IMPORTANCE OF THE RENIN-ANGIOTENSIN SYSTEM IN THE GENERATION OF KIDNEY FAILURE IN RENOVASCULAR HYPERTENSION

Objectives To determine the possible relationship between the degree o f dietary sodium intake and the development of renal failure during bl ockade of the renin-angiotensin system, Design Antihypertensive doses of captopril, an angiotensin converting enzyme, and hydralazine, a non -specific vasodilator, were administered in sham-operated and two-kidn ey, two clip Goldblatt hypertensive rats subjected to various degrees of dietary sodium intake, Methods The blood pressure, water intake, ur ine flow and sodium excretion of the animals were determined before an d during a 3-day period of drug administration, Plasma concentrations of urea and creatinine were measured as indicators of renal function a nd glomerular filtration rate, Results The blood pressure of the dippe d rats was higher than that of sham-operated rats (241 +/- 5 versus 15 0 +/- 4 mmHg), regardless of their sodium intake, Captopril administra tion failed to lower blood pressures of sodium-replete hypertensive ra ts, but in hypertensive rats fed either a low- or a 'no'-sodium diet t he blood pressure was reduced by 45 +/- 7 and 127 +/- 19 mmHg, respect ively, Furthermore, hydralazine reduced blood pressure in hypertensive rats fed a 'no'-sodium diet by a similar degree, to 99 +/- 8 mmHg. Ca ptopril, but not hydralazine, significantly increased plasma levels of urea and creatinine in hypertensive rats fed the 'no'-sodium diet, Co nclusion These findings indicate that angiotensin II plays an importan t role in the maintenance of renal function during blood pressure redu ction by angiotensin converting enzyme inhibition in volume-contracted renovascular hypertensive states.