Effects of high-energy phosphates on morphological and functional development in rat muscles

以Wistar大鼠为实验动物，研究了饲喂β-鸟苷丙酸(β-GPA)或肌酸对骨骼肌高能磷酸盐含量的慢性耗竭或负荷的影响。饲喂β-GPA后，比目鱼肌和趾长伸肌的收缩性能均向慢型方向移动，疲劳强度也有所提高，尤其是指长伸肌。应用β-GPA可引起快速抽动的足底肌肌球蛋白亚型的转变。由于受体数目的增加，β-GPA组的肌肉对葡萄糖的摄取和β-肾上腺素能受体的最大结合容量进一步增加。服用肌酸一般会引起相反的现象。提示高能磷酸盐的慢性耗竭刺激了线粒体的能量代谢，使肌塔向慢速方向移动。这也表明，如果三磷酸腺苷的合成能力得到提高，维持较高水平的高能磷酸盐可能不是提高抗疲劳能力所必需的。

Effects of chronic depletion or loading of high-energy phosphate contents in skeletal muscles by feeding either beta-guanidinopropionic acid (beta-GPA) or creatine were studied in Wistar rats. The contractile properties in both soleus and extensor digitorum longus (EDL) were shifted toward slower type by feeding beta-GPA.The fatigue resistance in these muscles, especially EDL,was also improved. Transition of myosin isoforms in fast-twitch plantaris muscle was induced by administration of beta-GPA.Greater glucose uptake and the maximum binding capacity of beta-adrenoceptor, due to an increased receptor number, were further observed in the musles of beta-GPA group. Administration of creatine induced, generally, opposite phenomena. It is suggested that chronic depletion of high-energy phosphates stimulates the mitochondrial energy metabolism and shifts the muscle towerd slower type. It is also indicated that maintenance of high-energy phosphates at higher levels may not be essential for the greater fatigue resistance, if the capacity of adenosine triphosphate synthesis is improved.