Reperfusion arrhythmias (RA) especially ventricular tachycardia (VT) and ventricular fibrillation (VF) remain the most important causes of sudden death following reperfusion. In isolated rat hearts grape seed proanthocyanidin extract (GSPE) had been proved to reduce the incidence of reperfusion-induced VF and VT. However the mechanism of this protection remained unclear. The aim of this study was to elucidate the potential mechanism of this protection of GSPE. The myocardial ischemia reperfusion (IR) model was induced by 30 min coronary occlusion and 120 min reperfusion in open chest anesthetized rats. The ultrastructure of ischemic cardiomyocytes was observed. An isobaric tag labeling for relative and absolute quantification (iTRAQ) proteomics was used to identify differentially expressed membrane proteins. Western blot was performed to verify the results of iTRAQ. The results demonstrated GSPE can significantly reduce the incidence of VT and VF induced by reperfusion in vivo. We identified 92 differentially expressed proteins. Western blot analysis confirmed GSPE increased the expression of Na(+)/K(+)-ATPase alpha1 subunit (p<0.01). We found the subunit distribution of Na(+)/K(+)-ATPase was changed after reperfusion. Na(+)/K(+)-ATPase alpha1 subunit was decreased in IR group (without GSPE-treated) compared to sham group while it was significantly increased in GSPE group. The decrease of free radical generation induced by GSPE may lead to the up-regulation of Na(+)/K(+)-ATPase alpha1 subunit. This change of subunit distribution may lead to the increase of activity of Na(+)/K(+)-ATPase which may result in the protection of GSPE against reperfusion arrhythmias. Our experiments provided new avenues for the treatment of reperfusion arrhythmias.