Relation between plasma renin activity, angiotensin, and aldosterone and blood pressure in mild untreated hypertension.

Plasma renin activity, arterial and venous angiotensin II (A II), plasma aldosterone, and sodium excretion were measured in a group of 101 patients with mild essential hypertension. For the total hour; arterial A II was 5.2 +/- 1.0 pg/ml; venous A II was 4.2 +/- 0.6 pg/ml; and plasma aldosterone was 5.0 +/- 0.45 ng/100 ml. All values were lower corresponding values for normal subjects on a high salt intake despite the fact that salt intake in the normal subjects exceeded that for the hypertensive group more than 3-fold. Moreover, when the range of diastolic blood pressure up to 114 mm Hg was divided into three successive class intervals of increasing severity, there was a negative correlation between diastolic blood pressure and both PRA and plasma aldosterone. Arterial A II showed an anomalous increase in the class interval 105-114 mm Hg, despite the fact that this group exhibited the lowest level of PRA. At diastolic blood pressures above 114 mm Hg, the PRA appears to rise again. The anomalous increase in arterial A II in the presence of marked suppression of PRA is consistent with the presence of a renin activator or accelerator factor in hypertensive plasma as postulated by others. It also identifies a possible mechanism whereby even small increases in PRA could exert an adverse effect on the hypertensive state.