氯唑沙宗对离体大鼠胸主动脉的抗收缩作用

Chlorzoxazone Inhibits Contraction in Rat Thoracic Aorta

目的研究氯哇沙宗（Chlorzoxazone，CZ）对离体大鼠胸主动脉的抗收缩作用。方法采用大鼠离体胸主动脉环灌流法，测定血管环张力的变化。实验观察：1）动脉环在KH液中稳定1h后，向浴槽内加入25mM KCI预收缩血管，5min后给予300μM氯哇沙宗，观察其对血管的作用，对内皮去除的血管重复上述步骤。2）动脉环处于平衡状态时先加入不同浓度氯哇沙宗（100，300，500μM），5分钟后给予25mMKCI，观察血管的收缩情况。3）无钙液反复冲洗动脉环，待血管稳定后，给予200μM氯哇沙宗或2μM维拉帕米，10分钟后加入含CaC12（0．1～2mM）的高钾液，观察血管的张力变化。结果1）时KCI预收缩的内皮完整或去内皮的大鼠胸主动脉，氯哇沙宗均有舒张作用。2）氯哇沙宗剂量依赖性地对抗KCI诱导的收缩作用（P〈0．05）。3）在无钙高钾液中，氯哇沙宗明显降低CaCl2所引起的胸主动脉环的收缩。结论氯哇沙宗非内皮依赖性的舒张大鼠离体胸主动脉。

Objective To investigate the vasodilatation effects of chlorzoxazone on rat thoracic aorta. Methods The tension of isolated thoracic aorta rings from wistar rats was measured using tissue organ bath system. Methods 1）The rings were contracted with KCI （25mM） after equilibration in KH solution for 1 hour,and then exposed to CZ （300μM）,the change of vasoconstriction curve was observed. The experiment was repeated in the rings without endothelium. 2）The aortic rings were pretreated with different concentration of chlorzoxazone （100,300,500μM） for 5 min, and then exposed to 25mM KCI. The antagonized contractions were measured. 3）Arterial rings were rinsed three times in a Ca^2＋ -free solution and then incubated for 20min, then equilibrated for 10min with 200 μM chlorzoxazone or 2μM verapamil before they were perfused with 60 mM K^＋ solution containing CaCl2 （0.11-2mM） to construct the concentration--response curve. Results Chlorzoxazone （300 μM）caused the relaxation of aorta rings with and without endothelium precontracted with high level of K＋ （25mM）. Chlorzoxazone （300 μM） pretreatment antagonized the contraction induced by 25mM KCI. Chlorzoxazone obviously reduced CaCl2 -- induced contraction in Ca^2＋ free and high K^＋ solution. Conclusions Chlorzoxazone can induce endothelium-independent relaxation in rat thoracic aorta.