The transcapillary escape rate of albumin (TERalb) is often elevated in patients 
with diabetic microangiopathy. The objective of this study was to examine the 
effect of enalapril on the TERalb of diabetic patients with albuminuria and 
normal or mildly elevated blood pressure. Seventeen diabetic patients with 
diabetic retinopathy, albuminuria, a diastolic blood pressure below 100 mmHg and 
increased TERalb participated in the study. Blood pressure and TERalb were 
measured before and after 14 days of therapy with enalapril, 20 mg daily for 14 
days. Systolic and diastolic blood pressure fell from 168 +/- 6 to 155 +/- 6 (p 
< 0.001) and from 87 +/- 2 to 81 +/- 2 mmHg (p < 0.005) respectively. Mean 
arterial pressure declined from 114 +/- 3 to 105 +/- 3 mmHg (p < 0.0001). The 
elevated TERalb decreased from 9.5 +/- 0.5 to 7.2 +/- 0.5%/hr (p < 0.005). In 
the hypertensive subset, systolic, diastolic and mean arterial pressure 
decreased significantly by 15, 7 and 10 mmHg (p < 0.005, p < 0.005 and p < 0.005 
respectively); TERalb decreased from 9.5 +/- 0.6 to 7.3 +/- 0.6 (p < 0.03). In 
the normotensive subset, arterial pressure remained unchanged and TERalb 
decreased from 9.0 +/- 0.8 to 6.8 +/- 1.0%/hr (p < 0.03). Plasma fructosamine 
decreased from 373 +/- 23 to 347 +/- 20 (p < 0.05) in the hypertensive group and 
remained unchanged in the normotensive patients. No correlation could be 
demonstrated between variation in TERalb and changes in blood pressure. In 
conclusion, enalapril decreases microvascular albumin leakage in patients with 
diabetic microangiopathy and normal or mildly elevated blood pressure.