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Some aspects of the physiological adaptation of lower vertebrates to marine environments McBean, Ralph Lachlan 1963

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SOME ASPECTS OP THE PHYSIOLOGICAL ADAPTATION OF LOWER VERTEBRATES TO MARINE ENVIRONMENTS  RALPH LACHLAN McBEAN B.Sc,  The U n i v e r s i t y of B r i t i s h Columbia, 1961  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 required standard  THE UNIVERSITY OF BRITISH COLUMBIA August, 1963  In presenting, t h i s t h e s i s i n p a r t i a l f u l f i l m e n t  of  the requirements for an advanced degree at the U n i v e r s i t y of B r i t i s h - C o l u m b i a , I agree a v a i l a b l e for reference  that the L i b r a r y  and study.  s h a l l make i t  I f u r t h e r agree  mission for extensive copying of t h i s t h e s i s for  freely  that p e r -  scholarly  purposes may be granted by the Head of my Department or by his representatives. c a t i o n of t h i s  It  i s understood that copying, or p u b l i -  t h e s i s for f i n a n c i a l gain s h a l l not be allowed  without my w r i t t e n p e r m i s s i o n .  Department of  Zoology  The U n i v e r s i t y of B r i t i s h Columbia,, Vancouver 8, Canada.Date  August, 1963  ABSTRACT I  STUDIES ON THE GLOMERULAR FILTRATION RATE OP RAINBOW TROUT (SALMO GAIRDNERI) Upon adaptation of rainbow t r o u t to 80$ sea water,  the glomerular f i l t r a t i o n r a t e , as measured by the method of i n u l i n clearance, was reduced from 156 + 8.9 to 10.0 + 2.6 m l . / k g . body weight/day.  Return to fresh water after one month  i n sea water was accompanied by a r a p i d re-establishment of the high glomerular f i l t r a t i o n r a t e .  This l a b i l i t y of the glomerular  f i l t r a t i o n rate i n the t r o u t i s probably an important factor contributing  to the reduction of urine flow associated with the  adaptation of the euryhaline form to sea water. The effects of adrenocortical and mammalian neurohypophysial hormones on the glomerular f i l t r a t i o n rate were studied.  Vasopressin and oxytocin, when administered e i t h e r  separately or together, s i g n i f i c a n t l y increased the  filtration  r a t e , aldosterone had no e f f e c t , while corticosterone caused a significant reduction. II  STUDIES ON ELECTROLYTE EXCRETION IN THE GREEN TURTLE (CHELONIA MIDAS) The e x t r a c e l l u l a r concentrations of sodium and potassium  i n the marine t u r t l e , Chelonia mydas mydas, were unchanged after adaptation to a fresh water environment.  At the same time the  u r i n a r y concentrations of these ions were s i g n i f i c a n t l y reduced. In a d d i t i o n , the " s a l t glands" of fresh water adapted j u v e n i l e t u r t l e s showed a 38$ regression i n absolute weight.  iii Feeding and s a l i n e - l o a d i n g of sea water adapted  turtles  e l i c i t e d r a t e s of sodium and potassium e x c r e t i o n g r e a t l y i n excess of those p o s s i b l e v i a the kidney.  F a i l u r e to detect  s i g n i f i c a n t changes i n these r a t e s f o l l o w i n g o c c l u s i o n of the c l o a c a f u r t h e r i n d i c a t e d that the major s i t e of e l e c t r o l y t e e x c r e t i o n a f t e r feeding  or s a l i n e - l o a d i n g was the s a l t gland.  Suppression of adrenocorticosteriod. synthesis by treatment w i t h amphenone "B" immediately a f t e r feeding or s a l i n e l o a d i n g reduced the e x c r e t i o n of sodium and potassium to unfed or non-loaded  levels.  The normal p a t t e r n of sodium e x c r e t i o n  but not of potassium e x c r e t i o n could be r e s t o r e d i n the amphenonet r e a t e d animals by the simultaneous a d m i n i s t r a t i o n of c o r t i costerone. The s i g n i f i c a n c e of the i n g e s t i o n of sea water i s discussed  i n r e l a t i o n to the h i g h e l e c t r o l y t e intake  w i t h the d i e t of these t u r t l e s .  associated  ACKNOWLEDGEMENTS I am p a r t i c u l a r l y g r a t e f u l to Dr. W. N. Holmes f o r his  d i r e c t i o n and guidance  throughout  the course of these  s t u d i e s , and to Dr. W. S. Hoar, Dr. P. Ford, and Dr. N. J . Wilimovsky —. Terpenning  f o r t h e i r a s s i s t a n c e and a d v i c e . I would a l s o l i k e t o express my thanks to Mr. J . (B. C. Department of R e c r e a t i o n and Conservation,  F i s h and Game Branch) f o r the supply of rainbow t r o u t , Dr. A. F. Carr ( U n i v e r s i t y of F l o r i d a ) and Dr. J . A. O l i v e r  (American  Museum of N a t u r a l H i s t o r y ) f o r the supply of green  turtles,  Dr. Walter Murphy (Ciba) f o r the g i f t  of a l d o s t e r o n e , Dr. R.  Gaunt (Ciba) f o r the g i f t of amphenone "B", Mr. F. G. Wood, J r . and the management of Marine S t u d i o s , Inc. f o r the p r o v i s i o n of  f a c i l i t i e s a t the Marineland Research Laboratory, S t . Augustine,  F l o r i d a , and Dr. C h a r l o t t e Froese  (Department of Mathematics,  U. B. C.) f o r a s s i s t a n c e i n preparing data f o r a n a l y s i s on the I. B. M. 1620 computer. The m a j o r i t y of t h i s work was done during the tenure of  a N a t i o n a l Research C o u n c i l of Canada Studentship.  TABLE OF CONTENTS Page ABSTRACT  ii  ACKNOWLEDGEMENTS  vi  PART I :  STUDIES ON THE GLOMERULAR FILTRATION  RATE OF RAINBOW TROUT (SALMO GAIRDNERI)  1  Introduction  2  M a t e r i a l s and Methods  7  Results  11  Figure I  13  Table I  14  Table I I  15  Figure I I  17  Table I I I  18  Discussion  19  Summary"  24  L i t e r a t u r e Cited  25  PART I I :  STUDIES ON ELECTROLYTE EXCRETION IN THE  GREEN TURTLE (CHELONIA MIDAS)  29  Introduction  30  M a t e r i a l s and Methods  31  Results  .  33  Table I  35  Figure I  36  Table I I  37  Figure I I  40  Page Table I I I  41  Table IV  44  Table V  46  Discussion  42  Summary  50  Literature Cited  51  PART I STUDIES ON THE GLOMERULAR FILTRATION RATE OF RAINBOW TROUT (SALMO GAIRDNERI)  Introduction The migration of diadromous t e l e o s t f i s h i s of considerable p h y s i o l o g i c a l i n t e r e s t because of the osmoregulatory problems which must be overcome.  The j u v e n i l e A t l a n t i c salmon  (Salmo s a l a r ) , for instance, which does not t o l e r a t e  salinities  over 10$<?as a parr (Huntsman and Hoar, 1939), must undergo changes which permit i t to maintain i t s osmotic and i o n i c e q u i l i b r i u m as i t moves into the sea. The problems faced by a f i s h subjected to a sudden increase i n s a l i n i t y , and some of the possible responses to these problems are best i l l u s t r a t e d by comparing the "normal" s i t u a t i o n s of water and s a l t balance i n freshwater and. marine teleosts. The blood and tissue f l u i d of freshwater t e l e o s t s  are  hypertonic to the environment (Baldwin, 1948; Black, 1957): the average freezing-point depression of freshwater blood i s about 0.57°C.  teleost  Freshwater f i s h thus continuously  absorb water, mostly through the o r a l and branchial e p i t h e l i a . No water i s normally ingested by freshwater f i s h (Smith, 1930), and water balance i s maintained by the production of a copious dilute urine.  The urine flow i s of the order of 25 - 100 m l . / k g . /  day, averaging about 50 (various sources c i t e d i n Black, 1957), but up to 300 m l . / k g . / d a y i n some forms ( N i c o l , I960), p o s s i b l y depending on the area and permeability of the body surface. The freezing-point depression of the urine i s less than 0.1°C. (various sources c i t e d i n Black, 1957).  S a l t s are l o s t i n the  urine and feces, and, to some extent, by d i f f u s i o n  through  - 3 surface t i s s u e s .  The loss of s a l t s i n the urine i s probably  minimized by reabsorption i n the kidney tubules (Krogh, 1939) and much of the l o s t s a l t s i s apparently replaced by s a l t s contained i n the food.  In a d d i t i o n , the g i l l s of at l e a s t  several freshwater species are able to a c t i v e l y absorb c h l o r i d e , bromide and sodium and probably other ions against a concentrat i o n gradient (Krogh, 1937 and 1939; Sexton and Meyer, 1955). In contrast to freshwater forms, marine t e l e o s t s are faced with osmotic d e s s i c a t i o n , the average osmotic concentrat i o n of the blood (freezing-point depression 0.78°C.) being only s l i g h t l y above that of freshwater species and considerably below that of sea water (freezing-point depression about 2 ° C . ) . Thus marine f i s h tend to lose water across the g i l l s and other body surfaces.  In order to replace the water l o s t i n t h i s way  marine f i s h swallow sea water.  Smith (1930) estimated that  / A n g u i l l a swallowed 50 - 135 m l . / k g . / d a y and absorbed about 75$ of t h i s i n the i n t e s t i n e , and Myoxocephalus swallowed 60 - 225 m l . / k g . / d a y and absorbed 60$.  Large q u a n t i t i e s of s a l t s are  absorbed with the water, although calcium, magnesium, and sulphate are poorly absorbed and are l a r g e l y passed out i n the feces.  The excess ions ( p a r t i c u l a r l y c h l o r i d e , sodium,  and potassium) absorbed with the ingested water are excreted mostly through the g i l l s (Smith, 1930) and, i n t h i s process, a large part of the absorbed water ( e . g . , 75$ i n the e e l , 50$ i n the sculpin) i s l o s t .  