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Electrolyte changes associated with transfer of the steelhead trout (Salmo gairdneri) into seawater Vickers, Mary Hope 1960

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ELECTROLYTE CHANGES ASSOCIATED WITH TRANSFER OF THE STEELHEAD TROUT (SALMO GAIRDNERI) INTO SEAWATER  by  MARY HOPE VICKERS B.A , U n i v e r s i t y of Toronto, 1957 a  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF SCIENCE  i n the Department of  ZOOLOGY  We accept t h i s t h e s i s as conforming to the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1960  in the  presenting  this thesis  r e q u i r e m e n t s f o r an  of  British  it  freely available  agree that for  Columbia,  Department  copying  gain  shall  or  not  shall  for reference  and  study.  I  for extensive  Department o f  publication  Up^jl  granted  o o l o ^  l g  C ;  by  . Columbia,  lUo  of  the  It i s  of t h i s t h e s i s  a l l o w e d w i t h o u t my  The U n i v e r s i t y o f B r i t i s h Vancouver Canada.  Date  be  copying  of  University  Library  his representatives.  be  the  the  p u r p o s e s may  o r by  that  advanced degree a t  fulfilment  I agree that  permission  scholarly  in partial  make  further this  Head o f  thesis my  understood  for financial  written  permission.  - i -  ABSTRACT  The purpose of the i n v e s t i g a t i o n was to e l u c i d a t e the mechanisms enabling the s u r v i v a l of euryhaline f i s h i n s a l t water*  Steelhead t r o u t (Salmo  g a i r d n e r i ) were t r a n s f e r r e d t o 60$ seawater and s e r i a l measurements made of the serum and muscle sodium and potassium content and of the t i s s u e water during a t e n day p e r i o d a f t e r t r a n s f e r * The i n i t i a l 24 hours i n seawater were c h a r a c t e r i z e d the t i s s u e s and a g r e a t increase  i n the body e l e c t r o l y t e s .  by a dehydration of  This was f o l l o w e d by a  r e g u l a t o r y phase which represented the m o b i l i z a t i o n of a c t i v e t r a n s p o r t mechanisms i n the muscles and g i l l t i s s u e s , enabling the e x c r e t i o n c a t i o n , sodium.  of the dominant e x t r a c e l l u l a r  The r e g u l a t i o n of potassium, the main i n t r a c e l l u l a r c a t i o n ,  assigned to the kidney.  was  The r e g u l a t i o n of t i s s u e potassium and water appeared t o  be dependant on the r e g u l a t i o n of sodium. A f t e r 110 hours i n seawater the r e g u l a t o r y animal to a new e q u i l i b r i u m which was c h a r a c t e r i z e d higher than f r e s h water c o n t r o l s , 2) c o n t r o l s , and 3)  processes had returned the by:  l)  serum c a t i o n s only 6%  muscle potassium 15% higher than f r e s h water  a lower t i s s u e water content than the f r e s h water c o n t r o l s .  The c o n t r o l of t h i s osmoregulatory adaptation t o a hypertonic environment i s d i s c u s s e d and p o s s i b l e hormonal a c t i o n considered.  - ii —  TABLE OP CONTENTS  Page I. II.  III.  INTRODUCTION  .  1  MATERIALS AND METHODS  5  1.  Care and Maintenance of F i s h . . . . .  . .  2.  Experimental Treatment....•  6  a.  Treatment and A n a l y s i s of Blood........  6  b.  Treatment and A n a l y s i s o f Muscle  7  3.  T r a n s f e r o f F i s h t o Seawater.  4.  S t a t i s t i c a l Analysis...............  0  . . . . . . . 6  •  8  RESULTS  9  1.  Comparison of Muscle A n a l y s i s Techniques................  10  2.  Values of Sodium and Potassium i n F r e s h Water P i s h . . . . . .  10  3.  Transfer of P i s h t o Seawater  14  a.  Changes i n Serum E l e c t r o l y t e s .  ••  b.  Changes i n Muscle Cations...........................  16  c.  Changes i n Muscle Water Content...  16  d.  Comparison o f E q u i l i b r i u m Values With Fresh Water Pish  IV.  V. VI. VII.  8  15  17  DISCUSSION  19  1.  Comparison With Values Reported i n the L i t e r a t u r e . . . . . . .  20  2.  Regulation of Serum C a t i o n s . .  20  3.  Regulation.of Muscle C a t i o n s .  23  4.  P o s s i b l e Regulatory Mechanisms...  26  ••  SUMMARY....  29  LITERATURE CITED  31  APPENDIX  34  - iii  -  LIST OF TABLES  Table 1  2  3  4  5  6  7  £.'  Page A Comparison of the Ashing Technique and the A c i d D i g e s t i o n Technique of Muscle A n a l y s i s . . . . . .  11  A Comparison of the P r e c i s i o n of the Ashing Technique and the D i g e s t i o n Technique o f Muscle A n a l y s i s . . . . . . . .  11  Values' of Serum'and Muscle E l e c t r o l y t e s i n F r e s h Water Salmo g a i r d n e r i . •  12  The E f f e c t of E x e r c i s e and Temperature on the Ionic Concentrations i n Serum and Muscle of Salmo g a i r d n e r i . .  13  A Comparison of the C a t i o n L e v e l s of Serum and Muscle i n Fresh Water F i s h and P i s h E q u i l i b r a t e d to S a l t Water.....  18  A Comparison of Sodium and Potassium Concentrations i n Serum and Muscle of Salmonid P i s h Sampled i n Fresh Water .  21  A Comparison of Sodium and Potassium Concentrations i n Serum and Muscle of Salmonid P i s h E q u i l i b r a t e d t o Seawater. . . . . . . . . . . . . . . . . . . . . . . . . . . . a . . . . . . . . . . . . . . . . . . . . .  21  Appendix  8  9  10  11  34  C a t i o n Values i n Normal P i s h Analysed as to Sex D i f f e r ences.  35  T r a n s f e r to 60$ Seawater. 1. Serum Sodium and Potassium. 2. Na/K R a t i o . . . . . . . . . . . . . . . . . . . . . . . . . . . . •  36  T r a n s f e r to 60$ Seawater. 3. Sodium and Potassium i n Wet Muscle. 4. Muscle Potassium/Sodium R a t i o . •  37  T r a n s f e r t o 60$ Seawater. 5. $ Tissue Water. ium and Potassium i n Dry Muscle....  38  6.  Sod-  - iv -  LIST OF FIGURES  Figure 1  2  3  4  Page S e r i a l Changes i n Sodium Content of Serum and Muscle A f t e r Transfer to 60% Seawater....  14  S e r i a l Changes i n Potassium Content of Serum and Muscle A f t e r Transfer to 60% S e a w a t e r . . . . . . . . .  14  A Comparison of the Rates of Sodium Loss and Potassium Accumulation i n the Muscle During A c t i v e Regulatory Phase......  16  K/Na Ratio i n Muscle Tissue During Transfer t o Seawater.. ...............................................  16  - V -  ACKNOWLEDGMENTS  The author wishes t o express g r a t i t u d e to Br« W.N. Holmes f o r advice and a s s i s t a n c e so f r e e l y g i v e n throughout t h i s p r o j e c t .  I would a l s o  l i k e t o thank Dr. C.7. Finnegan, Dr. P. Ford, and Dr. W.S. Hoar f o r t h e i r h e l p f u l suggestions throughout the y e a r .  To my f e l l o w graduate students. I am  g r a t e f u l f o r the opportunity I had to d i s c u s s .the many problems i n v o l v e d i n t h i s study.  INTRODUCTION  ~ 2  -  The c a p a c i t y of t e l e o s t f i s h , whether they be freshwater or marine s p e c i e s , to withstand the v a r y i n g osmotic demands of t h e i r environments i s a remarkable p h y s i o l o g i c a l phenomenon.  Fresh water f i s h must maintain concentrations of  e l e c t r o l y t e s i n t h e i r body f l u i d s which have an osmolarity s i g n i f i c a n t l y greater than t h e i r environment.  Marine t e l e o s t s , on the other hand, maintain t h e i r body  f l u i d s against a hypertonic environment which tend3 to dehydrate f l o o d the body f l u i d s with e l e c t r o l y t e s .  the t i s s u e s and  I t i s c l e a r , t h e r e f o r e , t h a t any f r e s h water  f i s h which i s capable of a d j u s t i n g i t s r e g u l a t o r y mechanisms to withstand the osmotic hazards  of seawater i s w e l l worthy of i n v e s t i g a t i o n .  Such a euryhaline f i s h  i s the Steelhead t r o u t (Salmo g a i r d n e r i ) . The p r i n c i p a l osmoregulatory  mechanisms i n f r e s h water f i s h are the  e f f i c i e n t r e a b s o r p t i o n of ions by the kidney tubules, the production of a copious hypotonic u r i n e , and p o s s i b l y the a c t i v e uptake of ions through the g i l l epithelium. In order to conserve water, marine t e l e o s t s d r i n k s a l t water and i n e f f e c t it,  distill  since the g i l l s appear to be able to a c t i v e l y excrete s a l t s , p o s s i b l y v i a the  "chloride secreting c e l l s " .  The kidneys of marine t e l e o s t s would seem to p l a y a  minor r e g u l a t o r y r o l e by producing the minimum amount of u r i n e necessary to remove t o x i c waste products from the body.  This u r i n e , although hypotonic to the body  f l u i d s , i s more concentrated than t h a t of f r e s h water f i s h , i n d i c a t i n g a p o s s i b l e a n t i - d i u r e t i c action.. Krogh (1939) and Black  These adaptations have been comprehensively  reviewed  by  (1957).  