GLUCONEOGENESIS FROM ASCORBIC-ACID - ASCORBATE RECYCLING IN ISOLATED MURINE HEPATOCYTES

Ascorbic acid synthesis and breakdown were investigated in isolated he patocytes prepared from fasted mice, Stimulation of gluconeogenesis by alanine or xylitol led to ascorbate synthesis, On the other hand, asc orbate or dehydroascorbate addition resulted in concentration-dependen t glucose production and elevation of the pentose phosphate pathway in termediate xylulose 5-phosphate. Stimulation of ascorbate oxidation an d/or the inhibition of dehydroascorbate reduction increased glucose fo rmation, Inhibition of the pentose phosphate pathway decreased glucose production from dehydroascorbate with increased accumulation of xylul ose 5-phosphate, These results suggest that ascorbate can be recycled by a novel way involving intermediates of the pentose phosphate pathwa y, gluconeogenesis and hexuronic acid pathway.