GJA1 and myocardial ischemia: This is based on the following observations: 1) myocardial ischemia and high concentration of extracellular Ca2+ may trigger intracellular calcium overload, thus leading to decrease of Cx43 protein, which favors the occurrence of cardiac arrhythmias and 2) anti-arrhythmic effects of verapamil were abolished by heptanol, a Cx43 uncoupler, or Gap 26, a Cx43 channels inhibitor, and accompanied by protection of Cx43 protein against ischemic insults via inhibiting L-type calcium channels.