Increased Adrenal Sensitivity to Angiotensin II in Low-Renin Essential Hypertension

A B S T R A C T Studies were undertaken to determine if the dissociation of aldosterone and plasma renin activity in low-renin essential hypertension is due to altered adrenal responsiveness to angiotensin II. The responsiveness of' the adrenal glands to angio- tensin II was determined by infusing graded doses of angiotensin II into normal subjects and into patients with essential hypertension and measuring changes in levels of' plasma aldosterone in response to the infusion. To minimize the influence of endogenous angiotensin II and ACTH, supplemental sodium and dexamethasone were given before the infusions. Levels of plasma aldosterone and plasma renin activity were determined in normal subjects anid in the same patients after the combined stimuli of furosemide and upright posture, a maneuver used to increase the level of en- dogenous angiotensin II. To determine if the changes in levels of plasma aldosterone during infusion of angiotensin II were due to alteration of the metabolic clearance of aldosterone, the metabolic clearance of aldosterone was meastured before and during the infu- sion of angiotensin II.