The Impact of Aerobic Exercise on Cardiomyocyte Proliferation/Apoptosis and Its Mechanism

Objectives:To discuss the influence of aerobic exercise on cardiomyocyte proliferation / apoptosis and its possible mechanism.Methods:Adult male Sprague-Dawley rats,weight about 180-220g,were assigned to 2 groups equally:normal control group and aerobic exercise group.Control group rats had conventional cage life and aerobic exercise group rats made 8-week aerobic exercise.Exercise was initiated at 15m/min,for 20min.The speed and duration were gradually increased to 20m/min and 60min(including the 20min at 15m/min),5° incline for per session.The exercise was performed 5 days per week for 8 weeks.After 8 weeks,to detect the cardiac function,we measured the changes in heart rate,LVSP,LVEDP,±dp/dtmax of the rats;After that,opened the thoracic and picked the heart for histologic section,Masson dyeing;Separated cardiomyocytes and observed by Laser Scanning Confocal Microscope;Stem cell factor(SCF),c-kit,Bax,Bcl-2 as well as p53 were assessed with immunohistochemistry;CyclinD2,CDK4,PCNA were assessed with Western blot analysis.Results:Compared to normal control group,heart coefficients,LVSP,LV dp/dtmax were all increased(P<0.05) in exercise group rats.HR and LVEDP were all declined(P<0.05).Moreover,aerobic exercise made dual-core cardiomyocytes increase in the rat heart(P<0.05);Furthermore,aerobic exercise made the MOD of c-kit(P<0.01),SCF(P<0.01),Bcl-2(P<0.05) increased significantly and Bax(P<0.05),p53(P<0.01) decreased significantly in the myocardium;With regard to cyclinD2 and CDK4,there were no significance(P>0.05).In addition,PCNA(P<0.01)were all increased.Conclusions:This paper confirmed the aerobic exercise could significantly improve cardiac function and the proliferation of myocardial cell;Aerobic exercise can inhibit the apoptosis of cardiomyocyte and found out that aerobic exercise could promote myocardial cell proliferation.The molecular mechanisms of exercise-induced of cardiac cell proliferation and apoptosis need further study.