0.3 f t / s e c f o r a n o t h e r  30 m i n u t e s .  Stepwise  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 f i s h f a t i g u e d i . e . - i t f e l l b a c k on t h e grid  1.3  l o c a t e d downstream from t h e  Once s t e a d y  v e l o c i t y was m a i n t a i n e d  velocity  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 against the current  to  Water  raised  30  u n t i l the  electrified  and w o u l d n o t swim a g a i n s t t h e w a t e r 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 w a t e r v e l o c i t y was resting  levels  to recover  (0.6-1.0 f t / s e c ) and  f o r one  Pressures  reduced  t h e f i s h was  to  allowed  hour. i n t h e d o r s a l a o r t a and  the  buccal  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 and r e c o v e r y p e r i o d .  Records used f o r the d a t a  activity  discussed  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 for  a few m i n u t e s a t t h e b e g i n n i n g , m i d d l e ,  e a c h 30 m i n u t e v e l o c i t y 10,  20,  increment.  obtained  2, 5,  45  and  provided  i n f o r m a t i o n on r e c o v e r y  and  end  S t r i p s of r e c o r d  60 m i n u t e s a f t e r f a t i g u e from  fatigue.  Water samples f o r oxygen d e t e r m i n a t i o n s taken roughly every period.  Thus i t was  of  were  15 m i n u t e s d u r i n g t h e e n t i r e p o s s i b l e to determine  the  test  oxygen  content of the water i n the r e s p i r o m e t e r d u r i n g each particular  swimming v e l o c i t y .  In a l l experiments  l e v e l s w e r e k e p t b e t w e e n 7 0 % and  110%  saturation.  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 low e n v i r o n m e n t a l Thus any  oxygen  (Smith - p e r s o n a l  of the respirometer  p l a c e d over  so t h a t t h e f i s h  swim w i t h i t s h e a d i n t h e d a r k e n e d end  of the  f i g u r e 2.  We  found  the could  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 P o s i t i o n o f t h e swimming f i s h  outside  discarded.  A p i e c e o f b l a c k p l a s t i c was u p s t r e a m end  and  communication).  d a t a c o l l e c t e d when t h e o x y g e n l e v e l was  t h e 7 0 - 1 1 0 % s a t u r a t i o n r a n g e was  oxygen  reduced.  i n t h e t u b e i s shown i n  t h a t sockeye r a p i d l y  learned  to  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 a shock i n the t a i l . in  one  in  the frequency Bainbridge  t u b e was  of t a i l beats  (T.B.F. - t a i l b e a t  frequency).  Obviously  and  i n a 1 1 % cm d i a m e t e r  a t t a i n only a small p o r t i o n of  normal t a i l beat  amplitude  of t a i l beats.  one  tube their  and h e n c e must i n c r e a s e Therefore  t h e swimming  S i n c e we  are i n t e r e s t e d  the  effort  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 t h a n  natural conditions.  of  amplitude  a d u l t salmon can  any  counting  (195 8) r e p o r t e d t h a t t h e swimming s p e e d  of the t a i l beat.  for  velocity  e v a l u a t e d by v i s u a l l y  i s d i r e c t l y r e l a t e d to the frequency  frequency  plastic.  swimming e f f o r t o f f i s h a t e a c h t e s t  the respirometer  fish  Thus t h e f i s h u s u a l l y swam w e l l  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 The  with  under  i n the  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 g r o u p o f s i m i l a r fish this disparity is  i s not of g r e a t  importance.  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  activity. likely  One  must remember t h a t t h e s e c h a n g e s  sized  What increased are  t o accompany g r e a t e r swimming s p e e d s u n d e r n a t u r a l  conditions. c)  "Routine"  Records  R e c o r d s 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 routine in  (low a c t i v i t y )  two w a y s .  performance f i s h were  F i s h were p l a c e d i n covered,  obtained  darkened  aquaria s u p p l i e d w i t h running water of the d e s i r e d temperature by  (5 o r 22°C).  Oxygen l e v e l s w e r e f o l l o w e d  s i p h o n i n g o f f s a m p l e s o f w a t e r and  applying  the  in  16 unmodified and  Winkler  technique  d o r s a l a o r t i c cannulae  that pressures  1962).  G e n e r a l l y r e c o r d s were  a 24-48 h o u r p e r i o d .  s i m i l a r techniques  R a n d a l l , e t al,  I n most c a s e s  so  without  obtained  (1965) u s e d  to record dorsal aortic  from rainbow t r o u t .  Buccal  were l e d o u t o f t h e tank  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  distrubing the f i s h . over  (Stroganov,  pressures  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 cannulated  f i s h placed  i n the respirometer  i n a g e n t l y moving stream  of water  The r e s p i r o m e t e r was c o m p l e t e l y and  and  overnight  (0.6-1.0  ft/sec).  covered w i t h b l a c k  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  aquaria.  from  plastic  i n covered  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  covered  a q u a r i a were s i m i l a r  (a t - t e s t showed  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 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 . placed i n covered  O n l y a f e w 5°C a c c l i m a t e d f i s h aquaria f o r recording.  were t e s t e d i n t h e r e s p i r o m e t e r  only.).  A l l 22°C  were fish  17  PART THE  EFFECT OF  ONE  SWIMMING A C T I V I T Y ON  CARDIOVASCULAR AND  CERTAIN  RESPIRATORY  PARAMETERS I N SOCKEYE SALMON INTRODUCTION I To and  assess the  e f f e c t s of a c t i v i t y  on  cardiovascular  r e s p i r a t o r y d y n a m i c s , f i s h w e r e c a n n u l a t e d and  as o u t l i n e d p r e v i o u s l y .  Thus i t was  " r o u t i n e " and  "active" records  and  f i s h was  a f t e r the  tested  possible to  obtain  from f i s h before,  during  f a t i g u e d by  swimming.  METHODS I Methods are  as o u t l i n e d i n t h e g e n e r a l  introduction.  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 are by  e x p r e s s e d as activity  fish. w i l l be  "% r o u t i n e " so t h a t c h a n g e s p r o d u c e d  can be  related to conditions  Exact numerical given  values  i n P a r t Two  in  quiescent  f o r the various  of t h i s  p a p e r and  parameters  i n accompanying  tables. RESULTS AND  DISCUSSION I  Mean a v e r a g e h e a r t  rate  i n both groups of f i s h t e s t e d  increased  (5 and  during  22°C).  activity  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 .  speeds h e a r t (fig.  swimming  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 g r o u p  3) . The  corrected  heart  r a t e s o f 22°C a c c l i m a t e d  f o r size.  shows t h a t a c o n s i d e r a b l e 4).  Smaller  l a r g e r ones.  jacks  were  A p l o t of weight vs. routine  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  (fig.  At higher  rate  heart  (T.B.F. = 132)  s i z e e f f e c t was p r e s e n t  f i s h had higher  heart  rates  A t - t e s t o f mean r o u t i n e h e a r t  than  rate of  j a c k a n d a d u l t g r o u p s showed t h a t a s i g n i f i c a n t  difference  e x i s t e d b e t w e e n t h e two means a t t h e 5 % l e v e l o f significance.  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  rate the jack  d a t a was m u l t i p l i e d b y 0.85 and t h e d a t a f r o m and  adult  j a c k salmon combined. A s i m i l a r p l o t o f weight vs. routine heart  and if  a t - t e s t w e r e a p p l i e d t o t h e 5°C t e s t g r o u p t o d e t e r m i n e a w e i g h t f a c t o r was p r e s e n t .  I n t h i s c a s e 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 routine heart the  rate  r a t e s o f j a c k and a d u l t  b e t w e e n mean  fish.  Consequently  j a c k a n d a d u l t d a t a was c o m b i n e d w i t h n o c o r r e c t i o n  i n t h e 5°C t e s t g r o u p . jacks  S m i t h ' s 15°C d a t a c o n t a i n e d  no  and hence r e q u i r e d no c o r r e c t i o n . T h e r e a p p e a r e d t o be no p a r t i c u l a r p a t t e r n o f  heart  r a t e change accompanying each i n c r e a s e  velocity.  I n some c a s e s h e a r t  the v e l o c i t y increased;  i n water  rate rose i n i t i a l l y  after  e s p e c i a l l y when t h e f i s h p u t  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 g r o u p s o f s o c k e y e before,  d u r i n g and a f t e r a c t i v i t y  are illustrated.  These g r o u p s 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 temperatures. o f the. mean.  Values  a r e means + 1 s t a n d a r d  error  0  100  120  S40  TAIL BEAT FREQUENCY  160  580  (beots/mln)  200  0  20  40  60  MINUTES. AFTER FATIGUE  20  Legend f o r F i g u r e The  effect  ( r o u t i n e ) and The  4 o f w e i g h t on h e a r t  moderately a c t i v e f i s h  f i s h were a c c l i m a t e d  represent regression  and  data for individual l i n e s and  r a t e of is  illustrated.  t e s t e d a t 22°C. fish.  Least  t h e i r equations are  resting  Points  squares  included.  21 on  a b u r s t o f s p e e d f o r a few  seconds.  In o t h e r  instances  the r a t e remained steady or r o s e s l o w l y d u r i n g the m i n u t e s i n w h i c h any  one  v e l o c i t y was  o v e r a l l e f f e c t of stepwise v e l o c i t y rise  i n h e a r t r a t e as n o t e d  applied.  The  i n c r e a s e s was  earlier.  30  a general  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 in  f i g u r e 5 and  6.  There i s very heart r a t e of fishes and in  Smith  little  i n f o r m a t i o n on  i n response  changes i n  to a c t i v i t y .  Randall  (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  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 o f  p o s t e r i o r p a r t o f t h e body. o r no  change.  a 15% r i s e trout  S t e v e n s and  the  I n t r o u t t h e r e was Randall  (1967  i n heart r a t e i n moderately  little  a,b)  observed  active  rainbow  (Salmo g a i r d n e r i ) swimming i n a t u b e f o r 10  Following a c t i v i t y heart r a t e of t h e i r quickly to pre-exercise In  the r e s t i n g  f i s h dropped back  levels. sucker  (Catostomus  macrocheilus)  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 which i n h i b i t s heart rate. decrease  During  minutes.  activity  t h e r e i s an  the  apparent  i n v a g a l tone which a l l o w s a 75% i n c r e a s e i n  heart rate.  I n j e c t i o n of a t r o p i n e b l o c k s the  vagus  and  produces c a r d i o a c c e l e r a t i o n i n the r e s t i n g  sucker.  In  t h e r a i n b o w t r o u t h o w e v e r , t h e r e i s no v a g a l  tone  in  resting  f i s h and m o d e r a t e swimming a c t i v i t y  only a 15% r i s e 1967  a,b).  in heart rate  R a n d a l l and  (Stevens  Stevens  and  produces  Randall;  (1967) f o u n d  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 A)  records  Segments o f d o r s a l a o r t i c and b u c c a l  pressure  r e c o r d s o f a 1440 g a d u l t s o c k e y e r e s t i n g q u i e t l y i n an a q u a r i u m . a quiescent B)  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 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.  A t y p i c a l p r e s s u r e r e c o r d f r o m an a c t i v e  swimming i n t h e r e s p i r o m e t e r .  (T.B.F.  fish  The r e c o r d i s f r o m a  778 g j a c k swimming a g a i n s t a w a t e r c u r r e n t o f ft/sec  from  = 176 b e a t s / m i n ) .  The f i g u r e  1.8  shows  t h a t s t r u g g l i n g p r o d u c e s an e l e v a t e d d o r s a l a o r t i c blood pressure  f o r about  30 s e c o n d s .  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 A)  records  R e c o r d 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 s o c k e y e i n t h e r e s p i r o m e t e r a t 15°C. v e l o c i t y was r a i s e d  f r o m 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. accompanies the onset mm B)  The w a t e r  A rapid rise  o f swimming.  i n blood  pressure  Pressures are i n  Hg. Record taken  f r o m a 1506 g a d u l t s o c k e y e a t  22°c d u r i n g r e c o v e r y f r o m f a t i g u e .  The g r a p h 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  with  time.  D o r s a l a o r t i c p r e s s u r e d r o p s and d o r s a l a o r t i c and buccal pulse pressure deminish a r e i n mm  Hg.  w i t h time.  Pressures  40  r  30  T  20  water velocity up ¥  1  2 0 sees.  6  3 0  [ WIIKilllSSIIIBi IHBitflll mmmmm Buccal pressure  Fatigue  +2 mins.  + 1 0 mins.  + 45 mins.  + 1 2 0 mins. 8 sees. I 1  40 30 20 «Dorsal aortic pressure Fatigue  + 2 mins.  + IO mins.  +45 mins.  + 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, kisutch,  as a t r o p i n e  Onchorynchus  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  in r e s t i n g fish. Thus t h e r e a p p e a r t o be  two  types  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 One  of these  the other  appears aneural as  i n nature.  i s the  c a r d i o a c c e l e r a t i o n cannot be  I f there  must s p e e d t h e h e a r t  o u t p u t g o e s up  s t r o k e v o l u m e and 1967  b).  d i d not  Johansen occur  An  Laurent,  1957.  o n l y by  1957). does  Randall,  i n response t o i n c r e a s e d venous r e t u r n unanaesthetized  cod  f l o w i n t h e r e s t r a i n e d cod  e l e v a t i n g the  s t r o k e volume.  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  o f L a b a t et  suggested  can be  increased  not  that observed  c o n d i t i o n s of h i s experiment.  Tachycardia  i n the c a t f i s h  He  i n t h e c o d b u t was  somewhat u n n a t u r a l  free-swimming cod.  (Gadus morhua)  I t m i g h t be  to the  study  and  the  that cardioacceleration  due  the  mechanism  nerves serve Mott,  (Stevens  (1962) 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 occurs  return  of  i n t r o u t d u r i n g a c t i v i t y as  t h a t s t r o k e volume almost doubled.  