In freshwater f i s h , where s a l t r e t e n t i o n i s imperative, one would expect a p r i o r i t h a t a s a l t r e t a i n i n g mechanism would be present.  In mammals the adrenal  cortex produces compounds which f u n c t i o n i n s a l t r e t e n t i o n , and the most a c t i v e of these, aldosterone, has r e c e n t l y been demonstrated i n the p e r i p h e r a l blood of spawning salmon ( P h i l l i p s e t a l , 1959) while the a n t e r i o r i n t e r r e n a l has been i d e n t i f i e d as i t s s i t e of s y n t h e s i s i n Fundulus ( P h i l l i p s and Mulrow, 1959),  This  -  3  -  would seem to be f u r t h e r i n d i c a t i o n of the homology thought to e x i s t between the i n t e r r e n a l t i s s u e of t e l e o s t s and the mammalian adrenal c o r t e x . no evidence  However, there i s  extant to i n d i c a t e whether t h i s aldosterone i s p h y s i o l o g i c a l l y a c t i v e  i n the f i s h and i f so what i t s a c t i o n may  be.  The observation t h a t the  of Fundulus i s quiescent i n s a l t water ( P i c k f o r d e t a l , 1957)  interrenal  supports the view  that sodium r e t a i n i n g s t e r o i d s ( v i z . aldosterone) produced by the i n t e r r e n a l promote s u r v i v a l i n f r e s h water.  The quiescence  of the i n t e r r e n a l i n s a l t water i s  considered to be a r e s u l t of the decreased (Chester Jones, 1956).  demand f o r s a l t r e t a i n i n g s t e r o i d s  The v a l i d i t y of t h i s i n t e r p r e t a t i o n i s open to question  since Holmes (1959) has shown t h a t the c o r t i c o s t e r o i d s , DCA  and  hydrocortisone,  promote l o s s of sodium through the g i l l s i n a s a l t loaded f i s h , and Sexton (1955) has demonstrated t h a t DCA i n the g o l d f i s h g i l l , carbohydrate  depressed  the uptake of sodium against a d i f f u s i o n g r a d i e n t  Other s t e r o i d s , which i n the mammal e f f e c t  predominantly  metabolism, have been i d e n t i f i e d i n the serum and i n t e r r e n a l t i s s u e of  salmonid f i s h .  An increase i n serum 17-hydroxycorticosteroids and an increase i n  i n t e r r e n a l volume have been observed Olivereau, I960).  i n smolting salmon (Fontaine and Hatey,  I t i s s i g n i f i c a n t to note t h a t during the smolting p e r i o d  f i s h e s are most able to withstand t r a n s f e r to seawater (Houston, 1959;  1954; salmonid  Koch, 1959)«  In a d d i t i o n , s t r u c t u r e s other than the i n t e r r e n a l t i s s u e have been p o s t u l a t e d as p o s s i b l e organs of osmoregulation.  Fontaine and Hatey (1959) claimed the  identification  of c o r t i c o s t e r o i d s i n the corpuscles of stannius, although t h i s observation i s at variance with the f i n d i n g s of Ford (1959) and P h i l l i p s (pers. comm.). has described the urohypophysis which may  Enami (1959)  w e l l have an osmoregulatory r o l e .  I t i s p o s t u l a t e d that a neurohumour a s s o c i a t e d with the p o s t e r i o r p i t u i t a r y i s important  i n the maintenance of osmotic  water (e.g. Chester Jones, 1956). Grabe (1954) who  balance  i n t e l e o s t s upon t r a n s f e r to sea  This p o s t u l a t e i s based on the work of Arvy and  demonstrated an increase i n neurosecretory m a t e r i a l i n the supra-optic  - 4 -  nucleus l e s s than one h a l f hour a f t e r t r a n s f e r to seawater.  Recent work by  F r i d b e r g and Olsson (1959) have confirmed these observations i n G-asterosteus, i n the higher vertebrates,  compounds having ADH, pressor,  and oxytocic  have been i d e n t i f i e d i n the t e l e o s t neurohypophysis (Herring, The  1915j  As  activity  H e l l e r , 1941),  f a c t that p i t u i t a r i e s from marine t e l e o s t s are more a c t i v e than those of f r e s h  water f i s h i n promoting water r e t e n t i o n i n the f r o g i n d i c a t e s the presence of a greater amount of oxytocin  i n the marine f i s h (Weise, 1959).  t h a t i n v i v o i n j e c t i o n s of oxytocin  Holmes (1959) showed  decreased the i n v i t r o r e s p i r a t o r y rate i n the  kidney i n Salmo c l a r k i c l a r k i , while a large dose of vasopressin respiration.  enhanced kidney  Furthermore, Holmes (1959) has demonstrated that vasopressin  diminished  the r e n a l e x c r e t i o n of sodium i n sodium loaded t r o u t . I t would appear t h a t the p o s t e r i o r p i t u i t a r y hormones are a c t i v e i n sea water t e l e o s t s , although t h e i r mode and s i t e of a c t i o n i s by no means w e l l understood. When a f i s h i s t r a n s f e r r e d from f r e s h to s a l t water, i t must be able t o pump out the incoming ions i f i t i s t o s u r v i v e .  I f measurements are made of the  changes observed i n i o n i c content of the blood and t i s s u e s a f t e r a euryhaline i s t r a n s f e r r e d t o saltwater, be made.  fish  then an i n s i g h t i n t o the osmoregulatory mechanism may  The purpose of t h i s i n v e s t i g a t i o n was to examine these changes i n e l e c t r o l y t e  composition and t i s s u e water.  Steelhead t r o u t , t h e r e f o r e , were t r a n s f e r r e d from  freshwater t o seawater and s e r i a l measurements were made of the changes i n serum and muscle sodium and potassium l e v e l s and i n t i s s u e water content.  In t h i s way an  adequate d e s c r i p t i o n of the normal osmoregulatory changes under these conditions be  obtained.  could  MATERIALS AND METHODS  - 6  1.  -  Care and Maintenance of F i s h Hatchery r a i s e d y e a r l i n g steelhead t r o u t (Salmo g a i r d n e r i ) of s i m i l a r  genetic stock were obtained from Cultus Lake Hatchery, B r i t i s h courtesy of the B.C. Game Department,  Columbia, by the  In Vancouver the f i s h were stored i n outdoor  cement tanks supplied with running d e c h l o r i n a t e d water, the temperature of which remained between 4,5 and 5.0° C, during the experimental p e r i o d .  Stock f i s h were  f e d weekly (Clark's f i n g e r l i n g f i s h food), whereas the experimental f i s h were not fed  f o r a week p r i o r t o , nor during time i n seawater.  A l l f i s h were allowed to  e q u i l i b r a t e f o r a t l e a s t a week a f t e r t r a n s p o r t a t i o n before being used experimentally,  2.  Experimental Treatment Flame photometric (Zeiss FP 5) estimations of sodium and potassium f o r  muscle and serum samples were made on each f i s h .  These values were expressed i n  m i l l i e q u i v a l e n t s (meq.) of i o n per kilogram of serum and muscle r e s p e c t i v e l y .  The  water content of a l l muscle samples was c a l c u l a t e d from f r e s h and dry weights of the  samples. Upon removal from the tank, the body weight and f o r k l e n g t h were recorded.  Paper towels were wrapped around the c l o a c a to prevent contamination of the blood, the  caudal f i n severed one inch p o s t e r i o r to the anus and the e f f e r e n t blood c o l l e c t e d  i n a c e n t r i f u g e tube.  Muscle samples were then taken.  This process took about 8  minutes per f i s h to complete. A l l glassware used i n analyses was pyrex and a l l chemicals used were CP reagent grade. a.  Treatment and A n a l y s i s of Blood The c o l l e c t e d blood was allowed to c l o t i n a r e f r i g e r a t o r f o r 30-45 minutes.  I t was then c e n t r i f u g e d f o r 15 minutes a t 1500 RPM,  and the serum was pippetted o f f  and stored i n stoppered tubes. Analyses were made on 0,2 or 0.5 ml, serum, which was digested w i t h a drop  - 7 -  of HC1 and d i l u t e d t o 25 ml. (1/125 d i l u t i o n ) or to 50 ml,,(l/lOO d i l u t i o n ) respectively.  I n i t i a l l y , d u p l i c a t e d i l u t i o n s were made from a s e r i e s of samples  i n order to t e s t the accuracy of d i l u t i o n . was  Subsequently,  only one d i l u t i o n per f i s h  analyzed. Sodium and potassium values were read on the same d i l u t i o n s  Sodium was necessary.  read against a 10 mgm.%  (l/lOO).  sodium standard and no i n t e r f e r e n c e standard  Potassium values were read against a 0.5 mgm,%  was  i n t e r f e r e n c e standard.  Standard curves were obtained f o r sodium and potassium flame photometer readings and unknown samples were c a l c u l a t e d from these standard curves.  Precision for  sodium was - 2 meq./L and f o r potassium was - ,5 meq./L, b.  Treatment and A n a l y s i s of Muscle D u p l i c a t e muscle samples (about 1 gram) were removed from the d o r s a l muscle  mass on e i t h e r s i d e of the v e r t e b r a l column j u s t a n t e r i o r to the d o r s a l f i n . the adhering s k i n and f a t was pan and weighed.  