glükagoniga

Glükagoniga refers to glucagon, a peptide hormone produced by alpha cells of the pancreatic islets in humans. It is an essential regulator of glucose metabolism and acts to increase blood glucose levels when needed, counterbalancing the effects of insulin.

Mechanism and action: glucagon binds to the glucagon receptor on hepatocytes, a Gs-protein–coupled receptor. This triggers an increase in cyclic AMP and activation of protein kinase A, stimulating glycogenolysis and gluconeogenesis. The result is hepatic glucose output that raises blood glucose. Glucagon also promotes lipolysis in adipose tissue and provides substrates for gluconeogenesis by increasing amino acid uptake in the liver.

Physiological role: during fasting, exercise, or hypoglycemia, glucagon secretion increases to maintain energy supply. Its release is stimulated by low blood glucose, specific amino acids (notably alanine and arginine), and sympathetic activity; it is inhibited by high glucose and by insulin.

Structure and pharmacology: glucagon is a 29-amino-acid peptide. In medicine, glucagon is supplied in injectable forms for emergency treatment of severe hypoglycemia, and a ready-to-use nasal glucagon product is available in some regions. Pharmacokinetics vary by route: intravenous administration has a rapid onset but short duration; intramuscular or subcutaneous administration has a slower onset with a longer, more variable duration.

Clinical notes: glucagon is typically used when oral carbohydrate administration is not possible or unsafe. Side effects may include nausea and vomiting; hypersensitivity is rare. In some clinical situations, such as prolonged hypoglycemia with depleted hepatic glycogen stores, responsiveness to glucagon may be reduced.