Myocardial infarction size at 2 and 24 hours after reperfusion (n = 8 at each time point). Myocardial infarction size was detected using TTC staining. Myocardial infarction area was increased between 2 and 24 hours after reperfusion in all intervention groups. PostC significantly reduced myocardial infarction size after reperfusion. Both AG490 (a selective JAK2 inhibitor) and Wortmannin (a selective PI3K inhibitor) abolished cardioprotection of PostC. *p < 0.05 compared with I/R-2 h and I/R-24 h groups respectively; #p < 0.05 compared with I/R-2 h, PostC-2 h, PostC+AG490-2 h and PostC+wort-2 h groups respectively. IS = Infarction size, LV = Left ventricle, AAR = Area at risk.