Converting enzyme inhibitors normalize the reduced adrenal responsiveness to angiotensin II in essential hypertension.

Forty to fifty percent of patients with essential hypertension are unable to modify their adrenal and renal vascular responses to angiotensin II with changes in sodium intake. These individuals have been termed 'non-modulators'. To define the role of angiotensin II in mediating this abnormality, angiotensin II infusions were performed in 31 sodium-restricted subjects before and after 72 h of converting enzyme (ACE) inhibition. Forty percent of these patients had a reduced adrenal response to angiotensin II. When the ACE inhibitor was given to normotensive subjects or hypertensive modulators no change in adrenal responsiveness to angiotensin II was observed. In contrast, in the non-modulators, short-term ACE inhibition significantly enhanced the angiotensin II dose-response curve (P less than 0.01). In a subset of five non-modulators, a third angiotensin II infusion was performed 6-8 weeks after starting the ACE inhibitor. A further enhancement of the adrenal response to angiotensin II was observed at this time point. There was no discernible difference between the response of the non-modulators and the modulating essential hypertensive patients or normotensive controls. Thus, in nearly half of the patients with essential hypertension, ACE inhibition appears to correct an abnormality in the sodium-mediated modulation of adrenal responses to angiotensin II, suggesting that this abnormality reflects an alteration in the interaction of angiotensin II and its receptor.