| Objective: to figure out the pathological process and mechanism of exercise-induced myocardial micro-damage by discussing the time-course characters and rules of TNF-a,ICAM-1and ADAMTS-1 expression in myocardium.Method: 100 SD male rats were grouped into 3 groups: the control group(C,n=20),one-time exhaustive swimming group(O,n=40),2-week repeated exhaustive swimming group(R,n=60).rats were sacrificed at 0,6,12,and 24 h after exhaustive swimming.The expression of TNF-a,ICAM-1and ADAMTS-1 in myocardium were detected in the approach of immunofluorescence,immunochemistry and image analysis.Results:1.The expression of myocardium TNF-a showed a tendency of “increase-decrease” after both models of exhaustive swimming,and reached the summit 6 hours after swimming,greatly significant difference were found between all time-course groups and the control group(p<0.01).The myocardium TNF-a in R group expressed faster than that of O group,while its expression in O group was greater than that of R group(p<0.05).The expression of myocardium TNF-?at left ventricle was greater than that of inter-ventricular septum and right ventricle in O group(p<0.05),while it was greater at right ventricle than left ventricle and inter-ventricular septum in the R group(p<0.05).2.The expression of myocardium ICAM-1 also showed a tendency of “increase-decrease” after both models of exhaustive swimming,and reached the summit 6 hours after swimming,greatly significant difference were found between all time-course groups and the control group(p<0.01)except for its expression at inter-ventricular septum and right ventricle in the 24 h R group(P>0.05).the expression of myocardium ICAM-1 in R group was faster than that of O group,while its expression at left ventricle in O group was greater than in R group(P<0.05),and its expression at inter-ventricular septum and right ventricle in R group were greater than that in O group(P<0.05,p<0.01).3.The expression of myocardium ADAMTS-1 reached its peak at 0 h after exhaustive swimming and showed a tendency of decrease afterwards,greatly significant difference were found between all time-course groups and the control group(p<0.01)except for the 12 h and 24 h R group.The expression of myocardium ADAMTS-1 in O group was faster and greater than that of the R group.The expression of myocardium ADAMTS-1 at left ventricle was highly significant than at inter-ventricular septum and right ventricle after both models of exhaustive swimming(P<0.01).Conclusion:1.the expression of myocardium TNF-a increased after both models of exhaustive swimming and R group showed a faster expression which indicates that repeated exhaustive swimming do more harm to the myocardium than one-time exhaustive swimming.TNF-a is an initiation factor of inflammatory reaction,which mediates inflammatory cell infiltration and other cytokine to damage the myocardium,might be an initiation factor of inflammatory reaction which leads to myocardium damage.2.the expression of myocardium ICAM-1 showed similar time-course change after both models of exhaustive swimming but R group expressed faster,which indicates that ICAM-1 mediates the adhesion of inflammatory cell earlier in R group than O group.The expression of ICAM-1 relatesto the expression of TNF-a positively after exhaustive swimming which indicates that TNF-a stimulates the expression of ICAM-1 to take part in the adhesion and infiltration of inflammatory cell at the early stage,finally leads to myocardium micro-damage.3.the expression of myocardium ADAMTS-1 reached its peak immediately after exhaustive swimming.ADAMTS-1 degrades extracellular matrix proteins,fibrillates myocardium and prohibits the growth of vessel promotes the formation of atherosclerosis,and finally leads to myocardium micro-damage.4.the damage of exhaustive swimming changes at different parts of the heart.According to the expression of these 3 factors,it might be that left ventricle is thicker and has more myocardial cells which lead to a greater expression than the inter-ventricular septum and right ventricle after one-time exhaustive swimming.The inter-ventricular septum and right ventricle are thinner,lighter and have less myocardial cells,so it is easier to damage at the same work load after repeated exhaustive swimming. |
PDF Full Text Request