that blood  i s no  aneural  sympathetic  venous r e t u r n  i n the r e s t r a i n e d but but  vagus,  p r o d u c e d by r e l e a s e  s i n c e no  ( C o u t e a u x and  studied.  case i n the t r o u t , then  v a g a l tone i n response to a c t i v i t y .  Cardiac  i n the f i s h  i s a n e u r a l mechanism i n v o l v i n g the  vagal tone i n f i s h ,  f i s h heart  of  i n an  unrestrained  followed increased  (Amerius n e b u l o s u s ) a c c o r d i n g al.  (1961) .  They c o n c l u d e d  venous to that  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 the d i r e c t a c t i o n of  25 p r e s s u r e on  the myocardium.  Thus t h e r e may  be  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 N e u r a l c o n t r o l may vagus nerve or  be  aneural  through the d i r e c t myocardium.  present through the c o n t r o l may  be  be  i n f l u e n c e o f p r e s s u r e on  p r e s e n t w h i c h a c t on  a cardioaccelerator  heart.  Shepherd  s u b s t a n c e may  (1965) r e p o r t e d  i n d o g s t h a t was  not  related to  catecholamines.  Breton et a l  Jensen  the  not  must be  More s t u d y i s r e q u i r e d  that  i s present  in  i t s release.  endogenous  C e r t a i n l y such a mechanism  i n c r e a s i n g venous  i n what could  c a t f i s h heart  in  return.  A n o t h e r more p l a u s i b l e e x p l a n a t i o n exercise  for  r e l a t e s to the  substances i n the blood i t s e l f . released  hagfish an  i s p r e s e n t and  response to  possible  If  t o d e t e r m i n e i f an  c a r d i o a c c e l e r a t i o n of the  s u b s t a n c e s c o u l d be  the  i t was  a catecholamine.  e x p l a i n the  of a c c e l e r a t o r  the  elevation  s t i m u l a t i o n of  a mechanism m e d i a t i n g  cardioacceleration during  in  substance from the  mechanism o f c a r d i o a c c e l e r a t i o n manner i t o p e r a t e s .  present  supply  circulating  endogenous s u p p l y of c a r d i o a c c e l e r a t o r the h e a r t there  myocardium.  endogenous  be  (1963) r e p o r t e d  b r a n c h i a l h e a r t t h a t was  the  (1964) o b s e r v e d  to i s o l a t e a cardioaccelerator  about  cardioacceleration  of heart r a t e f o l l o w i n g e l e c t r i c a l teleost heart.  the  cardioacceleratory  T h e r e i s some e v i d e n c e t h a t an of  fish.  a c t i o n of  brought  It i s also possible that  s u b s t a n c e s may  in  a variety  i n t o the blood  presence  These  i n response  26 to  activity  system.  and thus produce changes i n t h e c a r d i o v a s c u l a r  Nakano a n d T h o m l i n s o n  (1967) h a v e m e a s u r e d  increased l e v e l s o f catecholamines trout  (Salmo g a i r d n e r i ) .  observed  i n t h e b l o o d o f swimming  R a n d a l l and Stevens  (1967)  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  i n j e c t i v e o f 2-7 u g e p i n e p h r i n e  into the subintestinal  v e i n o f s o c k e y e and c o h o s a l m o n a t 15°C. 1 ug o f e p i n e p h r i n e  injected  following  Less  than  i n salmon a p p a r e n t l y  slowed  the 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 fish.  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  cardioaccelerator  i n s a l m o n and t h a t t h e e f f e c t s o f l o w  epinephrine  c o n c e n t r a t i o n c a n b e masked b y a c t i o n o f  the vagus.  Thus i n t h e s a l m o n t h e r e may b e two m e c h a n i s m s  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 The  activity.  f i r s t may b e n e u r a l a n d i n v o l v e r e l e a s e o f v a g a l  t o n e d u r i n g a c t i v i t y w h i l e t h e s e c o n d may b e a n e u r a l a n d be  associated w i t h the a c t i o n o f blood-bourne  a c t i n g on t h e h e a r t . the r e l a t i v e The activity for  Further study  importance presence  i s required to elucidate  o f t h e s e two m e c h a n i s m s i n s a l m o n .  of catecholamines  i n the blood  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 b e some  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  blood.  Catecholamine-containing  s c a t t e r e d throughout  ( B e r n , 1967.  v o n E u l e r and Fange, 1961.  during site  into the  t i s s u e has been  t h e body o f t e l e o s t s ,  r e g i o n o f t h e head k i d n e y 1961.  catecholamines  found  much o f i t i n t h e  v o n E u l e r , 1953,  Ostlund,  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 of t e l e o s t s .  catecholamines  Thus t h e r e a p p e a r t o b e a d e q u a t e s u p p l i e s  of 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 which 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 The  activity.  increases i n heart rate with successively  h i g h e r swimming s p e e d s shown i n f i g u r e 3 c o u l d b e r e l a t e d to the concentration of c i r c u l a t i n g  catecholamines.  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 a s 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 procedure are i l l u s t r a t e d pressures recorded and  i n f i g u r e 7.  Since blood  i n the dorsal aorta are pulsatile  o s c i l l a t e between a maximal  (systolic)  ( 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 were c a l c u l a t e d .  and m i n i m a l i n the vessel  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 g r o u p s c o u l d b e most e a s i l y  compared.  Mean b l o o d p r e s s u r e s w e r e c a l c u l a t e d u s i n g t h e following  formula: Average b l o o d  pressure  = Systolic Pressure + 2(Diastolic 3 Burton the  Pressure)  (1966) s u g g e s t e d t h a t t h i s f o r m u l a  gave  " t r u e " o r " a r e a 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 .  S u c h 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  t h e a r i t h m e t i c mean o f t h e s y s t o l i c a n d d i a s t o l i c  pressures  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 t h e t i m e  28  Legend f o r F i g u r e 7 Figure  7 shows c h a n g e s i n d o r s a l a o r t i c  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 h a d b e e n f a t i g u e d b y swimming.  three groups o f f i s h  F i s h were  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 . mean a v e r a g e s + 1 s t a n d a r d  blood  acclimated Points are  e r r o r o f t h e mean.  AREA  M E A N BLOOD P R E S S U R E  (%  routine)  29 course  of a pressure  o s c i l l a t i o n within the vessel.  F i g u r e 8 i l l u s t r a t e s w h a t i s meant b y a " t r u e " o r  "area  mean" p r e s s u r e . At a l l t h r e e t e s t temperatures pressures little then  change d u r i n g t h e i n i t i a l  r o s e above r o u t i n e l e v e l s  swimming e f f o r t . and  showed  swimming p e r i o d and  i n response t o i n c r e a s i n g  F i s h a c c l i m a t e d a n d t e s t e d a t 22°C  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  in response t o a c t i v i t y . I n t h e same f a s h i o n a s w i t h t h e h e a r t r a t e d a t a , a significant disparity  i n r o u t i n e average blood  pressure  was a p p a r e n t b e t w e e n mean a v e r a g e b l o o d p r e s s u r e o f j a c k s a n d a d u l t s a t 22°C level). than it  ( s i g . w i t h t - t e s t a t t h e 0.01  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  of jacks.  J a c k d a t a was m u l t i p l i e d b y 1.1 t o a d j u s t  to adult levels.  T h e r e was n o 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 a v e r a g e p r e s s u r e s .05  than  a t 5°C  (t-test,  level). Mott  estimates  (195 7)  taken  summarized t h e a v a i l a b l e b l o o d  pressure  f r o m a v a r i e t y o f f i s h a n d 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 a n d b e t w e e n d i f f e r e n t species of f i s h . on p r e s s u r e Lyon  She r e p o r t e d n o i n f o r m a t i o n  changes i n a c t i v e ,  unrestrained  (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  fishes.  i n sharks  rose  as h i g h a s 50 mm Hg d u r i n g s t r u g g l i n g o r swimming. Recently, rise  S t e v e n s and R a n d a l l  i n s y s t o l i c pressure  (1967 a) r e p o r t e d a 1 6 %  and a 2 1 % r i s e  in diastolic  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  pressure  r e c o r d t o i l l u s t r a t e w h a t i s meant b y t h e " t r u e mean" or  " a r e a mean" o f a p u l s a t i l e  pressure.  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 b e l o w t h e s o l i d  line.  a r e a mean b l o o d p r e s s u r e is  shown.  The f o r m u l a f o r c o m p u t i n g  i s i n c l u d e d and a sample  calculation  31  pressure trout. and  i n the d o r s a l a o r t a of moderately a c t i v e rainbow 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  s y s t o l i c pressures  v e i n showed no rapid  pulse pressure  increases  activity. figure  r o s e by  The  in blood  a b o u t 40%. but  pressure  diastolic The s u b i n t e s t i n a l  t h e r e were  irregular  i n the v e s s e l  during  changes i n d o r s a l a o r t i c p r e s s u r e  7 appear comparible  w i t h those  in  of Stevens  and  Randall. The  increase i n blood  a c t i v i t y could result 2)  increased  pressure  f r o m 1)  s t r o k e v o l u m e and  show t h a t h e a r t  3)  increased peripheral  of these  factors.  v o l u m e i s c a l c u l a t e d and of the  in producing  importance of s t r o k e volume  elevated blood  increased.  system d i d not  Since  pressure.  can  increase  C e r t a i n l y the  suggests that  I f r e s i s t a n c e of the  change i n t h e  and  stroke  n o t m e a s u r e d d i r e c t l y we  elevated heart rate during a c t i v i t y o u t p u t has  Our  rate increased during a c t i v i t y  t h a t s t r o k e volume appeared t o i n c r e a s e .  say n o t h i n g  during  increased heart rate,  r e s i s t a n c e o r some c o m b i n a t i o n data  observed  cardiac  circulatory  face of increased  cardiac  o u t p u t t h e n one  w o u l d e x p e c t an  to r e s u l t .  crux of the problem then appears r e l a t e d  The  to r e s i s t a n c e i n the c i r c u l a t o r y R a n d a l l and intravenously k i s u t c h ) and pressure  Stevens  increase i n blood  system.  (1967) i n j e c t e d  i n t o r e s t i n g coho s a l m o n  injection.  epinephrine  (Onchorynchus  observed elevated d o r s a l a o r t i c  after  pressure  I n j e c t i o n o f an  blood ec-adrenergic  32 b l o c k i n g agent, phenoxybenzamine, a b o l i s h e d the in blood  p r e s s u r e p r o d u c e d by  concluded in  epinephrine.  t h a t t h e r e are oC-adrengergic  the g i l l s  and  rise  They  receptors  g e n e r a l body c i r c u l a t i o n of  present  salmon.  These w o r k e r s a l s o found t h a t phenoxybenzamine abolished r i s e s of blood  pressure  that occurred  t h e f i s h w e r e swimming.  Thus i t a p p e a r e d  while  that  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 m i g h t be responsible for blood with  pressure  increases associated  swimming. The  blood  c o u l d be due  pressure  changes i n t h e d o r s a l a o r t a  to v a s o d i l a t i o n of the 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 been demonstrated  (Keyes and  S t e e n and  be  t o t h e a c t i o n o f <£ and  due  Kruysse,  Bateman, 1932.  1931.  The  partly  w o r k o f R a n d a l l and  1964.).  v a s o d i l a t i o n could  demonstrated  subsequently  gills. the  Baumgarten  (personal communication) demonstrated the  o f b o t h oC and A r e c e p t o r s In  i n the g i l l s  of rainbow  and  presence trout.  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  the p e r i p h e r a l c i r c u l a t i o n diminishes Stevens,  Krawkow  r e c e p t o r s on t h e  S t e v e n s has  p r e s e n c e o f oc r e c e p t o r s and Randall  The  has  1967)  (Randall  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  o f a d d i t i o n a l v e s s e l s has that during a c t i v i t y  there  occurred.  One  could  i s some p o w e r f u 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  and opening hypothesize  control  of 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 of epinepherine  or  adrenergic  33  receptors.  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 w h i c h may  be p r e s e n t  i n the p e r i p h e r a l c i r c u l a t i o n  (Randall - p e r s o n a l communication). m e c h a n i s m w o u l d be  receptors  important  as  A vasodilatory  i t would prevent  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 the f a c e large increases in cardiac We  are thus unable  large of  output. t o say e x a c t l y what  factors  produce e l e v a t e d blood pressure d u r i n g a c t i v i t y . increased c a r d i a c output  i s a major c a u s i t i v e  h o w e v e r t h e r e s i s t a n c e o f the undoubtably  factor  c i r c u l a t o r y system i s  of c o n s i d e r a b l e importance.  of c i r c u l a t i n g catecholamines  Probably  and  The  effects  the presence  of  «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  present  o f R a n d a l l and  study  Stevens  supports  the  observations  (1967) t h a t t h e r e s i s t a n c e o f  the v a s c u l a r system drops 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 o x y g e n 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 o x y g e n u p t a k e one  a doubling of  pressure  should observe  i f the 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 o x y g e n c o n s u m p t i o n i s 5-10 levels  ( f i g u r e 11)  one  might expect  p r e s s u r e s t o accompany s e v e r e i n c a r d i a c output uptake.  Obviously  alone this  Alternately, result  blood  times  very high  routine blood  exercise i f increases  f a c i l i t a t e e l e v a t e d oxygen i s not the case  ( f i g u r e 7,  table VIII).  