| Previous studies indicated that lot of free radical species are generated during exercise. Free radical species has high vivacity and oxidative capacity, and they can cause the oxidization of biomolecules. And this may result in the damage of cell structure, especially the structure and function of mitochondria. At the same time, antioxidant enzymes was also generated in skeletal muscle in response to substantial episodes of damaging exercise or serial training regimens; Little direct information exist to support the generation of free radicals in the process of exercise, The majority of the evidence, for instance: MDA and DNA, are derived from the detection of tissue isolated from animals which is an indirect index of ROS generation. And they cannot detect the exact volume free radical species directly and simultaneously. In addition, it is also difficult to define the relationship between ROS generation and exercise intensity. In this study, C2C12 was stimulated to contract in vitro and ROS was detected with DCFH fluorescent probe. ROS associated lipid peroxides MDA, superoxide dismutase SOD and Na+, K+ATPase activities were also detected simultaneously in order to define the changes of antioxidant ability in mitochondria. We just aimed to make pilot study on the time course of release of an oxidizing free radical species or quantity- phase of the contraction intension. Results:1 .Skeletal muscle myotubes displayed a large and rapid increase in superoxide production during stimulation, peaking at 60min and 120min, which declined relatively slowly after stimulation was terminated. And indicate that stimulated cultures of myotubes can induce a rapid releaseof superoxide anions, but the volume of increase is also vary with regard to time variation.2. mitochondria SOD activity was found to increase transiently after the contractile activity, they were still significantly higher than baseline at 150min and 180min(p<0. 05), lipid peroxide MDA also increased at 90min, then generally declined to control levels. atl50min and 180min. There was no influence on MDA contention This indicated that myotubes contract can induce the increase of SOD activity, but it has little influence on MDA content. after electric stimulation.3. The activity of Na+, K+ATPase was found to increase transiently at 90min, then declined, the activity was lower than the baseline values at 150min and 180min after the contractile activity. This indicated that long-term contract exercise can induce the decline of the Na+, K+ATPase activity.Our result indicated that electricity stimulated cultures skeletal muscle myotubes with wave pulses of 20 ms in duration at 5 Hz and 45V/well may have the same effect as aerobic exercise to exhaustion invivo. Thus, our model base on the study of C2C12 myotubes contraction maybe regard as an ideal one in the study of skeletal muscle contraction. This foundation of model may give us more evidence to further our study on the mechanism of free radical generation and related signal transudation. This is also an availability platform to study on stay or elimination free radical generation. in vivo.
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