removed, the sample was  After  placed i n a t a r e d aluminum  Samples were d r i e d to constant weight at 109° C., reweighed, and  the per cent water content c a l c u l a t e d . Two methods of f r e e i n g the ions i n the muscle were used. ashing technique.  an  Weighed dry muscle samples (about 0.2 gram) were ashed i n  platinum c r u c i b l e s at 1000° C. f o r s i x hours. remaining was  The f i r s t was  The white c r y s t a l l i n e m a t e r i a l  then d i s s o l v e d i n concentrated h y d r o c h l o r i c a c i d and d i l u t e d to 100  ml,  i n a volumetric f l a s k . The ashing technique i s tedious and t h e r e f o r e the m a j o r i t y of the muscle samples were digested, using a m o d i f i c a t i o n of the technique described by Gordon (1959).  Each muscle sample was p l a c e d i n a t e s t tube and to t h i s was  ION n i t r i c a c i d , 0,2 ml, 30% H 0 , and a drop of c a p r y l i c a l c o h o l . ?  heated f o r one hour a t 60° C,  2  added 1,0-1,5 ml.  This was  then  The r e s u l t i n g s o l u t i o n was n e u t r a l i z e d by the a d d i t i o n  of 1 ml. 15N ammonia hydroxide, and made up to 100 ml, with d i s t i l l e d water. An i n t e r f e r e n c e standard f o r potassium determination was  found to be  -  unnecessary.  8 -  The c o n c e n t r a t i o n o f p o t a s s i u m was r e a d a g a i n s t a 10 mgm,$ s t a n d a r d  c u r v e and each v a l u e r e c o r d e d was a mean o f d u p l i c a t e read, a g a i n s t a 0 . 7 6 8 mgm.$ i n t e r f e r e n c e analysed.  3,  Sodium v a l u e s were  s t a n d a r d and s i m i l a r d u p l i c a t e samples were  The a c c u r a c y o f each mean v a l u e was c a l c u l a t e d f r o m t h e average  f r o m t h e mean o f t w e n t y d u p l i c a t e -  samples.  samples.  2 , 5 m e q . / k g , w e t w e i g h t , and f o r  deviation  The a c c u r a c y f o r t h e p o t a s s i u m was  sodium - 0 . 5 m e q . / k g . w e t  weight.  F i s h T r a n s f e r r e d t o S a l t Water E x p e r i m e n t a l f i s h were t r a n s f e r r e d ' d i r e c t l y f r o m f r e s h w a t e r  t o 60$''' s e a w a t e r  (Na  287 m e q , / L , K  5.95 m e q , / L ) .  and t h e t e m p e r a t u r e was c o n s t a n t a t 1 0 ^ 0 . 5 ° C,  The s e a w a t e r t a n k s were a e r a t e d  F i s h were removed f o r a n a l y s i s  at  v a r i o u s i n t e r v a l s a f t e r t o sea w a t e r d u r i n g a t e n day p e r i o d .  4,  Statistical  Analysis  The s t a t i s t i c a l t r e a t m e n t o f t h e d a t a c o l l e c t e d i n t h i s f o l l o w s t h e i n s t r u c t i o n s g i v e n b y Snedecor and c o v a r i a n c e  (1956) f o r t  investigation  t e s t s , regression analyses,  analysis.  S a l i n i t y was measured on an e l e c t r i c a l c o n d u c t i v i t y b r i d g e , u s i n g a s a l i n i t y of 31.88 was considered 100$ seawater.  - 9 -  RESULTS  -  1.  Comparison o f Muscle  10  -  Techniques  I t was n e c e s s a r y f i r s t  of a l l  t o d e t e r m i n e w h e t h e r t h e sodium and  p o t a s s i u m v a l u e s o b t a i n e d f r o m t h e two d i f f e r e n t  t y p e s of muscle a n a l y s i s  (ashing  and d i g e s t i o n ) were c o m p a r a b l e , o r w h e t h e r t h e t y p e o f t r e a t m e n t i n t r o d u c e d a systematic  e r r o r w h i c h w o u l d r e n d e r t h e two t r e a t m e n t s n o t s t r i c t l y  comparable.  Sodium and p o t a s s i u m v a l u e s o b t a i n e d i n t h e two t r e a t m e n t s were compared u s i n g a t  test  (Snedecor, 1956),  I n order to avoid differences  c o n t e n t of t h e t i s s u e s , t h e i o n i c weight.  due t o t h e v a r y i n g  water  c o n c e n t r a t i o n s were e x p r e s s e d as m e q » / k g , d r y  The r e s u l t s o f t h i s c o m p a r i s o n a r e p r e s e n t e d i n Table  1,  B o t h t h e sodium and p o t a s s i u m v a l u e s o b t a i n e d b y a s h i n g were  consistently  h i g h e r t h a n t h o s e o b t a i n e d by d i g e s t i o n , a l t h o u g h o n l y t h e p o t a s s i u m v a l u e s were significantly different  (p = < . 0 l ) .  B o t h t h e a s h i n g t e c h n i q u e and t h e  t e c h n i q u e have t h e same l e v e l o f a c c u r a c y , as shown i n T a b l e A l l muscle c a t i o n , c o n c e n t r a t i o n s r e p o r t e d i n t h i s  digestion  2, i n v e s t i g a t i o n were  obtained using the d i g e s t i o n technique,  2.  V a l u e s o f Sodium and P o t a s s i u m i n F r e s h Water P i s h A s e r i e s o f f r e s h w a t e r s t e e l h e a d were sampled t o e s t a b l i s h t h e n o r m a l  c o n c e n t r a t i o n s o f serum and m u s c l e sodium and p o t a s s i u m i n t h i s h y p o t o n i c  environment.  The r e s u l t s were a n a l y z e d i n o r d e r t o e s t i m a t e t h e i n f l u e n c e o f s i z e and sex on the v a r i a b l e s measured. No s i g n i f i c a n t c o r r e l a t i o n was d e m o n s t r a t e d between body w e i g h t i n t h e r a n g e o f 6 0 - 2 0 0 grams and t h e v a r i a b l e s measured. differences  significant  i n b l o o d and muscle v a l u e s be d e m o n s t r a t e d between male ( i m m a t u r e and  m a t u r e ) and f e m a l e f i s h , . fell  Nor c o u l d any  However t h e serum sodium c o n c e n t r a t i o n o f t h e f e m a l e  i n t h e u p p e r l i m i t s o f t h e n o r m a l r a n g e and t h a t o f t h e males i n t h e l o w e r  (Table 1 , A p p e n d i x ) .  fish part  - 11 -  Table 1. A Comparison of the Ashing Technique and the A c i d D i g e s t i o n Technique of Muscle A n a l y s i s * Ionic Concentration i n meq./kg. d r y weight Technique  K  Na  Ashing  43.5 i 1.95 (N == 11)  526 i 11.2 (N = 11)  Acid  39.8 t 1.55 (N == 16)  486 10.7 (N = 16)  t = 1.18 ), > . l  t = 2.60* P^.02,^.01  Digestion  1  Table 2. A Comparison of the P r e c i s i o n of the Ashing Technique and the D i g e s t i o n Technique o f Muscle A n a l y s i s . Technique  Average D e v i a t i o n Prom the Mean Wet Weight  Digestion  .  Dry  Weight  2  K  Na  0.57  2.62  1.63  " 5.70  0.51  2.50  1.56  5.92  Na Ashing  1  Expressed i n meq./kg. wet weight Expressed i n meq./kg. d r y weight  K  Table 3»  Salmo g a i r d n e r i Fresh Water Values of Serum and Muscle E l e c t r o l y t e s January, 1960 Na Mean  Serum meq./L  K SE  N  Na/K  Mean  ± SE  N  ± .14 (13)  150.0  ± 146  (13)  3.24  meq./kg. wet muscle  8.88  ± .32  (16)  109  2.30  meq./kg. dry muscle  39.8  ± 1.5  (16)  486  ± 10.7 (16)  io water content  77.8  i ,15  (24)  Mean  + SE  N  47.8  i 3.4 (13)  12.5  - .5  Muscle  (16)  (16)  Table 4, The E f f e c t o f E x e r c i s e and Temperature on the Ionic Concentrations the Serum and Muscle of Salmo g a i r d n e r i . Muscle  Serum  Treatment Na  in  K  $ H 0 2  Na  K  Exercise  151 t 3 (3)  1.68 1 .3 (3)  77.7 i 3.4 (3)  8.97 i .32 (3)  106 i 2 (3)  Controls  150 i 1 (13)  3.24 - .1 (13)  77.8 i .2 (13)  8.88 i .32 (13)  107 i 2 (13)  P value  >.5  <.01  6 hours a t 2° C  135 i 6 (3)  2.7 i .1 (3)  Controls a t 6° C  134 - 2 (10)  3.46 - .2 (9)  P value  >.5  ^>.5  P<.08,>.02  Ionic concentrations expressed i n meq./L serum, or meq./kg. wet weight i  One standard e r r o r of the mean, (S.E.).  Sample s i z e i s i n d i c a t e d i n parentheses.  - 14 -  I t appears that f o r the purposes of these experiments n e i t h e r sex nor body weight exerted a s i g n i f i c a n t e f f e c t on serum and muscle  electrolytes.  An attempt was made t o evaluate the e f f e c t s of two f a c t o r s , exercise and temperature, which c o u l d p o s s i b l y b i a s the experimental r e s u l t s . for  Pish exercised  30 minutes showed a serum potassium c o n c e n t r a t i o n s i g n i f i c a n t l y lower than the  unexercised c o n t r o l s , although none of the other v a r i a b l e s measured was changed. A s i m i l a r decrease i n serum potassium was recorded f o r f i s h kept a t 2° C. f o r s i x hours (when compared with c o n t r o l s kept a t 6° C « ) , although again none of the other v a r i a b l e s was changed (Table 3 ) .  3.  T r a n s f e r of P i s h to Seawater The response of Salmo g a i r d n e r i a f t e r t r a n s f e r to 60% seawater i s shown  i n F i g u r e s 1 and 2 (and i n Tables 9, 10, and 11 of the Appendix), be d i v i d e d i n t o three d i s t i n c t phases: a c t i v e r e g u l a t i o n ; and (3)  ( l ) a stage of adjustment;  This response (2)  may  a stage of  a stage of e q u i l i b r i u m .  The i n i t i a l adjustment phase, which continued f o r the f i r s t 24 hours, was c h a r a c t e r i z e d by an increase i n the t o t a l c a t i o n c o n c e n t r a t i o n of both blood and muscle* and by a dehydration of the t i s s u e s .  