Short-term administration of captopril and nifedipine and exercise-induced albuminuria in normotensive diabetic patients with early-stage nephropathy.

Recent studies have demonstrated that short-term angiotensin converting enzyme (ACE) inhibition with captopril can reduce urinary albumin excretion rate (UAER) after exercise in normotensive diabetic patients with early-stage nephropathy. The aim of this study was to investigate whether this effect of ACE inhibition was due to a systemic hypotensive action or a specific action at the intrarenal level. Thus, we compared the acute effects of captopril and the Ca2(+)-channel blocker nifedipine on exercise-induced UAER in normotensive (blood pressure less than 165/95 mmHg) diabetic patients who were normoalbuminuric or microalbuminuric at rest (stage 2 or 3 of diabetic nephropathy). Twenty-five stage 2 diabetic nephropathy patients, 39 stage 3 diabetic nephropathy patients, and 12 nondiabetic subjects performed five submaximal cycloergometric exercises (90% of theoretical heart rate) on nonconsecutive days. The first two exercises were performed in basal conditions; the next three exercises were performed 24 h after administration of captopril (25 mg twice daily) or nifedipine AR (20 mg twice daily) or placebo (1 tablet twice daily) according to a randomized double-blind crossover trial. After placebo, blood pressure and UAER did not change at rest or 1 h after exercise. After captopril, blood pressure at rest and during exercise was similar to that observed after placebo. UAER at rest was not modified, whereas 1 h after exercise, it was significantly decreased both in stage 2 and stage 3 diabetic nephropathy patients (P less than 0.001). After nifedipine, blood pressure decreased significantly at rest and during exercise in respect to placebo and captopril. UAER at rest did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)