植物性雌激素金雀异黄素对人心房肌的电生理效应

目的:研究植物性雌激素金雀异黄素(genistein,GST)对人心房肌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(10-100μmol/L)抑制人心房肌纤维的舒张期(4相)除极化速率(VDD)和起搏细胞放电频(RPF),此外,GST(100 μmol/L)缩短APD_(90).应用L型钙通道开放剂BayK8644(0.5 μmol/L)可拮抗GST对人心房肌纤维的上述电生理效应,但NO合酶阻断剂L-NAME(1 mmol/L)对GST的效应并无影响.结论:GST对人心房肌具有负性变时作用,并可缩短复极化时程.这些效应可能与其抑制钙离子内流有关.

Effects of phytoestrogen genistein on electrophysiology of human atrial fibers

AIM: To study the electrophysiological effects of phytoestrogen genistein (GST) on human atrial fibers. METHODS: Parameters of action potential (AP) in human atrial special fibers were recorded using standard intracellular microelectrode technique. RESULTS: GST (10-100 micromol/L) decreased the velocity of diastolic (phase 4) depolarization (VDD) and rate of pacemaker firing (RPF), besides, GST (100 micromol/L) shortened the duration of 90 % repolarization of action potential (APD90). L-type Ca2+ channel agonist Bay K8644 (0.5 micromol/L) antagonized the inhibitory effects of GST on human atrial fibers, while pretreatment of the fibers with N(G)-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), an NO synthase inhibitor, failed to affect the electrophysiological effects of GST. CONCLUSION: GST exerted a negative chronotropic action and induced an accelerated repolarization of human atrial fibers. These effects were likely due to reduction in calcium influx.