During t h i s p e r i o d the serum and muscle  sodium rose 24% and 125% r e s p e c t i v e l y , while the t i s s u e water and potassium both f e l l 4% below the c o n t r o l v a l u e s .  A l l these changes, w i t h the exception of muscle  potassium, were s i g n i f i c a n t l y d i f f e r e n t from f r e s h water values ( P < » 0 1 ) . T h i s phase of adjustment was f o l l o w e d by a r e g u l a t o r y phase during which time (24-110 hours) the i o n i c balance of the f i s h was returned t o e q u i l i b r i u m . r e g u l a t i o n f i r s t became apparent i n the muscles a f t e r 24 hours i n seawater.  This  It  * T i s s u e concentrations r e f e r r e d t o i n the t e x t w i l l be expressed i n terms of dry t i s s u e weight, since values expressed i n terms of wet weight would be i n f l u e n c e d by the degree of h y d r a t i o n of the t i s s u e s .  F i g u r e 1,  S e r i a l Changes i n Sodium Content of Serum and Muscle After- Transfer to 60% Seawater,  ,,,to f o l l o w page 14  F i g u r e 2»  S e r i a l Changes i n Potassium Content of Serum and Muscle A f t e r Transfer to 60$ Seawater,  •«»»to f o l l o w page 14  - 15 -  c o n s i s t e d of the a c t i v e e x t r u s i o n of sodium accompanied by an a c t i v e accumulation of potassium i n the muscles*  A f t e r 36 hours i n s a l t water the serum sodium value  and the water content of the t i s s u e s s t a r t e d t o r e t u r n t o normal, and appeared to reach an e q u i l i b r i u m a f t e r 110 hours i n s a l t water*  Presumably the f i s h had returned  to a steady osmotic state and a new combination o r balance of r e g u l a t o r y f a c t o r s enabled them to maintain t h i s constant m i l i e u i n t e r i e u r • i n the hypertonic a.  environment,  Changes i n Serum E l e c t r o l y t e s The i n i t i a l increase i n serum sodium represents the inward d i f f u s i o n of  ions with the osmotic g r a d i e n t *  The r e g u l a t o r y processes i n i t i a t e d a f t e r about 36  hours i n s a l t water enabled the animal t o excrete sodium a t the r a t e of 0*41 meq»/liter  't' of serum/hour* Th?" changes observed i n serum potassium were v e r y d i f f i c u l t t o i n t e r p r e t as o n l y f i v e values were s i g n i f i c a n t l y d i f f e r e n t from the f r e s h water c o n t r o l s * Since potassium occurs i n such a low c o n c e n t r a t i o n i n the serum when compared t o sodium, any small e r r o r s i n d i l u t i o n c o u l d s i g n i f i c a n t l y a f f e c t the measurement of potassium but not i n f l u e n c e the measurement of sodium.  For t h i s reason a l i n e a r  r e g r e s s i o n of serum potassium a g a i n s t time i n s a l t water was constructed. The formula so obtained (Y = 3*90 - *0045X ) expresses the r e l a t i o n s h i p between these two v a r i a b l e s .  The slope of -.0045 d i d n o t d i f f e r s i g n i f i c a n t l y from a slope of  zero, i n d i c a t i n g t h a t there was probably no s i g n i f i c a n t change i n serum potassium during the experimental p e r i o d . . The r a t i o of sodium to potassium was c a l c u l a t e d f o r the serum t o determine whether the c a t i o n s v a r i e d independently during the treatment, o r whether they remained p r o p o r t i o n a l t o each other throughout the experimental p e r i o d . sodium/potassium interpret.  Serum  values showed no c l e a r cut trend and hence are very d i f f i c u l t t o  One can say f i r s t t h a t the value of 66, maintained a f t e r 216 hours i n  s a l t water i s s i g n i f i c a n t l y higher than the f r e s h water sodium/potassium  r a t i o (P<^.0l),  - 16 -  and second t h a t although the p r o p o r t i o n of sodium/potassium d i d v a r y considerably, i t was maintained between the l i m i t s of 77 and 38. b.  Changes i n Muscle Cations During the p e r i o d 24-66 hours a f t e r t r a n s f e r to s a l t water, there was  a  l i n e a r d e c l i n e i n the dry muscle sodium c o n c e n t r a t i o n , according to the r e g r e s s i o n I ss 108 - 0.69 X.  T h i s r a t e of sodium l o s s of 0.69 meq./kg. dry weight/hour  h i g h l y s i g n i f i c a n t w i t h a c o r r e l a t i o n c o e f f i c i e n t ( r ) of 0.92.  was  A l s o during 24-96  hours a f t e r t r a n s f e r t o s a l t water there was a r i s e i n muscle potassium according to  the formula I = 434 + 1.24 X.  T h i s r a t e of increase i n muscle potassium of  1.2 meq./kg./hour was a l s o h i g h l y s i g n i f i c a n t ( r = 0.89). of not  Comparison of the r a t e  l o s s of sodium w i t h the r a t e of g a i n of potassium showed t h a t these r a t e s are s i g n i f i c a n t l y d i f f e r e n t (Figure 3)« E x p r e s s i o n of the changes i n muscle sodium and potassium i n terms of f r e s h  weight i n d i c a t e d trends s i m i l a r to those described f o r the d r y weight v a l u e s although the  changes were l e s s dramatic* The r a t i o of potassium to sodium i n the muscle t i s s u e shows a sigmoid  r e l a t i o n when p l o t t e d against time i n seawater (Figure 4)«  Upon t r a n s f e r to seawater  an- increase i n e x t r a c e l l u l a r sodium caused the r a t i o to f a l l from a value of 12 to 5 i n 24 hours, t h e r e a f t e r r i s i n g t o an e q u i l i b r i u m l e v e l a t 110 hours.  The  new  e q u i l i b r i u m value of 10 i s lower than the f r e s h water c o n t r o l although the d i f f e r e n c e i s not s i g n i f i c a n t , (>.50 P < . 1 0 ) . c«  Changes i n Muscle Water Content During the i n i t i a l 36 hours i n s a l t water the t i s s u e water content f e l l  from 77.8 % to 75.0 % .  Thereafter the t i s s u e s slowly regained water u n t i l a new  e q u i l i b r i u m of 76.5 % water content was e s t a b l i s h e d i n the t i s s u e s a f t e r approximately 110 hours i n seawater.  Figure 3#  A Comparison of the Rates of Sodium Loss and Potassium Accumulation i n the Muscle During A c t i v e Regulatory Phase,  ,«to f o l l o w page 16  Figure 4,  K/Na Ratio i n Muscle Tissue During Transfer to Seawater,  • to f o l l o w page 16  K /Na  §h  RATIO  IN  MUSCLE  17  d.  -  Comparison of the E q u i l i b r i u m Values With F r e s h Water F i s h Comparison of these e q u i l i b r i u m values with those of the f r e s h water  c o n t r o l s (Table 5) emphasizes the f a c t t h a t a new established.  T h i s e q u i l i b r i u m was  e q u i l i b r i u m had  c h a r a c t e r i z e d by the f o l l o w i n g :  values only 6% higher than the f r e s h water c o n t r o l s ; (2) concentration tissues.  15% higher than the c o n t r o l s ; and  (3)  indeed been (l)  serum c a t i o n  a dry muscle c a t i o n  a lower water content of  I t i s i n t e r e s t i n g to note t h a t the r e g u l a t o r y process(es) returned  the the  blood ions to a l e v e l only s l i g h t l y higher than the f r e s h water c o n t r o l s , while the c a t i o n content of the wet t i s s u e s was  21% higher than t h a t i n the c o n t r o l s .  - 18 -  Table 5. A Comparison o f the C a t i o n Levels of Serum and Muscle Between Fresh Water C o n t r o l s and F i s h E q u i l i b r a t e d to S a l t Water. Substance  Blood  Variable  K meq /L  3.24  3.29  - 1.5  153  163  + 6.53  Na/K  48  51  + 7.3  >.50  $H 0  77.8  76.7  - 1.4  <.01  Na meq./kg.  40  54  + 35  lfmeq./kg.  486  562  + 16.0  T o t a l Cations  538  614  + 14.1  12.5  10.4  - 16  Na meq./kg.  8.88  12,6  + 42.0  K*"meq./kg.  108.6  131.0  + 20.0  117.5  143  + 21.7  93  + 30  2  +  T o t a l Cations Extracellular space  Probability  160.4  Na/K wet  % Change  150  Total Cations  dry  S a l t Water Equilibrium  Na meq./L e  Muscle  Fresh Water  grams/kgm. wet t i s s u e  61  +  6$  <£.02>.01* >.50  ^1.01 <.01  ** ** **  <i .10 > .05 ^-.01 <.01  ** **  19 -  DISCUSSION  - 20 -  1.  Comparison W i t h V a l u e s R e p o r t e d i n t h e  Literature  The v a l u e s o b t a i n e d i n t h e n o r m a l f r e s h w a t e r f i s h compare w e l l those d e s c r i b e d i n the l i t e r a t u r e salmonid f i s h e s  (Table 6 ) .  for  Salmo g a i r d n e r i and o t h e r c l o s e l y  hormones a r e more a c t i v e t h a n androgens i n p r o m o t i n g sodium r e t e n t i o n 1951).  It  is worthwhile  sex  ( e . g . Gennes  stressing the f a c t t h a t i n a study of  e l e c t r o l y t e m e t a b o l i s m , t h e a g e , sex and p h y s i o l o g i c a l be t a k e n i n t o a c c o u n t ,  related  The o b s e r v a t i o n t h a t t h e serum sodium l e v e l s were h i g h e r  i n the female f i s h i s i n l i n e w i t h the w e l l e s t a b l i s h e d f a c t t h a t female  and B r i c a i r e ,  with,  c o n d i t i o n o f t h e a n i m a l s must  s i n c e t h e v a r i a b i l i t y o b s e r v e d by d i f f e r e n t w o r k e r s i s no  d o u b t r e l a t e d t o one o r more o f t h e s e  factors.  