Effect Of Endurance Training On Rats Myocardium Hsp72mRNA Expression And Tolerance To Acute Exercise

As intrinsic protecting proteins, heat shock proteins widely exist in many organisms and could be synthesized by almost all kinds of cell. Heat shock proteins could be induced, and they are considered to play an essential role in maintaining cell stabilization and protecting them to survive all kinds of disturbed environments. Previous studies have demonstrated that heat shock proteins play an essential role in reducing myocardial ischemic-reperfusion injury and protecting cardiomyocytes against apoptosis, and exercise could induce HSP70 expression, which may imply that exercise maybe an available method for us to prevent or cure cardiopathy.The purpose of this study was to observe the effect of long time moderate endurance training on rats myocardium Hsp72mRNA expression and tolerance to acute exercise, to inspect the changes of superoxide dismutase(SOD), catalase(CAT) and malonldehyde (MDA), to investigate the possible mechanism and protecting function of long time moderate endurance training and offer some theories for physical exercise.36 purebred male Spargue-Dawley rats (weight : 180±10g) were divided into two groups : Controlled group (C, n=18) and Trained group (T, n=18), carrying out 1 week adaptability training and 6 week endurance training. After 6 week endurance training, rest for 24 hours, we chose 6 rats from Controlled group and Trained group respectively as basic groups; remained rats of two groups were put through an acute exercise, then they were killed after post-exercise 0 hour and post-exercise 24 hour. According different groups, We chose rats myocardium and inspected myocardium Hsp72mRNA expression with RT-PCR method, SOD , CAT activity with spectrophotometer method, and MDA content with TBA method. Experiment results : (1)After 6 weeks'endurance training, rats in Controlled group were fat and rats in Trained group were well situated, the weight was also obviously different between the two groups (P<0.05). (2)From the behavior of facing acute exercise, we concluded that Controlled group could not adapt acute exercise stress quickly, but Trained group could.(3)After 6 weeks'endurance training, compared with Controlled group, the myocardium Hsp72mRNA expression and SOD activity of Trained group were obviously increased (P<0.01), but CAT activity observed no change.(4)Compared with Controlled basic group, post-exercise 0 hour, myocardium Hsp72mRNA expression obviously increased in Controlled group (P<0.01), it was still significant after 24 hours (P < 0.01); post-exercise 0 hour, myocardial Hsp72mRNA expression also obviously increased in Trained group (P<0.01), but it returned to basic level after 24 hours. We made a comparison of the two groups and found that myocardium Hsp72mRNA was significant different after post-exercise 0 hour and post-exercise 24 hour (P<0.01).(5)Compared with Controlled basic group, post-exercise 0 hour, SOD activity and the value of SOD/MDA obviously increased (P<0.05) in Controlled group, after 24 hours MDA content also obviously increased, but value of SOD/MDA observed no change (P>0.05). Post-exercise 0 hour, SOD activity obviously increased in Trained group, MDA content obviously decreased and the value of SOD/MDA increased significantly(P<0.01), it still exhibits significant difference after 24 hours(P<0.01). CAT activity only obviously increased after post-exercise 0 hourin Trained.group(P<0.05). Conclusions:(1)Endurance training could control weight effectively and make body adapt acute stress quickly.(2)Long time moderate endurance training could increase Hsp72mRNA expression in rats myocardium, enhance SOD activity and decrease the content of myocardium overoxidation production MDA. It shows that the increase of Hsp72mRNA expression and SOD activity induced by endurance training play an essential role in enhancing myocardial adaptability and endurance, and play an essential role in maintaining cell inenvironment stability.(3)The Hsp72mRNA expression increased significantly in rats myocardium during acute exercise show that Hsp72mRNA could be regulated by stress, and it's an intrinsic self-protect mechanism of cell. Hsp72mRNA also reflect the stress degree in a certain extent when it increases quickly to protect cells. Hsp72mRNA expression increasing less in Trained group than in Controlled group after same acute exercise show that endurance training could enhance rats myocardium against stress.(4)Acute exercise stress could activate the activity of rat myocardium SOD and make SOD activity and MDA content increase shows that there is an unbalance between radical metabolition and antioxidation system. Endurance training could make myocardial antioxidation system change adaptably, enhance the ability of radical elimination, reduce myocardium oxidative injury during acute stress and make the unbalance diminish.(5)Hsp72mRNA expression and SOD activity have a similar change, which indicates some relations between them. Hsp72 may be associated with antioxidation enzyme to enhance the antioxidation ability of cells and resist the injury induced by stress.(6)According to our study, we speculate that long time moderate endurance training is favorable to protecting our heart, and enhancing the adaptability and endurance of our heart. We can employ it for better health.