Restoration of glycogenesis in hepatocytes from starved rats.

Hepatocytes isolated from the liver of rats starved for two days synthesized glycogen only when incubated in the presence of both glucose and glucogenic precursors (combinations of alanine, glycerol, pyruvate, lactate or fructose). Unlabeled glucogenic precursors facilitated the incorporation of U-14C]glucose into glycogen. Unlabeled glucose likewise greatly enhanced glycogen synthesis from isotopically labeled lactate and other glucogenic precursors.In those systems which contained no added endocrines glucose dampened glycogen phosphorylase activity in a cAMP-independent fashion. Fructose is unable to mimic the effects of glucose on glycogen deposition and on glycogen phosphorylase activity.