e l e v a t e d a c t i v e oxygen uptake c o u l d  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 o f 5-10  to account f o r elevated  times routine  l e v e l s by  oxygen d i f f e r e n c e alone, w o u l d h a v e t o be of f u l l y  we  arterio-venous  t h i s difference at routine - i . e . 1/5  t o 1/10  h a v e no  d a t a on A-V  oxygen  have c a l c u l a t e d c a r d i a c output d a t a from oxygen are unable to conclude whether increased  output or  increased  elevated  arterio-venous  a c t i v e oxygen uptake.  (ventral a o r t i c blood b;  38%  Since  saturated,  v e n t r a l a o r t i c blood  Randall,  1966  b;  and  70%  even a 5 - f o l d i n c r e a s e A-V  saturated,  are  pressure  does not  o u t p u t t h e r e must be of the  saturated  i n oxygen u p t a k e by  increasing  the  I t f o l l o w s then that i n the  increase  face  of  this  i n the oxygen t r a n s f e r  increased increase  oxygen uptake.  Figure  As  proportionately with  decreases in peripheral  cardiac  resistance  c i r c u l a t o r y s y s t e m w h i c h accompany e l e v a t e d  output during  cardiac  P r o b a b l y b o t h o f t h e s e mechanisms  a s s o c i a t e d w i t h the  blood  and  for  m i g h t e x p e c t an  f a c t o r of the g i l l s .  Randall,  to account  o u t p u t must i n c r e a s e m a r k e d l y and one  large  Holeton  100%  A-V  impossible  oxygen d i f f e r e n c e a l o n e .  increase  account  the reported  S t e v e n s and  dorsal a o r t i c blood  i n b o t h c a s e s ) t h e n i t w o u l d be  cardiac  oxygen d i f f e r e n c e s  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  1967  that  differences  u p t a k e we  for  levels  fish.  S i n c e we and  increased  extremely small  active  oxygen uptakes  cardiac  swimming. 9 shows t h a t p u l s e  pressure  i n the  dorsal  35  Legend f o r F i g u r e 9 T h i s f i g u r e shows c h a n g e s 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 a n d a f t e r swimming activity  i n t h r e e t e s t groups o f sockeye salmon.  a r e means + 1 s t a n d a r d  e r r o r o f t h e mean.  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 .  No  Values  standard  36 aorta rose during  swimming i n t h e 5 and 15°C  groups  f e l l b e l o w r o u t i n e l e v e l s i n t h e 22°C g r o u p . s i g n i f i c a n c e of these r e s u l t s i s discussed Two  of t h i s paper  increases  F i s h i n t h e 5°C  t e s t g r o u p showed  b e l o w r o u t i n e l e v e l s i n t h e 15°C e t a l (1967) r e p o r t e d stopping  Changes  dropped  test fish.  Smith  t h a t t h i s d r o p a t 15°C was v e n t i l a t i o n movements and  w i t h t h e i r m o u t h s h e l d open. similar  variability large  activity.  i n t h e 22°C g r o u p and t h e r a t e  to the f i s h  i n Part  showed c o n s i d e r a b l e  in respiratory rate during  were s l i g h t  The  (p.64).  Respiration rate data ( f i g u r e 10).  and  Brett  due  swimming  (1964, 1967)  reported  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.  Fry  o f v e n t i l a t i o n was different  species  Since  out t h a t  a common phenomenon i n a number o f of  fish.  t h a n a d u l t s o c k e y e a t 22°C  t - t e s t ) i t was n e c e s s a r y t o make  corrections.  cessation  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 5% l e v e l ,  (1957) p o i n t e d  The r e s p i r a t o r y r a t e d a t a  (sig.at appropriate  of the  jacks  w e r e t h e r e f o r e m u l t i p l i e d b y 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 combined.  T h e r e was  f r o m b o t h j a c k s and  no s i g n i f i c a n t d i f f e r e n c e  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  adults  between  (t-test,  5% l e v e l o f s i g n i f i c a n c e ) h e n c e no c o r r e c t i o n was necessary. Active,  standard  and r o u t i n e o x y g e n  consumption  37  Legend f o r F i g u r e Figure  10  10 shows c h a n g e 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 i n c r e a s i n g swimming a c t i v i t y fatigue.  V a l u e s a r e means + 1 s t a n d a r d  mean and a r e t a k e n and  error of the  from three groups of f i s h  t e s t e d a t the i n d i c a t e d temperature.  is evident  and f o l l o w i n g  s i n c e some f i s h c o n t i n u e d  acclimated  Large  variability  to ventilate  period while others  ceased  during  the  entire activity  ventilation  and  swam i n t o t h e w a t e r c u r r e n t w i t h t h e i r mouths o p e n .  VENTILATION  k  o r  " OJ  0  1  RATE  (%  O  0 —  0 —  (mouth closures/min)  routine) Ol  -  0 —  g\D O  0 r  INJ Oi  ~  CJ O  W «r>  o  '  o  —  M  0 ©  ro — ro 01 01 C O ©  000  ~1 '  38  values  a r e shown i n f i g u r e 11 a n d t a b l e V I .  d a t a were e x t r a c t e d uptake values  f r o m B r e t t ' s work.  projecting this  i n f i g u r e 11. as  Routine  routine values  activity  level  have been  obtained  on d i f f e r e n t c u r v e s  Such a p r o c e d u r e may b e s l i g h t l y  inaccurate  i t assumes t h a t r o u t i n e oxygen c o n s u m p t i o n  a t t h e same a c t i v i t y  a t a l l temperatures.  spontaneous a c t i v i t y  i s temperature dependent  personal  communication).  metabolic  oxygen  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 by  These  Indeed, (Brett -  B r e t t ' s measure o f r o u t i n e  r a t e a t 15°C i s p r o b a b l y a g o o d  of r o u t i n e metabolic  occurs  estimate  r a t e t o u s e as a b a s i s  for calculation  i n t h e p r e s e n t study s i n c e h i s f i s h were s t u d i e d virtually (Brett, Buccal  identical  conditions  respirometer  1965). pressures  increased  markedly during  i n t h e 5 and 22°C t e s t g r o u p s reported and  i n t h e same  under  n o d a t a on b u c c a l  swimming  (figure 12).  pressures  Smith  in fish  (1967)  acclimated  t e s t e d a t 15°C. I t i s a p p a r e n t f r o m f i g u r e 11 t h a t o x y g e n  r i s e s markedly during  activity  i n r e s p i r a t o r y gas exchange.  n e c e s s i t a t i n g an  consumption  increase  I t i s thus not 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  pressure  activity.  i n recorded r e s p i r a t o r y  The l a r g e v a r i a b i l i t y  r a t e s and t h e d r o p i n r a t e a t h i g h e r  rise  during  swimming s p e e d s  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 Figure  11  11 i s a s e m i - l o g a r i t h m i c  u p t a k e and swimming e f f o r t .  p l o t o f oxygen  Values f o r various  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 each group.  Standard e r r o r s are given  test  means f o r  i n table VI  s i n c e they 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 this  plot.  R o u t i n e o x y g e n u p t a k e was o n l y  i n a g r o u p o f j a c k s o c k e y e a t 15°C.  measured  The r o u t i n e  oxygen  u p t a k e f o r t h e s e j a c k s was p r o j e c t e d o n t o t h e d a t a f o r other  g r o u p s , a s shown b y t h e a r r o w , s o t h a t an  of routine metabolic The  line  r a t e c o u l d b e made f o r t h e s e g r o u p s .  f o r 22°C a d u l t s was o b t a i n e d  the values  estimate  o f f i g u r e 19.  by e x t r a p o l a t i n g  40  L e g e n d 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 swimming a c t i v i t y Buccal pressure  increased  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 .  i s t h e maximum p r e s s u r e  t h 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 . averages + 1 standard  recorded i n  Values  a r e mean  e r r o r o f t h e mean a n d 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 temperature. at  15°C.  No d a t a  i s a v a i l a b l e on b u c c a l  pressures  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 s p e e d s w h i l e o t h e r s rapidly.  continued  to ventilate  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 c u r r e n t w i t h t h e i r mouths open.  Others  v e n t i l a t i o n movements a t a l l a c t i v i t y  the  continued  levels.  In g e n e r a l  l a r g e r f i s h t e n d e d 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 than t h e s m a l l e r f i s h hence 15°C  Smith's  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  ventilation  movements w o u l d b e 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 p u m p i n g s u c h a d e n s e medium as w a t e r o v e r t h e gills  r e q u i r e s a l a r g e component o f t h e r e s t i n g  consumption  (Schumann and P i i p e r ,  1966)  s h u t t i n g down t h i s e n e r g y - c o n s u m i n g b e o f v a l u e t o swimming f i s h .  oxygen  any means o f  mechanism would  Once t h e f i s h h a s a t t a i n e d  a s u f f i c i e n t forward motion or i s remaining s t a t i o n a r y i n a water c u r r e n t of moderate v e l o c i t y ventilating to  f l u s h the  i t could  stop  and a l l o w t h e s t r e a m o f w a t e r r u s h i n g  past  gills.  We h a v e f r e q u e n t l y o b s e r v e d l a r g e s a l m o n  whose  swimming and r e s p i r a t o r y movements s u g g e s t 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 .  Large f i s h placed i n the respirometer  i n a m o d e r a t e w a t e r c u r r e n t o f t e n swim s l o w l y i n t o t h e c u r r e n t w i t h m o u t h h e l d open and no movements.  forward ventilatory  As s o o n as swimming movements c e a s e  the f i s h d r i f t s back  i n the water c u r r e n t  and  respiratory  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 r e s u m e s swimming.  At h i g h water v e l o c i t i e s  there  42 i s no c e s s a t i o n mouth h e l d  o f swimming and t h e f i s h swims  open.  ventilation  I t a p p e a r s t h e n , t h a t swimming a n d  a r e l i n k e d i n some way a s a means o f s a v i n g  e n e r g y i n swimming  fish.  Before proceeding with w i l l be summarized. increase blood  during  pressure  the discussion the results  Both heart  r a t e and b l o o d  Elevated  appeared t o be accompanied by a drop I t seems l i k e l y t h a t  output would increase markedly during  cannot be f a c i l i t a t e d  venous oxygen d i f f e r e n c e s alone.  Indeed,  levels  s e v e r e e x e r c i s e a n d we h a v e shown t h a t  increase  cardiac  exercise.  o x y g e n c o n s u m p t i o n r i s e s 5-10 t i m e s r o u t i n e  an  pressure  swimming i n s o c k e y e s a l m o n .  in peripheral resistance.  during  with  such  by increased  arterio-  I t i s therefore  important  t o h a v e some i d e a o f w h a t c h a n g e s i n c a r d i a c  output  accompany e x e r c i s e  we d i d  not  i n salmon.  Unfortunately  m e a s u r e c a r d i a c o u t p u t d i r e c t l y h e n c e we must  calculate i t using Since  the Fick  principle.  d a t a w e r e a v a i l a b l e on h e a r t  r a t e and  o x y g e n c o n s u m p t i o n i t was p o s s i b l e t o c a l c u l a t e o u t p u t and s t r o k e v o l u m e a t r o u t i n e a n d a c t i v e of performance f o r a l l three  cardiac levels  temperature groups.  These  c a l c u l a t i o n s w e r e 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 o x y g e n u p t a k e  f r o m f i g u r e 11 i s 48 mg 0 / K g / h r 2  - Assuming t h e f i s h w e i g h 1 Kg and t h a t venous oxygen l e v e l s remain  constant  arterio-  43 - A s s u m i n g 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 / K g / h r = 0.8 mg 0 / K g / m i n . 2  2  a t h e a r t r a t e = 31  beats/min.  0.8 = 0.0258 mg 0 / K g / b e a t , 31  0.0258 x .7  = 0.01806 m l 0 / K g / b e a t 2  - 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 m l b l o o d 0. 09  - s t r o k e volume.  - i f s t r o k e v o l u m e i s 0.2007 m i s / s t r o k e c a r d i a c output  = s t r o k e volume x h e a r t r a t e  = 0.2007 x 31 = 6.22 m l / m i n c a r d i a c The  Holeton  and R a n d a l l  They m e a s u r e d  b l o o d oxygen l e v e l s w i t h a van S l y k e apparatus blood  samples o f v a r y i n g h e m a t o c r i t .  study  t h e mean h e m a t o c r i t A hematocrit  of 5 f i s h  Smith  using  In t h e present a t 15°C was 23.4  o f 23 c o r r e s p o n d s  to a blood  o x y g e n c a p a c i t y o f 8.5 v o l s % on H o l e t o n graph.  (1967 b)  a g r a p h i n w h i c h h e m a t o c r i t was c o m p a r e d w i t h  the 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 .  +1.36%.  output.  a b o v e c a l c u l a t i o n s a r e b a s e d on a b l o o d  o x y g e n c a p a c i t y o f 9 v o l s %. presented  then  and R a n d a l l ' s  (1966) m e a s u r e d t h e h e m a t o c r i t o f 8 s o c k e y e  s a l m o n a t 11-16°C and f o u n d Smith's value corresponds  a mean v a l u e o f 26+3.8%.  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  S i n c e t h e mean v a l u e o f S m i t h ' s and t h e p r e s e n t 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 of significance)  the mid-point  (t-test,  0.05  of the blood  graph. study  level  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 b e 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 s a l m o n u s e d i n t h i s s t u d y - i . e . 9 v o l s %. procedure and  o f course,  Such a  assumes t h a t r a i n b o w t r o u t b l o o d  sockeye salmon b l o o d have s i m i l a r oxygen  w h i c h may n o t n e c e s s a r i l y b e t h e c a s e .  Since  capacities there  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 necessary  B l a c k e t j a l (1966) f o u n d of A t l a n t i c and  t o adopt t h e above  procedure  t h a t t h e b l o o d oxygen c a p a c i t y  s a l m o n i n t h e summer was 8.3+0.67 v o l s  t h e h e m a t o c r i t was 23.2+1.70%.  %  Since a hematocrit  o f 23 c o r r e s p o n d s  t o a b l o o d o x y g e n 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 g r a p h 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 a p p e a r s t h a t t h e u s e o f such a g r a p h 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  previous calculations of cardiac  output  w e r e b a s e d on t h e a s s u m p t i o n t h a t v e n t r a l a o r t i c c o n t a i n s no oxygen  (Ferguson  dorsal aortic blood  i s fully  Holeton  (1967 b ) .  and R a n d a l l  however, found  and B l a c k ,  blood  1941) a n d t h a t  s a t u r a t e d as r e p o r t e d b y The l a t t e r  investigators  the ventral aortic blood of quiescent  rainbow t r o u t t o be approximately S t e v e n s and R a n d a l l  (1967 b) f o u n d  Stevens and R a n d a l l suggest  70% saturated while i t t o be 3 8 % s a t u r a t e d  that their  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  lower  ventral  from higher  45 blood I t was  PCC>2 l e v e l s t h a n t h o s e o f H o l e t o n and thus n e c e s s a r y t o c a r r y out  Randall.  further calculations  b a s e d on v e n t r a l a o r t i c o x y g e n l e v e l s o f 38  and  70%  14.  There  saturation respectively. Results is  are  shown i n f i g u r e s 13  a marked i n c r e a s e  produced by of the  i n c a r d i a c o u t p u t and  activity.  It is difficult  c a l c u l a t e d f i g u r e s can  study.  and  stroke  to decide which  be b e s t a p p l i e d t o  unsaturated  l e v e l s i n the  l i g h t o f s t u d i e s b y H o l e t o n and  b)  and  S t e v e n s and  w i t h oxygen a t r o u t i n e  Randall  k n o w l e d g e o f v e n t r a l a o r t i c PCO-j  (1967 w e  b).  c o m b i n a t i o n of oxygen w i t h hemoglobin. that v e n t r a l a o r t i c blood l e v e l o f s a t u r a t i o n as  be  With  upon  no  nothing the  I t seems u n l i k e l y  oxygen remains a t a  swimming e f f o r t  activity  Randall  deduce  c a n  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^  One  this  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  is completely  (1967  volume  constant  increases.  might expect 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 q u i t e low d u r i n g  facts  i n m i n d we  o f f i g u r e s 13 and  maximal a c t i v i t y .  may  then suggest t h a t the  14 m o s t l i k e l y r e p r e s e n t s  s c o p e o f c a r d i a c o u t p u t and c o u l d be  What i s t h e  the  portion  actual that  sockeye salmon.  s t r o k e volume produced by  oxygen d e l i v e r y t o the facilitated  shaded  s i g n i f i c a n c e of the 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  c o u l d be  these  s t r o k e volume f i g u r e s  calculated for adult  Increased  Bearing  i n 3 ways:  tissues during (1)  activity? exercise  tachycardia,  46  Legend  for Figure This  13  figure illustrates  on c a r d i a c o u t p u t o f f u l l y and r e s t i n g values  active  (just p r i o r to  sockeye salmon.  Cardiac  fatigue)  output  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  different The  (routine)  the e f f e c t of temperature  l e v e l s of v e n t r a l a o r t i c blood  oxygen  shaded p o r t i o n o f t h e graph r e p r e s e n t s  s t r o k e volumes  salmon.  saturation.  the range  t h o u g h t t o b e most r e p r e s e n t a t i v e  c a r d i a c output l e v e l s i n sockeye  three  of  of true  ouV\ne  r  c  ©  ventral 0% sat'd.  b\ood  blood  38 % sen v,. ventral aorYic blood = 70% sat'd.  47  Legend  for Figure  14  This figure  illustrates  the e f f e c t of temperature  on s t r o k e v o l u m e o f f u l l y a c t i v e ( j u s t p r i o r and r e s t i n g  ( r o u t i n e ) sockeye salmon.  to fatigue)  Stroke  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 l e v e l s of v e n t r a l a o r t i c blood shaded  oxygen  p o r t i o n of the graph represents  saturation.  different The  the range of s t r o k e  v o l u m e v a l u e s t h o u g h t 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  blood ° 7 0 % sat'd.  ventral aortic  48 (2)  increased  s t r o k e volume and  (3) i n c r e a s e d  venous oxygen l e v e l d i f f e r e n c e s .  arterio-  In-humans a n d d o g s  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 o x y g e n e x t r a c t i o n a r e t h e n o r m a l 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  exercise  (Rushmer, 1 9 6 2 ) . The s i t u a t i o n a p p e a r s somewhat d i f f e r e n t S t e v e n s and R a n d a l l  (1967 b) r e p o r t e d  in fish.  a 15% r i s e i n  h e a r t r a t e , an a l m o s t 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 v o l u m e and o n l y s l i g h t c h a n g e s i n a r t e r i o - v e n o u s oxygen l e v e l s  i n moderately active trout.  indicates that similar occur during a c t i v i t y our  Our  s o r t s o f h e a r t r a t e changes i n salmon.  We h a v e assumed i n  cardiac output c a l c u l a t i o n s that  arterio-venous  oxygen d i f f e r e n c e does n o t change d u r i n g I n S t e v e n s and R a n d a l l ' s  activity.  s t u d y s u c h changes were n o t  observed, undoubtably because t h e i r  f i s h were  f o r o n l y 10 m i n u t e s a t m o d e r a t e v e l o c i t i e s . l i k e l y t h a t A-V  study  swimming I t seems  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  levels of 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 o x y g e n  would increase d i r e c t l y w i t h the a c t i v i t y the d u r a t i o n o f heavy e x e r c i s e .  level  and  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  w h a t c h a n g e s i n A-V  accompany  exercise.  l e v e l s may  I t appears t h a t changes i n s t r o k e  severe volume  49 do  accompany e x e r c i s e h o w e v e r t h e m a g n i t u d e o f  changes i s not  known.  I t a p p e a r s t h a t t r o u t , and are  these  able to u t i l i z e  t h r e e mechanisms o f  oxygen uptake d u r i n g s t r o k e v o l u m e and  probably  increasing  exercise; tachycardia,  possibly increased  salmon,  elevated  arterio-venous  oxygen l e v e l d i f f e r e n c e s . Factors  i n f l u e n c i n g the  f i s h h e a r t w i l l be d i s c u s s e d p a r t of t h i s paper U n t i l now  (p. we  s t r o k e volume of  more f u l l y  i n the  the  second  71) .  have c o n f i n e d  our d i s c u s s i o n  to  c h a n g e s 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 .  s h a l l now  parameters i n f i s h were f a t i g u e d by  We  consider  i n the time p e r i o d a f t e r the  l e v e l s of a c t i v i t y which  fatigue levels,  a n i m a l s may  basal metabolic  r a t e w i t h accompanying use  the  ( B r e t t , 1962).  w i t h the presence of anaerobic lactic  and  Following exercise f o r about 8 hours 1962. be  Under t h e s e  S t e v e n s and  present  in fish  of  their  anaerobic  conditions  Oxygen d e b t i s a s s o c i a t e d  metabolites  p y r u v i c a c i d s and  o f m u s c l e g l y c o g e n and  approach  e x p e n d o v e r 20 t i m e s  a n i m a l goes i n t o oxygen debt.  s u c h as  fish  swimming.  At very h i g h  energy reserves  these  i n the  w i t h the  blood  expenditure  h i g h e n e r g y p h o s p h o r u s compounds.  in trout, blood  l a c t a t e remains  ( B l a c k e t a l , 1961, Balck,  1966).  1962.  elevated  Brett,  Thus o x y g e n d e b t  f o r some t i m e a f t e r a c t i v i t y .  may  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 o x y g e n d e b t was p r e s e n t period.  i n o u r f i s h d u r i n g t h e one h o u r  Heart r a t e decreased but d i d not reach  l e v e l s a f t e r one h o u r  ( f i g u r e 3) w h i l e b l o o d  approached or f e l l below r o u t i n e l e v e l s During the  post-exercise  recovery  pulse pressure  routine  pressure  (figure 7).  i n the dorsal aorta of  22°C g r o u p r e m a i n e d b e l o w r o u t i n e l e v e l s .  Pulse  p r e s s u r e was v a r i a b l e a n d t e n d e d t o r e m a i n a b o v e r o u t i n e levels  i n t h e 15°C t e s t g r o u p w h i l e  i n t h e 5°C  group i t approximated r o u t i n e l e v e l s d u r i n g (figure 9).  rate declined during recovery groups b u t f a i l e d t o reach (figure 10).  pressure  recovery  I n t h e 15°C t e s t g r o u p v e n t i l a t i o n  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 h o u r .  hour  test  rate  Ventilation  i n t h e 5 a n d 22°C a c c l i m a t i o n  r o u t i n e l e v e l s w i t h i n one  I n t h e 5 and 22°C g r o u p s  remained h i g h d u r i n g the recovery  buccal period  ( f i g u r e 12) . These o b s e r v a t i o n s o x y g e n d e b t was s t i l l and  suggest that  present  considerable  one h o u r a f t e r  fatigue  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. pressure  E l e v a t e d h e a r t r a t e and b u c c a l  i n d i c a t e t h a t more w a t e r a n d b l o o d w e r e  pumped t h a n 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 Unfortunately,  no o x y g e n c o n s u m p t i o n d a t a  being  levels.  i savailable  to substantiate t h i s conclusion or t o allow the c a l c u l a t i o n of blood be  flow.  Low b l o o d  pressures  during recovery  could  associated 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 of the  peripheral circulation.  Vasodilation of vessels  serving  51 the muscles or opening of a d d i t i o n a l v e s s e l s could 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 o f oxygen  debt.  abolition  Such a m e c h a n i s m w o u l d b e 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 t h a n mammals  speed  vascularized  (Stevens - p e r s o n a l communication).  52  SUMMARY 1)  The  during 2)  h e a r t r a t e o f sockeye salmon r o s e  successively greater  swimming  substantially  activity.  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  i n p a r t to a r e l e a s e of v a g a l tone i n sockeye. suggested that c i r c u l a t i n g catecholamines  elevated heart rate during 3)  Dorsal  a o r t i c blood  exercise. pressure  increased  as a r e s u l t o f i n c r e a s e d  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  The  p e r i p h e r a l r e s i s t a n c e of the  system probably 5)  decreases during  during  cardiac s t r o k e volume.  circulatory  activity.  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 response  t o a c t i v i t y were v a r i a b l e , differences fish.  an  a l s o produce  swimming, p r o b a b l y  4)  It is  and/or  e n d o g e n o u s 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  due  indicating that there  i n v e n t i l a t i o n movements b e t w e e n  In g e n e r a l ,  saving of energy.  r e f l e x connection  different  f i s h t e n d e d t o swim w i t h t h e i r  h e l d open a t h i g h v e l o c i t i e s , considerable  are  undoubtably The  o f swimming and  mouths  with  p o s s i b i l i t y of  ventilation  a  is  discussed. 6)  In t h o s e  buccal pressures that the  f i s h which d i d v e n t i l a t e during rose markedly w i t h a c t i v i t y ,  i n c r e a s e d w a t e r movements was gills.  occurring  activity  indicating across  53 7) by The  St-r.oke v o l u m e and the F i c k p r i n c i p l e , accuracy  rose markedly w i t h  of these  c a r d i a c o u t p u t and  c a r d i a c output,  calculated activity.  calculations in predicting actual  s t r o k e volumes i n i n t a c t f i s h i s  questionable. 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  appears f a c i l i t a t e d by gills, by  tachycardia,  increased water flow over  i n c r e a s e d c a r d i a c o u t p u t and  increased arterio-venous  9)  Hematocrit  c a p a c i t y of the approximately 10)  i n sockeye  data  possibly  oxygen d i f f e r e n c e s .  i n d i c a t e d t h a t the blood  sockeye salmon used i n t h i s  9 vols  the  oxygen  study  was  %.  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  approached or f e l l below p r e - e x e r c i s e h o u r b u t h e a r t r a t e and  levels after  buccal pressure  High post-exercise flows of blood  and  pressure  remained  one  elevated.  water suggest  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)  Following e x e r c i s e , elevated f l u s h i n g of  muscles w i t h blood pressure  (as s u g g e s t e d b y  a drop i n blood  i n c o m p a r i s o n t o r o u t i n e l e v e l s ) may  e l i m i n a t i o n o f o x y g e n d e b t and metabolites.  the  removal of  hasten  anaerobic  the  54  PART  TWO  THE EFFECTS OF TEMPERATURE ON CERTAIN CARDIOVASCULAR AND RESPIRATORY PARAMETERS OF QUIESCENT AND SWIMMING SALMON INTRODUCTION Probably a l l l i v i n g temperature v a r i a t i o n s In g e n e r a l , extreme  t h i n g s e x p e r i e n c e some  i n the course of t h e i r  temperature f l u c t u a t i o n s  lifetimes.  a r e l e s s r a p i d and  i n t h e s e a t h a n i n f r e s h w a t e r o r on t h e l a n d .  Hence, most m a r i n e f i s h w o u l d be e x p e c t e d t o b e l e s s tolerant their  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 t h a n  freshwater r e l a t i v e s .  as t h e s a l m o n ,  Anadromous f i s h ,  spend p a r t o f t h e i r  lives  such  i n fresh  water  and p a r t i n t h e s e a , 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 s o c k e y e s a l m o n must b e a b l e t o t o l e r a t e rapid  t e m p e r a t u r e c h a n g e s a s t h e y move f r o m t h e s e a t o  fresh water.  T h e s e a n i m a l s must t h e n b e a b l e t o o p e r a t e  at a v a r i e t y o f temperatures. the  fairly  In t h i s  investigation  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 a n d  respiratory  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  studied. Although there i s considerable information 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 i n a v a r i e t y o f organisms  (Giese,  1962.  available  processes  P r o s s e r and Brown,  55 1961)  l i t t l e h a s b e e n done on t h e e f f e c t s o f  on c i r c u l a t i o n  in fish.  