van der Meulen Jack H, Urbanchek Melanie G, Cederna Paul S, Eguchi Tomoaki, Kuzon William M
Ann Arbor Veteran's Administration Medical Center, The Institute of Gerontology and Department of Surgery, University of Michigan, USA.
Plast Reconstr Surg. 2003 Oct;112(5):1336-46. doi: 10.1097/01.PRS.0000081464.98718.E3.
The authors tested the hypothesis that, after denervation and reinnervation of skeletal muscle, observed deficits in specific force can be completely attributed to the presence of denervated muscle fibers. The peroneal nerve innervating the extensor digitorum longus muscle in rats was sectioned and the distal stump was coapted to the proximal stump, allowing either a large number of motor axons (nonreduced, n = 12) or a drastically reduced number of axons access to the distal nerve stump (drastically reduced, n = 18). A control group of rats underwent exposure of the peroneal nerve, without transection, followed by wound closure (control, n = 9). Four months after the operation, the maximum tetanic isometric force (Fo) of the extensor digitorum longus muscle was measured in situ and the specific force (sFo) was calculated. Cross-sections of the muscles were labeled for neural cell adhesion molecule (NCAM) protein to distinguish between innervated and denervated muscle fibers. Compared with extensor digitorum longus muscles from rats in the control (295 +/- 11 kN/m2) and nonreduced (276 +/- 12 kN/m2) groups, sFo of the extensor digitorum longus muscles from animals in the drastically reduced group was decreased (227 +/- 15 kN/m2, p < 0.05). The percentage of denervated muscle fibers in the extensor digitorum longus muscles from animals in the drastically reduced group (18 +/- 3 percent) was significantly higher than in the control (3 +/- 1 percent) group, but not compared with the nonreduced (9 +/- 2 percent) group. After exclusion of the denervated fibers, sFo did not differ between extensor digitorum longus muscles from animals in the drastically reduced (270 +/- 20 kN/m2), nonreduced (301 +/- 13 kN/m2), or control (303 +/- 10 kN/m2) groups. The authors conclude that, under circumstances of denervation and rapid reinnervation, the decrease in sFo of muscle can be attributed to the presence of denervated muscle fibers.
在骨骼肌去神经支配和重新神经支配后，观察到的比肌力缺陷可完全归因于失神经支配肌纤维的存在。切断支配大鼠趾长伸肌的腓总神经，并将远端残端与近端残端吻合，使得大量运动轴突（未减少组，n = 12）或数量大幅减少的轴突（大幅减少组，n = 18）能够接入远端神经残端。对照组大鼠仅暴露腓总神经，不进行横断，随后缝合伤口（对照组，n = 9）。术后四个月，在原位测量趾长伸肌的最大强直等长力（Fo）并计算比肌力（sFo）。对肌肉横截面进行神经细胞黏附分子（NCAM）蛋白标记，以区分神经支配和失神经支配的肌纤维。与对照组（295±11 kN/m²）和未减少组（276±12 kN/m²）大鼠的趾长伸肌相比，大幅减少组动物的趾长伸肌sFo降低（227±15 kN/m²，p < 0.05）。大幅减少组动物的趾长伸肌中失神经支配肌纤维的百分比（18±3%）显著高于对照组（3±1%），但与未减少组（9±2%）相比无差异。排除失神经支配纤维后，大幅减少组（270±20 kN/m²）、未减少组（301±13 kN/m²）和对照组（303±10 kN/m²）动物的趾长伸肌sFo无差异。作者得出结论，在去神经支配和快速重新神经支配的情况下，肌肉sFo的降低可归因于失神经支配肌纤维的存在。
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