Acute renal effects of angiotensin converting enzyme inhibition in microalbuminuric type 1 diabetic patients

The renal effects of intravenous injection of 40 mg enalapril were investigated in 16 normotensive microalbuminuric type 1 (insulin-dependent) diabetic patients. After enalapril the following changes were observed: fractional albumin clearance ( Alb) decreased from 9.9 (3.0–23.8) to 8.2 (2.0–18.3)×10^–6 (2P<0.01); filtration fraction (FF) decreased from 0.260 (0.225–0.312) to 0.253 (0.190–0.297) (2P<0.01); renal plasma flow (RPF) increased from 565 (411–690) to 623 (449–785) (2P<0.01); and glomerular filtration rate (GFR) remained stable at 149 (128–181) versus 150 (124–185) ml · min^–1 (NS). These values were unchanged after placebo (n=8), except for RFP which decreased from 606 (401–701) to 559 (381–677) ml · min^–1 (2P<0.05) and GFR which was reduced from 148 (111–173) to 138 (111–167) (2P<0.05). A reduction in mean blood pressure from 94 (87–103) to 89 (79–101) mmHg (2P<0.05) was found in the enalapril group and a minor reduction in the placebo group from 97 (83–106) to 96 (81–104) mmHg (2P<0.05) was also noted. The relative changes in systolic blood pressure in the enalapril group correlated with changes in Alb (Spearman'sr=0.66, 2P<0.02) and FF (r=0.53, 2P<0.05). Acute inhibition of angiotensin converting enzyme does not reduce the pathological hyperfiltration in these patients and a reduction in Alb and FF can not be dissociated from the reduction in blood pressure.