Granulocyte Colony Stimulating Factor Directly Inhibits Myocardial Ischemia-Reperfusion Injury Through Akt–Endothelial NO Synthase Pathway

Objective— Granulocyte colony stimulating factor (G-CSF) has been reported recently to prevent cardiac remodeling and dysfunction after acute myocardial infarction through signal transducer and activator of transcription 3 (STAT3). In this study, we examined acute effects of G-CSF on the heart against ischemia-reperfusion injury.Methods and Results— Rat hearts were subjected to global 35-minute ischemia and 120-minute reperfusion in Langendorff system with or without G-CSF (300 ng/mL). G-CSF administration was started at the onset of reperfusion. Triphenyltetrazolium chloride staining revealed that G-CSF markedly reduced the infarct size. G-CSF strongly activated Janus kinase 2 (Jak2), STAT3, extracellular signal-regulated kinase (ERK), Akt, and endothelial NO synthase (NOS) in the hearts subjected to ischemia followed by 15-minute reperfusion. The G-CSF–induced reduction in infarct size was abolished by inhibitors of phosphatidylinositol 3-kinase, Jak2, and NOS but not of mitogen-activated protein kinase kinase (MEK).Conclusions— These results suggest that G-CSF acts directly on the myocardium during ischemia-reperfusion injury and has acute nongenomic cardioprotective effects through the Akt–endothelial NOS pathway.