Role of adrenal renin-angiotensin system in the control of aldosterone secretion in sodium-restricted rats

Abstract

This study examined the effect of the pharmacological manipulation of adrenal renin-angiotensin system (RAS) on aldosterone secretion from in situ perfused adrenals of rats kept on a normal diet and sodium restricted for 14 days. Neither the angiotensin-converting enzyme inhibitor captopril nor the nonselective angiotensin II receptor antagonist saralasin and the AT1 receptor-selective antagonist losartan affected basal aldosterone output in normally fed rats. In contrast, they concentration dependently decreased aldosterone secretion in sodium-restricted animals, with maximal effective concentration ranging from 10− 7 to 10− 6 M. Captopril (10− 6 M), saralasin (10− 6 M), and losartan (10− 7 M) counteracted aldosterone response to 10 mM K+ in sodium-restricted rats but not in normally fed animals. Collectively, these findings provide evidence that adrenal RAS plays a role in the regulation of aldosterone secretion, but only under conditions of prolonged stimulation of zona glomerulosa probably leading to overexpression of adrenal RAS.