Short-term effect of captopril on renal haemodynamics in chronic renal failure

Glomerular filtration rate (GFR), effective renal plasma flow, and creatinine clearance were measured in ten patients with stable chronic renal failure (GFR less than 50 ml/min) before, during and after 1 month's treatment with captopril. Plasma angiotensin II decreased significantly during treatment (P less than 0.05) and increased after the drug was stopped. Renin concentration increased with captopril (P less than 0.02) and urine protein excretion decreased (P less than 0.05). Blood pressure did not change in any individual. There was no alteration in baseline GFR, effective renal plasma flow, or creatinine clearance, with or without captopril. Following a high-protein meal there was no increase in any of the measured renal haemodynamic parameters before, during, or after taking the drug. There was a significant increase in plasma creatinine while taking captopril (P less than 0.02) which reversed on cessation of the drug. These results suggest that in stable chronic renal failure the human renal microvasculature is unresponsive to inhibitors of angiotensin-converting enzyme.