Lieber R L, Fridén J O, Hargens A R, Feringa E R
Exp Neurol. 1986 Mar;91(3):435-48. doi: 10.1016/0014-4886(86)90042-7.
Morphometric properties of rat soleus and extensor digitorum longus muscles were studied 1 year following complete thoracic spinal cord transection (spinal cord level T9). Both muscles demonstrated almost complete type 1 to type 2 muscle fiber type conversion after 1 year. Muscle fiber atrophy was observed in both muscles. Type 2 fiber atrophy occurred to about the same extent in both muscles. Atrophy was most severe for the soleus type 1 fibers (50% decrease in size). Calculations based on the fiber type and size changes observed indicate that the percentage of the muscle cross-sectional area occupied by each fiber type was almost the same for both muscles 1 year after transection. Discriminant analysis of the data indicated that the percentage of type 2 fibers present in the muscle was the best discriminator between the various groups. These morphometric data provided a basis for understanding the contractile results presented in the previous study as well as insights into the mechanism of transformation in skeletal muscle. Furthermore, inherent differences between type 1 and type 2 fibers were demonstrated between predominantly slow and predominantly fast muscles. Thus, after almost one-half a lifetime of transection, rat muscles are almost completely transformed to fast muscle, and, regardless of initial conditions, have nearly identical properties.
在完全胸段脊髓横断（脊髓水平T9）1年后，研究了大鼠比目鱼肌和趾长伸肌的形态测量学特性。1年后，这两块肌肉均表现出几乎完全的1型到2型肌纤维类型转换。在这两块肌肉中均观察到肌纤维萎缩。2型纤维萎缩在两块肌肉中发生的程度大致相同。比目鱼肌1型纤维萎缩最为严重（大小减少50%）。基于观察到的纤维类型和大小变化进行的计算表明，横断1年后，每块肌肉中每种纤维类型所占肌肉横截面积的百分比几乎相同。对数据的判别分析表明，肌肉中2型纤维的百分比是不同组之间的最佳判别指标。这些形态测量数据为理解先前研究中呈现的收缩结果以及深入了解骨骼肌转化机制提供了基础。此外，在主要为慢肌和主要为快肌之间，1型和2型纤维的固有差异也得到了证明。因此，在横断近半生后，大鼠肌肉几乎完全转化为快肌，并且无论初始条件如何，都具有几乎相同的特性。
