The Influence On Utrophin After One-off Hypoxic Exposure After Eccentric Contractions In Muscle

Subject:As homologous protein of dystrophin, utrophin has the potential to replace dystrophin. Eccentric exercise which has obvious damage may cause EIMD is chosen to simulate HiLo to study the impact of EIMD membrane damage and molecular mechanisms from the perspective of utrophin protein.Method:70 male Sprague-Dawley rats were randomly divided into 3 groups, which included sedentary group, exercise in normoxic rest and in normoxic rats, exercise in norraoxic and rest in hypoxia rats. The latter two groups were randomly divided into 3 groups:24H、48、72H.Oxygen concentration of low-oxygen zones is 12.7%. Two rats from each group were examined for sarcolemma integrity using Evans blue dye (EBD). Rats run on a treadmill at the speed of 26.8 m/min with a slope of -16°,5 min×10 times with an interval of 1 min. The protein content and mRNA content of dystrophin and utrophin of skeletal muscle was detected by western blot, RT-PCR, fluorescent-immunohistochemistry.Result:The results showed that after one-time centrifugal movement the EBD-positive muscle fibers appeared at 24H both in normoxia 2411 and hypoxic 24H. In normoxia group the EBD positive cells were first increase and then decrease. In hypoxic group the EBD positive cells were gradually reduced, and were significantly higher than the sedentary group (P<0.05). As time goes by, the mRNA content of dystrophin in skeletal muscle gradually decreased in normoxia and hypoxic groups, and were significantly declined compared to sedentary group(P<0.05). Compared tc sedentary group, the content of utrophin in normoxia 24H and 48H increased markedly (P<0.05). The content of utrophin in normoxia 72H was down to the level of sedentary group. The content of the utrophin gradually increased in each hypoxic group, which was significantly higher than sedentary group (P<0.05). The content of utrophin didn’t accord with the mRNA content of them. It may show that the expressions of this protein wsa controlled by not only gene transcription regulation, but also other regulatory mechanism.Conclusion:1. Hypoxic exposure after one-off eccentric contractions not only accelerated the damage of cell membrane but also extended the sarcolemma injury.2. Hypoxic exposure after one-off eccentric contractions can increase utrophin protein expression.