Faulkner J A, Jones D A, Round J M
Department of Medicine, University College and Middlesex Hospital Medical School, Rayne Institute, London.
Q J Exp Physiol. 1989 Sep;74(5):661-70. doi: 10.1113/expphysiol.1989.sp003318.
Our purpose was to determine the amount of injury to extensor digitorum longus (EDL) and anterior tibial (ATB) muscles of mice from 1 h to 30 days following passive shortening and lengthening, shortening contractions and lengthening contractions. The shortening-lengthening cycle was of 600 ms duration and was repeated every 5 s for 30 min. Contractions were produced during either the shortening or lengthening phase with stimulation at 100 Hz for 300 ms. The amount of injury was evaluated by the decrease in the number of fibres in a cross-section of the muscle and in the maximum isometric tetanic force (Po). Passively shortened and lengthened and actively shortened EDL and ATB muscles showed no evidence of injury. At 3-5 days after lengthening contractions, EDL and ATB muscles showed an inflammatory response. At 3-5 days, the number of fibres in the cross-section of the injured EDL muscles was 65% of that of the contralateral control EDL muscle, whereas no change was observed in the number of fibres in the injured ATB muscles. By 3 days, the presence of myoblasts, myotubes and central nuclei indicated regeneration of fibres. One hour after shortening contractions, the Po of EDL and ATB muscles decreased to about 75% of the contralateral control value, but recovered completely by 3 days. In contrast, 1 h after lengthening contractions the Po of EDL and ATB muscles decreased to 52 and 40% respectively of the contralateral control value and then both recovered to about 65% within 3 h. For the ATB muscle, the Po showed a secondary decrease to 49% of the contralateral control value at 1 day and for the EDL muscle, to 47% at 3 days. Each muscle recovered gradually and by 30 days the number of fibres and the Po of the injured muscles were not significantly different from values for contralateral control muscles.
我们的目的是确定小鼠趾长伸肌（EDL）和胫前肌（ATB）在被动缩短和延长、缩短收缩和延长收缩后1小时至30天内的损伤程度。缩短-延长周期持续600毫秒，每5秒重复一次，共30分钟。在缩短或延长阶段，以100赫兹的频率刺激300毫秒产生收缩。通过肌肉横截面积中纤维数量的减少和最大等长强直力（Po）来评估损伤程度。被动缩短、延长以及主动缩短的EDL和ATB肌肉均未显示损伤迹象。在延长收缩后3至5天，EDL和ATB肌肉出现炎症反应。在3至5天时，受损EDL肌肉横截面积中的纤维数量为对侧对照EDL肌肉的65%，而受损ATB肌肉中的纤维数量未观察到变化。到3天时，成肌细胞、肌管和中央核的存在表明纤维开始再生。缩短收缩1小时后，EDL和ATB肌肉的Po降至对侧对照值的约75%，但在3天时完全恢复。相比之下，延长收缩1小时后，EDL和ATB肌肉的Po分别降至对侧对照值的52%和40%，然后在3小时内均恢复至约65%。对于ATB肌肉，Po在1天时再次降至对侧对照值的49%，对于EDL肌肉，在3天时降至47%。每块肌肉逐渐恢复，到30天时，受损肌肉的纤维数量和Po与对侧对照肌肉的值无显著差异。
