Influences Of Recombinant Human Erythropoietin On Myocardial Ischemia-reperfusion Injury In Rats And The Relationship With Autophagy

Objective To explore the effects of recombinant human erythropoietin(rhEPO) on myocardial diastolic and systolic function, the levels of serum myocardial enzymes, ischemic and infarct areas, the protein expressions of microtubule associated protein light chain 3(LC3)and Beclin1 in myocardium and the ultrastructure of cardiomyocytes through the establishment of myocardial ischemia/ reperfusion(I/R) model in rats. We focused on the protective effects of rhEPO on rat myocardial I/R injury and the relationship with autophagy in order to provide new drug targets for exploring intervention against I/R injury.Methods 80 SD rats were randomly divided into 5 groups :sham-operated group(Sham group), ischemia-reperfusion group(I/R group), rhEPO treatment group(rhEPO group), rhEPO + autophagy activator Rapamycin treatment group(rhEPO +Rap group)and Rapamycin treatment group(Rap group). Myocardial ischemia- reperfusion(I/R)models were established through ligated the coronary artery, and hemodynamic indices include intraventricular pressure were monitored during the procedure. Serum creatine kinase(CK) and lactate dehydrogenase(LDH) of different groups were detected after the reperfusion. Myocardial infarct areas were measured by applying evans blue and TTC staining respectively. The protein expressions of autophagy associated genes LC3 and Beclin1 in myocardium were identified by western blotting. Autophagy vacuoles and ultrastructures of cardiomyocytes were observed by transmission electron microscope.Results Compared with Sham group, I/R group, rhEPO group, rhEPO+Rap group and Rap group showed obvious myocardial infarct, and they had much weaker cardiac function,higher levels of serum CK,LDH and more significantly increased expressions of LC3Ⅱ/ LC3Ⅰand Beclin1. Damaged myofilaments and autophagic vacuoles were observed by transmission electron microscope. Compared with I/R group, rhEPO group and rhEPO+Rap group showed improved cardiac function,their serum CK and LDH levels were much lower, myocardial infarct areas were obviously narrower, and the expressions of LC3Ⅱ/ LC3Ⅰand Beclin1 were more significantly decreased, and the autophagic vacuoles were not observed. Compared with rh EPO group, rhEPO+Rap group and Rap group presented more weakened cardiac function, higher levels of serum CK and LDH, larger myocardial infarct areas and higher expressions of LC3Ⅱ/ LC3Ⅰand Beclin1, and autophagic vacuoles were observed. Compared with rhEPO+Rap group, Rap group showed more reduced cardiac function,higher levels of serum CK and LDH, larger myocardial infarct areas, higher expressions of LC3Ⅱ/ LC3Ⅰand Beclin1.Conclusions(1)Myocardial I/R injury in rats can lead to serious myocardial infarction and cardiac dysfunction.(2)Myocardial I/R injury can significantly increase autophagy in cardiomyocytes.(3)rhEPO has obvious protective effects on rat myocardial I/R injury. The mechanism may be related to the decrease of autophagy.