title: Effects of phytoestrogen genistein on electrophysiology of human atrial fibers.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ma
authors.forename: Su
authors.initials: S
authors.lastname: Liu
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Su-Yang
authors.initials: SY
authors.lastname: Yu
authors.forename: Rui-Rong
authors.initials: RR
authors.lastname: He
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004566:Electrodes; D004594:Electrophysiology; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology*; D006325:Heart Atria / Q000187:drug effects; D006801:Humans; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations
chemical_list: D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D019833:Genistein; D002118:Calcium