Villar-Palasi C
Department of Pharmacology, Medical School, University of Virginia, Charlottesville 22908, USA.
Biochim Biophys Acta. 1995 May 11;1244(1):203-8. doi: 10.1016/0304-4165(95)00006-w.
The effect of insulin injection on skeletal muscle glycogen synthase activation was studied in anesthetized, normal, fed rats. Insulin stimulated the conversion of glycogen synthase to the active I form, increased the concentration of glucose 6-phosphate, and activated glycogen synthase phosphatase. A close correlation between glucose 6-phosphate concentrations, per cent glycogen synthase in the active I form, and phosphatase activity was found. When boiled extracts of muscle from control and insulin-injected animals were added to glycogen pellets containing phosphatase 1G, the difference in phosphatase activity between muscle extracts from insulin-injected and control rats was restored, indicating that the phosphatase was activated by heat-stable factors. Deproteinized muscle extracts from control and insulin-injected rats, at concentrations equivalent to those present in muscle, were tested for the activation of glycogen synthase by purified protein phosphatases 1 and 2A. The activation with the insulin extracts was four-fold larger than with the control extracts. When the extracts from insulin-injected rats were treated with glucose 6-phosphatase, the difference in activation with the control rat extracts was canceled. It would appear that, as in other insulin sensitive tissues, in skeletal muscle the increase in glucose 6-phosphate subsequent to the activation of glucose transport by insulin contributes to the activation of glycogen synthase.
在麻醉的、正常进食的大鼠中研究了胰岛素注射对骨骼肌糖原合酶激活的影响。胰岛素刺激糖原合酶转化为活性I型，增加6-磷酸葡萄糖的浓度，并激活糖原合酶磷酸酶。发现6-磷酸葡萄糖浓度、活性I型糖原合酶的百分比与磷酸酶活性之间密切相关。当将对照动物和胰岛素注射动物的肌肉煮沸提取物添加到含有磷酸酶1G的糖原沉淀中时，胰岛素注射大鼠和对照大鼠肌肉提取物之间的磷酸酶活性差异得以恢复，表明该磷酸酶被热稳定因子激活。对来自对照大鼠和胰岛素注射大鼠的脱蛋白肌肉提取物进行测试，其浓度相当于肌肉中的浓度，以检测纯化的蛋白磷酸酶1和2A对糖原合酶的激活作用。胰岛素提取物的激活作用比对照提取物大4倍。当用6-磷酸葡萄糖酶处理胰岛素注射大鼠的提取物时，与对照大鼠提取物的激活差异消失。似乎与其他胰岛素敏感组织一样，在骨骼肌中，胰岛素激活葡萄糖转运后6-磷酸葡萄糖的增加有助于糖原合酶的激活。
