Why doesn't glucagon promote glycogenolysis in muscle?

Question

Insulin stimulates glycogenesis in both liver and in muscles. Epinephrine stimulates glycogenolysis in both liver and muscles. But glucagon stimulates glycogenolysis in liver only. Why is this so?

Answer 1

The liver is the main site of glucagon receptors in the body whereas skeletal muscle does not have glucagon receptors. Therefore, glucagon cannot exert its effect on skeletal muscles.

This relates to the overall purpose of the organs. A major role of the liver in the body is to release glucose into the blood so that it may be used by other organs that have high energy needs, such as muscle. So when glucagon is released, this is a signal that there is not enough glucose in the blood and the liver fulfills its role by breaking down glycogen and releasing it for use by other organs such as muscle.