Epinephrine and glucagon have which one of the following effects on glycogen metabolism in the liver?
|A||The net synthesis of glycogen is increased.|
|B||Glycogen phosphorylase is activated, whereas glycogen synthase is inactivated.|
|C||Both glycogen phosphorylase and glycogen synthase are activated but at significantly different rates.|
|D||Glycogen phosphorylase is inactivated, whereas glycogen synthase is activated.|
a. Epinephrine and glucagon both cause increased glycogen degradation in the liver.
b. Therefore, glycogen phosphorylase activity is increased, whereas glycogen synthase activity is decreased.
c. Both cAMP-dependent protein kinase and its substrate, phosphorylase kinase, are also activated.