GPER mediated  estrogenic amelioration of sodium channel dysfunction in stressed human induced  pluripotent stem cell-derived cardiomyocytes            

Stress-induced excessive activation of the adrenergic system or changes in estrogen levels promote the occurrence of arrhythmias. Sodium channel, a responder to β-adrenergic stimulation, is involved in stress-induced cardiac electrophysiological abnormalities. However, it has not been established whether estrogen regulates sodium channels during acute stress. Our study aimed to explore whether voltage-gated sodium channels play roles in the rapid regulation of various concentrations of estrogen in stressed human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), and reveal the possible mechanism of estrogen signaling pathway modulating stress. An isoproterenol-induced stress model of hiPSC-CMs was pre-incubated with β-Estradiol at different concentrations (0.01 nmol/L, 1 nmol/L, and 100 nmol/L). Action potential (AP) and sodium currents were detected by patch clamp. The G protein-coupled estrogen receptor (GPER)-specific effect was determined with agonists G1, antagonists G15 and small interfering RNA. β-Estradiol at concentrations of 0.01 nmol/L, 1 nmol/L, and 100 nmol/L increased the peak sodium current and prolonged AP duration (APD) at 1 nmol/L. Stress increased peak sodium current, late sodium current, and shortened APD. The effects of stress on sodium currents and APD were eliminated by β-Estradiol. Activation of GPER by G1 exhibited similar effects as β-Estradiol, while inhibition of GPER with G15 and small interfering RNA ameliorated estrogenic actions. Estrogen, antagonized the stress-related abnormal electrical activity, and through GPER alleviated sodium channel dysfunctions in stress state in hiPSC-CMs. These results provide a novel mechanism through which estrogenic rapid signaling against stress by regulating ion channels.