Renal Haemodynamics and Comparative Effects of Captopril in Patients with Benign- or Malignant-Essential Hypertension, or with Chronic Renal Failure

Effects of captopril on arterial pressure (AP) and renal function were investigated in patients with non-malignant "benign" or malignant phase essential hypertension (EH group), or with chronic renal failure (CRF group). After captopril administration, AP and renal vascular resistance (RVR) decreased significantly, and renal blood flow (RBF) and plasma renin activity (PRA) increased in both groups. Glomerular filtration rate (GFR) increased in the EH group, but was unchanged in CRF. Filtration fraction decreased in the malignant hypertension and CRF groups. Significant correlations were found between baseline PRA and baseline RVR, and the captopril-induced decrease in mean AP, decrease in RVR, increase in RBF, and increase in GFR in the EH group, while these associations were not observed in CRF. These results indicate that the high AP, RVR, suppressed RBF and GFR in the EH group were closely related to activity of the renin-angiotensin system, but not so the low RBF and GFR in CRF. Small doses of captopril may improve impaired renal function in EH, and may not cause deterioration in the CRF group.