However, i f these ions were excreted  r e n a l l y , greater volumes of water would be required because of  - 4' -  the r e l a t i v e l y poor " c o n c e n t r a t i n g " a b i l i t y of the  teleost  kidney and the f i s h would enter a s t a t e of negative water balance.  The u r i n e i s g e n e r a l l y i s o t o n i c or s l i g h t l y  hypotonic,  and i t i s l i k e l y t h a t the g r e a t e r osmotic c o n c e n t r a t i o n compared to freshwater  forms i s e f f e c t e d by t u b u l a r r e a b s o r p t i o n of  water (Marshall and G r a f f l i n , 1932;  C l a r k e , 1934); however, the  u r i n e of marine t e l e o s t s i s never hypertonic Baldwin, 1948).  tSmith,  In order to minimize the r e n a l l o s s of water,  the r a t e of d i u r e s i s i n the marine t e l e o s t i s low, of 2 - 4 ml./kg./day (Smith, The  1930,  1959,  Black, 1957,  of the  Nicol,  rainbow t r o u t (Salmo g a i r d n e r i ) and  form, the steelhead t r o u t , maintain hypotonic  1932;  order  I960).  i t s anadromous  their milieu interieur  to the environment a f t e r t r a n s f e r to sea water (Houston,  I960).  Such a t r a n s f e r i n v o l v e s the p h y s i o l o g i c a l adjustment  from a c o n d i t i o n of c o n t i n u a l h y d r a t i o n and e l e c t r o l y t e d e p l e t i o n to the opposite dehydration  circumstance  of a sustained tendency towards  and excessive e l e c t r o l y t e i n t a k e , as o u t l i n e d above.  P a r t of t h i s p h y s i o l o g i c a l adjustment probably  involves a reduction  i n u r i n e flow of a magnitude comparable to the d i f f e r e n c es seen, between stenohaline freshwater and marine forms (R. M. Holmes, 1961).  F u r t h e r , i t has been suggested that such a r e d u c t i o n  i n u r i n e flow may  be achieved  by a lowering  of the  glomerular  f i l t r a t i o n r a t e (G. F. R.); i . e . , by a decrease i n the volume of plasma f i l t e r e d by the kidney Fontaine,  1956).  i n u n i t time (Smith,  1951;  - 5 L i t t l e data i s a v a i l a b l e on the glomerular f i l t r a t i o n rates of f i s h .  Clarke (1934) found the s c u l p i n (Myoxocephalus  octodecimspinosus), a marine t e l e o s t , to have an average urine flow of about 3.3 m l . / k g . / d a y and an average G. P . B . of 13.7 m l . / k g . / d a y (xylose clearance).  While considerable  reabsorption  of water i s i n d i c a t e d by these f i g u r e s , the f i l t r a t i o n rate i s small when compared w i t h the urine flow of freshwater  teleosts;  i . e . , i t i s l e s s than 50$ of the rate which would be required to produce a normal urine flow i n a freshwater  fish.  Further  evidence of the role of a low f i l t r a t i o n rate i n the low urine production of saltwater f i s h i s afforded by the presence of :aglomerular species ( e . g . , the t o a d f i s h , Opsanus tau) and species with degenerate glomeruli ( e . g . , the goosefish, Lophius p i s c a t o r i u s ) among the marine t e l e o s t s but not the teleosts.  freshwater  A p a r t i c u l a r l y s i g n i f i c a n t case occurs i n the s c u l p i n s .  The kidneys of Myoxocephalus octodecimspinosus are f u l l y glomerular, l i k e those of freshwater  f i s h e s , but those of M. scorpius are  only p a r t l y glomerular ( i . e . , glomeruli present and f u n c t i o n a l , but l e s s numerous).  Forster (1953) found that the urine flow  i n M. octodecimspinosus averaged 9.3 m l . / k g . / d a y while that i n M. scorpius averaged 2 m l . / k g . / d a y , a difference which may reasonably be interpreted as r e s u l t i n g from the (morphologically based) lower glomerular f i l t r a t i o n r a t e .  Evidence that the  glomerular f i l t r a t i o n rate of f i s h i s r e a d i l y changeable i s given by the r e s u l t s of Clarke (1934) who found that a 10-fold increase i n urine flow i n injured sculpins was accompanied by  - 6 a 5-fold increase At  in filtration  t h e p r e s e n t t i m e no m e c h a n i s m , n e r v o u s o r h o r m o n a l ,  i s known t o c o n t r o l f i l t r a t i o n vertebrates. little  rate.  r a t e i n mammals o r i n l o w e r  Nervous s t i m u l a t i o n i s g e n e r a l l y  considered  physiological significance i n kidney function.  both the s t e r o i d s secreted diuretic  hormone  by t h e a d r e n a l  (vasopressin)  cortex  of  However,  and t h e a n t i -  p r o d u c e d by t h e n e u r o h y p o h y s i s  have w e l l - e s t a b l i s h e d r o l e s i n t h e r e g u l a t i o n o f t h e mammalian kidney.  S i n c e b o t h t h e i n t e r r e n a l t i s s u e and t h e n e u r o h y p o p h y s i s  o f f i s h show i n c r e a s e d (Fontaine  a c t i v i t y during  and H a t e y , 1954; O l i v e r e a u ,  adaptation  t o sea water  I960; C a r l s o n  and Holmes,  1 9 6 2 ) , t h e hormones o f t h e s e o r g a n s w o u l d be t h e most choice  for investigatibn. The p u r p o s e o f t h i s  the  likely  glomerular f i l t r a t i o n  s t u d y was, t h e r e f o r e ,  t o examine  r a t e s o f f r e s h w a t e r and s e a w a t e r  a d a p t e d r a i n b o w t r o u t and a l s o t o d e t e r m i n e t h e e f f e c t s o f adrenocortical in  and p o s t e r i o r p i t u i t a r y  the f r e s h w a t e r form.  hormones on  filtration  M a t e r i a l s and Methods Rainbow trout (Salmo g a i r d n e r i , Richardson) of about 150 gm. weight were obtained from the Cultus Lake hatchery of the B r i t i s h Columbia Department of Recreation and Conservation, F i s h and Game Branch. The studies were conducted i n two separate series of experiments during winter and summer months.  During the winter,  "freshwater" f i s h were kept i n running dechlorinated tapwater at 6 C, and "sea water adapted" f i s h i n 80$ standard sea water at the same temperature.  The f i r s t group of sea water adapted  t r o u t was acclimated for 10 days i n the sea water before the determination of glomerular f i l t r a t i o n rate (G. F . R . ) . A second group was maintained i n sea water for one month and then returned to fresh water for 10 days before use.  F i s h used  during the summer months were kept under s i m i l a r conditions but at 10°C. A l l f i s h were fasted for at l e a s t a week previous to G. F . R. estimations. I n u l i n clearance was the method selected for the determination of G. F . R.  I n u l i n i s the agent of choice i n  contemporary glomerular f i l t r a t i o n s t u d i e s .  It i s a starch-  l i k e polysaccharide, of molecular weight somewhat over 5,000, commercially obtained from d a h l i a tubers.  It i s available i n  a. reasonably pure s t a t e , and i s amenable to precise determination i n plasma and u r i n e .  It i s physiologically i n e r t , non-toxic,  and produces no detectable change i n r e n a l c i r c u l a t i o n i n mammals,  Based on a standard sea water of 3 4 . 3 2 5 $ » s a l i n i t y (Lyman and Fleming, 1940).  even i n extremely large doses (Smith, 1956).  I t has the  lowest d i f f u s i o n rate known for any molecule small enough to be f r e e l y f i l t r a b l e .  I t i s completely f i l t r a b l e and i s not  bound to plasma proteins i n mammals, frogs, and Necturus. and i t i s not secreted or reabsorbed i n man and dogs (Smith, 1956). Evidence, although scarce, strongly indicates that t h i s i s also the case i n fishes (Shannon, 1934; Clarke, 1936).  Thus  the t o t a l amount of i n u l i n excreted by a f i s h i n a given time, d i v i d e d by the mean plasma concentration of i n u l i n during that time, w i l l give the t o t a l amount of plasma f i l t e r e d by the kidneys i n the given time. F i s h were removed from t h e i r respective holding f a c i l i t y , injected i n t r a p e r i t o n e a l l y w i t h 50 mg. i n u l i n i n 0.5 m l . i s o t o n i c saline (NaCl, 0.78$) and placed i n d i v i d u a l l y i n p l a s t i c tanks containing exactly one l i t r e of aerated fresh water or sea water at the same temperature.  Five hours after the i n j e c t i o n of  i n u l i n , a 20 m l . sample of the tank water was taken.  This was  considered to be the zero hour sample and s i m i l a r 20 m l . a l i q u o t s were taken at 5, 10, and 15 hours thereafter. Zero hour and terminal blood samples were also taken from separate i n u l i n injected groups of f i s h .  The blood was  c o l l e c t e d i n heparinized tubes and immediately centrifuged. P r o t e i n was p r e c i p i t a t e d from the plasma samples w i t h cadmium sulphate ( F u j i t a and Iwatake, 1931, as modified by Smith et a l , 1945) and the supernate was f i l t e r e d through washed cotton.  - 9 Duplicate 2 m l . samples of the plasma f i l t r a t e and s i m i l a r l y f i l t e r e d samples of the tank -water were analysed for i n u l i n according to the Schreiner (1950) modification of the d i r e c t r e s o r c i n o l method of Roe, E p s t e i n , and Goldstein (1949). Standard solutions of i n u l i n were included with each determination. The t o u l i n u l i n excreted, after c o r r e c t i o n for the q u a n t i t i e s removed i n previous samples, was c a l c u l a t e d for each time period and expressed i n mg./kg. body weight of f i s h . From these values, and the plasma i n u l i n concentration,  the  t o t a l volume of plasma f i l t e r e d up to the end of each sample period was c a l c u l a t e d as f o l l o w s : Total plasma f i l t e r e d (ml.) at any given time =  where u =  urine i n u l i n concentration (mg./ml.), v = volume of urine ( m l . ) , and p = plasma i n u l i n concentration (mg./ml.).  