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 glycogen storage disease (von Gierke) and hypoglycemia, particularly hypoglycemic coma due to exogenously administered insulin. SYN: HG factor, hyperglycemic-glycogenolytic factor, pancreatic hyperglycemic hormone. [glucose + G. ago, to lead]

- gut g. a substance of intestinal origin that is secreted into the blood following ingestion of glucose and is a potent stimulus to the secretion of insulin; its chemical structure and the biologic effects that it produces are different from those of g., and it cross-reacts with antibodies to g..

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glu·ca·gon 'glü-kə-.gän n a protein hormone that is produced esp. by the pancreatic islets of Langerhans and that promotes an increase in the sugar content of the blood by increasing the rate of breakdown of glycogen in the liver called also hyperglycemic factor, hyperglycemic-glycogenolytic factor

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n.

a hormone, produced by the pancreas, that causes an increase in the blood sugar level and thus has an effect opposite to that of insulin. Glucagon is administered by injection to counteract diabetic hypoglycaemia.

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glu·ca·gon (glooґkə-gon) 1. a polypeptide hormone secreted by the alpha cells of the islets of Langerhans in response to hypoglycemia or the presence of acetylcholine, certain amino acids, or growth hormone. It stimulates glycogenolysis in the liver by activating liver phosphorylase, promotes gluconeogenesis and ketogenesis, and stimulates the release of insulin by the pancreatic islets. Formerly called hyperglycemic-glycogenolytic factor. 2. [USP] a preparation of this hormone obtained from the organs of slaughtered food animals; used in the treatment of severe hypoglycemia, administered intramuscularly, intravenously, or subcutaneously. Because it decreases gastrointestinal motility, it is also used as an adjunct in gastrointestinal radiography. 3. g. (recombinant).