KCNJ5 and ventricular tachycardia: To investigate the contribution of the ventricular GIRK channel to ventricular arrhythmogenesis, isolated hearts from MLC2VCre(+):Girk1fl/fl and MLC2VCre(−):Girk1fl/fl mice, as well as wild-type and constitutive Girk4−/− mice, were subjected to burst pacing in the absence and presence of CCh to discern differences in susceptibility to ventricular tachycardia (VT) or fibrillation (VF) (Fig. 8a).