Although the  volume of urine excreted by the t r o u t was not known, the product (uv) was represented by the t o t a l weight of i n u l i n excreted at any time. The accumulated volume (ml.) of plasma f i l t e r e d was p l o t t e d against the time i n hours.  Each regression was f i t t e d  by the method of l e a s t squares, and the various regressions were compared by the a n a l y s i s of covariance (Snedecor, 1956). From the slopes of the l i n e s the glomerular f i l t r a t i o n rates were c a l c u l a t e d i n m l . / k g . body weight/day. Plasma and muscle sodium and potassium concentrations were measured i n freshwater and sea water adapted fish". A l l  m e a s u r e m e n t s were made w i t h a Z e i s s PP5 f l a m e C o n c e n t r a t i o n s were e x p r e s s e d  photometer.  as m i l l i e q u i v a l e n t s  per l i t r e  o f p l a s m a and a s m i l l i e q u i v a l e n t s p e r k i l o g r a m wet w e i g h t muscle. and  M u s c l e s a m p l e s were d r i e d  the percentage All  time  t o constant weight  w a t e r c o n t e n t was  hormones were i n j e c t e d  of the i n u l i n i n j e c t i o n .  determined. i n t r a p e r i t o n e a l l y a t the  and " P i t r e s s i n " , P a r k e -  D a v i s ) were a d m i n i s t e r e d i n a q u e o u s s o l u t i o n , as a s t a b i l i z e d suspension  s a l i n e , and a l d o s t e r o n e  a t 110°C. <•  Commercial p r e p a r a t i o n s of  o x y t o c i n and v a s o p r e s s i n ( " P i t o c i n "  ( S i g m a ) was p r e p a r e d  of  (d-aldosterone free  was g i v e n i n sesame o i l s o l u t i o n .  corticosterone i n isotonic  alcohol,  Ciba)  Results Several i n v e s t i g a t o r s have demonstrated the presence of an e x t r a - r e n a l , as w e l l as a r e n a l , excretory pathway i n the t e l e o s t fishes (Smith, 1930; Keys, 1931; Krogh, 1939; Holmes, 1959).  Therefore, when the G. F . R. i s measured by a n a l y s i s  of the environment, rather than of the urine per se, the p o s s i b i l i t y of e x t r a - r e n a l s e c r e t i o n or f i l t r a t i o n of i n u l i n must be examined.  This source of error was evaluated i n pre-  l i m i n a r y studies by the estimation of the i n u l i n output from fresh water trout i n which the cloaca was closed by a "purses t r i n g " l i g a t u r e immediately after the i n j e c t i o n of i n u l i n . Although the rate of appearance of i n u l i n i n the tank water was s i g n i f i c a n t , i t was extremely low (mean =0.42 m g . / k g . / h r . ) and h i g h l y v a r i a b l e .  I t i s p o s s i b l e , indeed probable, that  t h i s low rate of appearance of i n u l i n was due to leakage from the t i s s u e damaged at l i g a t i o n .  Therefore, the e x t r a - r e n a l  excretion of i n u l i n was considered to be n e g l i g i b l e . Another possible source of error i n t h i s type of estimation may r e s u l t from the production by the f i s h of some " i n u l i n o i d " chromogenic material.  This was i n v e s t i g a t e d by means of s a l i n e - i n j e c t e d  controls.  The average rate of appearance of n o n - i n u l i n chromogen  from s a l i n e - i n j e c t e d f i s h was equivalent to about 0.03 mg. i n u l i n / k g . / h r . (equivalent to less than 0.95 m l . f i l t r a t e / k g . / d a y ) and was not s i g n i f i c a n t ( p > 0 . 5 ) .  Thus the i n u l i n clearances  reported here are believed to ^represent v a l i d estimations of the glomerular f i l t r a t i o n r a t e . In a l l groups of trout studied, the cumulative t o t a l volume of glomerular f i l t r a t e v a r i e d d i r e c t l y with time according  - 12  -  to the equation Y = bX + a, where Y = the volume of glomerular f i l t r a t e i n m l . / k g . body weight, X = the time i n hours and a = the ordinate i n t e r c e p t .  I t f o l l o w s , then that b, the slope  of the l i n e described by the equation, w i l l represent the rate of clearance of i n u l i n , i n m l . plasma cleared per hour. Freshwater rainbow trout maintained at 6°C. showed a h i g h l y s i g n i f i c a n t rate of i n u l i n excretion which represented a G. F . R. of 156 + 8.9 m l . / k g . / d a y (Table I ) .  Adaptation of  the f i s h to 80$ sea water at 6°C. for 10 days r e s u l t e d i n a reduction i n G. F . R. to 10.0 + 2.6 m l . / k g . / d a y (Table I and Figure I ) .  This represented a very s i g n i f i c a n t decline to  only 6.8$ of the fresh water value.  Further, during the period  of acclimation to sea water, the tissue water and e l e c t r o l y t e composition had returned to values approximating those found i n the fresh water f i s h (Table I I ) . Trout which were maintained i n 80$ sea water at 6°C. for one month and then transferred back to fresh water at the same temperature showed a r e s t o r a t i o n of the previously observed f i l t r a t i o n rate (184.3 + 11.5 v s . 156.7 + 8.9 m l . / k g . / d a y ) . Although the mean rate was higher than the freshwater  controls,  the l e v e l of s i g n i f i c a n c e was borderline (Table I and Figure I ) . Rainbow trout maintained at 10°C. had a s l i g h t l y higher mean G. F . R. (169.0 + 11.8 m l . / k g . / d a y ) , than those maintained at 6 ° C , but the two values were not s i g n i f i c a n t l y o  different  (Table I I I ) .  Treatment of freshwater f i s h with a  single i n t r a p e r i t o n e a l dose of 100 m i l l i u n i t s vasopressin  FIGURE I  The accumulated glomerular f i l t r a t i o n of rainbow trout (Salmo g a i r d n e r i ) adapted to fresh water and sea water environments.  A l l f i s h were maintained i n running de-  c h l o r i n a t e d fresh water or 80$ sea water at 6°C.  -  13  -  TABLE I The e f f e c t of transfer to 80$ sea water on the glomerular f i l t r a t i o n rate of rainbow trout (Salmo gairdneri)» A l l f i s h were kept i n running dechlorinated tap water or 80$ standard sea water at 6°C.  No. of fish  Body wt. (g.)  Fresh water  14  186.0 +5.9  T=6.53X+1.81  15.68  0.37  0.92  <0.001  -  -  Sea water (from fresh water)  10  163.5 +8.4 "~  T=0.42X+ .68  3.96  0.11  0.52  < 0.001  1,92  180  Freshwater (from sea water)  9  152.3 +4.6 "~  I=7.68X-1.95  16.13  0.48  0.94  < 0.001  1,88  3.61  *  yx**  „ °b  " "**** r  P value on "r"  Covariance of f i l t r a t i o n rates degrees F "P" value of freedom value on "F" fT  n  < 0.001  >0.05<.l  Y = bX+a where T = t o t a l volume of glomerular f i l t r a t e i n m l . / k g . body weight, b = glomerular f i l t r a t i o n rate i n m l . / k g . body weight/hour, X = time i n hours and a = the ordinate i n t e r c e p t .  **  S  *** #***  Regression*  q  = standard deviation from the regression.  ^b r  =  =  s  "k * a n (  a : r <  l error of the regression c o e f f i c i e n t (b).  correlation coefficient. •4*  I  TABLE II The sodium, potassium and water composition of the plasma and muscle of freshwater and sea water adapted rainbow . t r o u t (Salmo g a i r d n e r i ) .  A l l f i s h were maintained i n de-  chlorinated tap water or 80$ standard sea water at 6°C.  No. of fish  Plasma  Muscle  Na (m-equiv./l.)  . K (m-equiv./l.)  $ water  Na (m-equiv./kg. wet muscle)  K  (m-equiv./k wet muscle  Fresh water  16  145.0 +1.6  2.33 +0.20  78.46 +0.32  7.13 +0.26  108.4 +0.8  Sea water (10 days)  10  160.0* +2.7  2.42 +0.20  78.26 +0.22  11.70* +0.70  112.3 +1.9  *p  0.001 with respect to the corresponding fresh water value  - 16 increased the G. F . R. to 263.0 + 19.7 m l . / k g . / d a y .  Similar  treatment with 100 mu. oxytocin enhanced the G. F . R. to an even greater degree (284.4 + 26.9 m l . / k g . / d a y ) .  Both these  rates were s i g n i f i c a n t l y higher than the i n t a c t  freshwater  c o n t r o l value (Table I I I and Figure I I ) .  The combination of  50 mu. vasopressin and 50 mu. oxytocin also increased the G. F . R. (247.0 + 2 3 . 5 m l . / k g . / d a y ) .  This value was not s i g n i f -  i c a n t l y d i f f e r e n t from the values obtained when the hormones were administered separately (Table I I I and Figure I I ) . There was no detectable change i n the G. F . R. of freshwater trout following a single i n t r a p e r i t o n e a l dose of 25JSg. aldosterone.  However, treatment with 5.0 mg. c o r t i -  costerone s i g n i f i c a n t l y reduced the G. F . R. to 126.0 + 14.6 m l . / k g . / d a y (Table I I I and Figure I I ) .  FIGURE I I  The effect of neurohypophysial and adrenocortical hormones on the glomerular f i l t r a t i o n rate of freshwater rainbow trout.  A l l f i s h were kept at 10°C. and were i n t r a p e r i t o n e a l l y  injected with the following doses of hormones: 100 mu. oxyt o c i n , 100 mu. vasopressin, 50 mu. oxytocin plus 50 mu. vasop r e s s i n , 25 yig> aldosterone and 5.0 mg. c o r t i c o s t e r o n e .  Accumulated glomerular filtrate (ml./kg.  B.W.)  TABLE I I I The effect of neurohypophysial and adrenocortical hormones on the glomerular f i l t r a t i o n rates, of freshwater trout (Salmo g a i r d n e r i ) .  rainbow  A l l f i s h were kept at 10°C. and  were i n t r a p e r i t o n e a l l y injected with the i n d i c a t e d doses of hormones.  