The g e n e r a l p a t t e r n o f a r i s e i n serum e l e c t r o l y t e s d u r i n g t h e f i r s t  36  h o u r s a f t e r t r a n s f e r t o sea w a t e r a,nd t h e g r a d u a l r e t u r n t o a new e q u i l i b r i u m w h i c h i s r e a c h e d a f t e r a b o u t 100 h o u r s i n t h i s h y p e r t o n i c medium, a g r e e s w i t h r e s u l t s  of  Koch ( 1 9 5 9 ) , Gordon (1959) and H o u s t o n ( i 9 6 0 ) , as shown i n T a b l e 7. The o b s e r v a t i o n t h a t t h e muscle p o t a s s i u m c o n t e n t of t h e f i s h t o s e a w a t e r r e m a i n s a t a l e v e l 15% h i g h e r t h a n t h e f r e s h w a t e r c o n t r o l s w i t h t h e f i n d i n g s o f Gordon ( o p . c i t . )  equilibrated is at  who r e p o r t e d t h a t t h e muscle p o t a s s i u m  variance after  240 h o u r s i n s e a w a t e r had r e t u r n e d t o t h e f r e s h w a t e r v a l u e .  2,  R e g u l a t i o n o f Serum C a t i o n s The s t e e l h e a d t r o u t s u r v i v e s w e l l when t r a n s f e r r e d t o 60% s e a w a t e r .  examine i t s c o n d i t i o n when a s t e a d y s t a t e has been r e a c h e d , t h a t i s 110 h o u r s transfer,  I f we after  t h e n we see t h a t t h e f i s h has p r o g r e s s e d i n some degree t o w a r d s t h e  characteristics  o f a marine f i s h  (Prosser,  1950).  Thus, t h e c o n c e n t r a t i o n of  sodium  i n t h e b l o o d i s somewhat e l e v a t e d above t h a t f o u n d i n t h e f r e s h w a t e r f i s h , w h i l e potassium c o n c e n t r a t i o n remains v i r t u a l l y unchanged.  I n t h e t i s s u e s , as r e p r e s e n t e d  b y m u s c l e , t h e w a t e r c o n t e n t has d e c r e a s e d i n t h e s e a w a t e r phase compared w i t h i n the f r e s h water s t a t e .  the  that  A t t h e same t i m e b o t h t h e amount o f sodium and p o t a s s i u m  Table 6* A Comparison of Sodium and Potassium Concentrations i n Serum and Muscle of Salmonid Pish Sampled i n Fresh Water,  Date Sampled  Species  Author  2  3.24  162,5  6.04  Houston (1959)  Fresh Water  155  5.0  P h i l l i p s and Brockway (1958)  Fresh Water 10°C  147  2.4  9.0 spring  Sept-April Fresh Water Breeding Season 20°C  148  4.2  144  8.93  January  Salmo g a i r d n e r i  January  Salmo t r u t t a  Summer  Salmo t r u t t a  Sept-April  Fresh Water  Salmo t r u t t a Oncorhyncus  Muscle meq./kg. wet muscle $H 0 Na K  150  Salmo g a i r d n e r i  Salmo t r u t t a  Treatment  Serum meq./L Na K-  77.8  J u v e n i l e s catadromous migrants  8.8  109  This  investigation  138.2  Gordon (1959)  14.4  143  Gordon (1959)  17.2  122  Spalding (1956)  10.3  123  McLeod (1958)  Table 7. A~ Comparison of Sodium and Potassium Concentrations i n Serum and Muscle of Salmonid P i s h E q u i l i b r a t e d to Sea Water, Salmo g a i r d n e r i  Salmo t r u t t a  January  Sept-April  Breeding Season  Salmo s a l a r  110 hours i n 60$ Seawater 10°C  160  2.8  240 hours i n 50$ SeaWater 20°C  162  3.8  240 hours i n 50$ Seawater 20°C  Downstream Migrants 110 hours i n f u l l Sea- 170 Water 6.3°C  76  14  125  This  investigation  9.7  141  Gordon (1959)  18 Koch and Evans (1959)  - 22 -  f o u n d i n w e t samples o f m u s c l e i s g r e a t e r when t h e t r o u t  i s i n a h y p e r t o n i c medium.  We know t h a t on t r a n s f e r t o s e a w a t e r t h e f i s h t a k e s s e a w a t e r i n t o (Smith, 1930).  The g u t mucosa, a l t h o u g h c a p a b l e o f some d i s c r i m i n a t i o n ,  a l l o w s sodium c h l o r i d e t o pass i n t o t h e body f l u i d s  its  gut  nevertheless  i n a c o n c e n t r a t i o n o f 287 m e q . / L .  T h i s i n g e s t i o n o f s e a w a t e r i s r e s p o n s i b l e f o r t h e r i s e i n t h e serum sodium d u r i n g the f i r s t  twenty f o u r hours i n seawater.  Nevertheless, the i n i t i a t i o n of  a c t i v e t r a n s p o r t mechanisms e n a b l e t h e a n i m a l t o r i d i t s e l f  o f t h e excess  additional ions,  and e v e n t u a l l y a t e q u i l i b r i u m t o m a i n t a i n an i n t e r n a l c o n c e n t r a t i o n o f 160 m e q . / L a g a i n s t an e x t e r n a l medium c o n t a i n i n g some 287 m e q . / L .  The w o r k o f S m i t h  (1930),  Keys ( 1 9 3 2 ) , K r o g h ( 1 9 3 9 ) and Holmes ( 1 9 5 9 ) , have d e m o n s t r a t e d t h a t t h e g i l l s t h e s i t e of t h i s a c t i v e e x c r e t i o n o f I n t r u e marine f i s h , b l o o d does n o t d i f f e r (Prosser,  1950).  concentration after  sodium.  s t e n o h a l i n e t o s e a w a t e r , t h e p o t a s s i u m c o n t e n t of  s i g n i f i c a n t l y from t h a t i n f r e s h water stenohaline  So i t  g r e a t l y from the  the  species  i s i n t h e case o f t h i s e u r y h a l i n e t r o u t w h e r e i n t h e  110 h o u r s i n s e a w a t e r d i d n o t d i f f e r  water c o n t r o l f i g u r e s .  are  potassium  fresh  S i n c e K r o g h ( 1 9 3 9 ) d e m o n s t r a t e d t h a t t h e g i l l membranes o f  t h e g o l d f i s h were u n a b l e t o t r a n s p o r t p o t a s s i u m i o n a g a i n s t a c o n c e n t r a t i o n  gradient,  w h i l e sodium and c h l o r i d e i o n s were t r a n s p o r t e d w i t h e a s e , we a r e j u s t i f i e d  in  assigning the r e g u l a t i o n of potassium to the kidney.  I n mammalian p h y s i o l o g y ,  c u r r e n t c o n c e p t o f r e n a l r e g u l a t i o n of p o t a s s i u m i n v o l v e s t h r e e p r i n c i p l e s ; t h r o u g h the g l o m e r u l u s , complete o b l i g a t o r y r e - a b s o r p t i o n i n the p r o x i m a l and r e s e c r e t i o n b y d i s t a l t u b u l e s ,  the  filtration  tubules  i n a c c o r d a n c e w i t h t h e needs o f t h e a n i m a l .  It  i s p o s t u l a t e d t h a t t h e r e e x i s t s in. t h e d i s t a l t u b u l e some exchange mechanism whereby a sodium i o n i s r o t a t e d i n t o t h e t u b u l e c e l l f o r 1958).  every potassium i o n secreted  (Mudge,  The h o r m o n a l c o n t r o l o f r e n a l f u n c t i o n i s b y no means w e l l u n d e r s t o o d ,  i t has been o b s e r v e d t h a t m i n e r a l o c o r t i c o i d s  i n c r e a s e u r i n a r y p o t a s s i u m , and a t  but the  same t i m e d e c r e a s e t h e c o n c e n t r a t i o n s o f t h i s c a t i o n i n t h e body f l u i d s and t i s s u e s . , .  - 23 -  It  i s p o s t u l a t e d t h a t t h e s e hormones f a c i l i t a t e  i n the d i s t a l convoluted  the a c t i v e s e c r e t i o n of  potassium  tubule.  This a c t i v e e x c r e t i o n of potassium i n the f i s h e q u i l i b r a t e d t o  seawater  i s c o n s i s t e n t w i t h t h e enhanced oxygen c o n s u m p t i o n o b s e r v e d i n t h e k i d n e y  of  Salmo c l a r k i c l a r k i s i m i l a r l y a d a p t e d t o 60% s e a w a t e r ,  I960).  (Holmes and S t o t t ,  I t appears t h e n , t h a t r e n a l e x c r e t i o n o f potassium i o n s accounts f o r t h e  maintenance  of a r e l a t i v e l y constant potassium c o n c e n t r a t i o n i n the b l o o d , despite the i o n i c c o n t e n t of the  3+  Changes i n Muscle  varying  serum,  Cations  I n o r d e r t o i n t e r p r e t t h e changes o b s e r v e d i n t h e muscle t i s s u e , first  consider the c o n s t i t u e n t p a r t s of t h i s t i s s u e .  any a n a l y s i s  o f m u s c l e e l e c t r o l y t e ? must t a k e i n t o a c c o u n t t h e two  i n t o which a l l  t i s s u e s are d i v i d e d ; v i z the e x t r a c e l l u l a r +  space.  A c c o r d i n g t o Manery  I t has l o n g been e s t a b l i s h e d t h a t Na  cells.  in their distribution,  Studies w i t h radioactive  this electrolyte  inequality,  for  compartments  space and t h e  are  intracellular  and t h a t K  predominantly  HI and P 0 ,  are found i n s i d e  the  sodium have c o n t r i b u t e d t o our u n d e r s t a n d i n g it  The p r e s e n t c o n c e p t o f t h e c e l l  +  present w i t h i n  f l u i d diffuses  into the  +  the  on t h e o t h e r h a n d , t e n d s t o d i f f u s e  t h e c e l l w i t h t h e c o n c e n t r a t i o n g r a d i e n t b u t i s pumped b a c k i n t o t h e  the  out  of  cellular  compartment a t a r a t e w h i c h m a i n t a i n s a h i g h i n t r a c e l l u l a r K c o n c e n t r a t i o n .  The  a c t u a l mechanism o f t r a n s p o r t a c r o s s t h e c e l l membrane i s o b s c u r e , b u t t h e f a c t it  is  cell,  b u t i s j u s t as r a p i d l y removed b y an a c t i v e p r o c e s s , w i t h t h e n e t r e s u l t t h a t K ,  is  +  i s one o f a dynamic e q u i l i b r i u m ; Na w h i c h  present i n a high concentration i n the e x t r a c e l l u l a r  c e l l s c o n t a i n v i r t u a l l y no s o d i u m .  