Comparison of the effects of the dipeptidyl peptidase inhibitors captopril, ramipril, and enalapril on water intake and sodium appetite of Sprague-Dawley rats.

Two experiments were performed with rats to study the effects of different inhibitors of angiotensin I (Ang I) converting enzyme on water intake and sodium appetite. Subcutaneous administration of low doses of either enalapril or ramipril, like captopril, was dipsogenic. Acute administration of ramipril also enhanced the drinking response to peripherally administered Ang I. Higher doses inhibited the drinking response to Ang I, administered acutely peripherally or centrally. Data provide behavioral evidence that enalapril and ramipril inhibit brain converting enzyme activity and are considerably more potent than captopril. All 3 compounds, administered chronically in food, induced an appetite for NaCl solution. Enalapril and ramipril were more potent than captopril. Plasma renin activity was increased by each of these inhibitors, but the magnitude of the increase was not clearly related to the amount of NaCl consumed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)