Covariance of f i l t r a t i o n rates No. of fish  Body weight  0.49  0.93  <0.01  29.07  0.82  0.91  <0.01  1,72  16.41  <0.01  Y=11.85X+1.7  37.62  1.12  0.88  <0.01  1,68  16.03  <0.01  159.7 +14.8  Y=10.29X-1.1  29.63  0.98  0.89  <0.01  1,60  9.65  <T0.01  9  160.2 +13.7  1= 7.74X+1.9  14.74  0.44  0.95  <0.01  1,68  1.08  >0.2  9  143.4 + 7.6  1= 5.25X-0.4  20.13  0.61  0.83  <0.01  1,68  5.37 < 0.025  Regression*  9  173.8 +10.9  1= 7.04X+2.9  17.36  10  152.0 +10.9  Y=10.96X+3.9  100 mu. Oxytocin  9  144.7 +13.1  50 mu. Vasopressin + 50 mu. Oxytocin  7  25 ;ug. Aldosterone 5.0 mg. Corticosterone  Control 100 mu. Vasopressin  * **  value  llpn value on "P"  »r"****  UP  Group  degrees of freedom  !lpt» value on " r "  **  "b***  111? II  Y = bX + a where Y = t o t a l glomerular f i l t r a t e i n m l . / k g . body weight, b = glomerular f i l t r a t i o n rate i n m l . / k g . body w e i g h t / h r . , X = time i n hours and a = the ordinate i n t e r c e p t . S  = standard deviation from the regression.  ***  = standard error of the regression c o e f f i c i e n t . H » r  =  correlation coefficient.  00 I  Discussion Dr. R. M. Holmes (1961) has r e c e n t l y been able to c o l l e c t urine from catheterized rainbow trout for periods up to 500 hours.  Under these c o n d i t i o n s , fresh water r a i n -  bow t r o u t , i n the same weight range as i n the present study, showed urine flows of 75 - 90 m l . / k g . / d a y and urine c h l o r i d e concentrations of 5 - 12 m M . / l .  This would suggest, on the  basis of our estimated G. F . R . , and at a plasma c h l o r i d e concentration of 137.2 m M . / l .  (Houston, 1959), that 43 - 52$  tubular reabsorption of water and 95 - 98$ tubular reabsorption of c h l o r i d e occurred i n the rainbow t r o u t i n fresh water.  In  the same study, Holmes reported t h a t , after adaptation of the rainbow t r o u t to sea water, the urine production had declined to 0.5 - 1.0 m l . / k g . / d a y and the urine chloride concentration had increased to 200 - 220 m M . / l .  The plasma c h l o r i d e con-  c e n t r a t i o n of sea water adapted rainbow trout was found by Houston (1959) to be 140 m M . / l .  Using the G. F . R. value of  10.1 + 2.6 m l . / k g . / d a y , i t would seem that 90 - 95$ reabsorption of water and 84 - 93$ reabsorption of chloride occurred i n the rainbow t r o u t adapted to sea water.  Apparently, therefore,  part of the homeostatic mechanism associated with the adaptation of rainbow t r o u t to sea water consists of a reduction i n the G. F . R. together with an increased renal tubular reabsorption of water.  These factors would w e l l account for the d r a s t i c  a n t i d i u r e s i s observed at t h i s time. The r a p i d re-establishment of the high glomerular f i l t r a t i o n rate upon return of the rainbow t r o u t from sea water  - 20 to fresh water suggests that the lower G. F . R. observed i n the sea water adapted f i s h was due to p h y s i o l o g i c a l rather than morphological or developmental changes ( c . f . Nash, 1931; Ford, 1956).  The mechanism which could effect such a r e v e r s i b l e  change i n G. F . R. i s u n c e r t a i n .  Probably i t involves changes  i n "glomerular a c t i v i t y " , that i s , i n the number of glomeruli functioning at any one time.  Richards and Schmidt (1924)  observed that blood d i d not flow i n the c a p i l l a r i e s of a l l the glomeruli of the frog kidney (pithed Rana pipiens) at one time, and that the flow i n a given a r t e r i o l e was normally intermittent.  Forster (1942) found a close c o r r e l a t i o n between  changes i n G. F . R. and changes i n glomerular a c t i v i t y i n the b u l l f r o g (Rana catesbiana).  His evidence also i n d i c a t e d that  the a c t i v i t y of i n d i v i d u a l glomeruli was an " a l l or none" phenomenon. The cause of glomerular intermittence i s not understood.  fully  I t would seem to be the r e s u l t of contraction of  the afferent glomerular a r t e r i o l e at i t s entrance to the glomerulus ( B i e t e r , 1930), thus explaining the  intermittent  a r t e r i o l a r blood flow observed by Richards and Schmidt.  However,  B e i t e r observed that i n at l e a s t some of the glomeruli of Rana catesbiana, an a r t e r i o l a r "shunt" i s present by means of which blood flow i n the c a p i l l a r i e s may cease while a r t e r i o l a r flow is  sustained. I f the proportion of i n a c t i v e glomeruli i s kept large  for any period of time i t would seem desirable to maintain a  high rate of blood flow to the tubules to enhance t h e i r secretory f u n c t i o n .  This i s r e a d i l y achieved i n the  mesonephric kidney where the tubules are supplied by the renal p o r t a l c i r c u l a t i o n as w e l l as by post-glomerular a r t e r i o l a r vessels.  The f u n c t i o n a l r e a l i t y of t h i s s i t u a t i o n i s demon-  strated by the much higher r a t i o of tubular clearance (phenol red) to glomerular clearance ( i n u l i n ) i n the lower vertebrates than i n the mammals with t h e i r r e l a t i v e l y high and constant f i l t r a t i o n - r e a b s o r p t i o n rate (Smith, 1951). The present study does not i n d i c a t e that a mammalian neurohypophysial hormone i s capable of causing the observed reduction i n G. P. B., however, n e i t h e r does i t e s t a b l i s h the converse.  Almost a l l studies of the e f f e c t s of mammalian  p o s t e r i o r p i t u i t a r y hormones on the water d i u r e s i s of lower vertebrates indicate a d i u r e t i c e f f e c t at low doses and an a n t i d i u r e t i c e f f e c t at high doses.  Richards and Schmidt (1924)  showed an.increase i n glomerular a c t i v i t y i n the frog (pithed Rana p i p i e n s ) a f t e r small doses of p i t u i t r i n "S", and a decrease i n a c t i v i t y a f t e r larger doses.  Adolph (1936) found that  i n j e c t i o n of "infundin" i n doses of 0.8 to 1.6 u n i t s / k g . intravenously and 2 to 92 u n i t s / k g . subcutaneously  lowered  glomerular a c t i v i t y i n the f r o g (R. pipiens) to between zero and 30$ of normal.  Burgess, Harvey, and Marshall (1933)  found that various doses of p i t r e s s i n intramuscularly (most greater than 100 mu./kg.) produced a reduced urine flow and G. P. R. during water d i u r e s i s i n the chicken (0.1 to 1.0  - 22 u n i t s / k g . ) and the a l l i g a t o r , A l l i g a t o r m i s s i s s i p p i e n s i s (0.05 to 1.0 u n i t s / k g . ) , but had no effect i n the f r o g , R. catesbiana (0.05 to 2.0 u n i t s / k g . ) or the freshwater f i s h , Ameriurus nebulosus (0.2 to 2.0 u n i t s / k g . ) .  cat-  Munsick,  Sawyer and Tan Dyke (1960) obtained a marked a n t i d i u r e t i c effect i n the fowl with arginine vasopressin and arginine vasotocin.  Holmes and Adams (1963) reported a decrease i n  urine flow i n the domestic duck (Anas platyrhynchos) with 5 doses of 0.5 u n i t s / k g . and of 2.5 u n i t s / k g . p i t r e s s i n i n t r a muscularly at 90 minute i n t e r v a l s , but found no effect from s i m i l a r l y administered doses of 0.05 u n i t s / k g .  Uranga (i960)  found that the intravenous i n j e c t i o n of 1 I . U . o x y t o c i n / k g . i n t o male anesthetized b u l l f r o g s (R. catesbiana) u s u a l l y had an a n t i d i u r e t i c e f f e c t ; however, at lower doses, he frequently obtained a d i u r e s i s accompanied by an increased G-. P. R. S i m i l a r l y , a d i u r e s i s and a n t i d i u r e s i s at low doses (5 doses of 0.05 u n i t s / k g . intramuscularly at 90 minute i n t e r v a l s ) and high doses (5 doses of 0.5 u n i t s / k g . and of 2.5 u n i t s / k g . i . m . at 90 minute i n t e r v a l s ) r e s p e c t i v e l y of p i t o c i n have been reported by Holmes and Adams (1963) for the domestic duck. Although they are probably equivalent to the "high" doses used by e a r l i e r workers, the r e s u l t s of the doses employed in-the present experiments suggest d i u r e s i s . difficult,  It is  however, to estimate to what extent these doses  were p h y s i o l o g i c a l or pharmacological since data on the rate  of uptake and the peripheral h a l f - l i f e of neurohypophysial and adrenocortical hormones i n poikilotherms i s l a c k i n g . vasopressin has not been found to occur i n f i s h .  Furthermore  The a n t i -  d i u r e t i c material extractable from t e l e o s t p i t u i t a r i e s i s instead arginine vasotocin ( H e l l e r and P i c k e r i n g , I960; Sawyer, Munsick and van Dyke, 1961). transfer  During the period immediately after  of the rainbow t r o u t to sea water there i s c e r t a i n l y  a depletion of p i t u i t a r y a n t i d i u r e t i c m a t e r i a l , probably arginine vasotocin (Carlson and Holmes, 1962).  Since corticosterone was  the- only hormone to cause.a reduction, i n the G. F . R. of fresh water rainbow t r o u t under the conditions of the present study, i t i s possible that the a n t i d i u r e t i c response reported by R. M. Holmes was due to the s t i m u l a t i o n of ACTH release by some neurohypophysial hormone.  This would be consistent w i t h the observed  increase i n adrenocortical a c t i v i t y during'the s r a o l t i f i c a t i o n of salmonid fishes (Fontaine and Hatey, 1954; Olivereau, I960), a period of h a l o p h i l i a and increased a b i l i t y to withstand transfe to sea water (Baggerman, I960; Houston, 1961).  