长时间电刺激引起肌肉结构损伤过程中细胞内各种元素的分布

利用快速冷冻固定和电子微探针技术，对电刺激诱发爪蟾延迟性肌肉损伤过程中肌浆网与胞浆钙、镁、钠、钾进行定量分析。电刺激后３ｈ，胞浆钙增加３．０ｍｍｏｌ／ｋｇｄｗ，肌浆网钙下降７．５３ｍｍｏｌ／ｋｇｄｗ。至刺激后６ｈ，胞浆钙增加达５．３３ｍｍｏｌ／ｋｇｄｗ，肌浆网摄取钙加强。在延迟性结构变化发展中，细胞内钠、钾也持续上升，而镁则逐渐下降。结果表明，延迟性肌肉结构异常与胞浆钙增高具有一致性。胞浆钙上升可能由于细胞内钠增加，钠－钙交换受抑及肌膜受损，外钙内流增加。肌浆网钙摄取下降则是运动后初期胞浆钙增高的另一途径。损伤肌中胞浆钾浓度有增高和下降两种变化，其意义与机制有待进一步探讨。

DISTRIBUTION OF INTRACELLULAR ELEMENTS DURING MUSCULAR STRUCTURAL DAMAGE INDUCED BY PROLONGED DLECTRICAL STIMULATION

Quantitative electron probe microanalysis of Ca,Mg,Na and K concentration insarcoplasmic reticulum(SR) and cytoplasm(CP) of Xenopus muscles with delayed structuraldamage prepared by rapid freeze and cryoultramicrotomy showed that Ca concentration in CPwas 3.07mmol/kg dw higher and Ca concentration in SR was 7.53 mmol/kg dw lower in themuscle 3 hours after prolonged electric stimulation than in control muscle.By 6 hours afterstimulation, CP Ca was 5.33mmol kg dw higher than control group,and SR Ca uptake in-creased. During delayed muscular structural alteration,intracellular Na and Cl concentration in-creased gradually and Mg decreased.These results indicate that delayed muscular alteration is re-lated to a rise in Ca concentration of CP; The rise in CP Ca results chiefly from increase in inflowof external Ca into the cells and a decrease in Ca-Na exchange. The decrease in SR Ca uptake isanother cause of the rise of CP Ca during the initial post-exercise period.