Skorjanc D, Traub I, Pette D
Faculty of Biology, University of Konstanz, D-78457 Konstanz, Germany.
J Appl Physiol (1985). 1998 Aug;85(2):437-41. doi: 10.1152/jappl.1998.85.2.437.
To investigate effects of sustained activity on major phenotypic properties, the left extensor digitorum longus muscle of young (15 wk) and aging (101 wk) male Brown Norway rats was subjected to 50 days of chronic low-frequency stimulation (CLFS; 10 Hz, 10 h/day). The contralateral muscle served as control. Changes in metabolic enzymes were analyzed by using glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase as reference enzymes of glycolysis and by using citrate synthase and 3-hydroxyacyl-CoA dehydrogenase as mitochondrial enzymes representative of aerobic-oxidative metabolism. Myosin heavy chain (MHC) isoforms were analyzed by SDS-PAGE. No differences existed between the enzyme activity profiles of control muscles from young and aging rats. CLFS induced similar increases in mitochondrial enzymes, as well as similar decreases in glycolytic enzymes. Although the MHC composition of the control muscles in the aging rats displayed a shift toward slower isoforms, the ultimate changes induced by CLFS led to nearly identical MHC phenotypes in both young and aging rats. These results demonstrate an unaltered adaptability of skeletal muscle to increased neuromuscular activity in the aging rat.
为研究持续活动对主要表型特性的影响，对年轻（15周龄）和老龄（101周龄）雄性挪威棕色大鼠的左趾长伸肌进行50天的慢性低频刺激（CLFS；10赫兹，每天10小时）。对侧肌肉作为对照。通过使用甘油醛-3-磷酸脱氢酶和乳酸脱氢酶作为糖酵解的参考酶，以及使用柠檬酸合酶和3-羟基酰基辅酶A脱氢酶作为代表有氧氧化代谢的线粒体酶，分析代谢酶的变化。通过SDS-PAGE分析肌球蛋白重链（MHC）亚型。年轻和老龄大鼠对照肌肉的酶活性谱之间没有差异。CLFS诱导线粒体酶有类似的增加，以及糖酵解酶有类似的减少。尽管老龄大鼠对照肌肉的MHC组成向较慢的亚型转变，但CLFS诱导的最终变化导致年轻和老龄大鼠的MHC表型几乎相同。这些结果表明老龄大鼠骨骼肌对增加的神经肌肉活动具有未改变的适应性。
