Strenuous Exercise On Rat Cardiomyocytes Myosin And Titin And Its Mrna

Objective To explore the effects of strenuous exercise on myocardial cells thick filament protein and its binding protein of rats, and provide morphological data for further studying the effects of strenuous exercise on the heart, the changes of myosin and titin and their mRNA were observed in rats at different times after single intense swimming and one week of intense swimming.Method Sprague Dawley Rats were randomly selected as quite control group, single intense swimming group and one week of intense swimming group. After exercises of rats'single intense swimming and one week of intense swimming, cardiac muscle were cut off at 0h, 1h, 3h, 6h, 12h and 24h. These specimens were treated respectively with regular procedures of paraffin sections. Myosin and titin were stained by immunohistochemistry and in situ hybridization. The distribution were observed under the light microscope and their changes of mean optics density and percentage of stained areas were calculated through the image analysis software.Result (1) After the experiment, the average weight of single strenuous exercise group increased and the weight of one week strenuous exercises group decreased significantly. Compared to the quite control group, the weight growth rate of single strenuous exercise group showed no significant difference. But one week strenuous exercises group was signicantly lower than the quite control group (P<0.01). (2) Observed under light microscope: Myosin and titin were expressed with stripe-like in myocardial muscle fibers in each group. After single strenuous exercise 0h~6h, rats'ventricular muscle and atrial muscle myosin and titin expression were gradually reduced. During 12h~24h, the expression of myosin and titin began to increase. Myosin and titin mRNA were distributed in the cytoplasm of myocardial cells. After single strenuous exercises from 0h to 24h, the expression of myosin and titin mRNA increased and then decreased gradually. The change of one week strenuous exercises group in 24 hours was similar with the single strenuous exercise group. (3) Statistical results: The amount of ventricular muscle and atrial muscle myosin and titin continuoursly decreased after single strenuous exercise from 0h to 6h, and gradually increased from 12h to 24h. Their mRNA began to increase from 0h, reached the highest point at 6h and then began to decrease from 12h to 24h after single strenuous exercise. The amount of myosin and titin decreased to the lowest at 6h after one week strenuous exercises, and then continuoursly increased from 12h to 24h. Their mRNA coutinuoursly rised from 0h to 6h after exercise, then 12h to 24h gradually being restored.Conclusion 1. Strenuous exercise led to rat's cardiac myosin and titin decrease. But this change was reversible. 2. Strenuous exercise led to rat's cardiac myosin and titin mRNA increased. The change was reversible too. 3. After exercise 24h, rats'cardiac myosin and titin and their mRNA were not returned to normal levels, strenuous exercise affects these two kinds of protein for a long time. 4. A long-term of one week strenuous exercise compared to single strenuous exercise, the impact of the amount of rat's cardiac myosin, titin and their mRNA were similar, but one week after strenuous exercise its change to a lesser extent. 5. Tips from the cardiac thick filament protein and its binding protein morphological point: strenuous exercise on myocardial cells have a certain degree of injury with long duration, which may be caused by exercise-induced arrhythmia and strenuous exercise-induced diseases such as myocardial infarction and sudden death of the important reasons.