Antihypertensive action of angiotensin-I converting enzyme inhibitors in the kidney.

Abstract

In order to elucidate the antihypertensive action of angiotensin-I converting enzyme inhibitors (CEIs) in the kidney, intrarenal (IR) administration of CEIs was performed in norepinephrine (NE) or angiotensin-II (AII) induced acute hypertension in conscious unrestrained rabbits. IR administration of the two kinds of CEIs, captopril (5 mg/kg) and MK-422 (1 mg/kg), dose which caused no significant effect when injected intravenously, elicited a prompt and marked depressor action in NE but not in AII induced hypertension. In addition, IR infusion of the angiotensin-II analogue, saralasin (2 and 10 micrograms/kg/min) showed no depressor effect in NE induced acute hypertension. These results indicate that the kidney plays an important role in the depressor action of CEIs in NE but not in AII induced hypertension and this effect may not be related to the IR renin-angiotensin system.