Aldosterone response to antihypertensive treatment.

To investigate whether changes in aldosterone during antihypertensive treatment would be related to alterations in the renin-angiotensin system or to changes in sodium-fluid balance, 54 essential hypertensives were hospitalized. Sodium intake was restricted to 55 mmoles per day. Levels of renin, angiotensin II and aldosterone were measured before and after two weeks treatment with atenolol (n=15), prazosin (n=15), the converting enzyme inhibitor MK 421 (n=6), verapamil (n=9) and the vasodilator L 6150 (n=10). Daily sodium excretion was determined from 24 h urine collections. The results indicate that, when renin or angiotensin levels do not change, the aldosterone response depends on alterations in sodium balance. When the renin system is depressed, sodium loss may prevent a large drop in aldosterone levels. It is concluded that during antihypertensive treatment body sodium status in itself modifies aldosterone secretion, irrespective of the renin-angiotensin system.