Department of Anatomy and Cell Biology, 4643 Medical Science II Building, University of Michigan, Ann Arbor, Michigan 48109, USA Department of Biology and Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA Institute of Gerontology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Restor Neurol Neurosci. 1996 Jan 1;10(2):77-84. doi: 10.3233/RNN-1996-10203.
Denervated extensor digitorum longus (EDL) muscles in rats rapidly lose mass and contractile force. After two months of denervation, mass and maximum tetanic force have fallen to 31% and 2% of the values of contralateral control muscles. Our purpose was to determine if grafting a long-term denervated muscle into an innervated site provides an effective means of restoring its structure and function. EDL muscles that had been denervated for periods of 2-12 months were freely grafted into innervated sites of EDL muscles in 4-month inbred host animals. Contralateral normally innervated EDL muscles from the same donors were implanted into the opposite legs of the same hosts. Two months after grafting, the muscles were removed and measurements were made in vitro of isometric contractile properties. The grafts were then prepared for morphological analysts. In all cases, the maximum forces generated by innervated grafts of denervated muscles were greater than those generated by denervated muscles. However, when compared with grafts of control muscles in the contralateral limb, grafts of previously denervated muscles showed a steady decline in structural and functional recovery corresponding to the time of previous denervation. The decline was especially pronounced for muscles denervated between 2 and 7 months prior to grafting. Grafts of 7-month denervated muscles were restored to only 17% of the maximum tetanic force of contralateral control grafts compared with 83% for grafts of 2-month denervated muscles. The longer a muscle had been denervated prior to grafting, the higher proportion of thin atrophic muscle fibers it contained. We conclude that grafting into an innervated site improves the mass and maximum force of a muscle over the denervated state, but the longer the period of prior denervation the poorer the recovery of the grafted muscles.
去神经支配的伸趾长肌（EDL）在大鼠中迅速失去质量和收缩力。去神经支配两个月后，质量和最大强直力分别下降到对侧对照肌肉的 31%和 2%。我们的目的是确定将长期去神经支配的肌肉移植到神经支配的部位是否提供了恢复其结构和功能的有效方法。已经去神经支配 2-12 个月的 EDL 肌肉被自由移植到同种异体宿主动物的神经支配 EDL 肌肉的神经支配部位。来自同一供体的对侧正常神经支配的 EDL 肌肉被植入同一宿主的对侧腿。移植后两个月，取出肌肉并在体外测量等长收缩特性。然后将移植物进行形态学分析。在所有情况下，神经支配的去神经支配肌肉移植物产生的最大力都大于去神经支配肌肉产生的最大力。然而，与对侧肢体对照肌肉的移植物相比，先前去神经支配的肌肉的移植物在结构和功能恢复方面表现出与先前去神经支配时间相对应的稳定下降。在移植前 2 至 7 个月去神经支配的肌肉中，下降尤为明显。与移植前 2 个月去神经支配的肌肉的移植物相比，移植前 7 个月去神经支配的肌肉的移植物仅恢复到对侧对照移植物最大强直力的 17%，而 2 个月去神经支配的肌肉的移植物为 83%。肌肉在移植前去神经支配的时间越长，其包含的薄萎缩肌纤维的比例就越高。我们得出结论，移植到神经支配的部位可以改善肌肉的质量和最大力，使其超过去神经支配的状态，但去神经支配的时间越长，移植肌肉的恢复越差。
