Comparison of systemic and regional hemodynamic effects of a diuretic, an angiotensin II receptor antagonist, and an angiotensin-converting enzyme inhibitor in conscious renovascular hypertensive rats.

The present experiments were designed to compare the antihypertensive action and the systemic and regional hemodynamic effects of a diuretic (furosemide), an angiotensin II (AngII) receptor blocker (Dup 753), and an angiotensin converting enzyme (ACE) inhibitor (enalapril) in conscious, two-kidney, one-clip renovascular hypertensive rats by the radioactive microsphere technique. Measurements were done 3 hours after a single dose treatment. Furosemide (20 mg/kg) produced a marked diuresis and tachycardia with no change in blood pressure; in comparison with control rats, furosemide-treated rats had total peripheral vascular resistance increased by 46.55% (p less than 0.01) and local vascular resistance increased in most organs, to a significant degree in the spleen, muscle, stomach, intestine, and skin (p less than 0.05 to 0.01). Dup 753 (20 mg/kg) and enalapril (10 mg/kg) decreased mean blood pressure by 41.89 +/- 7.17 mm Hg and 47.13 +/- 8.67 mm Hg, respectively (p less than 0.01), with tachycardia only in the Dup 753 group. Total peripheral and local vascular resistances in several tissues were significantly lower in both the Dup 753 and enalapril groups than in the furosemide group. In particular, both antiangiotensin agents, in contrast to furosemide, produced significant decrease in renal vascular resistance by 42.28% and 38.81%, respectively (p less than 0.01), with a tendency to increase the renal blood flow (of the intact kidney). No detectable differences were found in systemic and regional hemodynamic changes between the Dup 753 and enalapril group.(ABSTRACT TRUNCATED AT 250 WORDS)