of  has been d e m o n s t r a t e d t h a t r a d i o a c t i v e N a  permeable t o t h e c e l l membrane and w i l l r e p l a c e u n l a b e l l e d N a cell.  (1954)  1 and C I  + extracellular  one must  that  i s i n h i b i t e d b y c e r t a i n m e t a b o l i c p o i s o n s and t h e r e c e n t i s o l a t i o n o f ATPase f r o m  - 24 -  t h e c e l l membrane shows t h a t i t  is  i n d e e d d e p e n d e n t on m e t a b o l i c  K e e p i n g i n m i n d t h a t muscle t i s s u e space w h e r e i n 99% o f t h e K  +  i s composed o f l )  i s l o c a t e d ; and 2 )  e s s e n t i a l l y a plasma u l t r a f i l t r a t e  rise  an  the e x t r a c e l l u l a r  intracellular space w h i c h  is  c o n t a i n i n g 99% o f t h e t o t a l muscle N a , we can +  c o n s i d e r t h e movements o f i o n s i n t h e muscle a f t e r t r a n s f e r The i n i t i a l  processes.  to  i n serum sodium r e s u l t e d i n a more  seawater. concentrated  e x t r a c e l l u l a r f l u i d (ECF) and p o s s i b l y t h e d i f f u s i o n o f some sodium i n t o t h e c e l l s *  This  i n c r e a s e i n o s m o t i c p r e s s u r e o f t h e HGF t e n d e d t o d e h y d r a t e t h e c e l l s and some K appeared t o l e a v e the c e l l s , presumably w i t h the osmotic w a t e r .  Active  o f t h e t i s s u e e l e c t r o l y t e s commenced t w e n t y - f i v e h o u r s a f t e r t r a n s f e r ,  +  regulation the  sodium  b e i n g removed a t a r a t e o f 0 . 6 9 m e q . / K g , d r y m u s c l e / h o u r and t h e K b e i n g d e p o s i t e d t h e muscle a t a r a t e o f 1.24 m e q / k g . / h o u r ,  (Figure 3 ) .  The r e m o v a l of Na may be  i n t e r p r e t e d as a c o m b i n a t i o n o f t h e i n i t i a t i o n o f t h e N a the g i l l s  in  +  e x c r e t o r y mechanisms  in  o r t h e k i d n e y , t h u s d e c r e a s i n g t h e Na c o n c e n t r a t i o n o f t h e MSFj; and  p o s s i b l y o f t h e a c t i o n o f a pump w h i c h removed any e x c e s s sodium f r o m t h e muscle cells.  The a c c u m u l a t i o n o f K can o n l y be e x p l a i n e d b y t h e p r e s e n c e o f an a c t i v e  t r a n s p o r t mechanism w h i c h c a r r i e s t h e K  +  i n t o the c e l l .  r e s p o n s i b l e f o r t h e r e m o v a l o f Na f r o m t h e c e l l conclusive proof that Na  +  Whether t h i s pump i s  i s q u e s t i o n a b l e f o r we have no  a c t u a l l y accumulates i n the c e l l s or whether the  initial  i n c r e a s e i n m u s c l e sodium m e r e l y r e p r e s e n t s a more c o n c e n t r a t e d e x t r a c e l l u l a r It  is  fluid.  i m p o s s i b l e t o d e s c r i b e a c c u r a t e l y t h e mode o f a c t i o n o f t h e K pump,  or to determine whether i t  i s l i n k e d w i t h t h e t r a n s p o r t o f Na o u t o f t h e  w i t h o u t a knowledge o f t h e d i s t r i b u t i o n o f t h e two c a t i o n s between t h e and e x t r a c e l l u l a r i n the muscle.  also  compartments.  L e t us c o n s i d e r f i r s t  of a l l  cell,  intracellular  the d i s t r i b u t i o n of K  S i n c e t h e serum K, and t h e r e f o r e t h e i n t e r s t i t i a l  f l u i d , d i d not  change a p p r e c i a b l y d u r i n g t r a n s f e r t o s e a w a t e r , we may be c o n f i d e n t t h a t any i n c r e a s e i n t h e t o t a l muscle K r e p r e s e n t e d an i n c r e a s e i n t h e i n t r a c e l l u l a r of t h i s  cation.  concentration  - 25  The d i s t r i b u t i o n o f sodium on t h e o t h e r hand c a n n o t be determined from the d a t a a v a i l a b l e .  definitely  C o n s i d e r i n g t h e o b s e r v a t i o n t h a t y e a s t and  f r o g m u s c l e c e l l s have been shown t o a c c u m u l a t e Na when p l a c e d i n m e d i a h a v i n g a h i g h Na c o n c e n t r a t i o n  (Steinbach, 1954), i t  i s r e a s o n a b l e t o assume t h a t a 30$  i n c r e a s e i n t h e e x t r a c e l l u l a r Na c o n c e n t r a t i o n w o u l d r e s u l t t h e i n t r a c e l l u l a r Na c o n c e n t r a t i o n d u r i n g t h e i n i t i a l  i n a net increase  a d j u s t i v e phase.  in  Secondly  a c o n s i d e r a t i o n of t h e muscle c a t i o n c o n c e n t r a t i o n s f u r t h e r c l a r i f i e s t h e  situation.  A t e q u i l i b r i u m t h e m u s c l e t i s s u e c o n t a i n s 23 and 7 6 $ more K and Na r e s p e c t i v e l y  than  the f r e s h water animals.  in  We w o u l d assume " a p r i o r i " t h a t such a l a r g e i n c r e a s e  i n t r a c e l l u l a r K must be accompanied b y a p r o p o r t i o n a t e i n order t o m a i n t a i n the e l e c t r o l y t e That the further  intracellular  increase i n c e l l u l a r  balance b a s i c t o a l l b i o l o g i c a l  sodium  processes.  sodium c o n c e n t r a t i o n i s h i g h e r i n t h e s e a w a t e r a n i m a l  is  s u p p o r t e d b y a c o n s i d e r a t i o n o f t h e e x t r a c e l l u l a r volume i n t h e two m e d i a . The s i m p l e f o r m u l a : ECS Na  where  ECS  Nar «ig  X  M r  (Manery,  s Na  = t h e volume o f t h e e x t r a c e l l u l a r a l l t h e muscle sodium i s l o c a t e d  Na  s  1954)  s p a c e , based on t h e a s s u m p t i o n  that  extracellularly  = serum sodium c o n c e n t r a t i o n i n m e q . / L  Na ^  = total  sodium c o n c e n t r a t i o n i n m u s c l e i n m e q . / k g . w e t  rNa  = . 9 5 (Donnan f a c t o r )  HgO-  = gms. H ^ O / k g . serum  100 (assuming a s p e c i f i c  approximate e s t i m a t i o n of the e x t r a c e l l u l a r  g r a v i t y of l )  r e p r e s e n t a t i v e o f an a n i m a l w h i c h i s i n e q u i l i b r i u m w i t h i t s  above f o r m u l a , ECS  14_ 160  x  1000 .95  110 h o u r s as  e n v i r o n m e n t and  serum and m u s c l e sodium o b t a i n e d a t t h i s t i m e i n t h e  then =  g i v e s an  volume  C o n s i d e r i n g t h e f i s h w h i c h have been i n sea w a t e r f o r  s u b s t i t u t i n g the values f o r  tissue  =  92 g / k g . w e t muscle  - 26 -  S i m i l a r l y f o r the f r e s h water ECS _ 8 . 8 Y5o _  fish  1000 _ —95"  ...  , g/kgs wet muscle  T h e r e f o r e , i t w o u l d appear t h a t t h e e x t r a c e l l u l a r  space o f t h e  equilibrated  s e a w a t e r f i s h i s a p p r o x i m a t e l y 30% g r e a t e r t h a n t h e f r e s h w a t e r v a l u e . the assumption t h a t a l l  the N a  +  i s d i s t r i b u t e d i n the e x t r a c e l l u l a r  i s u n t r u e , then a r e a l increase i n the i n t r a c e l l u l a r  intracellular  account  fish*  seems most l i k e l y t h a t Na d i f f u s e s  compartment d u r i n g t h e f i r s t  however,  compartment  sodium must i n p a r t  f o r t h e i n c r e a s e i n t h e t o t a l muscle sodium o f t h e e q u i l i b r a t e d I n view o f t h i s evidence i t  If,  into  t w e n t y - f i v e hours i n seawater.  the  The  o n s e t o f r e g u l a t i o n i s marked by t h e a b i l i t y o f t h e c e l l s t o pump o u t some o f excess s o d i u m , and t r a n s p o r t K  +  i n t o the c e l l s .  Covariance a n a l y s i s  showed t h a t  t h e r a t e s a t w h i c h t h e s e two i o n s moved i n l a n d o u t o f t h e m u s c l e do n o t s i g n i f i c a n t l y f r o m one a n o t h e r  (P/L 25 T  )  >,10),  the  differ  and we may t h e r e f o r e p o s t u l a t e  t h e movement o f t h e s e i o n s i n o p p o s i t e d i r e c t i o n s  that  i s c o n t r o l l e d by t h e same t r a n s p o r t  mechanism.  4.  P o s s i b l e R e g u l a t o r y Mechanisms S i n c e t w e n t y - f o u r h o u r s e l a p s e d between t h e t r a n s f e r o f S t e e l h e a d  trout  t o s e a w a t e r and t h e i n i t i a t i o n o f r e g u l a t o r y p r o c e s s e s , we may i n f e r t h a t t h i s r e t u r n t o o s m o t i c e q u i l i b r i u m was p o s s i b l y u n d e r hormonal c o n t r o l . j u s t i f i e d i n considering c e r t a i n endocrine organs, a l b e i t  We a r e  of u n c e r t a i n  i m p o r t a n c e , and t h e i r p o s s i b l e p a r t i c i p a t i o n i n t h e a d a p t a t i o n o f t h i s t e l e o s t to s a l t water. interrenal  slow  then  osmoregulatory euryhaline  The e s t a b l i s h e d a c t i o n o f t h e hormones p r o d u c e d b y t h e  t i s s u e , t h e t h y r o i d , and t h e n e u r o h y p o p h y s i s w i l l be d i s c u s s e d i n  of the data obtained i n t h i s  investigation.  