EFFECTS OF CAPTOPRIL, ON AMBULATORY BLOOD-PRESSURE, RENAL AND CARDIAC-FUNCTION IN MICROALBUMINURIC TYPE-1 DIABETIC-PATIENTS

Objective : To study the effect of Captopril on ambulatory blood press ure, renal and cardiac function and extracellular volume in microalbum inuric Type 1 diabetic patients. Design : Randomized, double blind pla cebo controlled study of two years duration. Setting : University clin ic Patients : Twenty-two patients without hypertension. Intervention : Patients received 50 mg Captopril or placebo twice a day. Measurement s : Ambulatory blood pressure, renal function, extracellular volume, a nd echocardiographic indices of cardiac function and dimensions were a ssessed annually. Clinic blood pressure and urinary albumin excretion were measured every 3 months. Results : Twenty-four hour mean arterial blood pressure was unchanged in the Captopril group (mean +/- SD) (ba seline 93 +/- 4 and follow up 91 +/- 8 mmHg) and in the placebo group (96 +/- 7 and 97 +/- 10 mmHg, NS). Night/day ratio of blood pressure w as unaffected. Glomerular filtration rate was unchanged and renal plas ma flow increased in the Captopril (557 +/- 97 and 600 +/- 112 ml min( -1)) versus the placebo group (574 +/- 85 and 535 ml min(-1), p=0.05). Filtration fraction was reduced in the Captopril versus the placebo g roup (p<0.05). Extracellular volume and echocardiographically derived parameters were unaffected. The relative change in day time mean arter ial blood pressure in the Captopril group correlated with changes in u rinary albumin excretion (Spearmans r=0.85, p<0.05) unlike clinic mean arterial blood pressure (r=0.33, p=0.35). Conclusion : Diurnal rhythm of blood pressure was unaffected by long term administration of Capto pril. Renal plasma flow was increased and filtration fraction reduced. A significant association between changes in urinary albumin excretio n and blood pressure after Captopril was revealed only by the implemen tation of ambulatory blood pressure measurements.