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

Ascorbic acid synthesis was stimulated by glucagon, dibutyryl cyclic AMP, as well as phenylephrine, vasopressin or okadaic acid, in hepatocytes prepared from fed mice. However, no such effect was observed in glycogen-depleted cells from starved animals, either in the presence or absence of glucose. The rate of ascorbate synthesis showed close correlation 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. These results show that hepatic ascorbate synthesis is dependent on glycogenolysis, and indicate a regulatory role of ascorbate released by the liver.