light  - 27 -  It  is d i f f i c u l t  t o d e t e r m i n e w h e t h e r t h e hormones of t h e  a r e a c t i v e i n t h e a d a p t a t i o n o f t h i s a n i m a l t o sea w a t e r .  interrenal  The d e c r e a s e i n sodium  c o n t e n t o f t h e serum and m u s c l e s and i n c r e a s e i n t h e muscle p o t a s s i u m  concentration  r e c o r d e d d u r i n g t h e r e g u l a t o r y p h a s e , r e s e m b l e t h e changes o b s e r v e d a f t e r or during adrenal i n s u f f i c i e n c y i n higher vertebrates  adrenalectomy  ( C h e s t e r J o n e s , 1957)-.  i f we c h a r a c t e r i z e t h e r e g u l a t o r y mechanisms as i n i t i a t i n g t h e e x c r e t i o n o f f r o m t h e m u s c l e c e l l s and a l s o f r o m t h e g i l l c o r t i c o i d s as p o s s i b l e r e g u l a t o r s , f o r  e x c r e t i o n o f sodium i n t h e s a l t l o a d e d Salmo g a i r d n e r i  (Holmes, 1 9 5 9 ) .  and d e c r e a s e i n t h e p o t a s s i u m c o n t e n t o f t h e m u s c l e s o f Salmo t r u t t a changes w h i c h a r e o p p o s i t e t o t h o s e d e s c r i b e d i n t h i s  transfer to  investigation.  i n t e r r e n a l g l a n d , a r e more a b l e t o  seawater t h a n nonr-smolting f i s h ,  On t h e  t o l e r a n c e of any e u r y h a l i n e  sodium  (Spalding,  1956),  Although withstand  ( K o c h , 1959j H o u s t o n , 1 9 5 9 ;  I 9 6 0 ) , i t has y e t t o be d e m o n s t r a t e d t h a t a d r e n o — c o r t i c o i d s  adreno-  extrarenal  o t h e r h a n d , i n j e c t i o n s o f t h e same hormone (DOC) caused an i n c r e a s e i n t h e  s m o l t i n g f i s h w h i c h have an a c t i v e  sodium  e p i t h e l i u m , we must i n c l u d e t h e  i n v i v o t r e a t m e n t w i t h DOC p r o m o t e s  However,  increase the  Olivereau, salinity  fish.  The t h y r o i d a p p e a r s t o p l a y an i m p o r t a n t p a r t i n e n a b l i n g t h e s u r v i v a l euryhaline f i s h i n s a l t water.  Hickman (1959) has c o r r e l a t e d t h e h i g h e r  r a t e of the e u r y h a l i n e s t a r r y f l o u n d e r thyroid a c t i v i t y i n s a l t water.  (Platyichthyes stellatus)  metabolic  w i t h an i n c r e a s e d  He s u g g e s t s t h a t i t r e q u i r e s more e n e r g y t o pump  o u t e x c e s s i o n s , as i s n e c e s s a r y i n s e a w a t e r , occurs i n f r e s h water t e l e o s t s .  of  t h a n to produce a h y p o t o n i c u r i n e ,  The r e s u l t s o f t h i s  i n v e s t i g a t i o n seem t o  h i s f i n d i n g s because t h e a c t i v e t r a n s p o r t mechanisms i n i t i a t e d d u r i n g t h e phase w o u l d c e r t a i n l y r e q u i r e a d d i t i o n a l m e t a b o l i c  corroborate regulatory  energy.  I n mammals t h e p o s t e r i o r p i t u i t a r y hormone v a s o p r e s s i n i n f l u e n c e s w a t e r - e l e c t r o l y t e metabolism i n two ways,  First,  as  i t has an a n t i - d i u r e t i c  the  action,  p r o m o t i n g r e e . b s o r p t i o n o f w a t e r f r o m t h e k i d n e y t u b u l e , and s e c o n d , i t p r o m o t e s  the  - 28 -  r e n a l e x c r e t i o n o f t h e sodium i o n .  Although a l l a v a i l a b l e evidence i n d i c a t e s  t h e hormones o f t h e n e u r o h y p o p h y s i s a r e i m p o r t a n t i n t h e a d a p t a t i o n o f t e l e o s t s to s a l t water  eurybaline  ( A r v y and Grabe, 1 9 5 4 ; F r i d b e r g , 1 9 5 9 ; W e i s e l , 1 9 5 8 ) ,  r e s u l t s o f F o n t a i n e and R a f f y one of w a t e r r e t e n t i o n .  the  (1950) i n d i c a t e t h a t t h i s a c t i o n i s c e r t a i n l y  The r e s u l t s o b t a i n e d i n t h i s  that  not  investigation indicate  that  w a t e r r e t e n t i o n i s s e c o n d a r y t o t h e r e m o v a l o f excess sodium f r o m t h e body t i s s u e s and f l u i d s ,  as t h e t i s s u e w a t e r c o n t e n t s t a r t e d t o r i s e o n l y a f t e r t h e  e x c r e t i o n o f sodium was i n i t i a t e d .  The absence o f an a n t i - d i u r e t i c  v e r t e b r a t e s i s i n l i n e w i t h the suggestion of H e l l e r  active  action in  ( 1 9 5 6 ) and Sawyer (1956)  aquatic that  t h e d e v e l o p m e n t of w a t e r r e t a i n i n g mechanisms, as f o u n d i n a m p h i b i a n s and h i g h e r vertebrates, It  i s associated w i t h the a d a p t a t i o n of animals t o a t e r r e s t r i a l  is possible i n primitive vertebrates,  such as t h e t e l e o s t f i s h ,  n e u r o h y p o p h y s e a l hormones e x e r t t h e i r e f f e c t  that  the  o n l y on e l e c t r o l y t e b a l a n c e ,  (1959) has i s o l a t e d a f r a c t i o n , n a t r i f e r i n , f r o m t e l e o s t n e u r o h y p o p h y s i s p r o m o t e s t h e passage o f sodium t h r o u g h i s o l a t e d f r o g s k i n . to investigate the e f f e c t of  I t w o u l d be  o f n a t r i f e r i n and o x y t o c i n on t h e e x t r a r e n a l  life.  Maeta which interesting  excretion  sodium. I t t h u s a p p e a r s t h a t t h e o s m o r e g u l a t o r y mechanisms w h i c h f a c i l i t a t e  o f e u r y h a l i n e f i s h i n s a l t w a t e r a r e h o r m o n a l i n n a t u r e and e n a b l e t h e a n i m a l  survival to  pump o u t excess sodium w h i c h w o u l d o t h e r w i s e a c c u m u l a t e i n t h e t i s s u e s and body fluids.  The e v i d e n c e i n d i c a t e s t h a t t h e p o s t e r i o r p i t u i t a r y hormones accompanied by  an i n c r e a s e i n t h y r o i d a c t i v i t y a r e r e s p o n s i b l e f o r t h i s a d a p t a t i o n . i n t e r r e n a l hormones has y e t t o be d e m o n s t r a t e d .  The r o l e  of  - 29 -  SUMMARY  1,  C a t i o n concentrations for  serum:  of Steelhead t r o u t i n f r e s h water were found to be:  150 meq. 3,24 meq.  f o r muscle:  Na /litre +  K /litre +  8.8 meq, Na /kg« +  w  e  t tissue  109 meq, K / k g . wet t i s s u e +  and a t i s s u e water content of 77,8$,  2,  Upon t r a n s f e r t o 60$ seawater, the increase i n the sodium content of the serum  and muscle t i s s u e , was accompanied by a dehydration of the t i s s u e s during the f i r s t twenty-four hours a f t e r t r a n s f e r .  3,  The r e g u l a t o r y processes, i n i t i a t e d a f t e r twenty-four hours i n seawater, enabled  the  animal to excrete excess sodium ions from the blood and from the  compartments  intracellular  I t i s suggested t h a t a c t i v e t r a n s p o r t mechanisms m o b i l i z e d i n the g i l l s  and i n the muscle c e l l s enabled the removal of the excess c a t i o n s ,  4,  Since the e x c r e t i o n o f sodium from the muscle c e l l s was accompanied by an a c t i v e  d e p o s i t i o n of potassium i n the i n t r a c e l l u l a r  compartment, i t i s proposed that an  a c t i v e c a t i o n exchange mechanism was a c t i n g a t the membranes of these cells,  5*  A f t e r 110 hours i n seawater, the f i s h were returned t o a new e q u i l i b r i u m which  was c h a r a c t e r i z e d by: water f i s h , 2) and 3)  l)  a serum c a t i o n c o n c e n t r a t i o n only 6$ higher than the f r e s h  a muscle c a t i o n c o n c e n t r a t i o n 15$ higher than the f r e s h water f i s h ,  a t i s s u e water content lower than that of f r e s h water f i s h .  - 30 -  Although  the serum concentrations d i f f e r e d only s l i g h t l y from the f r e s h  water c o n t r o l s , the increased e l e c t r o l y t e c o n c e n t r a t i o n i n the t i s s u e s decreased the c o n c e n t r a t i o n g r a d i e n t between the e x t e r n a l environment and the c e l l u l a r compartment, thus decreasing the osmotic  6.  i n f l u x of i o n s .  The serum potassium values d i d not vary s i g n i f i c a n t l y during the treatment,  presumably due t o the e f f i c i e n t r e n a l e x c r e t i o n of t h i s i o n .  7*  The p o s s i b l e r o l e of the hormones of the t h y r o i d gland, the neurohypophysis  and the i n t e r r e n a l t i s s u e i n the i n i t i a t i o n and continuance  of the r e g u l a t o r y  mechanisms enabling the s u r v i v a l of t h i s euryhaline f i s h i n seawater are considered.  - 31  -  LITERATURE CITED  Black, V.So  1957© E x c r e t i o n and Osmoregulation Academic Press, New York.  i n The Physiology of F i s h e s .  Chester Jones, I . 1956. The Role of the Adrenal i n the C o n t r o l of Water and S a l t E l e c t r o l y t e Metabolism i n V e r t e b r a t e s . Man S o c E n d o c r i n . 5} 102-124, 0  1957.  The Adrenal Cortex.  Cambridge U n i v e r s i t y P r e s s .  Edwards, C. and E . J . H a r r i s . 1957. F a c t o r s I n f l u e n c i n g the Sodium Movement i n Frog Muscle With a D i s c u s s i o n of the Mechanism of Sodium Movement. J . P h y s i o l . 