DIFFERENCES IN THE PATTERN OF 



ELECTROLYTE AND WATER EXCRETION IN 



YOUNG AND OLD RATS OF BOTH SEXES 



IN RESPONSE TO ADRENAL STEROIDS 



P. A. Desaulles 

 Research Laboratories, Pharmaceutical Department, CIBA Limited, Basle 



It is a known fact that, with advancing age, the cell mass 

 and, correspondingly, the cell water content of the animal 

 decrease. This, together with a constant or increasing 

 extracellular water content, appears to be one of the true 

 signs of ageing (McCance and Widdowson, 1951; Olbrich and 

 Woodford-WilHams, 1956). 



Although the adrenals, and more especially the adrenal 

 steroids, play an important part in the maintenance of the 

 water and electrolyte balance, only comparatively little is 

 known about the influence of age on the activity of the 

 adrenals or on the sensitivity of the organism to adrenal 

 steroids in animals. We were therefore prompted to study in 

 rats of different ages the pattern of urine and urinary elec- 

 trolyte excretion after treatment with two genuine adrenal 

 steroids, aldosterone and Cortisol, following a load of physio- 

 logical saline solution amounting to 20 ml. per kg. 



In view of the very complex interrelationship existing 

 between pituitary, gonads, and adrenals during the develop- 

 ment of the animal from birth to maturity and old age, we 

 have also studied rats of both sexes. These animals were 

 chosen in three different groups, ranging in age from (a) five 

 weeks to (b) fifteen weeks to (c) one year and more. 



Methods 



All experiments were performed on adrenalectomized rats 

 of the same breed, in order to avoid interference between 

 the steroids injected and the steroid output of the animal's 



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