What is Glucagon?

A hormone consisting of a straight-chain polypeptide of 29 amino acyl residues, extracted from pancreatic alpha cells. Parenteral administration of 0.5–1 mg results in prompt mobilization of hepatic glycogen, thus elevating blood glucose concentration. It activates hepatic phosphorylase, thereby increasing glycogenolysis, decreases gastric motility and gastric and pancreatic secretions, and increases urinary excretion of nitrogen and potassium; it has no effect on muscle phosphorylase. As the hydrochloride, it is used in the treatment of type I glycogenosis (von Gierke disease) and hypoglycemia, particularly hypoglycemic coma due to exogenously administered insulin.