Angiotensin-converting enzyme inhibition, but not calcium antagonism, improves a response of the renal vasculature to L-arginine in patients with essential hypertension

Abstract —Endothelial function has been shown to be impaired in patients with essential hypertension. The purpose of the present study was to determine whether antihypertensive drug therapy improves impaired endothelium-dependent renal vasorelaxation in essential hypertensive patients without atherosclerosis. We evaluated the effects of intravenous infusion of l -arginine (500 mg/kg given over 30 minutes) on systemic and renal hemodynamics in 27 patients with mild to moderate essential hypertension who were randomly assigned to treatment with either the angiotensin-converting enzyme inhibitor imidapril or the calcium antagonist amlodipine for 12 weeks in a double-blind fashion. After the 12 weeks, the decrease in blood pressure was similar in the imidapril (n=14) and amlodipine (n=13) groups. The increase in renal plasma flow was also similar in both groups. l -Arginine–induced renovascular relaxation was increased by imidapril (renal plasma flow, 9.6±5.1% to 14.4±7.4%; renal vascular resistance, −10.4±8.1% to −16.7±9.2%, P l -arginine was significantly increased by imidapril (90±29% to 134±63%, P l -arginine/nitric oxide–mediated effects.