135 ( 3 ) : 567-580. Enami, M.  1959. The Morphology and F u n c t i o n a l S i g n i f i c a n c e of the Caudal Neurosecretory System of P i s h . In Comparative Endocrinology. Wiley Inc. New York.  Fontaine, M. and A, R a f f y . l e s Teleosteens.  1950. Le Facteur hypophysaire de Retention d*eau ehez C.R. Soc. B i o l . , P a r i s 144: 6-7.  and Hatey, J , 1952. On the L e v e l of 17 hydroxyketosteroids i n Salmon plasma, (Salmo s a l a r ) . J , C l i n , E n d o c r i n o l , and Metab. 12: 519-526. and Leloup-Hatey, J . 1959. Evidence of C o r t i c o s t e r o i d s i n the I n t e r r e n a l of a T e l e o s t (Salmo s a l a r ) . J . de P h y s i o l . 51.(3): 468-469. Ford, P e t e r . 1959. Some Observations on the Corpuscles of Stannius i n Comparative Endocrinology. John Wiley Inc., New York. F r i d b e r g , G. and R. Olsson.. 1959. Praeoptico-hypophyseal System (PHS), Nucleus t e b e r i s l a t e r a l i s (NTL) and Subcommisural Organ of Gasterosteus aculeatus a f t e r Changes i n Osmotic S t i m u l i . Z. Z e l l f o r s c h . 49: 531-540. de Gennes,  and H. B r i c a i r e .  1951.  Congr. Med.  Inr.  E v i a n 3_.  Gordon, M.S. 1959. Ionic R e g u l a t i o n i n the Brown Trout (Salmo t r u t t a L). Z o o l . 36 ( 2 ) : 227-252.  J . Exp.  H e l l e r , H.  1941. The D i s t r i b u t i o n of the P i t u i t a r y A n t i d i u r e t i c Hormone Throughout the Vertebrate S e r i e s . J . P h y s i o l . 99: 246-256.  H e l l e r , H.  1956. Water and S a l t E l e c t r o l y t e Metabolism Soc. E n d o c r i n o l . _ 5 : 25-43.  H e r r i n g , P.T.  1915.  Quart. J . Exp. P h y s i o l . 8:  Hickman, C.P., J r . 1959. The Osmoregulatory Flounder ( P l a t y i c h t h y s s t e l l a t u s ) .  i n Higher V e r t e b r a t e s .  Mem.  245.  Role of the Thyroid Gland i n the S t a r r y Can. J . Z o o l . 37: 997-1060.  Holmes, W.N. 1959. Studies on the Hormonal C o n t r o l of Sodium Metabolism i n the Rainbow T r o u t , Salmo g a i r d n e r i . A c t a E n d o c r i n o l . 31.: 587-602. 1960. E f f e c t of Various Hormones on Kidney R e s p i r a t i o n Rates i n the Cutthroat Trout, Salmo c l a r k i c l a r k i . A c t a E n d o c r i n o l . 33: 428-436. and G.H. S t o t t . 1960. Studies on the R e s p i r a t o r y Rates of E x c r e t o r y Tissues i n the Cutthroat Trout, Salmo c l a r k i c l a r k i . P h y s i o l . Z o o l . 32: 15-20, Houston, A.H. 1959, Osmoregulatory Adaptation of Steelhead Trout, Salmo g a i r d n e r i r i c h a r d s o n . to Sea Water. Can. J . Z o o l , 37: 729-748. Houston, A.H. I960. V a r i a t i o n s i n Plasma C h l o r i d e i n Hatchery Reared A t l a n t i c Salmon During Part-smolt Transformation and During Transfer to Sea Water; Nature 185: 632. Keys, A n c e l . 1931, C h l o r i d e S e c r e t i n g C e l l s i n the G i l l s of F i s h e s With S p e c i a l Reference to the Common E e l , J . P h y s i o l . 26: 368-377. Koch, H.J., J.C. Evans and E, Bergstrom, 1959. Sodium Regulation of P a r r and Smolt Stages of A t l a n t i c Salmon, Salmo s a l a r . Nature 184? 283. Krogh, A,  1939.  Osmotic R e g u l a t i o n i n Aquatic Animals.  Cambridge U n i v e r s i t y Press<,  MacLeod, R.A., R.E.E. Jonas and J.R. McBride. 1958, V a r i a t i o n s i n the Sodium and Potassium Content of the Muscle Tissue of P a c i f i c Salmon w i t h P a r t i c u l a r Reference to M i g r a t i o n . Can, J . B i o c h . 36: 1257-J.268. Maetz, J . , F. Morel and Lahlouh. 1959, N a t r i f e r i n : the Neurohypophysis of C e r t a i n V e r t e b r a t e s . Manery, J . F .  1954.  Water and E l e c t r o l y t e Metabolism.  Mudge, G.H,  1958.  The Kidney and Potassium.  N i c o l , J.A.  1960.  The B i o l o g y of Marine Animals.  A New Hormonal P r i n c i p l e i n Nature 184(16): 1236-1237. P h y s i o l . Rev. 34:  B u l l . N.T. Acad. Med. 34: Pitman and Sons, L t d .  334-417, 152-162. London.  O l i v e r e a u , M. I960, Etude volumetrique de l ' i n t e r r e n a l a n t e r i e u r au cours de l a s m o l t i f i c a t i o n de Salmo s a l a r L« A c t a E n d o c r i n . 33; 142-156. P h i l l i p s , A.M. and D.R. Brockway. 1958, Blood. Progr, F i s h . C u l t , 20:  The Inorganic Composition o f Brown Trout 58-61.  P h i l l i p s , J.G., W.N. Holmes and P.K. Bondy. 1959. A d r e n o c o r t i c o s t e r o i d s i n Salmon Plasma, (Oncorhyncus nerka). E n d o c r i n . 65 ( 5 ) : 811-817, and P,J. Mulrow, 1959. C o r t i c o s t e r o i d Production i n v i t r o by the I n t e r r e n a l Tissue of the K i l l i f i s h , Fundulus h e t e r o c l i t u s L i n n , Proc, Soc. Exp. B i o l , and Med, 101: 262-264, P i c k f o r d , G.E, 1953. A Study of the Hypophosectomized Male K i l l i f i s h , Fundulus h e t e r o c l i t u s . B u l l . Bingham Oceanogr. C o l l . 14 ( 2 ) : 5-41.  - 33 -  Prosser, C. e t a l . York.  1950. Comparative Animal Physiology.  W.B. Saunders Co. New  Sawyer, W.H. 1956. The Hormonal C o n t r o l of Water and S a l t E l e c t r o l y t e Metabolism With S p e c i a l Reference to the Amphibia. Mem. Soc. E n d o c r i n . 5.: 44-55. Cambridge Univ. P r e s s . Sexton, A.W. 1955. F a c t o r s I n f l u e n c i n g the Uptake of Sodium Against a D i f f u s i o n Gradient i n G o l d f i s h G i l l . Ph.D. T h e s i s , U. of M i s s o u r i . D i s s . Abstracts 15. 2270-2271. Smith, H,W. 1930, The Absorption and E x c r e t i o n of Water and S a l t s by Marine T e l e o s t s , Am, J . P h y s i o l . 93: 480-505. Shedecor, G.W.  1956. S t a t i s t i c a l Methods.  Spalding, M.H.  1956. Unpublished  Iowa State C o l l e g e Press.  Ames, Iowa.  data quoted i n Chester Jones, 1956.  Steinbach, H.B. 1954. The Regulation of Sodium and Potassium i n Muscle F i b r e s . Symp, Soc. Exp. B i o l . 8i 438-452. Weisel, G.F. 1958. The Comparative E f f e c t s of Fresh Water and Marine T e l e o s t ; P i t u i t a r i e s on the Water Balance o f Frogs. Copeia ( 2 ) : 86-91.  *  O r i g i n a l reference not consulted.  - 34 -  APPENDIX  Table 8«  Analysed as to Sex D i f f e r e n c e s * (Cation Values)  Serum meq./L serum Sex  Na SE  K M  Muscles i o n meq./kg. wet muscle  %  Na/K SE  E0 o  M  SE  Na M  SE  K M  SE  K/Na M  SE  Total  150.0 (13)  1.46  3.24 (13)  .139  478 (13)  3.43  77.8 (24)  .15  8.88 (16)  .322  108.6 (16)  2.31  12.47 (16)  .512  Male f i s h mature  147.8 (5)  2.30 .85  3.35 (5)  .246 .968  44.9 (5)  3.55 .203  78.0 (8)  .559 15.3  8.84 (5)  1.14  101.7 (5)  5.75  12.14 (5)  1.21  Male f i s h immature  148.5 (5)  77.5 (5)  0.27  8.97 (5)  0.42  113.9 (5)  3.6  12.80 (5)  .79  Female f i s h  152.5 (6)  77.8 (8)  .34  8.83 (5)  .44  109.9 (5)  2.82  12.57 (5)  .738  3.33 (2) 2.33  3.13 (6)  44.8 (2) .255  50.3  4.61  36 -  Table 9»  T r a n s f e r t o 60 % Seawater.  Treatment  1. 2.  Sample S i z e  •Na  N  Mean  10  9  20  Hours i n 60 % Seawater  Serum Sodium and Potassium meq./L. Serum Na/K R a t i o .  K  Na/K  SE  Mean  t  165.1  4.9  2.85  3.80  3  176  7.0  4.28  1.25  47  25  4  190  3.4  3.59  .55  55.3  7.42  36  5  193  4.9  4.21  1.08  52.1  7.65  48  3  182  19  4.84  .37  38.1  2.8  60  4  183  9.5  2.81  .37  66.8  6.3  66  4  182  4.8  3.95  .23  46.3  1.9  94  4  168  5.3  2.18  .15  77.3  8.7  110  4  160  5.6  3.29  .59  51.3  6.7  140  8  161  2.6  3.57  .30  46.8  3.1  166  8  168  6.2  4.30  192  4  156  8.2  216  4  151  3.8  2.38  .32  67.3  12.7  240  10  160  2.5  2.42  .20  69.7  5.6  i  SE  Mean  - SE  - 37 -  Table 10.  Transfer t o 60 % Seawater. 3. Muscle Sodium and Potassium/Kg. Wet Muscle. 4. Potassium : Sodium R a t i o s .  Treatment  Sample S i z e  K  Na  N  Mean  25  4  36  K/Na  SE  Mean  - SE  Mean  - SE  22.6  2.0  115  3.0  5.18  0.52  5  20.3  1.7  120  2.5  6.03  0.48  48  4  19.3  0.6  120  1.9  6.26  0.21  60  4  17.5  2.4  123  3.1  7.32  0.98  66  4  14.1  0.4  125  2.7  8.90  0.34  94  4  15.3  0.8  135  6.7  8.82  0.57  110  4  12.6  0.7  131  4.2  10.5  0.34  140  8  12.3  0.4  125  2.5  10.3  0.43  166  4  15.3  1.2  132  0.5  8.7  0.53  Hours i n Seawater  i  - 38 -  Table 11.  Transfer t o 60 % Seawater. .. 5. Potassium  Treatment  % Tissue Water.  6.  Sodium and  meq«/Kg Dry Weight.  Sample S i z e  % Water  Na meq./kg. Dry Muscle  Hours i n Seawater  N  Mean  - SE  Mean  25  4  75.3  0.31  36  5  74.9  48  4  60  i  K meq./kg. Dry Muscle  SE  Mean  90.2  6.6  466  10.7  0.31  80.8  6.1  478  9.5  75.8  0.75  80.5  5.2  500  16.9  4  75.8  0.68  72.1  7.7  507  24.5  66  4  75.6  0.71  57.8  2.6  513  7.9  94  4  75.7  1.44  63.1  4.3  554  10.8  110  4  76.7  0.55  53.9  1.4  561  17.0  140  8  77.0  0.40  53.6  1.5  547  11.4  166  4  76.1  0.95  63.8  3.8  552  9.5  i  SE  

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