Summary  Variations and  the  The  the  renal  important with  i n  the  tubular  factors  of  rainbow  on  the  trout  basis  vasopressin,  of  The  trout  f i s h  similar  reduced trol  to the  the  value.  of  the  i n  sea  water  and  significantly  had  no  F.  G. of  water  be  F.  R,  (G. are  73$  of  of of  after  the  the  on  gairdneri)  adaptation  accounted  preparations  G.  F.  G.  F.  corticosterone the  associated  (Salmo  largely  R.)  probably  trout  aldosterone  effect  P.  mechanisms  mammalian  injection  to  can  increased  detectable  R.  flow  rate  vasopressin/oxytocin  administration G.  rainbow  urine  reduced  oxytocin  of  homoiostatic  injections  intraperitoneal  water  the  reduction  Intraperitoneal  The  i n  f i l t r a t i o n  reabsorption  euryhalinity  observed  water  glomerular  intact  into  for  of fresh  R. into  fresh  R. significantly  fresh  water  con-  L i t e r a t u r e Cited Adolph, E . F . (1936). Control of urine formation i n the frog by the renal c i r c u l a t i o n . Amer. J . P h y s i o l . 117, 366379. Baggerman, B . fish.  ( i 9 6 0 ) . Factors i n the diadromous migrations of Symp. z o o l . Soc. Lond. No. 1, 33-60.  Baldwin, E . (1948). An Introduction to Comparative Biochemistry. 3rd e d i t i o n . Cambridge U n i v e r s i t y Press. B i e t e r , B . N . (1930). The effect of the splanchnics upon glomerular blood flow i n the f r o g ' s kidney. Amer. J . P h y s i o l . 91, 436-460. Black, V. S. (1957). E x c r e t i o n and osmoregulation. I n : Brown, M. E . ( E d . ) . The Physiology of F i s h e s , V o l . 1. Academic Press, New York. Burgess, IT. f . , Harvey, A . M. and M a r s h a l l , E . K . , J r . (1933). The s i t e of the a n t i d i u r e t i c a c t i o n of p i t u i t a r y e x t r a c t . J . Pharm. Exper. Therap. 49, 237-249. Carlson, I . H. and Holmes, ¥ . N . (1962). Changes i n the hormone content of the hypothalamo-hypophysial system of the rainbow trout (Salmo g a i r d n e r i ) . J . Endocrin. 24, 23-32. Clarke, R. W. (1934). The xylose clearance of Myoxocephalus octodecimspinosus under normal and d i u r e t i c c o n d i t i o n s . J . C e l l , and Comp. P h y s i o l . 5_, 73-82. (1936). Simultaneous xylose and i n u l i n clearances i n the s c u l p i n . B u l l . Mt. Desert I s l . B i o l . Lab. 1936, 25. Fontaine, M. (1956). The hormonal c o n t r o l of water and e l e c t r o l y t e metabolism i n f i s h . Mem. Soc. Endocrin. No. 5, 69-82. and Hatey, J . (1954). Sur l a teneur en 17-hydroxycorticosteroid.es du plasma de saumon (Salmo s a l a r , L . ) . C. R... Acad. S c i . , P a r i s . 239, 319-321. Ford, P.  (1956). Studies on the development of the kidney of the P a c i f i c pink salmon (Oncorhynchus gorbuscha Walbaum). Canad. J . Z o o l . 36, 45-47.  F o r s t e r , R. P. (1942). The nature of the glucose reabsorptive process i n the frog renal tubule. Evidence for i n t e r mittency of glomerular function i n the i n t a c t animal. J . C e l l . and Comp. P h y s i o l . 20, 55-69.  - 26 F o r s t e r , R. P. (1953). A comparative study of renal function i n marine t e l e o s t s . J . C e l l and Comp. Physiol* 42, 487-509. F u j i t a , A . and Iwatake, D. (1931). Bestimmung des echten Blutzuckers ohne Hefe. Biochem. Z. 242, 43-60. H e l l e r , H. and P i c k e r i n g , B . T. (1961). Neurohypophysial hormones of non-mammalian vertebrates. J . P h y s i o l . 155, 98-114. Holmes, R. M. (1961). Kidney function i n migrating salmonids. Rep. Challenger Soc. Camb. 3_, No. 13, 23. Holmes, W. N . (1959). Studies on the hormonal c o n t r o l of sodium metabolism i n the rainbow trout (Salmo g a i r d n e r i ) . Acta endocr., Copenhagen. 31, 587-602. Holmes, V. N . and Adams, B . M. (1963). The effects of adrenoc o r t i c a l and neurohypophysial hormones on the renal excretory pattern of the water loaded duck (Anas platyrhynchos). Endocrinology, 73, 5-10. Houston, A . H. (1959). Osmoregulatory adaptation of the s t e e l head trout (Salmo g a i r d n e r i Richardson) to sea water. Canad. J . Z o o l . 37, 729-748. (1960). V a r i a t i o n s i n the plasma l e v e l of chloride i n hatchery-reared y e a r l i n g A t l a n t i c salmon during p a r r smolt transformation and following transfer to sea water. Nature, Lond. 185, 632-633. Huntsman, A . G. and Hoar, W. S. (1939). Resistance of A t l a n t i c salmon to sea water. J . F i s h . Res. Bd. Canada, 4, 409-411. Keys, A . B . (1931). Chloride and water secretion and absorption by the g i l l s of the e e l . Z. v e r g l . Phys id.. 15, 364-388. Krogh, A . i (1937). Osmotic r e g u l a t i o n i n fresh water fishes by a c t i v e absorption of chloride i o n s . Z. v e r g l . P h y s i o l . 24, 656-666. (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. Lyman, J . and Fleming, R. H. (1940). J . Mar. Res. 3, 134-146.  Composition of sea water.  M a r s h a l l , E . K . , J r . and G r a f f l i n , A . L . (1932). The function of the proximal convoluted segment of the renal tubule. J . C e l l , and Comp. P h y s i o l . 1, 161-176.  - 27 Munsick, R. A . , Sawyer, W. H. and van Dyke, H. B . ( i 9 6 0 ) . Avian neurohypophysial hormones: pharmacological properties and t e n t a t i v e i d e n t i f i c a t i o n . Endocrinology 66, 860-871. Nash, J .  (1931). The number and s i z e of glomeruli i n the k i d neys of fishes w i t h observations on the morphology of the renal tubules of f i s h e s . Amer. J . Anat. 47, 425446.  N i c o l , J . A . C. ( i 9 6 0 ) . The Biology of Marine Animals. Interscience. New York. Olivereau, M. ( i 9 6 0 ) . Etude volumetrique de l ' i n t e r r e n a l anterieur 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. Acta endocr., Copenhagen, 33, 142-156. Richards, A . N . and Schmidt, C P . (1924). A d e s c r i p t i o n of the glomerular c i r c u l a t i o n i n the f r o g ' s kidney ahd observations concerning the a c t i o n of adrenalin and various other substances upon i t . Amer. J . P h y s i o l . 71, 178-208. Roe, J . H . , E p s t e i n , J . H. and G o l d s t e i n , H. P. (1949). A photometric method for the determination of i n u l i n i n plasma and u r i n e . J . B i o l . Chem. 178, 839-845. ' Sawyer, W. H . , Munsick, R. A . and van Dyke, H. B . (1961). Pharmacological c h a r a c t e r i s t i c s of the active p r i n c i p l e s i n neurohypophyseal extracts from several species of f i s h e s . Endocrinology 68, 215-225. Schreiner, G. E . (1950). Determination of i n u l i n by means of r e s o r c i n o l . Proc. Soc. Exper. B i o l . and Med. 74, 117-120. Sexton, A . ¥ . and Meyer, D. K. (1955). Effects of potassium, caesium and l i t h i u m ions.on sodium transport through g i l l s of g o l d f i s h . Fed. Proc. 14, 137. Shannon, J . A . (1934). The excretion of i n u l i n by the dogfish Squalus acanthius. J . C e l l , and Comp. P h y s i o l . 5_, 301-310. Smith, H. ¥ . (1930). The absorption and excretion of water and s a l t s by marine t e l e o s t s . Amer. J . P h y s i o l . 93, 480-505. (1932). Water r e g u l a t i o n and i t s evolution i n the f i s h e s . Quart. Rev. B i o l . 7, l-26<  - 28 Smith, H. W. (1951). The Kidney; Structure and Function i n Health and Disease. Oxford U n i v e r s i t y Press, New York. •  (1956). P r i n c i p l e s of Renal Physiology. U n i v e r s i t y Press, New York.  Oxford  , F i n k e l s t e i n . N . , Aliminosa, L . , Crawford, B . and Graber, M. (1945). ^he renal clearances of substituted hippuric a c i d d e r i v a t i v e s and other aromatic acids i n dog and man. J . C l i n . Invest. 24, 388-404. Snedecor, G. ¥ . (1956). S t a t i s t i c a l Methods. 5th e d i t i o n . Iowa State College Press, Ames, Iowa, U . S. A. Uranga, J . ( i 9 6 0 ) . D i u r e t i c response i n the b u l l f r o g (Rana catesbiana) to the i n j e c t i o n of oxytocin. Acta endocr., Copenhagen, suppl. 51, 35_, 139.  PART  II  S T U D I E S ON E L E C T R O L Y T E E X C R E T I O N GREEN TURTLE  I N THE  (CHELONIA MYDAS)  Introduction Except f o r the b r i e f period of egg-laying, f i v e species of t u r t l e are s t r i c t l y marine; namely, the green t u r t l e  (CheIonia  mydas), the loggerhead t u r t l e (Caretta c a r e t t a ) , Ridley's t u r t l e (Lepidochelys o l i v a c e a ) , the h a w k s b i l l t u r t l e (Lepidochelys imbricata) and the leatherback t u r t l e (Dermochelys c o r i a c e a ) . R e p t i l e s i n the sea, l i k e marine f i s h and marine b i r d s , have a high intake of e l e c t r o l y t e s ; yet as we s h a l l show, the concentrations of sodium and potassium i n the blood of the marine t u r t l e are c h a r a c t e r i s t i c of vertebrates g e n e r a l l y . In, view of t h e i r evolutionary relationship to the b i r d s , i t i s not s u r p r i s i n g to f i n d that some marine r e p t i l e s possess f u n c t i o n a l " s a l t glands" (Schmidt-Nielsen and Fange, 1958). These glands, l i k e those of marine b i r d s , produce a s e c r e t i o n considerably more concentrated than sea water w i t h respect to sodium and potassium (Schmidt-Nielsen and Fange, 1958).  The  " s a l t glands" of marine b i r d s were r e c e n t l y shown to be, at l e a s t i n p a r t , under the c o n t r o l of the adrenal cortex (Holmes, P h i l l i p s and B u t l e r , 1961a; Holmes, B u t l e r and P h i l l i p s , 1961b; P h i l l i p s , Holmes and B u t l e r , 1961).  