TJP1 and ventricular tachycardia: Recordings from ZO-1+/− animals demonstrate a high incidence of premature ventricular contractions (PVCs), short runs of bigeminy, and episodes of non-sustained ventricular tachycardia while WT animals remained in sinus rhythm indicative of a greater proclivity to arrhythmia in the absence of normal ZO-1 expression (Figure 4D,E).