Endocrinology, Vol 100, 1008-1013, Copyright © 1977 by Endocrine Society
Effect of acute potassium loading on plasma renin and on urinary aldosterone in rats
P Corvol, ME Oblin, P Degoulet, P Fressinaud and J Menard
The disposition of aldosterone radiometabolites in rats has been studied
following iv [3H]aldosterone administration. Of injected [3H]- aldosterone,
0.31% is recovered in 24 h urine as free aldosterone and 0.08% as
acid-labile conjugate. A simple, sensitive and reliable radioimmunoassay of
free aldosterone has been developed and the effect of acute oral potassium
loading (171, 513 or 769 mueq of KCl/100 g body weight) on 4 h aldosterone
excretion, plasma renin concentration and sodium and potassium balance has
been investigated. There was a positive correlation between log urinary
aldosterone and potassium load (r = 0.92, P less than 0.001). Potassium
induced a natriuresis which was correlated directly with the dose of
potassium administered (r = 0.89, P less than 0.001). Ptasssium loading
also increased plasma renin concentration which was correlated with the
sodium excretion rate (r = 0.64, P less than 0.01). Prevention of a
negative sodium balance during the 769 mueq potassium load was obtained by
administration of 513 mueq sodium. In this experiment, plasma renin
concentration increased little, whereas the aldosterone excretion rate was
as high as during the 769 mueq potassium load without sodium addition.
