Baroreflex regulation of renal sympathetic nerve activity and heart rate in renal wrap hypertensive rats

被引:26
作者
Vitela, M
Herrera-Rosales, M
Haywood, JR
Mifflin, SW
机构
[1] Univ Texas, Hlth Sci Ctr, Dept Pharmacol, San Antonio, TX 78229 USA
[2] Michigan State Univ, Dept Pharmacol & Toxicol, E Lansing, MI 48824 USA
关键词
baroreceptor; renal hypertension; cardiovasular regulation;
D O I
10.1152/ajpregu.00620.2004
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Despite its usefulness as a nongenetic model of hypertension, little information is available regarding baroreflex function in the Grollman, renal wrap model of hypertension in the rat. Baroreflex regulation of renal sympathetic nerve activity (RSNA) and heart rate (HR) were studied in male, Sprague-Dawley rats hypertensive (HT) for 1 or 4-6 wk after unilateral nephrectomy and figure-8 ligature around the remaining kidney or normotensive (NT) after sham surgery. Rats were anesthetized with Inactin and RSNA, and HR was recorded during intravenous infusions of sodium nitroprusside or phenylephrine to lower or raise mean arterial pressure (MAP). Response curves were analyzed using a logistic sigmoid function. In 1- and 4-wk HT rats the midpoints of RSNA and HR reflex curves were shifted to the right (P < 0.05). Comparing NT to 1- or 4-wk HT rats, the gain of RSNA-MAP curves was no different; however, gain was reduced in the HR-MAP curves at both 1 and 4 wk in HT rats (P < 0.05). In anesthetized rats the HR range was small; therefore, MAP and HR were measured in conscious rats during intravenous injections of three doses of phenylephrine and three doses of sodium nitroprusside. Linear regressions revealed a reduced slope in both 1- and 4-wk HT rats compared with NT rats (P < 0.05). The results indicate that baroreflex curves are shifted to the right, to higher pressures, in hypertension. After 1-4 wk of hypertension the gain of baroreflex regulation of RSNA is not altered; however, the gain of HR regulation is reduced.
引用
收藏
页码:R856 / R862
页数:7
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