Acute reduction of arterial blood pressure reduces urinary albumin excretion in Type 1 (insulin-dependent) diabetic patients with incipient nephropathy

Abstract

The effect of an acute reduction in arterial blood pressure upon kidney function was studied in 12 patients with Type 1 (insulin-dependent) diabetes and incipient nephropathy (persistent microalbuminuria). Renal function was assessed by measurement of the glomerular filtration rate (single bolus 51Cr-EDTA technique) and by the urinary albumin excretion rate (radioimmunoassay). The study was performed twice within 2 weeks, with the patients receiving a slow intravenous injection of either clonidine (225 μg) or saline (154 mmol/l) in random order. Clonidine reduced arterial blood pressure from 125/79±13/8 to 104/68±9/7 mmHg (p < 0.01), urinary albumin excretion rate from 68 (31-369) to 46 (6-200) μg/min (median and range) (p<0.01), and fractional clearance of albumin in all patients (median 29%) (p < 0.01). Glomerular filtration rate was 110±11 before and 106±13 ml/min/1.73 m2 after clonidine injection. The blood glucose concentration was 15±4mmol/l before and 14±5 mmol/l after clonidine injection. In agreement with findings in animal studies, our results suggest that microalbuminuria is to a large extent pressure-dependent, probably because of glomerular hypertension, and that autoregulation of glomerular filtration rate is normal in most patients with incipient diabetic nephropathy. © 1986 Springer-Verlag.