Aim To investigate tyrosine kinase(TK)and protein kinase C(PKC)are related to hemin,a heme oxygenase-1(HO-1)inducer,reduces ischemia/reperfusion(I/R)injury and which mechanisms are involved in the cardioprotective effects.Methods Infarct size was measured in isolated rat hearts following occlusion of the left anterior descending coronary artery for 30 min and subsequent reperfusion for 2 h.The ventricular function,lactate dehydrogenase(LDH)and creatine kinase(CK)during ischemia/reperfusion period were also observed.Results Infarct size,LDH and CK were reduced in the hemin(50 micrograms/kg)group compared with the control group.The myocardial performance was also improved in hemin group.Both Genistein,the inhibitor of PTK and Chelerythrine,the inhibitor of PKC blocked the infarct size-limiting effect and improvement in myocardial performance induced by hemin.Conclusion These data suggest that the involvement of PTK and PKC have been implicated in hemin-induced cardioprotection in rat hearts.