Rats After Exhaustive Exercise Is Not The Same Phase Of Myocardial Structure And Ecg Dynamic Change Research

Objective:When human body is undergoing strenuous exercise or excessive physical labor, the demand of oxygen and blood in myocardium will rapidly increase, However, the blood flowing in coronary arteries is relatively deficient. Due to the relative ischemia, cardiac function is often impaired and even the myocardium might be injured.Timely blood stream resuming after ischemia will make cardiac function and reversibility structure damage recover. But experiments studies discovered that myocardium injury had become worse during the recovery period after excessive physical exercise. In this study, we used Wistar rats to do exhaustive swimming exercise for a week. And then we selected immediately after exercise,3h,6h,24h,48h and 96h time points of six,observed ECG and myocardial morphological changes, and investigating changes in the characteristics of the myocardial morphology and cardiac function.The study aims at offering experiment evidence for searching myocardium injury in exercise.Materials and Methods:①Electrocardiogram:We chosed 24 male Wistar rats for the study, basing on the classic Thomas method to establish sport experimental animal models of myocardial injury. With DSI implantable ECG telemetry systems, we recorded swimming before and last exhaustive swimming immediately after exercise,3h,6h,24h,48h and 96h time course in conscious rats the electrocardiogram.②Detection of cardiac pathology:35 male Wistar rats were chosen and were randomly divided into normal control group (5) and exhaustive exercise group (30).We used light microscopy to observe histopathological changes in normal control group and exhaustive exercise group last exhaustive swimming immediately after exercise,3h,6h,24h,48h and 96h time course.③All of experimental data processing was done by statistical software SPSS 13.0.Results:①After a week of exhaustive swimming, rats were listless. Their food intake and weight declined; However, in normal control group, rats had flexible movement, clean fur. And their weight increased.②After exhaustive exercise at different phases rats appeared myocardial ischemic ECG ST-T changes.ECG ST-T elevation rate which immediately after exercise,3h,24h,48h was significantly higher than the normal control group(P<0.05 and P<0.05).ST-T elevation was at the highest rate immediately after exercise with gradual decreasing. It was at the lowest point at 6～12h. But it peaked again at 48h, and then declined again at 96h.③After one week's repeated exhaustive swimming, rats were observed under light microscope whose myocardial cells at different phases were with different degrees of damage after exercise. Conclusions: Long-term exhaustive exercise can inhibit the increase of rat's weight.ECG and cardiac pathology showed that significant myocardial ischemia appeared and hypoxia injury has delayed increasing phenomenon with the extended recovery time after exhaustive exercise.