The effect of insulin and glucose on fructose-2,6-P₂ in hepatocytes

The effect of insulin and glucose on fructose-2,6-P₂ turnover has been examined using isolated rat hepatocytes. Insulin (>10^-10M) increases the fructose-2,6-P₂ level in hepatocytes from fasted rats, or those pretreated with glucagon (<10^-10M) but not those from fed rats. Glucose (>10mM) also increases the fructose-2,6-P₂ and hexose-P levels in hepatocytes from starved rats, and its effect appears to be greater than that of insulin. Furthermore, insulin increases fructose-6-P,2-kinase activity and decreases cAMP levels in hepatocytes pretreated with glucagon, and it increases hexose-P concentration in hepatocytes from fasted rats. These results suggest that insulin antagonizes glucagon action by increasing fructose-6-P,2-kinase, decreasing cyclic AMP levels, and increasing hexose-P levels, resulting in increased concentrations of fructose-2,6-P₂.