182 



P. A. Desaulles 



in amount in animals of differing age and weight, the results 

 are expressed as percentages of the values of control animals 

 for urinary excretion in ml., and for sodium and potassium 

 excretion in m-mole. The differences between the sodium/ 

 potassium ratios of treated and control animals are, on the 

 other hand, expressed in absolute values. 



Results 

 Effect of aldosterone 



In the male rat, aldosterone produces a marked inhibition 

 of urinary output that is most pronounced in young animals 



% 



160 



uo 



120 

 100 

 60 

 60 

 AO 



ZO 



+ 

 



ZO 



40 



60 



lZ74^6789f 



Fig. 1. Urinary excretion of adrenalectomized male rats of dif- 

 ferent age groups treated with aldosterone (0-010 mg./kg.). 

 Abscissa: Duration of experiment (hours); collecting period 



2 hours. 

 Ordinate: Urinary excretion as a percentage of the values of 

 control animals. 

 Continuous line : 5-week-old rats. 

 Interrupted line: 15-week-old rats. 

 Dotted line : one-year- and more-old rats. 



and tends to diminish — at first in duration and then in 

 intensity — with increasing age (Fig. 1). 



