Hargroder G T, Talmadge R J, Silverman H
Exp Neurol. 1986 Nov;94(2):400-15. doi: 10.1016/0014-4886(86)90113-5.
The hind limb muscles of dy2J/dy2J mice appear more oxidative than normal hind limb muscles when assayed histochemically. In some cases, biochemical assay of oxidative capacity does not match histochemical data, and in some dy2J mice, particularly old animals, there appears to be a decline in biochemically assayed oxidative enzymes. The current study cyto-biochemically assayed succinic dehydrogenase activity of the gastrocnemius muscle in dy2J and normal mice. The assays were conducted over a maturation time course of 1 to 6 months of age. Additionally, the gastrocnemius muscle was divided into two distinct regions, a superficial region, containing largely glycolytic fast-twitch fibers (SGM), and a deeper region of mixed, largely oxidative fibers (DGM) in normal animals. Assay of the whole muscle and the two regions of each individual muscle showed that the dy2J muscle increased in SDH activity with maturation and was significantly greater than the change observed in normal muscle during the same period. The increase in the whole muscle SDH activity was accounted for increases noted in the SGM. The dy2J DGM, which showed marked morphologic degeneration, had neither an increase nor a decrease in measured SDH activity. Michaelis-Menton analysis of the enzymatic assay indicated that the Vmax, and not the Km, of the dystrophic muscle enzyme system was higher than normal, suggesting a change in quantity of enzyme present, and not altered function of the system. The observed increases occurred for 4 months of maturation and then began a decline, which was noted at 6 months. Coupled with the time course of gastrocnemius muscle degeneration (the glycolytic region was slow--very little by 4 months; the mixed was fast--highly degenerated by 1 to 2 months), the results of this study suggest that oxidative capacity in the dy2J gastrocnemius muscle increased with maturation until it became obscured by inherant muscle wasting in a particular dy2J muscle region. By comparison, analysis of the large glycolytic triceps muscle, a forelimb muscle which does not receive pseudomyotonia, indicated that this muscle did not increase in SDH activity in dystrophic animals, which showed the abnormal increase in the activity of the hind limb gastrocnemius. Thus the relationship of pseudomyotonia to increasing oxidative activity in the hind limb muscles of dystrophic animals was evident.
当采用组织化学方法检测时，dy2J/dy2J小鼠的后肢肌肉比正常后肢肌肉表现出更强的氧化能力。在某些情况下，氧化能力的生化检测结果与组织化学数据不匹配，并且在一些dy2J小鼠中，尤其是老年动物，经生化检测的氧化酶似乎有所下降。当前研究采用细胞生化方法检测了dy2J小鼠和正常小鼠腓肠肌的琥珀酸脱氢酶活性。检测在1至6月龄的成熟时间进程中进行。此外，在正常动物中，腓肠肌被分为两个不同区域，一个浅表区域，主要包含糖酵解型快肌纤维（SGM），以及一个更深的区域，主要是混合的氧化型纤维（DGM）。对每只动物的整个肌肉及其两个区域进行检测显示，dy2J肌肉的SDH活性随成熟而增加，并且显著大于同期正常肌肉中观察到的变化。整个肌肉SDH活性的增加是由于SGM中观察到的增加。表现出明显形态学退变的dy2J DGM，其测得的SDH活性既没有增加也没有减少。对酶促检测的米氏分析表明，营养不良肌肉酶系统的Vmax高于正常，而不是Km，这表明存在的酶量发生了变化，而不是系统功能改变。观察到的增加在成熟4个月时出现，然后开始下降，在6个月时被注意到。结合腓肠肌退变的时间进程（糖酵解区域退变缓慢 - 4个月时几乎没有变化；混合区域退变迅速 - 1至2个月时高度退变），本研究结果表明，dy2J腓肠肌的氧化能力随成熟而增加，直到在特定的dy2J肌肉区域被内在的肌肉萎缩掩盖。相比之下，对大的糖酵解型肱三头肌（一种不发生假肌强直的前肢肌肉）的分析表明，在营养不良动物中，该肌肉的SDH活性没有增加，而后肢腓肠肌的活性出现了异常增加。因此，假肌强直与营养不良动物后肢肌肉氧化活性增加之间的关系是明显的。
