Canstatin inhibited I/R-induced ventricular arrhythmia. PBS, canstatin (20 µg/kg) or verapamil (0.63 mg/kg) was intravenously administered to rats. Five minutes after the administration, I/R injury was induced by ligating LAD for 10 min (ischemia) followed by releasing it (reperfusion). ECG (lead II) was recorded throughout the experiments. (A) Representative ECG tracings of sinus rhythm during pre-ischemia, ST elevation during ischemia and arrhythmias in PBS-, canstatin- and verapamil-administered rats during reperfusion were shown. VT: ventricular tachycardia, VF: ventricular fibrillation, PVC: premature ventricular contraction. (B) Incidence (left), total duration (middle) and average duration (right) of ventricular arrhythmia (VT and VF) for 10 min after reperfusion were calculated from the ECG tracings and shown as mean ± standard error of the mean (S.E.M.) ((A): PBS, Canstatin: n = 5, Verapamil: n = 3, (B): n = 5). *, ** p < 0.05, 0.01 vs. PBS.