The object of t h i s i n v e s t i g a -  t i o n , therefore , was to determine whether a s i m i l a r pathway of c o n t r o l might e x i s t i n the marine t u r t l e , Chelonia mydas.  M a t e r i a l s and Methods Juvenile green t u r t l e s of the A t l a n t i c subspecies, Chelonia mydas mydas, obtained from the Lerner Marine Laboratory, B i m i n i , Bahamas, were maintained i n aquaria supplied with running sea water (sodium = 460. m-equiv./l., potassium = 7.63 m-equiv./ 1.) or, i n some cases, f r e s h water (sodium = 1.30 m-equiv./l., potassium = 0.08 m-equiv./l.) at 20 to 25°C. A l l animals were fed an ad l i b i t u m d i e t of chopped shrimp, added to the tanks each morning. To determine sodium and potassium output, t u r t l e s were removed from sea water, washed i n de-ionized f r e s h water and then placed i n beakers containing 400 ml. of de-ionized water. At zero, 1, 2, 3, 4, 5, and, i n some cases 6 hours a f t e r t r a n s f e r 10 ml. a l i q u o t s of water were withdrawn from the beakers and replaced with 10 ml. of de-ionized water.  The sodium and potas-  sium concentrations of these samples were determined with a Zeiss PF5 flame photometer and from the values so obtained the cumulative t o t a l outputs of these e l e c t r o l y t e s f o r each time i n t e r v a l were c a l c u l a t e d . In order to estimate the magnitude of the renal component of the t o t a l e l e c t r o l y t e excretion, the cloacae of one group of t u r t l e s were occluded by means of a s n a i l rubber plug held i n place by a "purse-string" l i g a t u r e . The e l e c t r o l y t e output of some animals was determined a f t e r the morning feeding, while that of other groups was estimated a f t e r 24 hours without food.  These groups are here-  i n a f t e r r e f e r r e d to as "fed" and "unfed" r e s p e c t i v e l y .  - 32 The average quantity of shrimp consumed by the  turtles  (at the morning feeding) was determined over a period of several weeks.  A weighed quantity of shrimp i n excess was introduced  into the tanks, and the surplus was again weighed when a l l animals had ceased to eat.  Consumption was expressed as grams  of shrimp per 100 grams body weight of t u r t l e . Some of the unfed animals were injected with NaCl to give a more precise c o n t r o l of the s a l t load than was possible with feeding.  Both fed and saline-loaded t u r t l e s were treated  with amphenone "B" (3,3'-bis-(p-arainophenyl)-2-butanone) simulate adrenalectomy.  Some of these "chemically adrena-  lectoriiized" animals were also given "replacement" of  to  injections  corticosterone. A l l i n j e c t i o n s were given intramuscularly i n the pectoral  region.  Saline-loaded t u r t l e s received a single i n j e c t i o n of  500 ^u-equiv. sodium (as NaCl) i n 0.1 m l . d i s t i l l e d water at zero time.  Amphenone "B" was injected i n isotoiic saline (50 m g . / m l . ) ,  each animal r e c e i v i n g 5 mg. immediately after feeding or one hour p r i o r to s a l i n e - l o a d i n g .  Corticosterone, prepared as a  s t a b i l i z e d suspension i n i s o t o n i c s a l i n e , was injected i n a single 2 mg. dose immediately p r i o r to the administration of amphenone. Blood samples were obtained by heart puncture and urine samples were c o l l e c t e d d i r e c t l y from the bladder by means of a p l a s t i c tube inserted through the cloaca*  - 33 At autopsy of the j u v e n i l e s and occasional large t u r t l e s that became a v a i l a b l e to the laboratory the weights of s a l t glands were recorded. The sodium and potassium composition of whole small f i s h , crustaceans* molluscs and algae c o l l e c t e d on the  shore,  and also of the shrimp used as food i n the laboratory, was determined after cold d i g e s t i o n i n sulphuric a c i d and n e u t r a l i z a t i o n with ammonium hydroxide.  The t o t a l water content of these  forms was also determined by drying to constant weight at 120°C. S t a t i s t i c a l analyses were c a r r i e d out according to Snedecor (1956).  The " i n i t i a l rate " of e l e c t r o l y t e excretion  was taken as the amount of sodium or potassium put out i n the f i r s t hour after t r a n s f e r .  "Terminal rates" of excretion were  derived from regressions c a l c u l a t e d by the method of l e a s t squares for the f i n a l 3 hours of the experimental periods.  Results 1.  Plasma and urine e l e c t r o l y t e s i n sea water and fresh water maintained t u r t l e s *  (Table  I).  Although the concentrations of sodium and potassium i n the plasma were s i g n i f i c a n t l y lower i n t u r t l e s maintained for 2 months i n fresh water these differences were small compared to the differences i n the concentrations of these ions i n the two environments. The urinary concentrations of sodium and potassium i n the sea water maintained t u r t l e s were considerably higher than i n the fresh water group.  I t i s i n t e r e s t i n g to note,  however, that the concentrations of these electrolytes i n the urine were less than i n the plasma both i n the fresh water and the sea water animals.  Furthermore, the r a t i o of sodium to  potassium i n the urine d i d not d i f f e r i n the two environments. The volumes of the urine samples obtained from the bladders of these t u r t l e s may be of l i t t l e s i g n i f i c a n c e , but they are  sugges-  t i v e of a lower urine production i n sea water.  2.  Nasal gland weights i n sea water and fresh water maintained turtles.  (Table I ) .  Juvenile green t u r t l e s kept for two months i n fresh water had nasal glands which were 38$ less i n absolute weight and 44$ l e s s i n r e l a t i v e weight than those of animals kept i n sea water.  TABLE I The plasma and urine e l e c t r o l y t e composition and the  salt  gland weights of juvenile green tur-tles (Chelonia mydas mydas) maintained i n sea water from b i r t h to 6 months of age and i n fresh water from 4 months after hatching to 6 months of age.  Group  No. of turtles  Sea water (0-6 months) Fresh water (4-6 months)  8  Body wt.  Plasma electrolyte concentration (m-equiv./l.)  Urine electrolyte concentration (m-equiv./l.)  Volume of urine sample (ml./lOO  Na  K  Na  K  Na:K  52.9 +4.9  157.8 +1.4  1.48 +0.03  46.6 +2.8  7.18 +0.33  6.6 +0.5  0.14 +0.01  59.1 +7.2  130.2 +1.0  2.58 +0.01  3.8 +0.3  0.46 +0.08  9.5 +1.8  0.25 .+0.03  g.  Absolute salt gland wt,  Relative S a l t gland wt. (mg./lOO g. (B.W.)  158.4 +14.4  303.2 +11.6  98.0 +16.1  170.4 +21.2  B.ff.)  **  Volume of urine that could be drained from the bladder at the time of sampling, * p < 0.02 ** p < 0.01 *** p < 0.001  significance of values with respect to the corresponding value for sea water adapted  turtles.  FIGURE I The excretion of (a) sodium and (b) potassium by fed and unfed green t u r t l e s (CheIonia mydas mydas) over a 5-hour period.  The fed animals ate 2.3 + 0.25 g. shrimp per 100  g. body weight of the following composition: 788.9 + 5 . 8 water per k g . wer weight, 54.4 + 1.3 m-equiv. sodium per k g . wet weight and 92.1 + 3.9 m-equiv. potassium per k g . wet weight.  Amphenone "B" was administered as a single  intramuscular dose (5 mg.) immediately after  feeding.  g.  - 36 -  TABLE I I The excretion of sodium and potassium by fed and unfed green t u r t l e s  (Chelonia mydas mydas) over a 5-hour p e r i o d .  The fed animals ate 2.3 + 0.25 g. shrimp per 100 g. body weight of the following composition: 788.9 + 5.8 g. water per k g . wet weight, 54.4 + 1.3 m-equiv. sodium per k g . wet weight and 92.1 + 3.9 m-equiv. potassium per k g . wet weight. Amphenone "B" was administered as a single intramuscular dose (5 mg.) immediately after  feeding.  I n i t i a l rate of excretion (u-equiv./hr. /100 g. B.W.)  Terminal rate of excretion (u-equiv./hr. /lOO g. B.W.)  Total e x c r e t i o n (u-equiv./lOO g. B.W.)  No. of turtles  Body wt. (g.)  11  93.9 +2.3  47.4 6.45 + 4.8 +1.04  •**  *#  Fed  9  68.1 +3.5  130.6 7.65 +17.6 +1.50  144.8 4.62 +40.2 +0.91  672.1 +88.6  24.62 +1.94  27.1 +2.2  Fed plus amphenone  9  81.4 +6.3  74.9 6.93 +13.0 +1.75  9.5 +11.5  127.8 +27.9  14.19 +1.73  8.5 +0.8  Treatment Unfed  Na  K  Na  K  Na  4.47 1.93 + 2.34 +0.38  -*#  *  71.1 + 5.3  K  Na:K  13U8 +0.81  ^  5.7 +0.6  * 1.50 +0.71  *  p < 0.02  significance  **  p < 0.001  with respect to corresponding value f o r unfed t u r t l e s .  - 38 3.  Sodium and potassium excretion of fed and unfed  turtles.  (Table I I and Figures l a . and b.) "Fed" t u r t l e s ate 2.3 + 0.25 g . shrimp per 100 g . body weight, at each feeding.  This shrimp contained 788.9 +  5.8 g. water/kg. wet weight, 54.4 + 1.3 m-equiv. sodium/kg. wet weight and 92.1 + 3.9 m-equiv. potassium/kg. wet weight. Turtles which had eaten shrimp excreted s i g n i f i c a n t l y higher amounts of sodium and potassium during the f i v e hours subsequent to feeding than d i d unfed animals.  Furthermore, both  the i n i t i a l and the f i n a l rates of excretion of these ions were s i g n i f i c a n t l y greater i n the fed t u r t l e s .  Treatment of fed  t u r t l e s w i t h amphenone "B" immediately after feeding reduced the i n i t i a l and terminal rates of excretion and the t o t a l exc r e t i o n of sodium and potassium to "unfed" l e v e l s .  The sodium:  potassium r a t i o , however, remained s i g n i f i c a n t l y higher than i n the unfed  4.  