Objective       To determine the effect of mitsugumin 53 (MG53) preconditioning on ischemia/reperfusion (I/R)-induced arrhythmias in the Langendorff perfused rat hearts.       Methods       The heart of 40 SD rats (8~10 weeks old

200~240 g) were isolated and then perfused with Langendorff. Then the heart were divided into sham-operation group (group S)

I/R group (group I/R)

low

middle and high dosed MG53 (0.35

0.7 and 1.4 μg/mL)+I/R groups (n=8). After the heart was perfused for 20 min

those from the I/R group were occluded for 30 min by the left coronary artery

and then followed by 30 min reperfusion. While the hearts of preconditioning group were firstly perfused with Langendorff for 10 min

and then with corresponding doses of MG53 dissolved in Krebs-Henseleit (KH). Surface echocardiography (ECG) was used to record arrhythmias continuously during the whole process of I/R.       Results       During reperfusion period

middle and high dosed of MG53 preconditioning significantly reduced the incidence of ventricular tachycardia (VT) (50% and 37.5% vs 75%

both P0.05) and the incidence of ventricular fibrillation (VF) (0 and 0 vs 37.5%

both P0.05)

shortened the duration of VT (3.7±5.0 and 2.2±3.6 vs 118.0±208.3 s

both P0.05) and the duration of VF (0 and 0 vs 310.9±604.1 s

both P0.05)

and decreased the reperfusion arrhythmia score (1.4±0.7 and 1.1±0.8 vs 3.4±2.4

P0.05 and 0.01 respectively) when compared with those indexes of group I/R.       Conclusion       MG53 preconditioning alleviates the I/R-induced arrhythmias in the isolated rat hearts significantly.