Lyon  (1926)  temperature  reported  that  s t i m u l i a p p l i e d t o the s k i n of sharks produced inhibition.  Grodzinski  of the embryonic directly with  (1950)  temperature.  isolated hearts  with  t e m p e r a t u r e up t o a  r a t e s t a r t s t o drop  e x p e r i m e n t s on h a g f i s h d o u b l e d f o r a 13°C It  the rates  at higher  temperatures  ( G r o d z i n s k i , 1954) .  i n temperature  i s generally believed  _In s i t u rate  (Jensen,  may  Jensen,  have other  suggested that  "conditions  and  systemic  c o m p l e x and c h a n g e s o f  on h e a r t  Indeed,  (Labat,  Mott  (195 7) intact  temperature  r e s i s t a n c e of the  Laffont  activity  and L a b a t  a r e v e r s a l of the e f f e c t s of  r a t e i n c a r p w h i c h was  acts  temperature  c a p i l l a r i e s as w e l l as t h e  of t h e myocardium". have demonstrated  rate  i n experiments with  cause changes i n t h e v a s c u l a r  gill  by  In a d d i t i o n ,  e f f e c t s on c i r c u l a t i o n .  animals are very may  1961).  almost  1961).  t h a t temperature  d i r e c t l y on t h e m y o c a r d i u m t o e l e v a t e h e a r t e t a l , 1961.  show  temperature  showed t h a t t h e h e a r t  rise  of  (Anguilla anguilla)  c h a r a c t e r i s t i c of the species; the  rate  (Salmo t r u t t a ) v a r i e d  Similarly,  of glass eels  a d i r e c t variance  cardiac  observed that the  sea t r o u t h e a r t  thermal  apparently  (1966) epinephrine  produced  temperature. Considerably  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 measures o f m e t a b o l i c  rate.  Numerous  r a t e h a v e b e e n made a t d i f f e r e n t  temperatures 1948. and  (Brett,  Prosser standard  Brett  1964.  F r y , 1957.  and Brown, 1 9 6 1 ) .  F r y and H a r t ,  In g e n e r a l ,  active  metabolism increase w i t h temperature  (1964) r e p o r t e d  a sharp c u t - o f f i n a c t i v e  r a t e a b o v e 15°C i n y e a r l i n g s o c k e y e s a l m o n .  metabolic  B r e t t suggests  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 a s warmer w a t e r h o l d s c o l d water.  They r e p o r t e d  than  (1941) s t u d i e d t h e e f f e c t  o f t e m p e r a t u r e upon t h e c o m b i n a t i o n  o f oxygen w i t h  that the blood  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 at environmental  limiting  p r o p o r t i o n a t e l y l e s s oxygen  I r v i n g et_ al_,  trout blood.  although  of four  saturated with  oxygen  t e n s i o n s a t t e m p e r a t u r e s b e l o w 25°C.  C o m p l e t e 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 b e l o w 25°C e v e n when t h e P C 0 i.e.  2  o f t h e b l o o d was 10 mm Hg -  a t t h i s CO^ t e n s i o n t h e r e was n o r o o t  B l a c k e t a l (1966) f o u n d t h a t t h e b l o o d salmon if  of the landlocked  (Salmo s a l a r ) c o u l d b e c o m p l e t e l y  the PC0  2  was 0-1 mm Hg a t 25°C.  effect.  saturated  A PCC> o f 10 mm 2  Hg h o w e v e r , p r o d u c e d a m a r k e d r o o t e f f e c t a t 2 5 ° C Recent s t u d i e s  (Beaumont and R a n d a l l  on r a i n b o w t r o u t a root effect  - personal  communication)  (SaImp g a i r d n e r i ) h a v e a l s o d e m o n s t r a t e d  i n t h e presence of low C 0  2  levels.  It  t h u s a p p e a r s t h a t as l o n g a s t h e PCC> o f s a l m o n i d 2  i s very  low i t can s t i l l  be f u l l y  saturated a t temperatures  b e l o w 25°C. The  object of this  blood  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 t e m p e r a t u r e upon some c a r d i o v a s c u l a r and  57 respiratory'parameters  i n quiescent  and  Thus c o m p a r i s o n s t o t h e e n v i r o n m e n t a l e n c o u n t e r e d by made and and  swimming  fish.  temperatures  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  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  c i r c u l a t o r y c o n t r o l examined.  possible limiting  exchange  In a d d i t i o n ,  e f f e c t s o f t e m p e r a t u r e upon  o r r e s p i r a t i o n c o u l d be  be  any  circulation  elucidated.  METHODS The  methods u t i l i z e d  to those  u s e d i n P a r t One  repeated  here.  the  Indeed, t h i s  values  It  section describes but  deals with  as a c t u a l p r e s s u r e s  "% o f r o u t i n e l e v e l s " as  i s hoped t h a t t h i s approach w i l l  somewhat b y h e l p i n g s e p a r a t e t h e e f f e c t s o f a c t i v i t y and and  respiration.  two  concepts:  On  - i.e. rates One.  the  the t e s t r e s u l t s  presentation  - i.e.  circulation  deals  1) 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 o v a s c u l a r and  exactly  in Part  t e m p e r a t u r e on  not  absolute  and  clarify  t h i s b a s i s P a r t Two  identical  are  r a t h e r than r e l a t i v e values  r e s u l t s are expressed r a t h e r t h a n as  study were  o f t h i s t h e s i s and  same r e s u l t s as P a r t One  numerical  in this  r e s p i r a t o r y p a r a m e t e r s and  with routine 2)  the  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  respiratory  parameters.  RESULTS AND  DISCUSSION  Figure rate before,  15 and  t a b l e I show c h a n g e s i n h e a r t  d u r i n g and  after activity  i n groups  of  58  L e g e n d f o r F i g u r e 15 This figure i l l u s t r a t e s during  i n c r e a s i n g swimming  from f a t i g u e . t h e mean.  Values  changes i n h e a r t  rate  e f f o r t and d u r i n g  recovery  a r e means + 1 s t a n d a r d  error of  59  L e g e n d 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 s o c k e y e 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  temperatures.  M a x i m a l 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 f r o m swimming fish just prior to fatigue. e r r o r o f t h e mean.  Values  a r e means + 1 s t a n d a r d  The number o f f i s h u s e d t o c a l c u l a t e  e a c h i s shown i n b r a c k e t s a d j a c e n t t o e a c h 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 general r i s e  -  i n rate occurred at  all  three temperatures  i n response to a c t i v i t y .  all  groups h e a r t r a t e dropped back towards  In  routine  levels during recovery. 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  temperature  on m a x i m a l 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 rate.  B o t h 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  nearly  l i n e a r r e l a t i o n s h i p to temperature. It  i s reasonable to conclude that  temperature  a c t s d i r e c t l y on t h e m y o c a r d i u m t o e l e v a t e h e a r t r a t e a s s u g g e s t e d b y L a b a t e t a l , (1961) Temperature  p r o b a b l y has  and  Jensen  (1961).  some e f f e c t on membrane  phenomena i n c a r d i a c m u s c l e and t h u s a f f e c t s t h e of beating.  rate  Hence t h e l i n e a r r e l a t i o n s h i p b e t w e e n  and h e a r t r a t e c a n b e e x p l a i n e d as a d i r e c t  temperature  influence  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  itself. 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 the small size.  In a d d i t i o n ,  spontaneous  l e v e l s a r e p r o b a b l y temperature dependent p e r s o n a l communication)  hence a c t i v i t y  routine heart rate at d i f f e r e n t Temperature limiting range.  activity (Brett  could  -  influence  temperatures.  a p p a r e n t l y e x e r t e d no  e f f e c t on h e a r t r a t e  to  drastic  i n t h e 5-22°C t e m p e r a t u r e  The h e a r t d i d n o t c e a s e t o b e a t a t h i g h o r  low  61 temperatures abnormality The recorded 17,  n o r was t h e r e a n y r e p e a t a b l e p a t t e r n o f i n the heart  rate.  e f f e c t o f temperature  a r e a mean b l o o d p r e s s u r e  on r o u t i n e and maximum i s shown i n f i g u r 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 a r e g i v e n i n  table  II.  I t i s evident that the greatest 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 , a t 15°C.  Routine  occurred  and a c t i v e b l o o d p r e s s u r e s a t 5 a n d  22°c w e r e e s s e n t i a l l y  similar.  The c h a n g e i n a r e a  mean b l o o d p r e s s u r e p r o d u c e d b y a c t i v i t y was a b o u t 6 mm Hg a t a l l t h r e e t e s t  temperatures.  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 recorded  i n t h e 15°C t e s t g r o u p a r e p o s s i b l e .  pressures A  size  e f f e c t may b e i n v o l v e d s i n c e t h e 15°C t e s t g r o u p h a d a mean w e i g h t  o f 165 2 g+129 a s c o m p a r e d t o w e i g h t s  o f 1230 g+137  (5°test g r o u p ) and 1080 g+113  group).  Large  (22° te§st  f i s h a r e b e l i e v e d t o have h i g h e r  pressures than  small f i s h  G r e e n e , 1904.  Hart,  blood  ( B u r g e r and B r a d l e y , 1 9 5 1 .  1943).  A p l o t of weight  p r e s s u r e a t 22°C showed t h a t t h e r e was a  vs. blood  significant  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 only a 17% r i s e (figure 18).  I f t h e weight  w i t h t h a t a t 22°C t h e n expected  i n s y s t o l i c blood  pressure  e f f e c t a t 15°C w e r e c o m p a r a b l e  t h e 15°C t e s t g r o u p w o u l d b e  t o h a v e a b o u t a 1 7 % 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 o r 22°C t e s t g r o u p s d u e 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  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  blood  those  62  L e g e n d 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 of  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  tested a t t h e i n d i c a t e d temperatures.  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 f r o m swimming f i s h prior to fatigue. of  t h e mean.  Values  just  a r e means + 1 s t a n d a r d  error  The number o f f i s h u s e d t o c a l c u l a t e  mean i s shown i n b r a c k e t s a d j a c e n t t o e a c h p o i n t .  each  63  Legend f o r F i g u r e This on  18  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  r o u t i n e a r e a mean b l o o d  pressure  i n the dorsal  o f a group o f a d u l t sockeye salmon a c c l i m a t e d a t 22°C.  Values represent  The l a s t  squares r e g r e s s i o n  and  the equation  given.  weight  data f o r i n d i v i d u a l  aorta  and t e s t e d fish.  l i n e o f Y on X i s i l l u s t r a t e d  64 o f t h e o t h e r t e m p e r a t u r e g r o u p s t h e n some o t h e r f a c t o r t h a n s i z e may b e 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 . nature o f t h i s factor  The  i s unknown a t t h i s t i m e .  Pulse pressure i n the dorsal aorta rose during activity  i n 5°C a c c l i m a t e d f i s h .  I n 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  levels  during 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 fatigue.  A similar  following  s l i g h t d r o p 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 g r o u p a n d i n t h i s g r o u p 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 exercise  period  (figure 9).  Since heart rate  w i t h temperature these r e s u l t s  increases  suggest that l e s s blood  i s pumped p e r h e a r t b e a t i n t h e 15 and 22°C t e s t t h a n i n t h e 5°C t e s t g r o u p .  groups  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 t e n d s t o l e v e l o f f a t t e m p e r a t u r e s above 15°c.  Such r e s u l t s s u g g e s t t h a t a c t i v e s t r o k e volume  may b e 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 a n d a c t i v e o x y g e n at d i f f e r e n t temperatures.  I t i s apparent that  consumption  temperature  e l e v a t e s m e t a b o l i c r a t e a n d t h a t f i s h c a n e x t r a c t more oxygen  a t higher temperatures i n response t o increased  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 higher temperatures.  Warm w a t e r c o n t a i n s l e s s  oxygen  t h a n c o l d w a t e r h e n c e f i s h must e x p e n d more e n e r g y t o e x t r a c t oxygen  a t higher temperatures.  must pump more w a t e r o v e r t h e g i l l s  To do t h i s  they  e i t h e r by i n c r e a s i n g  65  L e g e n d f o r F i g u r e 19 F i g u r e 19 shows o x y g e n c o n s u m p t i o n 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 temperatures. e r r o r o f t h e mean.  Values  Standard  a r e means + 1 s t a n d a r d  errors are omitted f o r the  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 . all  t h e d a t a and i n c l u d e s s t a n d a r d  T a b l e V I I shows errors.  66 the r a t e of t h e i r buccal the water current  pump o r b y swimming and  to f l u s h the g i l l s .  content of the water at high limit  a c t i v e metabolism.  Thus t h e  temperature could  i f c i r c u l a t o r y adjustments would  to  t h e e f f e c t i v e n e s s o f oxygen  d e l i v e r y at high  oxygen possibly  I t i s therefore interesting  to consider increase  allowing  temperatures.  operate  uptake  To do t h i s we  and shall  have  to consider  c a r d i a c o u t p u t , s t r o k e v o l u m e and e f f i c i e n c y  o f exchange  at the  The is  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  shown i n f i g u r e 13.  shaded the  gills. output  As p r e v i o u s l y d i s c u s s e d  the  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  a c t u a l range of c a r d i a c  sockeye salmon.  output f i g u r e s p o s s i b l e f o r  I t i s p o s s i b l e that temperature  v e n o u s s a t u r a t i o n and,  of  i f that  i s t h e c a s e , i t may  erroneous 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  influences be for  c a r d i a c output c a l c u l a t i o n s over a range of d i f f e r e n t temperatures - i . e . t h e venous b l o o d a t low t e m p e r a t u r e s than a t h i g h  may  ones.  be more  saturated  More work w o u l d  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 saturation. is  I n any c a s e t h e o n l y d a t a a v a i l a b l e t o us  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  should  be n e c e s s a r i l y It  of i t s values  cautious.  