@article{APS7528,
author = {Tao MA and Zhen-Zhong FAN and Rui-Rong HE},
title = {Electrophysiological effects of phytoestrogen genistein on pacemaker cells in sinoatrial nodes of rabbits.},
journal = {Acta Pharmacologica Sinica},
volume = {23},
number = {4},
year = {2016},
keywords = {},
abstract = {AIM: To study the electrophysiological effects of genistein (GST) on pacemaker
cells in sinoatrial (SA) nodes of rabbits.
METHODS: Parameters of action potential (AP) in SA node were recorded using
intracellular microelectrode technique.
RESULTS: GST (10 - 150 micromol/L) not only decreased the amplitude of action
potential (APA), maximal rate of depolarization (Vmax) [from (6.2 +/- 2.8) to
(2.8 +/- 1.4) V/s, P < 0.01], velocity of diastolic (phase 4) depolarization
(VDD) [from (55 +/- 14) to (38 +/- 8) mV/s, P < 0.01], and rate of pacemaker
firing (RPF) [from (154 +/- 23) to (107 +/- 25) beat/min, P < 0.01], but also
prolonged duration of 90 % repolarization of action potential (APD90) in a
concentration-dependent manner. Both elevation of calcium concentration (5
mmol/L) in superfusate and application of L-type Ca2+ channel agonist Bay K8644
(0.5 micromol/L) reversed the inhibitory effects of GST on pacemaker cells, while
pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), an NO
synthase inhibitor, failed to block the electrophysiological effects of GST.
CONCLUSION: GST exerted a negative chronotropic action and induced a delayed
repolarization of pacemaker cells in SA nodes of rabbits. These effects were
likely due to reduction in calcium influx and potassium efflux, but had no
association with NO release.},
issn = {1745-7254}, url = {http://www.chinaphar.com/article/view/7528}
}