[Behavior of the plasma renin activity and aldosterone after salt restriction and upright posture in essential hypertension].

In 100 patients with essential hypertension and 50 healthy subjects the relation between plasma renin activity (PRA) and plasma aldosterone level (Ald) was investigated. PRA as well as plasma aldosterone was estimated a) after a diet with normal sodium content (equals 120 mEq per day) provided for 3 days and after an 8 hrs rest ("L" value of PRA and Ald) and b) after sodium restriction (10 mEq per day) for 3 days and 3-4 hrs ambulation ("A" value of PRA and Ald). Concerning the behaviour of "L"- und "A"-PRA all patients were divided into 4 groups: a) patients with normal, b) rigid, c) low and d) high PRA. Despite differentiated values of PRA in patients of all groups a normal increase of the plasma aldosterone level was stated after sodium restriction in the diet and upright position. Even in 18% of healthy subjects with low PRA a normal increase of Ald after sodium restriction and upright position was observed. These results seem to prove that in patients with low and rigid PRA and in 18% of healthy subjects the renin-angiotensin system is not the main or only regulator of aldosterone secretion.