Inhibition by infused glycerol of gluconeogenesis from other precursors.

STEELE, R., B. WINKLER, AND N. ALTSZULER. Inhibition by infused glycerol of gluconeogenesis from other precursors. Am, J. Physiol. 22 l(3) : 883-888. 1971 .-Plasma glycerol contributes 20% of the carbon of glucose released to the blood by the liver in the 6to 7-dayfasted dog (shown by use of glycerol-UJ4C). This increases to 63y0 when bulk glycerol infusion increases total glycerol uptake from plasma threefold. In the postabsorptive state, plasma glycerol contributes 7y0 of the carbon of released glucose; this increases to 55y0 when bulk glycerol infusion increases total glycerol uptake eightfold. Total glucose release (shown by use of glucoseJ4C) increases only at the highest rates of glycerol infusion and then by only 207& It is demonstrated that the contribution of other-than-plasmaglycerol carbon to the immediate precursors of the glucose released to the blood must decrease when the bulk glycerol is infused in order for the fractional contribution of plasma glycerol carbon to the released glucose carbon to rise to the observed levels. In the long-fasted dog, where hepatic glycogen is not a glucose source, the contribution of carbon to the glucose precursors from gluconeogenie sources other than glycerol must decrease when bulk glycerol is infused.