Endocrinology, Vol 114, 1567-1570, Copyright © 1984 by Endocrine Society

ARTICLES

The effect of captopril treatment on potassium-induced stimulation of aldosterone production in vitro

CA Parkinson, SJ Belton and JH Pratt

Potassium and angiotensin (AII) show interdependence as stimuli of aldosterone production. However, potassium stimulates in vitro in the absence of AII. In the present study we examined for a contribution by AII to the in vitro stimulatory potential of potassium, an AII effect mediated on the adrenal before killing of the animal. Captopril, an angiotensin converting-enzyme inhibitor, was administered orally and by sc injection for 3 days so as to decrease levels of AII. Aldosterone secretory responses by adrenal capsules to graded increments in potassium were measured subsequently using a perifusion system. It was found that captopril pretreatment significantly reduced the magnitude of aldosterone secretory response to increments in potassium of 0.5 to 6.0 mM, from a baseline potassium concentration of 3.5 mM. Responses to the lowest increment in potassium, 0.5 and 1.0 mM, were virtually abolished by captopril treatment. The results suggest that AII sensitizes the adrenal glomerulosa such that very small changes in potassium concentration can affect aldosterone production.