appeared t h a t c a r d i a c output increased  s l i g h t l y with temperature at r o u t i n e l e v e l s of 1  A c t i v e c a r d i a c o u t p u t however, 5 t o 15°C  increased  only  activity.  markedly  from  and t h e n showed a t e n d e n c y t o l e v e l o f f a t  67 temperatures 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 v o l u m e a t r o u t i n e activity  l e v e l s changed v e r y l i t t l e  at the  different  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 at the higher temperatures. c a r d i a c o u t p u t was  calculated  As a c t i v e h e a r t r a t e and a c t i v e o s y g e n  I t must be remembered  that  from oxygen uptake v a l u e s .  increases d i r e c t l y with  temperature  uptake does n o t , c a l c u l a t e d  active  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 temperatures. Similarly,  c a l c u l a t e d a c t i v e cardiac output values  ( 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  temperature  as do o x y g e n c o n s u m p t i o n  values  difficult  t h e s t r o k e v o l u m e and  t o say whether  output curves of figures the b a s i s of t h e i r  13 and  ( f i g u r e 19).  It is cardiac  14 a r e r e a l o w i n g A number o f  factors  must be c o n s i d e r e d w h i c h w e r e n o t t a k e n i n t o  account  in the  calculation.  to  calculations. We  know t h a t a c t i v e h e a r t r a t e shows a  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  to the d i r e c t  o f t e m p e r a t u r e a c t i n g on t h e m y o c a r d i u m .  The  effects  During  blood pressure increases suggesting a possible i n c a r d i a c o u t p u t has o c c u r r e d .  linear  activity  increase  r a t e o f oxygen  u p t 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 . S u c h a d e c r e a s e c o u l d b e due oxygen i n the water,  to three factors;  2) i n a b i l i t y o f t h e g i l l s  o x y g e n 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  1)  insufficient  to transfer  cardiac output.  L e t us c o n s i d e r e a c h 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 It  i s known t h a t  decreases with likely  that  t h e oxygen c o n t e n t o f water  increasing  temperature.  l a c k o f oxygen c o u l d  Indeed, B r e t t  I t thus  limit  active  metabolism.  (1964) d e m o n s t r a t e d t h a t  active  oxygen  consumption o f y e a r l i n g  sockeye salmon i n c r e a s e d  the  o x y g e n c o n t e n t o f t h e w a t e r was r a i s e d  air  saturation.  Brett  only  t o 15 0%  in this  Secondly, a c t i v e oxygen uptake a t h i g h may b e l i m i t e d b y t h e i n a b i l i t y o f t h e g i l l s oxygen i n t o t h e b l o o d .  for  area.  temperatures  to transfer  The e x c h a n g e o f g a s e s w i l l  by t h e surface  area of the g i l l s  between  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 "transfer f a c t o r " which, according t o Randall,  et  al,  of  the respiratory  (1967),  i s "a m e a s u r e o f t h e r e l a t i v e surface  a r e a a v a i l a b l e f o r exchange,  as w e l l a s t h e d i f f u s i o n d i s t a n c e The o x y g e n t r a n s f e r  T  O  1 U  between b l o o d and  f a c t o r , TO^, i s d e f i n e d a s : Y 0 2  =  2  ability  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  water".  be  available  gas exchange and b y t h e d i f f u s i o n d i s t a n c e  water and b l o o d .  when  carried out preliminary  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  influenced  seems  MPi0  2  + Pe0 ) 2  - h(P^0  2  + Pv0 ) 2  where: VC> = o x y g e n 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 the buccal 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 opercular c a v i t y i.e. expired water a = a r t e r i a l blood leaving g i l l s 2  69 v  = venous b l o o d e n t e r i n g = m o l e c u l a r oxygen If  be  the transfer  factor  gills  increases there  a more e f f e c t i v e u p t a k e o f o x y g e n b y t h e g i l l s .  Indeed, R a n d a l l ,  et  al,  (1967) d e m o n s t r a t e d t h a t t h e  transfer  factor  exercise  i n rainbow t r o u t  this  increase  increased  almost f i v e - f o l d d u r i n g moderate (Salmo g a i r d n e r i ) .  lamellae,  increased  decreased thickness  thus appears that  of markedly increasing  the  the g i l l s same.  the effectiveness  during a c t i v i t y .  I t i s possible  that  is and  are capable  o f 0^ u p t a k e  P r o b a b l y salmon c a n do at higher  temperatures  their  transfer  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  metabolism. and  of g i l l  factors.  rainbow t r o u t  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 factor  closer  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 It  Presumably,  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  to the surface of the g i l l s ,  by  will  I t m i g h t be p o s s i b l e  to increase  t h u s s u p p l y more o x y g e n t o t h e g i l l s  however, v e n t i l a t i o n  a c o s t l y energy-consuming process i n water P i i p e r , 1966) h e n c e l a r g e  increases  ventilation  (Schumann  in ventilation  w o u l d n o t b e 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 transfer  factor.  transfer  factor  Our s t u d y d i d n o t a l l o w  a s we d i d n o t m e a s u r e o x y g e n  i n b l o o d and w a t e r a f f e r e n t Fry and  (195 7)  showed t h a t  us t o c a l c u l a t e  and e f f e r e n t  levels  to the g i l l s .  summarized t h e r e s u l t s o f o t h e r workers  the surface area of the g i l l s  o f 34  t r o p i c a l m a r i n e s p e c i e s was much l o w e r 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 species If  indeed, the r e s p i r a t o r y  surface area l i m i t s  m e t a b o l i s m i t seems a d d t h a t t r o p i c a l i n w a t e r c o n t a i n i n g l e s s oxygen s h o u l d have s m a l l e r g i l l  (toadfish). active  species,  living  than temperate  areas than temperate  regions, species.  Such o b s e r v a t i o n s s u g g e s t t h a t t h e r e s p i r a t o r y  surface  a r e a o f f i s h may n o t b e a s i m p o r t a n t a s t h e r a t e o f d e l i v e r y o f oxygen  to the g i l l s  in limiting  oxygen  uptake a t h i g h temperatures. A third  factor  might be t h e a b i l i t y d e l i v e r oxygen heart rate if  l i m i t i n g a c t i v e oxygen  uptake  of the cardiovascular  to the tissues.  system t o  We know t h a t  active  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  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  t i s s u e s c o u l d become i n a d e q u a t e . l e v e l s o f oxygen  reach the g i l l s  delivery to the  Indeed,  i f inadequate  a t h i g h temperatures  t h e n d o r s a l a o r t i c b l o o d would n o t be f u l l y and a r t e r i o - v e n o u s o x y g e n  saturated  l e v e l d i f f e r e n c e would  T h i s would n o t be a s i g n o f c a r d i a c  fail.  i n s u f f i c i e n c y but  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 the inspired It  water.  seems l i k e l y  d i m i n i s h e d a c t i v e oxygen  then, that the explanation f o r uptake a t h i g h temperatures  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 the water.  Brett'  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 b e d e p e n d e n t on o x y g e n l e v e l s this  i n t h e water  conclusion. Pulse pressure  d r o p s a t 15+22°C i n d i c a t i n g  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 If  support  indeed  a reduction  does occur  that  occurred.  i n s t r o k e volume a t h i g h e r  temperatures  i t appears t h a t t h e r e s u l t a n t decrease 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 heart rate.  by i n c r e a s e d  Thus t h e a b i l i t y o f t h e h e a r t  to increase  i t s r a t e of c o n t r a c t i o n i n the face of decreased  stroke  v o l u m e m i g h t s e r v e a s a means o f k e e p i n g  output  cardiac  as h i g h a s 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 occur a t high temperatures i n a c t i v e fish.what cause o f t h i s decrease? holds  c o u l d be t h e  S t a r l i n g ' s law o f the heart  t h a t s t r o k e volume output o f t h e h e a r t  i s directly  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 blood.  Accordingly,  muscle f i b r e s  i f the i n i t i a l  length of cardiac  i s increased by s t r e t c h i n g t h e heart  r e s p o n d s b y c o n t r a c t i n g more f o r c e f u l l y and e x p e l l i n g a consequently  completely,  l a r g e r amount o f b l o o d .  mammals i t i s known t h a t S t a r l i n g ' s l a w c a n b e by  the action of c i r c u l a t i n g  1962. as  S a r n o f f and M i t c h e l l ,  catecholamines 1962).  a d r e n a l i n e and n o r a d r e n a l i n e  c o n t r a c t i l i t y and t h u s can a l t e r producing  such  myocardial  c a r d i a c output by  a change i n s t r o k e volume.  decreased myocardial  modified  (Rushmer,  Substances  can a l t e r  In  I f higher  temperatures  c o n t r a c t i l i t y or interfered with  72 the  e f f e c t s of  in stroke  c i r c u l a t i n g catecholamines a decrease  volume c o u l d  F i g u r e 20 routine  and  result.  shows t h e  maximal r e c o r d e d r e s p i r a t o r y  respiratory  rate  temperature but  r e s p i r a t o r y r a t e d i d not  in active respiratory  Routine  increase  temperature.  rate resulted entire  as  some  test  w h i l e o t h e r s c e a s e d r e s p i r a t o r y movements  swam w i t h  mouths h e l d  open as d i s c u s s e d  activity  l e v e l s w o u l d be  increases with  e x p e c t e d as m e t a b o l i c  temperature  Both r o u t i n e  and  and  previously.  Increased v e n t i l a t i o n at higher temperatures at  routine rate  ( f i g u r e 19) .  maximal recorded b u c c a l  w e r e h i g h e r i n 22°C a c c l i m a t e d f i s h t h a n i n t h e t e s t group  ( f i g u r e 21).  pumped o v e r t h e elevated  gills  Thus t h e  increased  temperature.  Such r e s u l t s increased  t e m p e r a t u r e s or d u r i n g  activity.  In P a r t significantly p r e s s u r e and  the  One  amount o f  with  adjustment f a c i l i t a t e s  No  on  maximal r e c o r d e d  appear r e l a t e d to  f i s h continued to v e n t i l a t e during the period  rate.  a p p e a r e d t o show a g e n e r a l  in response to elevated  Variations  e f f e c t of temperature  i t was  influenced  5°C  water  both a c t i v i t y indicate that  oxygen uptake at  p o i n t e d out  that  heart rate, dorsal  respiratory rate  pressures  i n the  and respiratory high  size a o r t i c blood  22°C t e s t  group.  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 5°C  t e s t group.  e f f e c t on  I t appears then, that  c i r c u l a t o r y and  respiratory  the  size  parameters  was  in  73  L e g e n d 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 of adult  sockeye salmon  ventilation  i s illustrated.  rate  Maximal r e c o r d e d  rate d i d not n e c e s s a r i l y occur j u s t before  f a t i g u e a s some f i s h s l o w e d o r c e a s e d  ventilation  movements a t t h e h i g h e r w a t e r v e l o c i t i e s .  Values are  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 of 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  point.  ACCLIMATION TEMPERATURE  (°C)  74  L e g e n d 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  o f a d u l t sockeye salmon b e f o r e ,  pressure  d u r i n g and a f t e r t h e  f i s h h a d b e e n f a t i g u e d b y swimming i s i l l u s t r a t e d . Values  a r e mean a v e r a g e s + 1 s t a n d a r d  Buccal pressures  e r r o r o f t h e mean.  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  t h e mouth c a v i t y d u r i n g  ventilation.  5  O  5  10  15  ACCLIMATION TEMPERATURE  20  (°C)  25  75 enhanced by temperature.  Why t h e r e s h o u l d b e s u c h an  e n h a n c e m e n t o f t h e s i z e e f f e c t a t 22°C and n o t 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  influences  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  h e n c e a number o f f a c t o r s c o u l d b e r e s p o n s i b l e f o r t h e significant  s i z e e f f e c t a t 22°C.  I n c o n c l u s i o n we c a n s a y 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 p a r a m e t e r s  studied i n  t h e s e e x p e r i m e n t s w e r e shown t o b e a t l e a s t temperature dependent.  Undoubtably,  i n part  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 direct  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  reactions.  In a d d i t i o n ,  n o t show a n y d r a s t i c  t h e c i r c u l a t o r y system d i d  l o s s o f f u n c t i o n over the  t e m p e r a t u r e r a n g e o f 5-22°C, boundary  o f t h i s range  t e m p e r a t u r e f o r salmon The should  even though  i s near t h e upper (25°C - B r e t t ,  t h e upper lethal  195 2 ) .  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  i n no way i n h i b i t  t h e a b i l i t y o f sockeye  then,  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 a n d 22°C.  The f a c t t h a t o x y g e n l e v e l s  i n the 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 t h a t the performance high temperatures i s low.  suggests  o f t h e s e f i s h may b e l i m i t e d a t  i f t h e oxygen c o n t e n t o f t h e water  76  SUMMARY 1)  Increases i n h e a r t r a t e produced by  appeared  o f t h e same o r d e r o f m a g n i t u d e  activity  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  directly  i n f l u e n c e d b y t e m p e r a t u r e , p r o b a b l y due t o  a direct  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 m y o c a r d i u m .  