Inactivation of basal glycogen synthase by glucagon and epinephrine in hepatocytes from fed rats

Glucagon and epinephrine promote the inactivation of basal glycogen synthase in hepatocytes isolated from fed rats. However, this effect is only observable when the activation state of glycogen synthase is measured using the low glucose-6-P/high glucose-6-P activity ratio assay. This inactivation is the consequence of an increase in the kinetic parameters (S0.5 for UDP-glucose and M0.5 for glucose-6-P) of the enzyme. Therefore, this work demonstrates these hormones are also able to control glycogen synthase from fed animals.