pGlycogen synthase activation and phosphorylase inactivation by glucose were studied in hepatocytes isolated from fed or overnight-fasted lean or genetically obese (fa/fa) rats. In cells from fed animals, both the time course and dose-response to glucose of synthase activation were the same in both groups, despite higher levels of phosphorylase a in hepatocytes from obese animals. In contrast, in cells from fasted obese animals synthase activation with or without glucose was enhanced severalfold over that of lean controls, despite similar levels of phosphorylase a and of total (a + b) synthase activities. In both nutritional conditions glucose 6-phosphate concentrations were 2-3-fold higher in obese-rat hepatocytes than in lean-rat cells. In addition, synthase activation was transient in the fasted lean group, but was sustained in obese-rat hepatocytes. The rate of synthase activation was, however, comparable in lean- and obese-rat liver Sephadex G-25 filtrates, irrespective of the nutritional state of the donor rats. It is concluded that enhanced synthase activation in hepatocytes from starved obese rats might be due to an unbalanced synthase interconversion brought about by elevated glucose 6-phosphate concentrations and impaired kinase [van de Werve & Massillon (1990) Biochem. J. 269, 795-799], rather than to an intrinsic change in synthase phosphatase./p
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机译：在从进食或过夜禁食的瘦或遗传肥胖（fa / fa）大鼠分离的肝细胞中研究了葡萄糖对糖原合酶的激活和磷酸化酶的失活。在喂食动物的细胞中，尽管肥胖动物肝细胞中磷酸化酶α的水平较高，但两组的合成酶激活的时间和对葡萄糖的剂量反应都是相同的。相反，在空腹肥胖动物的细胞中，有或没有葡萄糖的合酶激活比瘦肉对照增强了几倍，尽管磷酸化酶a和总（a + b）合酶活性水平相似。在两种营养条件下，肥胖大鼠肝细胞中6-磷酸葡萄糖的浓度比瘦大鼠细胞中高6-2-3倍。另外，在禁食的瘦肉组中，合酶的激活是短暂的，但在肥胖大鼠的肝细胞中则持续存在。然而，不管供体大鼠的营养状况如何，在瘦和肥胖大鼠肝Sephadex G-25滤液中，合酶激活速率均相当。结论是饥饿的肥胖大鼠肝细胞中增强的合酶活化可能是由于6-磷酸葡萄糖浓度升高和激酶受损导致的合酶互变不平衡所致。 Massillon（1990）生物化学。 J. 269，795-799]，而不是合成酶磷酸酶的内在变化。
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