不同理化因素对肌肉疲劳影响的探讨

目的：探讨不同镁离子浓度、不同温度、前负荷对肌肉疲劳的影响及其可能机制。方法：制备蛙腓肠肌标本，在持续通氧灌流任氏液条件下，采用最大刺激强度，连续单刺激经过不同方法处理的蛙腓肠肌，以最大张力下降50％所需时间作为观察肌肉疲劳指标。结果：镁离子浓度为1mmol/L、10mmol/L均可延长蛙腓肠肌达到疲劳的时间，但作用效果不显著，镁离子浓度为5mmol/L对延长最大张力下降50％所需时间具有显著性作用（P＝0．05）。与正常对照组比较，前负荷分别为10g和20g组最大张力下降50％所需时间明显延长（P＜0．05），但两实验组差异无统计学意义（ P＞0．05）。温度为7℃蛙腓肠肌最大张力百分比下降速率相对减缓，温度为37℃下降速率相对增加。结论：随着镁离子浓度上升，抗肌疲劳时间延长，达最适浓度时，作用最强。适当增加前负荷可延长抗肌疲劳时间，高温比低温更容易诱发肌疲劳。

Discussion of Different Factors on the Frog Calf Muscle Fatigue Effect

Objective ：To investigate the concentration of magnesium ions ,different temperatures and pre-load on mus-cle fatigue and its possible mechanism .Methods ：Frog gastrocnemius specimens ,in continuous perfusion Ringer solution through oxygen conditions ,with maximum stimulation intensity ,continuous single stimuli processed through different methods frog gastrocnemius ,gastrocnemius maximum tension decreased to 50% of the time required for muscle fatigue as observed indicators .Results：Magnesium ion concentration of 1mmol/L ,10mmol/L can extend the frog gastrocnemius muscle to fatigue time ,but the effects were not significant ,magnesium ion concentration has significant effect for the time required for 5mmol/L to extend the maximum tension decreased 50% （P=0 .05） .Compared with the normal con-trol group ,pre-load are respectively 10g and 20g maximum tension decreased 50% time was significantly prolonged （P0 .05） .Under the temperature 7℃ , frog gastrocnemius muscle tension decline rate is relatively slow ,while under the temperature 37℃ decline rate of rela-tive increase .Conclusion：Along with the magnesium ion concentration increasing ,resistance to muscle fatigue time is prolonged .When reached the optimal concentration ,the strongest effect .Increased pre-load properly can prolong the time before muscle fatigue .High temperature induce muscle fatigue more easily than the low temperature .