ASCORBIC-ACID SYNTHESIS IS STIMULATED BY ENHANCED GLYCOGENOLYSIS IN MURINE LIVER

Ascorbic acid synthesis was stimulated by glucagon, dibutyryl cyclic A MP, as well as phenylephrine, vasopressin or okadaic acid, in hepatocy tes prepared from fed mice. However, no such effect was observed in gl ycogen-depleted cells from starved animals, either in the presence or absence of glucose. The rate of ascorbate synthesis showed close corre lation with the glucose release by hepatocytes. In mice the injection of glucagon increased plasma ascorbate concentration fifteenfold, and caused a sixfold elevation of the ascorbate content of the liver. Thes e results show that hepatic ascorbate synthesis is dependent on glycog enolysis, and indicate a regulatory role of ascorbate released by the liver.