HYPOTENSIVE EFFECTS OF ANGIOTENSIN-II ANALOGS AND ANGIOTENSIN CONVERTING ENZYME-INHIBITORS IN WATER-DEPRIVED BRATTLEBORO RATS

The hypotensive effects of three different angiotensin converting enzyme (ACE) inhibitors (captopril, enalapril, and lisinopril) and two angiotensin II (AII) analogues ([Sar1Ile5Ala8]AII and [Sar1Ile5Thr8AII) were compared in conscious, freely-moving Brattleboro rats after 14 h of water deprivation. There was no difference between the hypotensive effects of the three ACE inhibitors. Neither was there any difference between the hypotensive effects of the two All antagonists, although when administered following ACE inhibition, [Sar1Ile5Thr8]AII caused a transient pressor effect that was significantly less than that caused by [Sar1Ile5Ala8]AII. ACE inhibition caused a greater fall in blood pressure (BP) than AH antagonism and caused an additional fall in BP during All antagonism. These results indicate an additional hypotensive effect of ACE inhibitors, over that of AH antagonists, that is not readily accounted for in terms of nonspecific effects of the former or agonistic properties of the latter. © 1990 Raven Press, Ltd., New York.