DuP 753 is more effective than captopril on baroreceptor function in high-renin hypertension.

Abstract

High-renin hypertensive rats exhibit a general impairment of the baroreceptor reflexes. In the present study we compared the effect of the angiotensin converting enzyme inhibitor captopril (10 mg/kg per day) with the effect of the selective angiotensin subtype 1 receptor blocker DuP 753 (10 mg/kg per day) on the baroreceptor reflex bradycardia (progressive doses of phenylephrine) and baroreceptor reflex tachycardia (progressive doses of nitroprusside) in conscious rats 7 days after aortic ligation. Arterial pressure was markedly reduced after both acute (15-minute) treatment with captopril (123 +/- 6 versus 184 +/- 23 mm Hg) and DuP 753 (140 +/- 10.5 versus 181 +/- 5.4 mm Hg), but the depressed baroreceptor reflex bradycardia increased only after DuP 753 (1.13 +/- 0.22 versus 0.75 +/- 0.60 beats per minute [bpm]/mm Hg) and remained attenuated after captopril (0.54 +/- 0.086 versus 0.30 +/- 0.07 bpm/mm Hg). After a 2-day treatment, captopril reduced arterial pressure (95 +/- 5 versus 184 +/- 2.3 mm Hg) to lower levels than DuP 753 (119 +/- 6 versus 172 +/- 4.6 mm Hg), whereas the depressed baroreceptor reflex bradycardia remained unchanged with captopril (0.46 +/- 0.13 versus 0.31 +/- 0.076 bpm/mm Hg) and increased with DuP 753 (1.13 +/- 0.19 versus 0.38 +/- 0.12 bpm/mm Hg). Neither DuP 753 nor captopril administered acutely (15 minutes) or for 2 days significantly altered the depressed baroreceptor reflex tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)