Moerland T S, Wolf N G, Kushmerick M J
Department of Radiology, Harvard Medical School, Boston, Massachusetts.
Am J Physiol. 1989 Oct;257(4 Pt 1):C810-6. doi: 10.1152/ajpcell.1989.257.4.C810.
A creatine analogue, beta-guanidinopropionic acid (beta-GPA), was administered in the food (2% wt/wt) and the water (0.5% wt/vol) of male CD-1 mice. Uptake of the phosphorylated analogue and depletion of phosphocreatine in hindlimb muscle was monitored by 31P nuclear magnetic resonance and was found to be complete within 7 wk. After this time, the isomyosin composition of soleus, extensor digitorum longus (EDL), and ventricle was analyzed by pyrophosphate gel electrophoresis. The analogue was found to induce significant alterations in the type of myosin expressed in soleus and EDL. Normal soleus contains both intermediate (IM) and slow (SM) myosins, and treatment reduced the relative content of IM by approximately 50%. In EDL, treatment decreased fast isomyosin FM3 by 60% compared with controls. Sodium dodecyl sulfate-gel electrophoresis also showed a decrease of parvalbumin in EDL by approximately 50%. Treatment had no significant effect on the isomyosin composition of heart ventricle. Levels of physical activity and concentrations of serum glucose and thyroxine of treated mice were not significantly different from controls. These results indicate a role for intracellular energetics in mediating adaptive changes in the phenotype of muscle in mature animals.
将一种肌酸类似物β-胍基丙酸（β-GPA）添加到雄性CD-1小鼠的食物（2%重量/重量）和水中（0.5%重量/体积）。通过31P核磁共振监测后肢肌肉中磷酸化类似物的摄取和磷酸肌酸的消耗，发现7周内摄取和消耗完成。此后，通过焦磷酸凝胶电泳分析比目鱼肌、趾长伸肌（EDL）和心室的肌球蛋白异构体组成。发现该类似物可诱导比目鱼肌和EDL中表达的肌球蛋白类型发生显著改变。正常比目鱼肌同时含有中间型（IM）和慢型（SM）肌球蛋白，处理后IM的相对含量降低了约50%。在EDL中，与对照组相比，处理使快肌球蛋白FM3减少了60%。十二烷基硫酸钠凝胶电泳还显示EDL中小白蛋白减少了约50%。处理对心室肌球蛋白异构体组成无显著影响。处理小鼠的体力活动水平、血清葡萄糖和甲状腺素浓度与对照组无显著差异。这些结果表明细胞内能量代谢在介导成熟动物肌肉表型的适应性变化中起作用。
