Chlorzoxazone inhibits contraction of rat thoracic aorta

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• 作者：De-Li Dong ; Yan Luan ; Tie-Ming Feng ; Chang-Long Fan ; Peng Yue ; Zhi-Jie Sun ; Rui-Min Gu and Bao-Feng Yang
• 关键词：Chlorzoxazone ; Ca²⁺-activated K⁺channel ; Thoracic artery ; Relaxation
• 刊名：European Journal of Pharmacology
• 出版年：2006
• 出版时间：18 September 2006
• 年：2006
• 卷：545
• 期：2-3
• 页码：161-166
• 全文大小：486 K

文摘

Chlorzoxazone has been reported to activate the intermediate-conductance, Ca²⁺-activated K⁺ channels in aortic endothelial cells and to relax the artery. The aim of the present study was to characterize the chlorzoxazone-induced relaxation of rat thoracic artery. Chlorzoxazone did not affect the tension of the thoracic artery rings at rest, but relaxed the precontraction induced by 1 μM noradrenaline in an endothelium independent manner. Preincubation with chlorzoxazone also antagonized the contraction induced by 1 μM noradrenaline or 25 mM KCl. The chlorzoxazone-induced relaxation of the thoracic artery pre-contracted by noradrenaline was suppressed by 5 mM tetraethylammonium, 75 mM ethanol and 2 μM paxilline, but not by 2 μM clotrimazole. Chlorzoxazone relaxed the 4-aminopyridine-induced contraction. The pattern of chlorzoxazone-induced relaxation was different from that of verapamil, the L-type Ca²⁺ channel blocker. The inhibition of the noradrenaline-induced contraction by chlorzoxazone was attenuated when chlorzoxazone treatment was prolonged to 4 h. No difference in the contraction–relaxation was found between the artery rings from normal rats and those from rats that received 100 mg/kg chlorzoxazone for 7 days. We conclude that chlorzoxazone abolishes the contraction of rat thoracic artery induced by noradrenaline and that the effect of chlorzoxazone is endothelium independent and also not mediated by intermediate-conductance, Ca²⁺-activated K⁺ channels.