Effects of phytoestrogen genistein on electrophysiology of human atrial fibers.
Abstract
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.
Keywords:
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.