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目的：研究钾通道开放剂吡那地尔对５ＨＴ３受体介导的离体豚鼠回肠（ＧＰＩ）收缩反应的影响．方法：以等长换能器记录ＧＰＩ收缩反应．以［３Ｈ］ＧＲ６５６３０结合试验检测大鼠内嗅皮层５ＨＴ３受体的结合特性．结果：（１）２甲基５ＨＴ及５ＨＴ以剂量依赖方式引起ＧＰＩ的收缩；托品色创竞争性抑制此反应．（２）吡那地尔以剂量依赖方式抑制２甲基５ＨＴ和５ＨＴ引起的ＧＰＩ收缩，并增强托品色创或Ｂｅｎｅｓｅｔｒｏｎ对５ＨＴ诱发ＧＰＩ收缩的抑制作用，但不影响卡巴胆碱引起的ＧＰＩ收缩；吡那地尔对大鼠内嗅皮层５ＨＴ３受体与［３Ｈ］ＧＲ６５６３０的结合无影响．结论：吡那地尔可能通过激活突触前神经元ＡＴＰ敏感钾通道抑制由５ＨＴ３受体介导的ＧＰＩ收缩反应．
Objective: To study the effect of pinacidil, a potassium channel opener, on 5-HT3 receptor-mediated contraction of isolated guinea pig ileum (GPI). Methods: Equal length transducer recorded GPI contraction reaction. [3H] GR65630 binding assay to detect rat entorhinal cortex 5 HT3 receptor binding characteristics. Results: (1) 2 methyl 5 HT and 5 HT caused a dose - dependent manner in the contraction of GPI; Tropsch color competitive inhibition of this reaction. (2) Pinacidil inhibited the GPI contraction induced by 2methyl5HT and 5HT in a dosedependent manner and enhanced the inhibition of 5HT-induced GPI contraction by tropine or Benesetron Affect carbachol-induced GPI contraction; pinacidil had no effect on the binding of 5-HT3 receptor to [3H] GR65630 in rat entorhinal cortex. Conclusion: Pinacidon may inhibit GPI contractile response mediated by 5-HT3 receptor by activating presynaptic neuron ATP-sensitive potassium channel.