Deterioration of renal function during angiotensin converting enzyme inhibition in hypertensive patients with a poorly functioning solitary kidney.

During treatment with the angiotensin converting enzyme inhibitor, Captopril, glomerular filtration rate (GFR) decreased in three unilaterally nephrectomized hypertensive patients with a poorly functioning remaining kidney. The fall in GFR was not related to changes in the blood pressure, and was reversed when Captopril was stopped. In a fourth nephrectomized patient the initially normal GFR was not affected by captopril. These observations point to a functional reduction in GFR due to a withdrawal of an intrarenal action of angiotensin II. Maintenance of GFR may become critically dependent on a functioning renin-angiotensin system when renal perfusion pressure is reduced to a certain degree. Inhibition of angiotensin II formation may lead to a decrease in GFR in patients with renal hypertension and pre-existing renal insufficiency.