Effect of angiotensin I converting enzyme inhibition on circulating atrial natriuretic peptide in humans.

We investigated the effects of inhibition of angiotensin II (ANG II) formation with an ANG I converting enzyme inhibitor, namely Enalapril, on circulating levels of atrial natriuretic peptide (ANP). Seven normal volunteers received a low sodium diet in order to stimulate the renin-angiotensin system (period I). Subsequently, subjects maintained their low dietary sodium intake and received Enalapril perorally (period II). Each study period lasted for 6 days. Results indicated that subjects maintained a low dietary sodium intake with expected changes of the renin system before and during ANG I converting enzyme inhibition. Enalapril elicited a substantial fall in circulating ANP levels in six of the seven subjects studied. The causes of this change will have to be established but may possibly relate to hemodynamic consequences of Enalapril.