Systemic and renal hemodynamic changes after two-month treatment with enalapril in patients with essential hypertension.

Twelve essential hypertensive patients with normal renal function were treated once daily with a new angiotensin converting enzyme inhibitor, enalapril maleate, for about two months. In all patients, the drug-induced changes in blood pressure (BP), systemic and renal hemodynamics, plasma renin activity (PRA), and urine aldosterone (UA) were evaluated. Mean arterial pressure was significantly lowered. No significant changes in cardiac index, heart rate, and stroke index were observed, while peripheral vascular resistance index was significantly decreased. Plasma and blood volumes were not significantly altered. The effects on renal hemodynamics consisted of a significant increase in renal plasma flow (RPF), a decrease in renal vascular resistance, and no change in glomerular filtration rate (GFR). UA excretion was significantly reduced during enalapril therapy. The drug was well tolerated, and no side effects were observed. In summary, enalapril is able to reduce blood pressure through a vasodilatatory effect without change in cardiac output. It increases renal blood flow with no change in glomerular filtration rate.