West S P, Roy R R, Edgerton V R
Exp Neurol. 1986 Jan;91(1):174-82. doi: 10.1016/0014-4886(86)90035-x.
Effects of low thoracic spinal transection on muscle weights, fiber type distributions, and fiber cross-sectional areas (CSAs) of selected cat hind limb mixed-fast flexors and extensors and slow extensors were studied. Cats were spinalized at T12 at 2 weeks of age and maintained for 6 to 12 months. In general spinalization resulted in a decrease in muscle weights of extensors, while the weights of those muscles that function as either flexors or as both flexors and extensors were maintained. The percentages of fast-twitch [fast glycolytic (FG) and fast oxidative-glycolytic (FOG)] fibers increased and slow oxidative (SO) fibers decreased as a result of spinalization. However, FG fibers had a smaller CSA after spinal transection in both extensors and flexors. The total relative CSA of FG fibers per whole muscle was similar in spinalized and control cats. The relative muscle CSA occupied by SO fibers decreased in extensors and flexors as a result of a lower proportion of SO fibers and/or smaller SO fibers in spinalized cats. These findings suggest that muscles become more "fast-like" histochemically while little change occurs in the oxidative staining properties in either extensors or flexors in 6- to 12-month-old cats transected at 2 weeks of age. Further, these data suggest that the amount of muscle atrophy that occurs as a result of spinal transection is not closely related to the percentage reduction in SO fibers.
研究了低位胸段脊髓横断对特定猫后肢混合快肌屈肌、伸肌以及慢肌伸肌的肌肉重量、纤维类型分布和纤维横截面积（CSA）的影响。猫在2周龄时于T12水平进行脊髓横断，并维持6至12个月。一般来说，脊髓横断导致伸肌的肌肉重量下降，而那些兼具屈肌功能或同时具有屈肌和伸肌功能的肌肉重量则保持不变。脊髓横断后，快肌纤维[快糖酵解型（FG）和快氧化糖酵解型（FOG）]的百分比增加，慢氧化型（SO）纤维的百分比减少。然而，脊髓横断后，伸肌和屈肌中的FG纤维CSA均较小。脊髓横断猫和对照猫的每块肌肉中FG纤维的总相对CSA相似。由于脊髓横断猫中SO纤维比例较低和/或SO纤维较小，伸肌和屈肌中SO纤维所占的相对肌肉CSA降低。这些发现表明，在2周龄时进行脊髓横断的6至12月龄猫中，肌肉在组织化学上变得更像“快肌”，而伸肌或屈肌的氧化染色特性几乎没有变化。此外，这些数据表明，脊髓横断导致的肌肉萎缩量与SO纤维减少的百分比没有密切关系。
