The Correlation Between Apoptosis Of Rats Gastrocnemiuses Induced By Exercise Training And The Percentage Of Different Muscle Fiber

The apoptosis of skeletal muscle cells is correlated with the style, volume of training and the sub cell construction. Libera et al. have done some researches on the question, which type of muscle fiber is easier to apoptosis. The result of their research showed that type I skeletal muscle is easier to apoptosis than type â…¡ does. However, Zhou Jie et al. argued that type â…¡ skeletal muscle is easier to apoptosis than type â…  does. In this research, the exercise training models of different intensity were adopted, rats' gastrocnemiuses were studied, and the relationship between the apoptosis of skeletal muscle cells and the skeletal muscle fiber type was analyzed. Method:30 male adult Sprague-Dawley rats were randomly divided into three groups: control (C, n=10), middle intensity exercise (PME, n=10) and high intensity exercise (SHE, n=10). The rats of PME and SHE group ran on the treadmill to fatigue with the speed of 18 m/min(60⁷0% Vo_2max) and 26.8 m/min (90%Vo_2max) respectively. The rats in control group and in exercise group were killed by decapitation respectively in quiet status and immediately after exercise;the gastrocnemiuses were removed and tested further. The nuclei in apoptosis were labeled by TUNEL. The type I muscle fibers and type â…¡ muscle fibers were distinguished through ATPase coloration and the isoforms of MHC were separated into MHC â…  , MHC â…¡a, MHC â…¡b and MHC â…¡x through SDA-PAGE electrophoresis. Results:(1) Few TUNEL positive myonuclei were found in the control group. TUNEL positive myonuclei scattered in PME group and SHE group. The apoptosis index of PME group was 19.60 + 6.18%;the SHE group was 11.70+4.61%.(2) In PME group, the coefficient of apoptosis index and thepercentage of type II muscle fibers is 0.776 (PO.05);in SHE group, the coefficient of apoptosis index and the percentage of type II muscle fibers is 0.737 (PO.05).(3 )In PME group, the apoptosis index is high positive correlated with the percentage of MHCII a (r=0.786, PO.05);the coefficient of apoptosis index and the percentage of MHC lib is 0.364 (PO.05 );the percentage of MHC I is high negative correlated with the apoptosis index, the coefficient is -0.877 (PO.05). The results of SHE group is in accorded with the PHE group. Conclusion:The skeletal muscles with higher percentage of type II muscle fiber are easier to appear apoptosis, that's to say, the training on treadmills more easily induce skeletal muscles with high percentage of fast-twitch muscle fibers to occur apoptosis.