turtles.  Sodium and potassium excretion of saline-loaded  turtles.  (Table I I I and Figures I l a . and b . ) Separation of the renal component from the t o t a l exc r e t i o n by occlusion of the cloaca d i d not s i g n i f i c a n t l y a l t e r either the pattern of excretion.or the t o t a l amounts of sodium and potassium excreted when compared with the i n t a c t s a l i n e loaded c o n t r o l s .  The r a t i o i n which these ions were excreted  was, i n both instances,  s i g n i f i c a n t l y higher than i n the non-  loaded animals (p < .001) but did not d i f f e r s i g n i f i c a n t l y from that of the fed t u r t l e s .  Treatment with amphenone before saline  loading s i g n i f i c a n t l y reduced both the i n i t i a l rates of excretion and the t o t a l amounts of sodium and potassium excreted, but the terminal ratesof excretion were s i m i l a r to the c o n t r o l values. The r a t i o i n which these ions were excreted was s i g n i f i c a n t l y reduced after amphenone treatment, but not to the value observed for unfed animals ( c f . Tables I I and I I I ) .  Pre-treatment of  amphenone-injected animals with corticosterone increased the i n i t i a l rate of sodium excretion to a l e v e l higher than that of the c o n t r o l animals and the t o t a l amount excreted was restored. The i n i t i a l rate of potassium excretion was not increased.  In  the case of neither sodium nor potassium was the i n i t i a l excretory rate sustained and the terminal rates of excretion were s i g n i f i c a n t l y lower than those of the i n t a c t c o n t r o l s .  The  sodium:potassium r a t i o of the t o t a l excretion was s i m i l a r to that of the controls and was s i g n i f i c a n t l y higher than that of the amphenone treated t u r t l e s  (p •< 0.001).  FIGURE I I The excretion of (a) sodium and (b) potassium by saline-loaded juvenile green t u r t l e s (CheIonia mydas mydas). received a single intramuscular  Each animal  i n j e c t i o n of 500 ^-equiv.  sodium  as sodium chloride s o l u t i o n . Amphenone "B" (5 mg.) and c o r t i costerone (2.5 mg.) were administered loading.  a t the time of s a l i n e  Excretion was measured over a 6r-hour period.  30  TABLE I I I The excretion of sodium and potassium by the saline-loaded juvenile green-turtle (Chelonia mydas mydas).  Each animal  received a single intramuscular i n j e c t i o n of 500 ju-equiv. sodium as sodium chloride s o l u t i o n . Amphenone "B" (5 mg.) and corticosterone (2.5 mg.) were administered of saline loading. period.  at the time  Excretion was measured over a 6-hour  Treatment Intact controls  No. of turtles  Amphenone plus corticosterone  *  p < 0.02  **  p < 0.01  ***  p < 0.001  Terminal rate of e x c r e t i o n (ju.-equiv./hr.)  K  Na:K  2.42 +0.39  503.0 +32.2  22.49 +1.35  23.3 +1.2  98.8 +20.7  2.98 +0.40  601.9 +78.0  22.95 +0.93  25.5 +2.9  2.75 +1.04  37.5 +13.1  1.88 +0.46  234.6 +59.0  14.35 +2.06  14.5 +2.2  6.18 +1.51  12.2 +13.3  409.0 +44.8  13.55 +1.27  30.1 +2.1  K  Na  103.3 +1.7  117.0 +16.7  7.83 +1.32  63.4 +13.1  114.4 +7.2  118.9 +16.1  7.29 +0.75  8  102.5 +6.3  51.6 + 9.1  10  117.8 +5.7  #** 298.6 +26.9  10  T o t a l excretion (ju-equiv.) Na  Na  isA  Controls with occluded cloacae Amphenone  Body wt.  I n i t i a l rate of excretion (M-equiv./hr.)  *  *  0.93 +0.42  significance w i t h respect to corresponding value for i n t a c t control t u r t l e s .  i—•  Discussion With the exception of the elasmobranchs, the jawed vertebrates demonstrate a remarkable constancy i n the i o n i c composition of t h e i r e x t r a c e l l u l a r f l u i d s .  Whether the  species  i s t e r r e s t r i a l , fresh water, or marine i n h a b i t , the osmolar concentration of the m i l i e u i n t e r i e u r i s generally one-third to one-fourth that of "modern" sea water.  In t h i s respect Che Ionia  mydas appears to be no exception. The renal excretion of e l e c t r o l y t e s constitutes a p a r t i c u l a r l y acute problem i n any vertebrate when i t s access to fresh water i s l i m i t e d , a s i t u a t i o n which e x i s t s i n the normal habitat of the marine t u r t l e .  Many vertebrate animals have overcome  t h i s problem through the development of a v a r i e t y of "accessory" excretory structures  i n a d d i t i o n to the mesonephric and met-  anephric kidneys: namely, the g i l l s , the s k i n , and several forms of glandular organs.  These organs, although morphologically  d i v e r s e , possess the common property of enabling i o n s , p r i m a r i l y sodium and potassium, to be moved against an osmotic gradient. A s a l t - s e c r e t i n g gland was f i r s t demonstrated i n marine r e p t i l e s by Schmidt-Nielsen and Pange (1958).  These workers showed that  a gland s i t u a t e d i n the o r b i t of the eye was capable of elaborating a secretion w i t h twice the sodium concentration of sea water. On the basis of the data so far c o l l e c t e d , i t would seem that the renal excretory pathway i n the marine-adapted t u r t l e i . i s incapable of excreting the e l e c t r o l y t e s which may be ingested e i t h e r i n sea water or i n food.  The excretion of sodium and  - 43 potassium i n the present experiments represented an output far i n excess of that possible by the kidneys of these j u v e n i l e turtles.  On the basis of the urine composition found i t can be  c a l c u l a t e d that the water contained i n the d a i l y intake of shrimp was s u f f i c i e n t to excrete r e n a l l y only 67$ of the sodium and only 6$ of the potassium ingested i n the shrimp.  Samples of bladder  urine from adult marine t u r t l e s i n d i c a t e d no change i n the renal concentrating a b i l i t i e s with maturity (Table I V ) .  Furthermore,  since the t o t a l excretion of sodium and potassium was not s i g n i f i c a n t l y a l t e r e d i n the t u r t l e s w i t h l i g a t e d cloacae, we may conclude that the kidneys represented a minor excretory source of these ions under the conditions of our experiments. Thus, even considering the p o s s i b i l i t y of c l o a c a l reabsorption of water suggested for some t e r r e s t r i a l r e p t i l e s ( K h a l i l and , Abdel-Messeih, 1954), i t i s probable that these t u r t l e s could not remain i n p o s i t i v e water balance on the basis of renal excretion alone.  Although the evidence i s c i r c u m s t a n t i a l , i t  can be concluded that the excretion of sodium and potassium by both fed and saline loaded t u r t l e s was l a r g e l y from an e x t r a renal source.  Using larger specimens of Chelonia mydas i t was  possible to c o l l e c t s u b s t a n t i a l q u a n t i t i e s of the s a l t - g l a n d secretion.  This f l u i d contained 684.8 + 55.5 m - e q u i v . / l . of  sodium and 20.7 + 3.6 m - e q u i v . / l . of potassium (sodium.potassium r a t i o 37.7 + 4 . 4 ) .  The " s a l t gland" of t h i s species i s thus w e l l  suited for the excretion of sodium and potassium i n any ingested sea water with a net production of "osmotically free" water.  TABLE IV The e l e c t r o l y t e composition of urine sampled d i r e c t l y from the urinary bladders of two species of adult marine  turtles.  Species  Body weight (kg.)  Urine e l e c t r o l y t e concentrations (m-equiv./l.) Na  K  Na:K  Chelonia mydas mydas. (Green t u r t l e )  40.2 +1.7  11.5 +1.6  8.1 +1.3  1.47 +0.21  Lepidochelys olivacea ( R i d l e y ' s turtle)  9.09 +0.75 ~  20.5 +6.4  +2.4  8,. 6  2.33 +0.12  I t i s of i n t e r e s t to note that a l l the sodium contained i n the shrimp fed to the t u r t l e s was excreted i n the f i r s t 57 minutes of the experiment.  However, only 3.5$ of the  contained i n t h i s food was put out during t h i s time.  potassium Even at the  end of the five-hour experimental period only 11.6$ of the ingested potassium had been excreted whereas 528 ^z-equiv. of sodium i n excess of the amount contained i n 2.3 g. of shrimp had been released.  The s i g n i f i c a n c e of t h i s paradox i s obscure. Because of the observation that the sodium:potassium r a t i o  of nasal gland f l u i d (37.7) was considerably lower than that of sea water (60.4), i t  YJUS  decided to determine the body sodium  and potassium concentrations of a v a r i e t y of organisms suspected to be food sources f o r marine t u r t l e s and marine b i r d s (Table V). I f one considers a t u r t l e d r i n k i n g one l i t r e of sea water, then a l l the sodium contained i n t h i s sea water (470 m-equiv.) would be excreted i n 686 ml. of s a l t gland f l u i d . the potassium of f l u i d .  The excretion of a l l  (7.63 m-equiv.), however, would require only 369 ml.  Since no s i g n i f i c a n t change i n the sodium:potassium  r a t i o of s a l t gland f l u i d was apparent during prolonged periods of s e c r e t i o n , the t u r t l e would therefore produce 317 ml. of f l u i d f o r which there would be no potassium ions " a v a i l a b l e " from the ingested sea water.  Examination of the sodium and  potassium  concentrations i n nasal gland f l u i d from marine b i r d s (SchmidtN i e l s e n , Jorgensen and Osaki, 1958; Schmidt-Nielsen and  Sladen,  1958; Holmes et a l . , 1961a; P h i l l i p s et a l . , 1961) i n d i c a t e that a s i m i l a r s i t u a t i o n would also occur there.  