Estrogen increased peak INa but reduced both of
INaL and peak INa after stress
Some studies have shown that estrogen exert concentration-dependent dual
effects on ventricular electrical activity in guinea pigs (Kurokawa,
Kodama, Clancy, & Furukawa, 2016; Kurokawa et al., 2008). To test the
rapid effect of estrogen on sodium channel and whether it is dependent
on concentration, hiPSC-CMs were cultured with low, medium, and high
concentrations of estrogen for 1 hour. In our study, estrogen did not
alter I NaL at any concentration under normal
condition. In contrast, under stress state, estrogen at medium
concentration inhibited I NaL and this effect was
not observed for the low and high concentrations. Estrogen increased
peak I Na at all concentrations, but reduced the
augmentation in peak I Na at medium concentration
under stress state. Estrogen did not affect activation, inactivation and
recovery from inactivation of sodium channel under stress or basal
state. Although previous studies have revealed gender specific
differences in peak I Na andI NaL, the
effect of estrogen on those sodium currents is still unclear. Therefore,
our results further complement the role of sex hormone in regulating
sodium currents, and suggest for the first time that estrogen blunts the
increase in sodium currents caused by β-adrenergic overstimulation.