Effects of autophagy on myocardial injury induced by limb ischemia reperfusion in ischemic preconditioning in rats

Objective To investigate the role of autophagy in the reduction of myocardial injury induced by ischemia and reperfusion in rats. Methods Twenty-eight SD male rats (8 weeks old,weight 200-250 g) were divided into 4 groups using random number table method (n_i=7):sham operation group (group S),limb ischemia reperfusion group (group IR) limb ischemia reperfusion preconditioning group (group IPR),Autophagy inhibitor treatment group (group 3-MA).A limb ischemia reperfusion model was established by using the method of reperfusion 4 h after clamping bilateral femoral artery ischemia 4 hours.A limb ischemia reperfusion model was implementing Ischemia for 5 minutes and reperfusion for 5 minutes,after 3 cycles remaining,before closing femoral artery clamp 30 minutes.Group 3-MA was given intraperitoneal injection of 10% 3-MA 1.5 ml/kg before ischemic preconditioning 30 minutes.After reperfusion 4 h,rats were killed and took the apical tissue,observed the formation and pathological changes of the cell bodies under electron microscope,detected apoptosis by HE staining and TUNEL assay,measured the expression of LC3 by western blot. Results Compared with group S,the proportion of myocardial cell apoptosis was significantly increased,the expression of LC3-Ⅱ/LC3-Ⅰ was up regulation on group IR,group IPR and group 3-MA (P<0.05). Conclusion with the group IR,the proportion of myocardial cell apoptosis was significantly reduced,the expression of LC3-Ⅱ/LC3-Ⅰ was down regulation on group IPR (P<0.05).Compared with the group IPR,the proportion of myocardial cell apoptosis was significantly increased,the expression of LC3-Ⅱ/LC3-Ⅰ was down regulation on group 3-MA (P<0.05).