ACUTE EFFECTS OF CAPTOPRIL ON THE RENAL ACTIONS OF FUROSEMIDE IN PATIENTS WITH CHRONIC HEART-FAILURE

This study examined the effects of conventional doses of oral captopri l on the renal responses to oral furosemide in ambulant patients with stable chronic heart failure. Twenty-five men (mean age 63 years) were randomized to one of two groups. Group 1 received placebo on days 1 a nd 2 before furosemide. Group 2 received placebo on day 1 before furos emide and captopril thereafter (i.e., captopril before furosemide on d ay 2). Urine was collected after either placebo or captopril and after furosemide (taken after placebo or captopril pretreatment). Captopril by itself did not affect renal function. Captopril did, however, sign ificantly affect the renal response to furosemide. The increase in uri ne flow rate after furosemide in group 2 was decreased from 225% with placebo to 128% with captopril (p < 0.02). The increase in sodium excr etion after furosemide was decreased from 623% with placebo to 242% wi th captopril (p < 0.001). Pretreatment with captopril abolished the in crease in creatinine clearance after furosemide. The increase in urina ry albumin excretion (used as a marker of glomerular function) after f urosemide was also significantly blunted by captopril. Conventional do ses of captopril acutely inhibit the natriuretic and diuretic response s to furosemide at the glomerular level in ambulant patients with stab le chronic heart failure.