3)  I n no c a s e d i d t h e h e a r t c e a s e t o b e a t n o r  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 temperature range 4)  tested.  Although the blood pressure r i s e  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  produced by  temperatures,  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 at  15°C.  5) at  Dorsal aortic pulse pressure rose during 5°c b u t r e m a i n e d  activity  u n c h a n g e d 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 c h a n g e a t 22°C may b e 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 o x y g e n u p t a k e  increased  temperature but the rate o f increase of a c t i v e uptake decreased w i t h 7) with  oxygen  temperature.  The r a t e o f a c t i v e o x y g e n u p t a k e d i m i n i s h e s i n c r e a s i n g temperature, 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)  with  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 , or a combination of t h e s e f a c t o r s may  be a s s o c i a t e d  of oxygen uptake w i t h 9)  with  the diminished  increasing  temperature.  R o u t i n e r e s p i r a t o r y r a t e seemed  influenced  by  temperature.  rate  directly  78  GENERAL DISCUSSION T h i s s t u d y h a s g i v e n u s some i n f o r m a t i o n a b o u t 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 accompany s e v e r e e x e r c i s e i n s o c k e y e some 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 have been r e c o r d e d .  salmon.  on t h e s e  A g r e a t advantage  which  In a d d i t i o n , processes  of this  study  o v e r much o f t h e p r e v i o u s w o r k 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 w e r e u s e d .  C o n s i d e r a b l e work  h a s b e e n done on c i r c u l a t o r y c h a n g e s w h i c h exercise  i n mammals and r e c e n t l y ,  accompany  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 o u r r e s u l t s may b e compared w i t h those o f other workers. Chapman and M i t c h e l l physiology of exercise  (1965) h a v e r e v i e w e d t h e  i n humans,  They s u g g e s t  that  t h e c h i e f m e c h a n i s m s e n a b l i n g a human t o p e r f o r m  strenuous  e x e r c i s e a r e ; 1) t h e a b i l i t y  output  during activity, an o x y g e n d e b t ,  to increase cardiac  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  3) t h e p r e s e n c e o s h e m o g l o b i n  which  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, 4) m e c h a n i s m s w h i c h a l t e r t h e body d u r i n g e x e r c i s e . us t o s a y s o m e t h i n g  and  the pattern of blood flow to The p r e s e n t s t u d y  enables  o f t h e s e mechanisms i n salmon.  I n a y o u n g 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 f r o m 5.5 l i t r e s  o f blood/min  a t r e s t t o n e a r l y 5 times  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 r a t e and/or the  s t r o k e volume.  human a t h l e t e s show i n c r e a s e d (Rushmer, 1 9 6 2 ) .  Chapman and  i n c r e a s i n g the  In g e n e r a l o n l y t r a i n e d s t r o k e volume d u r i n g M i t c h e l l p o i n t out  the v a s t r e s p i r a t o r y s u r f a c e of the l i m i t maximal oxygen u p t a k e but of the heart  i s the  oxygen uptake. serves  as  "a f a i r  lungs does  activity  that  not  t h a t t h e pumping c a p a c i t y  sole l i m i t i n g  Therefore  heart  factor to a c t i v e  the maximal oxygen uptake  index of 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 u p t a k e 15-20 activity may on  times  increasing their  their r e s t i n g rate during  ( P r o s s e r and  show a 50-200 f o l d t h e o t h e r hand, can  r a t e o n l y 4-8  of  times  Brown, 1961)  oxygen  maximal  w h i l e some i n s e c t s  increase with exercise.  Fish  increase t h e i r r e s t i n g metabolic  during a c t i v i t y  (Brett,  1962) .  I t w o u l d a p p e a r t h e n t h a t some a i r - b r e a t h e r s show larger fish  increases of metabolic  rate with activity  than  do. Undoubtably such a d i s p a r i t y  i n c r e a s e the r e s t i n g metabolic  in ability  r a t e between f i s h  to 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 b e t w e e n t h e a q u a t i c and  terrestrial  environments.  f a r denser than a i r hence r e s p i r a t i o n costly, air  Water i s  i n w a t e r i s more  i n terms o f energy expended, than i t i s i n  (Schumann and  a large part of  Piiper,  1966).  Thus a f i s h may  expend  i t s r e s t i n g oxygen uptake through i t s  80 v e n t i l a t o r y movements.  Consequently, the r e s t i n g  oxygen  requirements 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 s c o p e f o r i n c r e a s i n g o x y g e n u p t a k e somewhat l o w e r i n f i s h t h a n i n mammals. S i m i l a r l y , w a t e r h o l d s f a r l e s s oxygen t h a n a i r hence the  c o s t o f r e m o v i n g 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 In a d d i t i o n , the  gills  Grey  i n water.  the r e s p i r a t o r y surface area o f  may l i m i t m a x i m a l m e t a b o l i c r a t e i n f i s h .  (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 a n d f o u n d a good c o r r e l a t i o n a c t i v i t y and s u r f a c e a r e a . mackeral gill  An a c t i v e f i s h  between  such as t h e  (Scomber s c o m b r u s ) h a d t h r e e t i m e s a s many  lamellae/mm o f f i l a m e n t as t h e s l u g g i s h  toadfish  (Opsanus t a u ) a n d 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 gill  was a l 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 .  Fry  (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  d e v e l o p m e n t o f t h e b r a n c h i a l pump amongst  different  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 in 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 . amongst to the  Thus,  the fishes there i s a great variation  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  maximal oxygen consumption o f f i s h ,  humans, d o e s n o t s e r v e a s a good  in ability then,  unlike that of  index 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 . It the  i s t h e low a v a i l a b i l i t y  o f oxygen i n t h e w a t e r and  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 the water fish,  which  r a t h e r t h a n any The  here The of  probably  circulatory  c a r d i a c output  and  s t r o k e volume d a t e r e p o r t e d  a c t i v e c a r d i a c output v a l u e s agree w i t h Holeton  (1966) f o r t h e r a i n b o w  same s p e c i e s .  We  and R a n d a l l  (table IX). those  t r o u t but are h i g h e r (1967 b)  should not attempt  f o r the  too c l o s e a  comparison  t h e s e v a l u e s however, s i n c e a l l the v a l u e s f o r  salmonids  w e r e c a l c u l a t e d b y t h e F i c k p r i n c i p l e and  b a s e d on a number o f a s s u m p t i o n s hold. and  More work i s n e c e s s a r y  w h i c h may  i n which  not  w i l l we  c a r d i a c output  f l o w probes or s i m i l a r d e v i c e s .  with  Only  then  be a b l e t o s a y c o n c l u s i v e l y w h a t s o r t o f b l o o d  f l o w accompanies a c t i v i t y In  in various  fish.  comparing the b l o o d f l o w data of the 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 of comparing the 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 , m e a s u r e m e n t , and d e g r e e o f a c t i v i t y o f t h e  will  are  always  s t r o k e v o l u m e d a t a c a n be m e a s u r e d d i r e c t l y  implanted  of  in  inadequacies.  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  than those of Stevens  of  l i m i t a c t i v e metabolism  a l l a f f e c t the values.  more a c t i v e a n i m a l s  methods animals  In g e n e r a l h o w e v e r ,  show h i g h e r c a r d i a c o u t p u t s  s l u g g i s h f o r m s as m i g h t be  the than  expected.  S t r o k e v o l u m e 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 for  a l l groups of animals.  0.25-2.0 m l / s t r o k e / k g .  The  t o t a l range i s  I n most c a s e s  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 of  the heart.  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 presence  u n i f o r m s t r o k e volume v a l u e s suggests a wide v a r i a t i o n to  of f a i r l y  that there i s  i n the a b i l i t y of the different  increase their heart rates.  species  Undoubtably such  variations  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 e x a m i n e t h e p h y s i o l o g i c a l m e c h a n i s m s permit of  e x e r c i s e i n humans and f i s h we f i n d a number  similarities.  markedly to can  which  B o t h humans and f i s h a r e c a p a b l e o f  increasing their  c a r d i a c output during e x e r c i s e  f a c i l i t a t e elevated metabolic rate. i n c u r an o x y g e n d e b t ,  L i k e man,  a l t h o u g h r e c o v e r y from  fish this  d e b t may t a k e some t i m e a s 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 present source  t o man  (Stevens,  1968).  Myoglobin i s  i n f i s h m u s c l e a n d p r o b a b l y s e r v e s a s an o x y g e n f o r emergency u s e .  F i s h blood 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 In  t h a n t h a t o f mammals  salmon a t l e a s t ,  ( P r o s s e r and Brown,  1961).  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 w o r k i s r e q u i r e d t o e l u c i d a t e these changes. and humans a p p e a r t o p o s s e s s of  mechanisms w h i c h  during strenuous reached  Thus b o t h  e s s e n t i a l l y t h e same s e t  f a c i l i t a t e elevated metabolic rate  exercise.  The l e v e l s o f p e r f o r m a n c e  a n d t h e amount b y w h i 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 which  fish  medium  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 t e 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 p a r a m e t e r s  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 t e m 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 temperature as d i d r o u t i n e rate.  I n no c a s e d i d f a i l u r e o f a n y p a r t o f t h e  circulatory tested  respiratory  system occur i n t h e temperature  (5-22°C).  salmon c i r c u l a t o r y  These r e s u l t s  range  suggest that t h e sockeye  system would o p e r a t e  successfully  w h i l e t h e f i s h w e r e swimming t h r o u g h w a t e r b e t w e e n 5 a n d 22°C.  I t must b e 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 h a d s t a b i l i z e d o r become a d j u s t e d to the a c c l i m a t i o n temperature. no  T h i s study has p r o v i d e d  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 c h a n g e s  on c i r c u l a t o r y p a r a m e t e r s a s m i g h t b e e n c o u n t e r e d when spawning  f i s h , l e a v e t h e s e a and e n t e r r i v e r s .  Possibly  a r a p i d t e m p e r a t u r e c h a n g e c o u l d h a v e 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 d e m o n s t r a t e d  here.  T h i s s t u d y h a s 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 free-swimming  fish  i n unrestrained,  subjected to various levels of  activity.  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 temperatures.  Many o f t h e  f a c t o r s d i s c u s s e d r e m a i n l a r g e l y u n e x p l a i n e d and f a r  84 more w o r k i s r e q u i r e d  in this  details of cardiovascular i n f i s h can be  described.  f i e l d before a l l of the  and r e s p i r a t o r y mechanisms  85  REFERENCES B a i n b r i d g e , R. (1958) . The s p e e d o f swimming o f f i s h as r e l a t e d t o s i z e a n d t o t h e f r e q u e n c y a n d amplitude o f t h e t a i l beat. J . Expt. B i o l . , 35 ;1Q9-133. B e r n , H.A. ( 1 9 5 7 ) . Hormones a n d e n d o c r i n e g l a n d s o f fishes. S c i e n c e , 158 (3800) :455-462. B l a c k , E.C., A.R. C o n n e r , K.C. Lam, a n d W.G. C h i u . (1962). 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S t e v e n s . ( 1 9 6 7 ) . The r o l e o f a d r e n e r g i c r e c e p t o r s i n c a r d i o v a s c u l a r changes a s s o c i a t e d w i t h e x e r c i s e i n salmon. Comp. B i o c h e m . P h y s i o l . , 21:415-424.  R o b e r t s o n , O.H., M.A. K r u p p , N. Thompson, S.F. Thomas, and S.F. Hane. ( 1 9 6 6 ) . B l o o d p r e s s u r e and h e a r t w e i g h t i n i m m a t u r e and s p a w n i n g P a c i f i c salmon. Am. J . P h y s i o l . , 210:957-964. Rushmer, R.F. (1962). E f f e c t s of nerve s t i m u l a t i o n and hormones on t h e h e a r t ; t h e r o l e , o f t h e h e a r t i n g e n e r a l c i r c u l a t o r y r e g u l a t i o n . In Handbook o f P h y s i o l o g y , S e c t . 2, V o l JL:533-550. Rushmer, R.F., O.A. S m i t h , and E.P. L a s h e r . (1960). N e u r a l mechanisms o f c a r d i a c c o n t r o l d u r i n g e x e r t i o n . P h y s i o l . Rev., 4_0, S u p p l . 4:27-34. Sarnoff,  S . J . and J.H. M i t c h e l l . ( 1 9 6 2 ) . The c o n t r o l of the f u n c t i o n of the heart. I n Handbook o f P h y s i o l o g y , S e c t . 2, V o l . j.:489-532.  S a u n d e r s , R.L. (1961). The i r r i g a t i o n o f t h e g i l l s in fishes. I - S t u d i e s o f the mechanism o f branchial irrigation. Can. J o l . Z o o l . , 39: 637-653. Schumann, D. and J . P i i p e r . ( 1 9 6 6 ) . Der S a u e r s t o f f b e d a r f d e r Atmung b e i F i s c h e n n a c h M e s s u n g e n an d e r n e r k o t i s i e r t e n S c h o l e i e (Tinea t i n e a ) . Pflugers A r c h . g e s . P h y s i o l . 288:15-26. Shelton,  G. and D.R. Jones. (1965). Central blood and h e a r t o u t p u t i n s u r f a c e d and submerged frogs. J . Expt. B i o l . , 42:339-357.  pressure  90 S h e p h e r d , J.T. ( 1 9 6 5 ) . E x e r c i s e and c i r c u l a t i o n . P r o c . I n t . Un. P h y s i o l . S c i . , 4:153-156. Smith,  L.S. ( 1 9 6 6 ) . Blood volumes of t h r e e salmonids. J . F i s h . Res. Bd. 