| At present, much attention is being paid on the effect of Ca2+ signal transduction on cell functions. As one of the messengers in the cell, Ca2+ stirs up a series of reactions by combining with the receptors. It was found in many studies that the exercise led to the decrease of Ca2+ transportation capacities of sarcoplasmic reticulums (SR) and mitochondria (Mit). Cytoplasmic Ca2+ accumulation may be an important factor that caused skeletal muscle fatigue. However, the evidence about the Cytoplasmic Ca2+ accumulation after exercise has not been found yet. A systematic study was carried out, therefore, to observe the effect of pH on Cytoplasmic Ca2+ and its time course in order to analyze how acute exercise influenced the Cytoplasmic Ca2+ homeostasis. This study was conducted at the cell level to know the mechanisms about exercise-induced fatigue, which may provide scientific training with theories foundation.The results indicated as the following. (1) The blood lactate significantly increased during acute high intensity exercising (p<0.01). Although it began to decrease 48hrs after the exercise, it was still higher after than that before exercise (p<0.01). In comparison with pre-exercise state, the blood lactate didn't show significant change during or after middle intensity exercising. Thus, the above results demonstrated the inner environment of organism got to be acidic during and after high intensity exercise, and which was still kept in a long time.(2) Both total calcium and free Ca2+of blood serum decreased after high intensity exercising, and reached the minimal value 24hrs after the exercise (p<0.01). Although they began to get back 48hrs after exercise, they were still lower than that before exercise (P<0.01). That the changes of blood calcium was the same as the Mit calcium showed the significant decrease of blood calcium might be caused mainly by the increased Mit calcium of skeletal muscle cells after high intensity exercise. As to the relation between blood lactate and calcium, there was lack of the direct evidence to explain that the change of blood calcium was induced by blood lactate.(3) With desmin immunohistochemical labeling, the isolation culture method was tested a simpler and a more convenient technique to get individual skeletal muscle cells, which was . Some of factors were as following: 0.25% trypsin, 800-1 OOOrpm centrifugation speed, DMEM with 10% fetal bovine serum and pre-plating for 2 hours or much longer.(4) The proliferation capacity of myogenic precursor cells (mpc) varied among the rats at different ages. The older the rats were, the worse their mpc proliferation was. Acute exercise enhanced the proliferation of skeletal muscle satellite cells, especially the high intensity exercise,which were probably related to the calcium metabolism change of skeletal muscle cells induced by exercise.(5) When the skeletal muscle cells were in the rest state, cytoplasmic Ca2+oscillated beyond a definite base line, which shaped in the Ca2+ wave approximately as the sine curve. However, when the skeletal muscle cells were in the acid condition, cytoplasmic Ca2+ first increased, then decreased, and in the end came into being a new Ca2+ homeostasis under the base line. Not only the swing but also the frequency of cytoplasmic Ca2+wave changed while muscle cells were in acidity, which were closely correlated with the increase of cytoplasmic H+.(6) In this study, the cytoplasmic Ca2+ didn't accumulate when skeletal muscle cells were in acid condition, maybe which is due to the faint and short-term acid stimulus ( pH=6.9 ) as well as cells in good shape. The result suggested that cytoplasmic Ca2+ changed differently in every period of high intensity exercise. If the acid stimulus to cells were not strong enough, the Ca2+ transfer system of Mit and SR could re-adjust cytoplasmic Ca2+ into a new homeostasis.(7) Much more proliferation of satellite cells after acute exercise might show that the skeletal muscle cell would have been injured which would accelerate the proliferat...
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