Response of the kidney to furosemide. II. Effect of captopril on sodium balance.
We investigated the role of the renin-angiotensin-aldosterone (RAA) system during furosemide (F) administration. The effects of adding captopril (C) (25 mg . 6 hr-1) to F (40 mg daily for 3 days) were studied in six normal subjects equilibrated to a daily sodium (Na) intake of 270 mmoles. Without C, F produced a marked natriuresis but Na+ excretion fell sharply between drug doses. This resulted in neutral Na balance (+22 +/- 58 mmoles . 3 days-1; mean +/- SE). Plasma angiotensin (AII) and aldosterone (Aldo) rose, but mean blood pressure (MBP) was unaltered. C abolished the F-induced increases in AII and Aldo but did not modify the pattern of Na+ excretion. Na+ balance remained neutral (+42 +/- 54 mmoles . 3 days-1). With C alone, Na+ balance was positive (+110 +/- 30 mmoles . 3 days-1; P less than 0.02). In protocols C alone and F + C, MBP fell by a comparable amount. F alone and F + C increased plasma norepinephrine and prostaglandin E2 metabolite; these did not change with C alone. In conclusion, activation of the RAA system by F is not essential for the compensatory increase in Na+ reabsorption that maintains Na+ balance after F.(ABSTRACT TRUNCATED AT 250 WORDS)
D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology*; D005665:Furosemide / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000187:drug effects*; D009318:Natriuresis / Q000187:drug effects*; D011392:Proline / Q000031:analogs & derivatives*; D012079:Renal Circulation / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism
D005665:Furosemide; D011392:Proline; D002216:Captopril; D012964:Sodium