Roy R R, Acosta L
Exp Neurol. 1986 Jun;92(3):675-85. doi: 10.1016/0014-4886(86)90308-0.
The effects of low thoracic spinal cord transection on muscle weights, fiber type compositions and, fiber cross-sectional areas of selected hind limb muscles were studied. Adult cats were spinalized at T12 and maintained for approximately 6 months. Some spinalized cats were exercised on a treadmill 30 min/day, 5 days/week to determine the role of weight support in maintaining the muscle properties. Spinalization resulted in a significant decrease in the weights of most extensors, whereas the flexors or those that act as both flexors and extensors were maintained near control values. All muscles showed a significant increase in the percentage of fast-twitch fibers and decrease in slow oxidative fibers following spinalization. In addition, the predominant fast fiber type in each muscle tended to have the largest decrease in cross-sectional area in the spinalized cats. The atrophic and fiber type adaptations were less pronounced in the exercised cats. In contrast, the relative cross-sectional area of high oxidative fibers generally was similar among the three groups. These results demonstrated that the muscles below the level of the lesion became more "fast-like" histochemically following spinal cord transection, whereas the oxidative properties were relatively unaffected. Further, daily exercise involving weight support appeared to be an important deterrent to these atrophic responses, particularly in the muscles that normally have a postural function (i.e., the slow extensors).
研究了低位胸段脊髓横断对选定后肢肌肉的重量、纤维类型组成和纤维横截面积的影响。成年猫在T12水平进行脊髓横断，并维持约6个月。一些脊髓横断的猫在跑步机上每天锻炼30分钟，每周5天，以确定体重支持在维持肌肉特性中的作用。脊髓横断导致大多数伸肌重量显著下降，而屈肌或兼具屈肌和伸肌功能的肌肉则维持在接近对照值的水平。脊髓横断后，所有肌肉的快肌纤维百分比显著增加，慢氧化纤维减少。此外，脊髓横断的猫中，每块肌肉中占主导地位的快肌纤维类型往往横截面积下降最大。在运动的猫中，萎缩和纤维类型适应性变化不太明显。相比之下，高氧化纤维的相对横截面积在三组中通常相似。这些结果表明，脊髓横断后，损伤平面以下的肌肉在组织化学上变得更像“快肌”，而氧化特性相对未受影响。此外，涉及体重支持的日常运动似乎是这些萎缩反应的重要抑制因素，尤其是在通常具有姿势功能的肌肉（即慢伸肌）中。
