AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 1 109-R115, Copyright © 1992 by American Physiological Society

ARTICLES

Renal nerve activity in rats with spontaneous hypertension: effect of converting enzyme inhibitor

H. Kumagai, D. B. Averill and C. M. Ferrario
Department of Brain and Vascular Research, Cleveland Clinic Foundation, Ohio 44195.

We studied the effects of chronic oral inhibition of angiotensin-converting enzyme on the baroreflex control of renal sympathetic nerve activity (RSNA) and heart rate (HR) in 14-wk-old conscious spontaneously hypertensive rats (SHR; n = 12) and age-matched Wistar-Kyoto rats (WKY; n = 11). Rats were treated with lisinopril (10 mg.kg-1.day-1 in tap water) or vehicle for 7 days. We evaluated the baroreflex control of efferent RSNA and HR in awake rats 2 days after implantation of electrodes around the renal sympathetic nerves. The relation between mean arterial pressure (MAP) and either RSNA or HR was analyzed by a logistic function curve during intravenous infusions of phenylephrine and nitroglycerin. The maximum gain of the curve was considered as the sensitivity of the baroreflex. MAP in lisinopril-treated SHR averaged 93 +/- 3 mmHg, a value lower than that obtained in vehicle-treated SHR (147 +/- 5 mmHg) but not in WKY (96 +/- 4 mmHg). In vehicle-treated SHR baroreflex sensitivity (-4.3 +/- 0.5% change nerve activity/mmHg) was significantly (P less than 0.005) smaller than that of WKY (-15.8 +/- 1.5%/mmHg). Seven days of oral treatment of lisinopril caused significant improvement of the baroreflex sensitivity in SHR (-10.5 +/- 0.7%/mmHg, P less than 0.01). The maximum gain of MAP and HR relation of lisinopril-treated SHR was also larger (P less than 0.05) than that of vehicle-treated SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

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