Regulation of protein metabolism by a physiological concentration of insulin in mouse soleus and extensor digitorum longus muscles. Effects of starvation and scald injury.
Regulation of protein metabolism by a physiological concentration of insulin in mouse soleus and extensor digitorum longus muscles. Effects of starvation and scald injury.
复制标题
小鼠比目鱼肌和趾长伸肌中胰岛素生理浓度对蛋白质代谢的调节。
作者：
K. Frayn;P. Maycock
1. 虽然高浓度胰岛素会影响骨骼肌蛋白的合成和降解，但目前尚不清楚这些影响在多大程度上与生理浓度有关。在小鼠比目鱼肌和指长伸肌中，研究了生理浓度（100 mu单位/ml）胰岛素对肌肉蛋白质合成（用[3H]酪氨酸测量）和肌肉蛋白质降解（用环己亚胺存在下酪氨酸释放量测量）的影响。2. 胰岛素显著刺激了两种肌肉的蛋白质合成，但降解的抑制作用仅在指长伸肌中可见。3. 饥饿24小时降低了蛋白质合成率，增加了指长伸肌的分解率。饥饿使比目鱼对胰岛素刺激蛋白质合成的敏感性增加。4. ；20%表面积的背侧全皮肤厚度烫伤导致比目鱼肌和指伸肌总蛋白含量下降，在伤后第3天达到最大。伤后2 d比目鱼肌蛋白合成出现障碍；降解未受影响，体外合成和降解在指长伸肌中均未受到显著影响。5. 讨论了体外蛋白质代谢研究的优点和局限性。
1. Although high concentrations of insulin affect both synthesis and degradation of skeletal-muscle protein, it is not known to what extent these effects occur with physiological concentrations. The effects of a physiological concentration of insulin (100 mu units/ml) on muscle protein synthesis, measured with [3H]tyrosine, and on muscle protein degradation, measured by tyrosine release in the presence of cycloheximide, were studied in mouse soleus and extensor digitorum longus muscles in vitro. 2. Insulin significantly stimualated protein synthesis in both muscles, but an inhibition of degradation was seen only in the extensor digitorum longus. 3. Starvation for 24 h decreased the rate of protein synthesis and increased the rate of breakdown in the extensor digitorum longus. Sensitivity to insulin-stimulation of proteins synthesis in the soleus was increased by starvation. 4. ;a 20%-surface-area full-skin-thickness dorsal scald injury produced a fall in total protein content in soleus and extensor digitorum muscles, maximal on the third day after injury. Soleus muscles 2 days after injury showed an impairment of protein synthesis; degradation was unaffected and neither synthesis nor degradation in vitro was significantly affected in the extensor digitorum longus. 5. The advantages and limitations of studies of protein metabolism in vitro are discussed.