Exercise Preconditioning Activates AMPK And Promotes GLUT4 Translocation To Participate In Late Cardioprotection

Objective: Repeated short-term and high-intensity intermittent aerobic exercise can improve the ability of myocardium to tolerate ischemia and hypoxia and protect the myocardium from long-term continuous ischemia and hypoxia injury.Exercise-induced endogenous myocardial protective effect is called exercise preconditioning(EP).AMP-activated protein kinase(AMPK)is an important energy receptor in the body,which is involved in myocardial protection during ischemia / reperfusion injury.AMPK can be used as an upstream kinase of glucose transp orter 4(GLUT4)to participate in the translocation and expression of GLUT4.Translocated GLUT4 can assist glucose molecules to enter the cell and play an important role in maintaining the homeostasis of myocardial energy metabolism.From the point of view of myocardial energy metabolism,taking t he activation level of myocardial AMPK and the degree of GLUT4 translocation as the main breakthrough point.This paper discusses the changes of AMPK and GLUT4 in the late stage of EP myocardial protection,in order to provide updated theoretical and experimental basis for the study of the mechanism of myocardial protective effect of EP.Methods: 80 healthy SD rats were randomly divided into 4 groups: control group(C group),late exercise preconditioning group(LEP group),exhaustive exercise group(EE group)and late exercise preconditioning + exhaustive exercise group(LEP+EE group).The EP model was established by using a one-time high-intensity intermittent aerobic exercise(10 min exercise,10 min rest)with a speed of 30 m / min and a slope of 0 °for 4 times.The model of exercise-induced myocardial injury was induced by a high intensity exhaustive exercise with a speed of 30 m/min.1.The content of cTnI in plasma was detected by chemiluminescent immunoassay.2.The morphology and structure of myocard ial tissue and the degree of myocardial ischemia and hypoxia were detected by HBFP stain ing.3.The contents of AMPK ?,p-AMPK ? and GLUT4 in myocardial tissue were detected by immunoblotting.4.The level of energy metabolism in myocardial tissue was evaluated,and the degree of GLUT4 translocation was detected by immunofluorescence method.Results: 1.Plasma troponin I level: Compared with C group,there was no significant difference in plasma cTnI level in LEP group(P>0.05),while plasma cTnI level in EE group was significantly higher than group C(P<0.05).Compared with C group,the level of plasma cTnI in LEP + EE group was decreased significantly(P<0.05).2.HBFP staining: Compared with C group,punctate bright red ischemic and hypoxic positive regions can be occasionally seen in cardiomyocytes in LEP group.T here was no significant difference in myocardial MOD values in LEP group(P>0.05).In EE group,there were large masses of bright red ischemic and hypoxic positive areas in cardiomyocytes,and the ischemic and anoxic injury was obvious.Myocardial MOD values in EE group was significantly increased(P<0.05).Flaky or spotted bright red ischemic and anoxic positive areas appeared in cardiomyocytes in LEP+EE group.Myocardial MOD values in LEP+EE group was significantly increased(P<0.05);compared with EE group,the positive area of myocardial ischemia and hypoxia decreased in LEP+EE group.The values of myocardial MOD in LEP+EE group decreased significantly(P<0.05).3.Western blotting: Compared with C group,the expression of p-AMPK ? and GLUT4 in LEP group was tend to increase,but there was no significant difference(P>0.05);the expression of AMPK ? in EE group was significantly increased(P<0.05);the expression levels of p-AMPK ? and GLUT4 in LEP+EE group were significantly increased(P<0.05).The expression of p-AMPK ? and GLUT4 in LEP+EE group was significantly higher than that in EE group(P<0.05).4.Results of immunofluorescence method: Compared with C group,thick linear yellow immunoreactive areas were often seen on the myocardial cell membrane in LEP group.The co-localization degree of WGA and GLUT4 on myocardial cell membrane in LEP group was significantly increased(P<0.05);In EE group,punctate yellow immunoreactive areas were occasionally found on the myocardial cell membrane,and there was no significant difference in the degree of co-localization between WGA and GLUT4(P>0.05).In LEP+EE group,lumps or thick lines of yellow immunoreactive areas could be seen on the myocardial cell membrane,and the degree of co-localization of WGA and GLUT4 was significantly increased(P<0.05).Compared with EE group,the co-localization degree of WGA and GLUT4 on myocardial cell membrane in LEP+EE group was significantly increased(P<0.05).Conclusion: Late exercise preconditioning activates AMPK to alleviate myocardial ischemia and hypoxia inj ury caused by high intensity exhaustive exercise.AMPK,as an upstream kinase of GLUT4,participates in the regulation of GLUT4 expression and translocation.Exercise preconditioning promotes GLUT4 translocation by activating myocardial AMPK,optimizes myocardial energy metabolism,and enables AMPK and GLUT4 to participate in the late myocardial protect ive effects of exercise preconditioning.