Glucagon regulates blood glucose via control of hepatic glycogenolysis and gluconeogenesis and via regulation of insulin release from the ß cell. Pharmacological administration of glucagon increases blood glucose in normal and diabetic subjects, and produces positive inotropic and chronotropic cardiovascular effects, relaxation of smooth muscle in the gastrointestinal tract and stimulation of growth hormone secretion. The actions of glucagon are mediated via a single adenylate cyclase-coupled glucagon receptor that also couples to the phospholipase C-inositol phosphate (PLC-IP) pathway leading to Ca2+ release from intracellular stores.