Studies on the regulation of glycolysis in isolated fetal rat hepatocytes

The contribution to the glycolytic flux by glycogen breakdown versus glucose phosphorylation has been determined in isolated fetal rat hepatocytes, prepared in different media and subsequently incubated with different glucose concentrations. A high glucose concentration in cells prepared in a medium containing a high concentration of inorganic phosphate decreases the contribution to the glycolytic flux by glycogenolysis to less than 15%. It is suggested that one of the factors which initiate glycogenolysis in the living animal after birth is a lowered blood glucose concentration, independent of hormonal changes. Under conditions where glycogenolysis does not contribute the larger part to the glycolytic flux, the control of glycolysis is shifted from glycogen breakdown to the glucose phosphorylation step and phosphofructokinase.