Glucagon is a a 29
amino acid polypeptide acting as an important
hormone in
carbohydrate metabolism. The polypeptide has
molecular weight of 3485 daltons and was discovered in
1923 by Kimball and Murlin. They studied
panreatic extracts and found a additional substance with
hyperglycemic properties. Glucagon was sequenced in late 1950s. Fuller understanding of its role in physiology and disease was established in 1970s when a specific
radioimmunoassay[?] was developed.
His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-Arg-Ala-Gln-Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Th
The hormone is synthesized and secreted from A cells of pancreatic islets (islets of Langerhans).
Glucagon raises the level of
glucose (sugar) in the
blood by causing the
liver to release its intracellular stores of glucose. Normally, the
alpha cells[?] of the
pancreas (in areas called the
Islets of Langerhans) make glucagon in response to hypoglycaemia in the body.
An injectable form of glucagon is essential first aid in cases of
severe hypoglycemia. The glucagon is injected and quickly raises blood glucose levels. It works only if there is glucose stored in liver cells, and it won't work again until those stores are replenished.
Glucagon has also inotropic[?] properties. Although it is impracticable in heart failure, it has some value in treatmeant of myocardium depression of
betablocker[?] overdose.