Ca2+ activity in atrial myocytes
To investigate the inhibitory effect of isorhamnetin on abnormal diastolic SR Ca2+ activity, a Ca2+imaging study was performed using isolated atrial myocytes. Isolated atrial myocytes in the AngII group showed a significantly higher frequency of diastolic Ca2+ sparks in the presence of isoproterenol than in the controls. In contrast, isorhamnetin treatment reversed AngII-induced diastolic Ca2+ spark frequency (Fig. 2A-B). Additionally, AngII treatment increased the Ca2+ spark amplitude, whereas isorhamnetin treatment restored it (Fig. 2C). These findings indicate that isorhamnetin has inhibitory effects on the vulnerability of AF by alleviating diastolic aberrant SR Ca2+ activities.