Xide Hu

and 10 more

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.

Gabriel Adzika

and 13 more

Background and Purpose: The immune system is implicated in the pathogenesis of pathological cardiac hypertrophy (PCH). However, there is currently no therapeutic intervention to prevent PCH. Here, we aimed at preventing pathological cardiac hypertrophy (PCH) during chronic catecholamine stress via modulating adaptive inflammatory by targeting adenylyl cyclases (ACs) and G protein-coupled receptor kinase 5 (GRK5) in cardiomyocytes and immune cells. Experimental Approach: PCH was induced in mice by chronic isoproterenol injections. In vitro, peritoneal macrophages were challenged with lipopolysaccharide under stress. Further experiments employed the therapeutic interventions Amlexanox and Forskolin to inhibit GRK5 and activate ACs-cAMP, respectively. Cardiac functions were assessed with echocardiography. Inflammatory markers were assessed with ELISA and RT-qPCR (in vivo and in vitro). GRK5 localizations in macrophages were assessed by immunofluorescence, and alterations in protein expression were analyzed with immunoblotting. Histological assessments were done with Masson, H&E and IHC staining. Key Results: PCH mice had deteriorating cardiac functions and morphological remodeling, accompanied by massive immune cell infiltrations. Similarities were observed proinflammatory markers upregulation, as were IL-10 found downregulated both in vivo and in vitro. However, the combination of Amlexanox and Forskolin modulated adaptive inflammatory responses and also maintained proper cardiac morphology and function. The single therapies of neither Amlexanox nor Forskolin were able to attain the aforementioned with much efficacy as their combination therapy. Conclusion: The combination therapy of ALX and FSK has the therapeutic potential of preventing the occurrence of pathological cardiac hypertrophy during CCS by modulating adaptive inflammatory responses while maintaining normal cardiac function.