RESUMEN
The aim of our study was to evaluate the acute effect of nifedipine, a calcium channel blocker, on exercise-induced microalbuminuria in normotensive and normoalbuminuric type 1 diabetic patients. Fifteen normotensive diabetic patients who were normoalbuminuric at rest (8 males and 7 females; age 16-35 years) and 10 normal subjects (6 males and 4 females; age 18-40 years) performed 4 submaximal cycloergometric exercises (90% of theoretical maximum heart rate); the first two exercises were performed in basal condition and the other 2 after 24 h of therapy with nifedipine AR (20 mg/b.i.d.) or placebo (2 cps/die). One hour after exercise in basal condition the microalbuminuria was 78 +/- 17 micrograms/min in diabetic patients vs 16 +/- 4 micrograms/min in normal subjects (p less than 0.001). After placebo no significant changes with respect to basal levels were observed 1 hour after exercise in either diabetic patients (82 +/- 16 microgram/min) or normal subjects (20 +/- 5 micrograms/min). In diabetic patients after nifedipine, systolic blood pressure was reduced both at rest and after exercise (p less than 0.05) with respect to basal condition or placebo. The urinary albumin excretion rate at rest was not modified, but it was significantly reduced 1 hour after exercise: 58 +/- 15 micrograms/min (p less than 0.01 vs placebo). This reduction correlated well with the reduction of exercise blood pressure in diabetic patients (r = 0.91, p less than 0.001). Our results indicate that acute administration of nifedipine reduced exercise-induced microalbuminuria in normotensive diabetic patients, probably by means of a reduction in exercise blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)