Effect of Adrenal Steroids on Body Electrolytes 185 



young animals (due to potassium retention), whereas adult 

 and old animals return to a range within control values, the 

 adult group reacting more readily than the old animals. 



In the female rat, aldosterone also reduces the urinary out- 

 put, but to a somewhat smaller extent than in males ( —40 per 

 cent on the average, against about —60 per cent in males) 

 (Fig. 4). As in males, young animals tend to respond more 



% 



160 

 140 

 120 

 100 



eo 



60 

 AO 



ZO 



+ 







20 

 40 

 60 

 80 



IZJ4^6 78 9t 



Fig. 4. Urinary excretion of adrenalectomized female rats of dif- 

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

 Figures as for Fig. 1. 



markedly although there is a certain delay in the onset of the 

 effect. In contrast to males, with increasing age a short 

 period of urinary retention is followed by a strong diuretic 

 response. 



On sodium excretion aldosterone exerts a very pronounced 

 inhibiting effect of about the same relative intensity as in 

 males in all age groups (Fig. 5). In contrast to that in males, 

 this effect is followed by a period of sodium excretion, most 

 marked in old animals (+80 per cent), the values returning 

 towards the norm in the ninth hour. 



