196 Discussion 



find that in young animals there is very httle difference in water diuresis 

 as compared to that in animals 33 days old. Between adult animals and 

 33-day-old ones there is no difference, but between 23 and 33 days there 

 are variable, but statistically significant differences in the excretion of 

 the water load. 



Heller: That is almost exactly what we found; our age groups were 

 20-22 and 29-31 days after birth. 



Borst : Has diurnal rhythm been taken into account by Dr. Desaulles 

 and Dr. Kfecek? Big differences can arise if the controls and experiments 

 are not done at the same time each day. 



Kfecek : Our experiments and controls were always done at the same 

 time in the morning. They were done in summer and in winter, with the 

 same results. 



Desaulles : Ours were done very early in the morning. 



Adolph: Did you run controls without the hormones? 



Desaulles: Every group was run with controls. 



Borst: Light is not important. In blind people the diurnal rhythm 

 remains normal if they are in light during the night and in the dark 

 during the day. 



Desaulles : We cannot cope with every activity, but we did think that 

 light might be one of the problems. 



Fourman: Dr. Desaulles, you drew an analogy between the effects of 

 aldosterone and of Cortisol on the excretion of sodium and potassium. 

 If one considers the excretion ratio of these two ions in the urine, the 

 effects do appear to be analogous. Fred Bartter and I first became 

 interested in this question in 1949, when we began some studies which we 

 completed about a year ago (1957. J. clin. Invest., 37, 872). In the human 

 we were impressed with the fact that Cortisol produces a large increase 

 in the excretion of potassium which is transient even if the administra- 

 tion of Cortisol is continued. It is not necessarily accompanied by a 

 retention of sodium, but it is associated with an increase in the pH of the 

 urine. With aldosterone, on the other hand, the loss of potassium is not 

 transient ; it is accompanied by retention of sodium and the pH of the 

 urine does not change. On the basis of these experiments we felt that the 

 effects of these two steroids on the electrolytes were quite different. We 

 even suggested that the early effect of Cortisol on potassium was secon- 

 dary to a release of potassium from the tissues. 



Desaulles: That is my opinion too. 



Fourman: What strikes me is that pharmacologists are mistaken as 

 long as they equate these end-effects of excretion of sodium and potas- 

 sium, and as long as they speak about the alteration in Na/K ratio and 

 use this as a measure of aldosterone effect. I think the early effect of 

 Cortisol on potassium may be a tissue effect ; on the other hand the effect 

 of aldosterone on the secretion of sodium may well be a renal effect, and 

 I think you think so too. 



Desaulles: Partly, yes. The Cortisol effect on potassium is surely 

 cellular. 



Fourman : The early rise in potassium excretion with Cortisol is probably 

 a cellular effect. The results will not be very reliable if you assay a 



