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Phytoestrogen genistein inhibits carotid sinus baroreflex in anesthetized male rats

Wang Yihe, Wang Sheng, He Ruirong

Department of Physiology, Medical College of Chinese People^s ARmed Police Forces.Tianjin(300162)；Department of Physiology, Institute of Basic medicine, Hebei Medical University,Shijiazhuang(050017)

Abstract

The purpose of this study was to determine the effect of phytoestrogen genistein (GST) on carotid sinus baroreflex in 30 anesthetized male rats by perfusing the isolated carotid sinus in vivo. The results obtained are as follows. (1) By perfusion with GST (50μmol/L), the functional curve of baroreflex was shifted to the right and upward, with a peak slope (PS) decrease from 0.36±0.01 to 0.23±0.01 (P<0.01) and a reflex decrease (RD) in mean arterial pressure from 39.75±1.58 to 27.00±0.60 mmHg (P<0.001), while the threshold pressure (TP) and saturation pressure (SP) were significantly increased from 65.63±2.1 to 82.05±1.95 mmHg (P<0.001) and from 192.23±3.90 to 215.76±3.75 mmHg (P<0.001), respectively. Among the functional parameters of carotid baroreflex, the changes in RD, PS and TP were dose-dependent. (2) Pretreatment with Bay K 8644 (500 nmol/L), an agonist of calcium channels, could completely abolish the inhibitory effect of GST on carotid baroreflex. (3) Preperfusion with an inhibitor of NO synthase, L-NAME (100 μmol/L), did not affect the inhibitory effect of GST. It is proposed that the inhibitory action of GST on carotid baroreflex may be mediated by the inhibition of Ca~(2+) channel of vascular smooth muscle, but not by NO release from endothelium.

Key words: Genistein;Bay K 8644;Baroreflex;Mean arterial pressure

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Citing This Article：

Wang Yihe, Wang Sheng, He Ruirong. Phytoestrogen genistein inhibits carotid sinus baroreflex in anesthetized male rats. Acta Physiol Sin 2002; 54 (4): (in Chinese with English abstract).