Objective:To investigate the antioxidative effect and mechanism of luteolin on rat cardiomyocytes and isolated hearts fol owed by simulated ischemia/reperfusion(SI/R) injury. Methods:The left ventricular cardiomyocytes and the isolated hearts from adult rats were subjected to SI/R injury. The experiment groups included control, SI/R, luteolin + SI/R(Lut + SI/R), vitamin E(Vit E) + SI/R, and LY294002 + luteolin + SI/R(LY + Lut + SI/R) groups. Cell viability, shortening amplitude, lactate dehydrogenase(LDH) release, superoxide dismutase(SOD) activity, the production of reactive oxygen species(ROS) and malondialdehyde(MDA), expression levels of Akt, phosphorylated Akt, NOX2(gp91phox), NOX2 m RNA, mitogen-activated protein kinase(p38 MAPK) and phosphorylated p38 MAPK were al measured after 3-h simulated ischemia and 2-h simulated reperfusion procedure in cardiomyocytes. Vit E was used as a standard control. The contractile function of isolated hearts was further observed after they were subjected to 30-min global ischemia and 120-min reperfusion. Results:Pretreatment with 8-μmol/L luteolin substantially increased cel viability and shortening amplitude, while reducing evidence of oxidative stress-induced damage in the cel s. In addition, the expression of NOX2, NOX2 m RNA and phosphorylation of p38 MAPK were al downregulated. Furthermore, pretreatment with 40-μmol/L luteolin improved the recovery of myocardial contractile function fol owing SI/R-induced injury, and luteolin markedly increased phosphorylation of Akt. However, all of the above effects were partially inhibited by the phosphatidylinositol 3-kinase(PI3K) inhibitor, LY294002. Conclusions:Luteolin prevents SI/R-induced myocardial damage by reducing oxidative stress-induced injury in isolated rat hearts and cardiomyocytes, and the cardioprotection induced by luteolin was partial y mediated by the PI3K/Akt pathway. Objective: To investigate the antioxidative effect and mechanism of luteolin on rat cardiomyocytes and isolated hearts followed by simulated ischemia / reperfusion (SI / R) injury. Methods: The left ventricular cardiomyocytes and the isolated hearts from adult rats were subjected to SI / R The experimental groups included control, SI / R, luteolin + SI / R (Lut + SI / R), vitamin E (Vit E) + SI / R, and LY294002 + luteolin + SI / R (LY + Lut + SI Cell viability, shortening amplitude, lactate dehydrogenase (LDH) release, superoxide dismutase (SOD) activity, the production of reactive oxygen species (ROS) and malondialdehyde (MDA), expression levels of Akt, phosphorylated Akt, NOX2 gp91phox), NOX2 m RNA, mitogen-activated protein kinase (p38 MAPK) and phosphorylated p38 MAPK were al measured after 3-h simulated ischemia and 2-h simulated reperfusion procedure in cardiomyocytes. function of isolated hearts was further observed after they were su bjected to 30-min global ischemia and 120-min reperfusion. Results: Pretreatment with 8-μmol / L luteolin substantially increased cel viability and shortening amplitude, while reducing evidence of oxidative stress-induced damage in the cel s. In addition, the expression of NOX2, NOX2 m RNA and phosphorylation of p38 MAPK were al downregulated. Furthermore, pretreatment with 40-μmol / L luteolin improved the recovery of myocardial contractile function follow SI / R-induced injury, and luteolin markedly increased phosphorylation of Akt. However, , all of the above effects were inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. Conclusions: Luteolin prevents SI / R-induced myocardial damage by reducing oxidative stress-induced injury in isolated rat hearts and cardiomyocytes, and the cardioprotection induced by luteolin was partial y mediated by the PI3K / Akt pathway.