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C a n a d a , 23:471-485.  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 m o d e r a t e swimming a c t i v i t y i n r a i n b o w trout. J . E x p t . B i o l . , 46:307-315.  Stevens,  E.D. and D.J. R a n d a l l . (1967 b ) . C h a n g e s o f g a s c o n c e n t r a t i o n s i n b l o o d and w a t e r d u r i n g m o d e r a t e 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.  S t r o g a n o v , N.S. (1962). Methods o f s t u d y of r e s p i r a t i o n in fish. 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 , O l d b o u r n e P r e s s , London. Wolf,  K.  (1963). teleosts.  Physiological salines for freshwater 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 s u m m a r i z e d in  tabular  fashion.  In t h e f o l l o w i n g t a b l e s  these  symbols a r e used: x  = mean  average  +S.D.  = + 1 standard  +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 u s e d t o c a l c u l a t e e a c h mean a v e r a g e . Each v a l u e r e p r e s e n t s a different fish.  deviation  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 . Routine t a i l beat frequency corresponds to the minimal a c t i v i t y l e v e l that 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 Table  I  Heart r a t e data before,  d u r i n g and a f t e r t h e  t h r e e t e s t g r o u p s w e r e f a t i g u e d b y swimming.  TABLE I a) 5°C H e a r t R a t e  (beats/minute) T.B.F.  w e i g h t (g) X  length*  1220  48.5  Minutes A f t e r  128  140  15 0  165  31.3  34. 2  37.5  40. 7  43. 7  45. 0  routine  2  Fatigue  10  20  45  60  42. 0  41.1  37. 9  39. 0  42.0  5  +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  9  9  6  6  7  6  7  7  7  7  6  4  9  n  b) 15°C H e a r t R a t e  (beats/minute) T.B.F  w e i g h t (g) x +S.E. n  Length+  Routine  95  Minutes a f t e r Fatigue  •  125  153  182  2  7  14  30  50  1652  55. 9  52.0  62. 0  69. 0  80.0  83. 0  83. 0  73. 0  75.0  77. 0  72.0  129  19. 0  2.5  5.0  4.0  3.0  1.5  2.0  4.5  4.0  5.0  4.0  6  6  6  6  6  6  6  6  6  6  6  6  length* - fork length length+ - t o t a l  length  (cm) (cm)  TABLE I c)  22°c H e a r t R a t e  (Cont'd)  (beats/minute) T.B.F.  w e i g h t (g) x +S.D.  length* routine  Minutes A f t e r  120  132  140  150  160  2  101  100  105  105  105  103  1100  48.7  86.2  310  5.1  5.6  8.8  8.8  3.2  3.3  7.1  1.6  2.3  3.9  2.9  1.2  1.5  3.2  6  5  +S.E.  93.5  n  11  10  9  7  5  5  5 99.9  15.0 16.5 5.7 7  6.3 7  Fatigue  10  20  45  60  107  104  101  88.8  11.9  10.3  4.9  4.2 6  6  length* - fork length  9.6 10.9 3.9 6  (cm)  4.4 6  95  Legend f o r Table 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 aortae o f the three t e s t groups.  i n the dorsal  D a t a shows  pressures  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 w e r e f a t i g u e d b y 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.  w e i g h t (g)  lenqth*  routine  Minutes  128  140  15 0  165  37. 0  37.0  38. 0  42. 0  38. 0  2  After  Fatigue  10  20  45  60  37. 0  34.0  34. 0  34.0  33.0  5  1230  48. 7  +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  9  8  6  6  5  4  6  7  7  7  6  4  X  n  9  31.8  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.  w e i g h t (g)  length*  Minutes  routine  128  140  15 0  165  27.5  31.0  31.0  33. 0  34. 0  34. 0  2  After  Fatigue  10  20  45  60  33. 0  30. 0  30. 0  29. 0  30.0  5  1230  48. 7  +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  9  8  5  6  5  4  6  7  7  7  6  4  X  n  9  length* - fork length  (cm)  TABLE I I c)  S y s t o l i c Blood Pressure  - 15°C  (mm  (Cont'd)  Hg) Minutes A f t e r Fatigue  T.B.F w e i g h t (g) x +S.E.  100  routine  150  185  45. 0  46. 0  55. 0  55. 9  48. 0  129  19. 0  1.2  1. 0  1.8  2. 7  6  6  6  6  6  6  D i a s t o l i c Blood Pressure  46. 0  125  1652  n  d)  length*  - 15°C  (mm  x +S.E. n  length*  routine  15  30  40. 0  43. 0  41. 0  50  43. 0  44.5  1.3  2. 1  2.3  2.2  2.3  3.0  6  6  6  6  6  6  i  Minutes After Fatigue  125  150  185  41.0  40. 0  42. 0  49. 0  100  7  Hg) T.B.F  w e i g h t (g)  4  4 40. 0  15  30  50  38. 0  35. 0  37.0  36.  7  1652  55. 9  42. 0  129  19. 0  1.0  1.4  1. 7  3.3  1.3  3. 4  1.5  2.0  2.3  3.  6  6  6  6  6  6  6  6  6  6  6  6  length* - t o t a l length no s t a n d a r d d e v i a t i o n s f o r means  (cm) available  TABLE I I (Cont'd) e)  S y s t o l i c Blood Pressure  - 22°C  (mm Hg) T.B.F.  w e i g h t (g) x  length*  Minutes A f t e r  routine  132  148  160  180  33.8  32. 3  34. 2  35.5  39.2  4.5  5.5  5.0  3.8  4.6  2.6  2.7  2. 6  2.6  3.2  2.9  2.2  2.5  6  5  3  3  3  3  3  3  4.7  6.7  6.8  6. 3  +S.E.  113  1.8  1.4  2.8  3.1  6  5  Blood Pressure  - 22°C  x  length*  routine  30.0  (mm Hg) Minutes A f t e r  T.B. F. w e i g h t (g)  32.7  30. 7  60  4. 5  5.5  f) D i a s t o l i c  45  6.0  340  12  20  31. 7  +S.D.  9  10  30. 3  47. 3  9  5  30. 7  1080  n  2  Fatigue  132  148  160  180  2  30.4  31. 8  36. 0  28. 7  28. 3  5  Fatigue  10  20  45  60  29.0  30.0  28. 7  28. 0  1080  47. 3  30. 2  31. 3  +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  6  5  6  5  3  3  3  3  3  3  n  9  9  12  length* - fork length  (cm)  99  Legend f o r T a b l e I I I Pulse pressure  i n the dorsal aorta of three  g r o u p s 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 f a t i g u e d b y swimming.  were  TABLE I I I a)  Dorsal A o r t i c Pulse Pressure  (mm Hg) - 5°C T.B.F.  w e i g h t (q)  length*  Minutes A f t e r  Fatigue  routine  128  140  150  165  2  5  10  20  45  60  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  9  8  5  6  5  4  6  7  7  6  6  4  X  9  n  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.  w e i g h t (g) x +S.E. h  length+  1652  55.9  129  19.0  6  6  Minutes A f t e r  Fatigue  routine  100  125  150  185  4  7  15  30  50  6.0  5.0  5.0  4.0  6.0  3.0  6.5  5.0  6.0  5.0  (standard e r r o r s not a v a i l a b l e ) 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) l e n g t h + - 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 Pulse  Pressure  (mm Hg) - 22 C T.B.F.  w e i g h t (g) X  Fatigue  routine  132  148  160  180  10  20  45  60  47. 3  3.8  3.8  3.8  4.3  3.2  2.7  2.0  2.0  1.7  length*  1080  Minutes A f t e r  +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  6  5  6  5  3  3  3  3  n  9  9  12  length* - fork length  (cm)  102  Legend f o r T a b l e IV Ventilation f i s h before, by  swimming.  r a t e i n t h e t h r e e groups o f t e s t  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  TABLE IV a) V e n t i l a t i o n R a t e  (mouth c l o s u r e s / m i n u t e ) - 5°C T.B.F.  w e i g h t (g)  length*  routine  139  147  155  105.0  115.0  1108. 3  48.0  40. 0  93.4  +S.D. 383. 9  5.6  9. 8  11. 6  25. 0  +S.E. 145. 1  2.1  3.5  5.2  11. 2  n  7  8  5  x  7  b) V e n t i l a t i o n R a t e  Minutes A f t e r  5  2  length+  10  20  45  60  79. 0  75. 0  67. 0  58. 0  65. 0  67. 0  33.4  5. 6  7. 2  8. 7  7. 7  14. 0  5. 4  19.3  2. 1  2. 7  3. 3  2: 9  5. 7  2. 7  7  7  7  7  6  4  3  (mouth c l o s u r e s / m i n u t e ) - 15°C T.B.F.  w e i g h t (g)  5  Fatigue  routine  Minutes A f t e r  100  125  153  .4  7  Fatigue  15  30  50  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  6  6  6  6  x  n  1652  6  6  6  6  6  6  6  l e n g t h * - f o r k l e n g t h (cm) l e n g t h + - t o t a l l e n g t h (cm)  TABLE IV c) V e n t i l a t i o n Rate  (Cont'd)  (mouth c l o s u r e s / m i n u t e ) - 22°C T.B.F.  Minutes After  Fatigue  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  115  122  119  127  138  113  114  111  106  101  96.7  +S.D. +S.E. n  1040  47.1  77.4  295  4.8  17.3  12.5  16.0  14.4  9.0  25.4  14.1  13.2  11.2  11.6  98.5 1.6  5.8  7.2  6.5  6.5  4.5  12.7  5.3  4.7  4.2  4.4  9.  3  9  9  6  5  4  4  7  8  7  7  length* - fork length  16.4 22.4 6.2  9.1  7  6  (cm)  105  Legend f o r T a b l e V Maximal pressure  recorded  o f two g r o u p s o f f i s h a c c l i m a t e d respectively.  In t h i s  i n the buccal  cavity  and t e s t e d a t 5 and 22°C  case only data  for adults  a s 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 o t be to adult  levels.  i s given corrected  TABLE V a) Maximum P r e s s u r e  i n Buccal  Cavity  (Adult data  (mm Hg) - 5 C T.B.F.  w e i g h t (g) X  +S.D. +S.E. n  length* routine  only)  Minutes A f t e r Fatigue  132  142  147  150  167  2  5  10  20  45  60  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  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  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  5  5  2  4  3  3  2  3  3  4  4  3  3  93.5 5  (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 Buccal  w e i g h t (g) l e n g t h * r o u t i n e  C a v i t y (mm Hg ) - 22 C T.B.F. 126 115 147 163  2  Minutes A f t e r Fatigue 20 5 10 45  60  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  3  3  3  3  2  2  3  3  3  3  3  3  X  n  3  length*  - fork length  (cm)  107  Legend f o r T a b l e V I Table VI 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 temperatures.  Prior to testing,  tested at d i f f e r e n t the f i s h were  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  acclimated carried  out.  Legend f o r T a b l e V I I This t a b l e g i v e s the 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 g r o u p o f a d u l t s o c k e y e a t t e m p e r a t u r e s o f 15-22°C.  salmon  TABLE V I ( a l l C> U p t a k e d a t a i n Mg 0 / K g / h r ) 2  Metabolic x  R a t e - 5.5°C ( A d u l t s , x w e i g h t - 1510g+124) Standard Active Source 30.45 502.0  +S.D.  2.98  +S.E.  0.84  n Metabolic x  2  11  136.5 43.17 10  R a t e - 15°C ( J a c k s , x w e i g h t - 745g+8.97) Standard Active Source 70.7 730.0  +S.D.  7.9  90.2  +S.E.  3.9  45.1  n  4  Metabolic x  Brett, unpublished  Brett, unpublished  4  R a t e - 15°C ( A d u l t s , x w e i g h t - 1431.8g+40.6) Standard Active Source 44.0 717.0  +S.D.  12.9  73.8  +S.E.  5.8  24.6  n  5  9  Brett,  1965  TABLE V I (Cont 'd) (all 0 Metabolic x  U p t a k e d a t a i n Mg 0 / K g / h r )  R a t e - 20 C ( A d u l t s , x w e i g h t - 1730g+219) Standard Active Source 76. 9 786. 0  +S.D.  19. 0  94. 9  +S.E.  7.2  28. 6  n  7  11  Metabolic x  Brett,  R a t e - 22°C ( A d u l t s ) Standard Active 145.0 800. 0  unpublished  Source extrapolated f i g u r e 19.  from  TABLE V I I Hematocrit data W e i g h t (g) x  (Temp. . = 15-22°Cj  Fork length  (cm)  Hematocrit  1460.0  53.9  23.4  +S.D.  183.0  2.4  3.1  +S.E.  81.9  1.1  1.4  5  5  n  5  110  Legend f o r T a b l e This pressure  VIII  t a b l e compares the  i n the  three  t e s t groups w i t h  from oxygen uptake d a t a .  For  the  increase  doubled cardiac blood  pressure  output.  pressure  The  should  t a b l e shows t h a t  i s f a r l o w e r t h a n w o u l d be  probably increases  markedly w i t h  Since  exercise.  double  to  a  observed  expected  cardiac  exercise there  changes i n the r e s i s t a n c e of the v a s c u l a r  accompanying  calculated  i n o x y g e n u p t a k e i s s o l e l y due  the b a s i s o f oxygen uptake d a t a .  be  that  aortic  example i f oxygen u p t a k e  doubles then d o r s a l a o r t i c blood if  observed d o r s a l  on  output must  system  TABLE V I I I Temperature  (°C)  Oxygen U p t a k e ( f i g . 11) (Mg 0 / K g / h r ) 2  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  Routine 5.5  15.0  22.0  x  48.0  Active  Routine  Expected Active  Routine  Active  29.3  304.5  502.0  29.3  37.0  +S.E.  —  43.2  1.1  2.8  n  —  10  8  4  717.0  44.0  51.0  24.6  1.0  1.0  6  6  —  31.3  37.0  31.3  1.4  2.5  x  72.0  +S.E.  —  n  —  9  x  145.0  800.0  +S.E.  12  5  -  -  — 44.0  438.2 — 172.8  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 a n d s t r o k e v o l u m e 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 I X C a r d i a c Output Animal  Temperature  and  S t r o k e Volumes o f a V a r i e t y  S t r o k e Volume ml/stroke/kg  Cardiac  of  Animals  Output  Method  Reference  ml/min/kg  man  60.0-100.0  dog  139. 0  Ibid.  cat  690. 0  Ibid.  frog  20  octopus  7-9  1.0  (approx.)  0.31-2.01*  57.0 5.0-32.2  P r o s s e r and Brown, 1962  Ventricular displacement  S h e I t o n and J o n e s , 1965  Fick  Johansen, 1965  principle  Opsanus t a u (toadfish)  10.1  Fick principle, minimum v a l u e s  Mott,  Tetrodon (puffer)  15.5  As  above  Ibid.  13. 7  As  above  Ibid.  maculatus  Stenotomus c h r y s o p s (scup) Gadus m o r h u a (cod)  0.31 - d o u b l e s with increased venous r e t u r n .  9. 3  * calculated  Electromagnetic flowmeter  1957  Johansen, 1962  f r o m a h e a r t r a t e o f 16 b t s / m i n  TABLE I X C a r d i a c O u t p u t and Animal  Temperature  (Cont'd)  S t r o k e Volumes o f a V a r i e t y  S t r o k e Volume ml/stroke/kg  Cardiac  of  Animals  Output  Method  ml/min/kg  Myoxocephalus scorpius (sculpin)  15-18  Squalus a c e n t h i a s (dogfish)  11-17  0. 25-.94 t o 1,88 when ventricle perfused.  Salmo g a i r d n e r i (rainbow t r o u t )  12-18  0.85-2.0  65.0-100.0  0.15 0.7  7.5 (resting) 38.0 (modAs a b o v e erately active)  4-8  27. 75  (resting) (moderately active)  resting-fully active  Onchorynchus n e r k a (sockeye salmon)  Reference  9.0-24.8 +  resting-fully  Goldstein, e t a l 1964  L i g a t i o n and weighing of h e a r t . Flow from ventral aorta.  B u r g e r and Bradley, 1951  Fick principle  Holeton, 1966  active  5  0.67-1.39  20.74-65.07  15  0.60-1.12  31.08-92.94  20  0.65-1.04  49.65-101.89  22  0.73-0.99  62.65-103.7 calculated  Fick principle  Stevens and R a n d a l l 1967 b. Present study  Fick principle r e s t i n g - VA 7 0 % s a t d . a c t i v e - VA 0% s a t d .  f r o m a h e a r t r a t e o f 36  bts/min  

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