Effects of phytoestrogen genistein on delayed afterdepolarization and triggered activity induced by ouabain in guinea pig papillary muscles

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Journal Title:
ACTA PHYSIOLOGICA SINICA
Issue:
Volume 54, Issue 05, 2002
DOI:
Key Word:
phytoestrogen;genistein;delayed afterdepolarization;papillary muscles;electrophysiology;ouabain;17β-estradiol

Abstract: The purpose of this study was to investigate the effects of phytoestrogen genistein (GST) on delayed afterdepolarization (DAD) and triggered activity (TA) induced by ouabain in guinea pig papillary muscles. Action potentials (APs) were recorded from the guinea pig papillary muscles with standard glass microelectrode technique. The results are as follows: (1) DAD and TA induced by ouabain (1 μmol/L) were markedly inhibited by pretreatment with GST (10, 50, 100 μmol/L) in a concentration-dependent manner. (2) NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), an NO synthase inhibitor, failed to affect the above effects of GST. (3) 5 μmol/L 17β-estradiol (E2) or 10 μmol/L GST alone showed no effects on DAD and TA, whereas GST combined with E2 at the same doses exerted significant inhibitory effects on DAD and TA. Since GST is known to reduce the calcium influx, it is suggested that GST might have antiarrhythmic effects, possibly by reducing calcium influx. The antiarrhythmic effects of GST may contribute to its cardioprotective action.

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