Elevated heterogeneities in cardiac conduction and AP repolarization, which may occur in relation to aging and other cardiac diseases, can be reduced by melatonin via its action in the modulation of myocardial Cx43 [198] and ion channels, improvement of cardiomyocyte physiology, and generation and conduction of APs, ultimately protecting against arrhythmogenesis [18, 56]. The gene discussed is GJA1; the disease is heart disorder.