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目的:研究植物性雌激素金雀异黄素(genistein,GST)对家兔窦房结起搏细胞的电生理效应及其作用机制.方法:应用经典玻璃微电极方法.结果:GST(10-150μmol/L)不仅以剂量依赖性方式抑制窦房结起搏细胞的零相最大上升速度(V_(max)),舒张期除极速度(VDD),起搏放电频率(RPF)和动作电位幅度(APA),而且延长复极化90％时间(APD_(90)).提高灌流液中钙离子浓度以及应用L型钙通道开放剂Bay K8644(0.5μmol/L)均可逆转GST对起搏细胞的上述电生理效应,但NO合酶阻断剂L-NAME(1 mmol/L)对GST的效应并无影响.结论:GST对家兔窦房结具有负性变时作用,并可延长复极化时程.这些效应可能与其抑制钙离子内流及钾离子外流有关.
OBJECTIVE: To study the electrophysiological effects of phytoestrogen genistein (GST) on pacemaker cells of sinoatrial node in rabbit and its mechanism of action.Methods: The classical glass microelectrode method was used.Results: GST (10- 150μmol / L) not only inhibited the maximal zero phase velocity (Vmax), diastolic depolarization rate (VDD), pacemaker discharge frequency (RPF) and action potential amplitude of sinoatrial pacemaker cells in a dose-dependent manner (APA), prolonged 90% of the repolarization time (APD 90), increased calcium concentration in the perfusate and application of the L-type calcium channel opener Bay K8644 (0.5 μmol / L) , But NO synthase blocker L-NAME (1 mmol / L) had no effect on the effect of GST.Conclusion: GST has a negative variable effect on sinoatrial node in rabbits and can extend the complex Polarization duration.These effects may be related to their inhibition of calcium influx and potassium efflux.