Effects of phytoestrogen genistein on electrophysiology of human atrial fibers.
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.
Ma
Tao
T
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China.
Liu
Su
S
Zhang
Wen-Li
WL
Zhao
Hong
H
Yu
Su-Yang
SY
He
Rui-Rong
RR
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
D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D019833:Genistein; D002118:Calcium