INJURY TO MUSCLE-FIBERS AFTER SINGLE STRETCHES OF PASSIVE AND MAXIMALLY STIMULATED MUSCLES IN MICE
INJURY TO MUSCLE-FIBERS AFTER SINGLE STRETCHES OF PASSIVE AND MAXIMALLY STIMULATED MUSCLES IN MICE
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DOI：
10.1113/jphysiol.1995.sp020980
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发表时间：
1995-10-15
影响因子：
5.5
通讯作者：
FAULKNER, JA
中科院分区：
文献类型：
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作者：
BROOKS, SV;ZERBA, E;FAULKNER, JA
1.我们的目的是研究收缩所致损伤的最初机制。大多数关于收缩损伤机制的研究都是基于在疲劳高峰多次重复收缩后不久或在延迟发作损伤高峰几天后所做的观察。因此，基于这些研究的结论由于机械和生化事件的相互作用以及时间的推移而变得复杂。我们研究了在这种情况下小鼠整个骨骼肌单伸展后立即发生的与收缩引起的损伤相关的初始力学事件。我们测试了这样的假设，即紧随一次拉伸后，收缩引起的损伤的严重程度是应变和平均力的函数。因此，伸展肌肉所做的工作将是最好的损伤程度预测指标。将指长伸肌调整到最适力长度(L(O))。被动(未受刺激)和最大激活肌肉暴露于相对于肌肉纤维长度的10、20、30、50或60%的单个拉伸(L(女))，速率为2 L(女)S(-1)。损伤的大小由拉伸后1分钟的力赤字表示，以拉伸前最大力的百分比表示。通过对单次拉伸后立即固定的肌肉纤维的超微结构的电子显微镜分析，直接证实了损伤的发生。对于主动肌肉，只需30%的拉伸就会产生明显的力量不足，而对于被动肌肉，需要更大的应变。超过50%的伸展导致被动肌肉比最活跃肌肉的力量不足更大。对于任何一种情况，伸展肌肉所做的功是最好的损伤程度预测因子，对于最活跃的肌肉，力量不足的变异性占76%，对于被动肌肉，占85%。
1. Our purpose was to investigate the initial mechanisms responsible for contraction-induced injury. Most studies of mechanisms of contraction-induced injury have been based on observations made either shortly after many repeated contractions at the peak of fatigue, or days after, at the peak of delayed onset injury. As a result, conclusions based on these studies are complicated by interactions of mechanical and biochemical events, as well as the passage of time. We studied the initial mechanical events associated with contraction-induced injury immediately following single stretches of whole skeletal muscles of mice in situ.2. We tested the hypothesis that immediately following a single stretch, the severity of contraction-induced injury is a function of both strain and average force. Consequently, the work done to stretch the muscle would be the best predictor of the magnitude of injury. Extensor digitorum longus muscles were adjusted to optimum length for force (L(o)). Passive (not stimulated) and maximally activated muscles were exposed to single stretches of 10, 20, 30, 50 or 60% strain, relative to muscle fibre length (L(f)), at a rate of 2 L(f) s(-1).3. The magnitude of injury was represented by the force deficit 1 min after the stretch expressed as a percentage of the maximum force prior to the stretch. The occurrence of injury was confirmed directly by electron microscopic analysis of the ultrastructure of muscle fibres that were fixed immediately following single stretches.4. For active muscles, a single stretch of only 30% strain produced a significant force deficit, whereas for passive muscles, a larger strain was required. Stretches of greater than 50% strain resulted in greater force deficits for passive than for maximally activated muscles. For either condition, the work done to stretch the muscle was the best predictor of the magnitude of injury, accounting for 76% of the variability in the force deficit for maximally activated muscles, and 85% for passive muscles.