Hence i n view of the  TABLE V The water, sodium and potassium composition of the types of food p o s s i b l y eaten by marine r e p t i l e s and marine b i r d s .  f  - 46 -  Body weight (g.)  Body Water ( g . / k g . body weight)  E l e c t r o l y t e content (m-equiv./kg. body water) Na  K  Na:K  Teleosts Lagodon rhomboides ( p i n f i s h ) Menticirrhus americanus (southern k i n g f i s h ) Trachinotus carolinus (pompano) Mugil cephalus ( s t r i p e d mullet) Cyprinodon variegatus (sheepshead minnow) Menidia b e r y l i n a (tidewater s i l v e r s i d e )  6.93+1.40 4.88+0.54 3.89+0.35 0.80+0.05 3.78+0.33 2.44+0.17  757.2+ 789.8+ 797.4+ 789.2+ 737.4+ 735.7+  4.0 3.2 1.1 1.1 5.0 5.1  2.76+0.33 0.08+0.01 2.43+0.13 1.80+0.45  750.2+ 3.2 758.2+10.6 663.6+ 4.0 719.5+ 2.2  7.47+0.46 (without s h e l l )  126.6+ 4.7 112.4+ 0.7 101.1+15.1 111.7+ 1.3 100.1+ 4.4 125.1+ 1.5  0.59+0.03 0.50+0.01 0.93+0.09 0.63+0.02 0.81+0.02 0.55+0.03  110.4+ 4.1 109.6+ 0.3 233.2+ 3.9 330.5+19.3  130.5+ 127.9+ 116.0+ 90.2+  1.7 2.0 2.3 4.5  0.85+0.02 0.87+0.02 2.02+0.04 3.76+0.35  816.5+ 4.8 ~  167.4+ 6.1 ~~  104.3+ 0.3 ~  1.60+0.07 ~  751.0+10.9 946.8+ 3.9 893.8+ 4.4 898.5+ 1.2 831.4+ 3.9  103.4+ 4.1 305.5+ 9.2 93.7+ 6.5 378.3+16.9 89.4+ 6.1  104.4+ 224.7+ 598.2+ 97.0+ 80.0+  0.99+0.03 1.36+0.03 0.16+0.01 3.93+0.26 1.11+0.04  75.1+ 67.2+ 91.7+ 70.9+ 80.4+ 68.4+  5.3 1.3 6.3 0.8 2.6 1.9  Crustaceans Peneus s e t i f e r u s (white shrimp) Palaemonetes v u l g a r i s (glass shrimp) Uca p u g i l a t o r ( f i d d l e r crab) Arenaeus c r i b r a r i u s (surf crab) Molluscs Venus mercenaria (clam) Algae Ulva lactuca Codium f r a g i l e Gracilaria foliifera Hypnea c e r v i c o r n i s Enteromorpha flexuosa  Common names taken from American F i s h e r i e s Society Special P u b l i c a t i o n No. 2, I960.  2,0 1.8 9.7 4.3 4.0  c o n s i s t e n t l y low sodium:potassium r a t i o s of t h e i r  foodstuffs,  i t i s possible that these animals drink sea water not only to. obtain osmotically free water but also to enable the excretion of the large amounts of potassium ingested food.  That i s , sodium  from ingested sea water may act as a " v e h i c l e " for the e x t r a renal excretion of d i e t a r y potassium.  Indeed, on the basis of  a few determinations by the phenol red technique (Smith, 1930), i t can be estimated that j u v e n i l e green t u r t l e s ingested 1.33 + 0.1 m l . of sea water per 100 g. body weight per day (W. N . Holmes and E . L . McBean, unpublished observation).  This volume would  contain s u f f i c i e n t sodium to permit the excretion of the  "excess"  potassium i n the food. In e a r l i e r studies w i t h marine b i r d s i t has been shown that e l e c t r o l y t e excretion by the nasal glands i s dependent upon an i n t a c t adrenal cortex (Holmes et a l . , 1961a; P h i l l i p s et a l . , 1961).  To i n v e s t i g a t e the p o s s i b i l i t y of a s i m i l a r  control mechanism i n the marine t u r t l e , adrenalectomy would be the approach of choice.  This operation i s d i f f i c u l t i n t u r t l e s ,  however, because of the diffuse nature of the gland,  ^o simulate  adrenalectomy, treatment with amphenone "B" was therefore employed. This compound i n h i b i t s the production of the normal adrenal s t e r o i d i n mammals (Hertz, T u l l n e r , S c h r i c k e r , Dhyse and Hallman, 1954), reducing the synthesis of 17-hydroxycorticoids, corticosterone, aldosterone, and 17-ketosteroids, apparently by a non-specific a c t i o n on several enzyme systems (Rosenfeld and Bascom, 1956;  48  -  Renold, Crabbe, Hernando-Avendano, Nelson, Ross, Emerson and Thorn, 1957; Jenkins, Meakin and Nelson, 1961).  Amphenone  i n h i b i t s adrenal steroidogenesis i n r e p t i l e s also ( P h i l l i p s , Chester Jones and Bellamy, 1962), and, although some steroids may be synthesized, i t was considered that a r e l a t i v e  adrenal  i n s u f f i c i e n c y of the treated t u r t l e s would supervene.  The  s i g n i f i c a n t reduction i n the i n i t i a l rates of excretion and i n the t o t a l amounts of sodium and potassium excreted a f t e r treatment of the fed and saline-loaded t u r t l e s with amphenone suggests that the s a l t glands i n Chelonia mydas are dependent upon a f u l l y f u n c t i o n a l adrenal cortex.  The re-establishment  of rapid sodium  excretion when corticosterone was administered with the amphenone r e i n f o r c e s t h i s hypothesis.  The decline i n the terminal rates  of sodium and potassium excretion by these t u r t l e s may have r e f l e c t e d the metabolism of exogenous hormone. The present work, i n conjunction with previous  studies  of the extra-renal excretory process i n marine birds (Holmes et a l . 1961a  and b, P h i l l i p s et a l . 1961) and salmonid t e l e o s t s (Holmes,  1959), suggests a generalized pattern of response by extra-renal excretory organs to adrenocortical s t e r o i d s .  This response i s  one of a net increase i n the excretion of both sodium and potassium. I t i s thus antagonistic to the usual renal response to these hormones with respect to sodium excretion but complementary with respect to potassium excretion.  That i s to say, while the extra-renal  output of sodium i s increased by adrenal s t e r o i d s , the renal output i s u s u a l l y decreased, but both the renal and extra-renal  - 49 -  excretion of potassium are increased.  An enhancement of potassium  excretion v i a the kidneys would be a d i s t i n c t advantage to marine species since t h e i r d i e t s are probably high i n potassium (Table V). The increase i n the renal tubular reabsorption of sodium caused by c o r t i c o s t e r o i d s , although tending to diminish the net output, i s i n s i g n i f i c a n t i n view of the sodium concentrating capacity of the extra-renal pathways.  \  Summary The " s a l t gland" appears to be the predominant route of sodium and potassium excretion i n the marine t u r t l e CheIonia mydas mydas. The kidney of the marine t u r t l e i s probably not capable of maintaining a p o s i t i v e water balance i n the face of the e l e c t r o l y t e loads presented by sea water and food. Treatment with amphenone reduced the sodium and potassium excretion of fed and saline-loaded marine t u r t l e s .  The  administration of corticosterone p a r t i a l l y corrected t h i s reduction.  Thus the excretion of e l e c t r o l y t e s by the s a l t  gland appears to be dependent upon a f u l l y functional adrenal cortex. Marine t u r t l e s may ingest sea water i n order to obtain the sodium necessary for the extrarenal excretion of the large amounts of potassium contained i n t h e i r food.  L i t e r a t u r e Cited Hertz, R . , T u l l n e r , W. W., S c h r i c k e r , J . A . , Dhyse, F . G. and Hallman, L . F . (1955). Studies on amphenone and r e l a t e d compounds. Rec. Prog, i n Horm. Res. 11, 119-147. 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 ) . Acta endocr., Copenhagen, 31, 587-602. , P h i l l i p s , J . G. and B u t l e r , D. G. (1961a). The effect of adrenocortical steroids on the renal and e x t r a renal responses of the domestic duck (Anas platyrhnchus) after hypertonic saline l o a d i n g . Endocrinology 69, 483-495. , B u t l e r , D. G. and P h i l l i p s , J . G. (1961b). Observations on the effect of maintaining glaucous-winged g u l l s (Larus glaucescens) on fresh water and sea water for long p e r i o d s . J . Endocrin. 23, 53-61. Jenkins, J . S . , Meakin, J . W. and Nelson, D. H. (1959). A comparison of the i n h i b i t o r y effects of 2 - m e t h y l - l , 2 - b i s (3-pyridyl)-l-propanone and amphenone B on adrenal c o r t i c a l secretion i n the dog. Endocrinology 64, 572-578. K h a l i l , F . and Abdel-Messeih, G. (1954). of some desert r e p t i l e s and mammals. 407-414.  Water content of t i s s u e s J . Exp. Z o o l . 125,  P h i l l i p s , J . G . , Holmes, W. N . and B u t l e r , D. G. (1961). The effect of t o t a l and subtotal adrenalectomy on the r e n a l and e x t r a - r e n a l response of the domestic duck (Anas platyrhnchus) to saline l o a d i n g . Endocrinology 69, 958-969. , Chester Jones, I . and Bellamy, D. (1962). Biosynthesis of adrenocortical hormones by adrenal glands of l i z a r d s and snakes. J . Endocrin. 25, 233-237. Renold, A . E . , Crabbe, J . , Hernando-Avendano, L . , N l s o n , D. H . , Ross, E . J . , Emerson, K . , J r . and Thorn, J . (1957). I n h i b i t i o n of aldosterone secretion by amphenone i n man. New E n g l . J . Med. 256, 16-21. e  Rosenfeld, G. and Bascom, W. D. (1956). The i n h i b i t i o n of steroidogenesis by amphenone B: studies i n v i t r o with the perfused c a l f adrenal. J . B i o l . Chem. 222, 565-580. Schmidt-Nielsen, K. and Fange, R. (1958). S a l t glands i n marine r e p t i l e s . Nature, Lond., 182, 783-785. , Jorgensen, C. B . and Osaki, H . (1958). E x t r a r e n a l s a l t - e x c r e t i o n i n b i r d s . Amer. J . P h y s i o l . 193. 101-107.  - 52 Schmidt-Nielsen, K. and Sladen, W. J . L. (1958). Nasal s a l t secretion i n the Humboldt Penguin. Nature, Lond., 181, 1217-1218. Smith, H. W. (1930). The absorption and excretion of water and s a l t s by marine t e l e o s t s . Amer. J . P h y s i o l . 93, 480-505. Snedecor, G. YT. (1956). S t a t i s t i c a l methods. 5th e d i t i o n . Iowa State College Press, Ames, Iowa, U7 S. A.  

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