- Biochemistry, Physiology. a heterocyclic amine, C5H9N3, released by mast cells when tissue is injured or in allergic and inflammatory reactions, causing dilation of small blood vessels and smooth muscle contraction.
- Pharmacology. a commercial form of this compound, obtained from histidine and used chiefly in the diagnosis of gastric and circulatory functions.
- an amine formed from histidine and released by the body tissues in allergic reactions, causing irritation. It also stimulates gastric secretions, dilates blood vessels, and contracts smooth muscle. Formula: C 5 H 9 N 3See also antihistamine
- A physiologically active depressor amine found in plant and animal tissue, derived from histidine by decarboxylation and released from cells in the immune system as part of an allergic reaction. It is a powerful stimulant of gastric secretion, constrictor of bronchial smooth muscle, and vasodilator.
- An organic compound found widely in animals and plants that in humans and other mammals is released as part of the body’s immune response, causing physiological changes including dilation of the blood vessels, contraction of smooth muscle (as in the airways), and increased gastric acid secretion. The itching and sneezing typical of respiratory allergies are caused by the release of histamine. Chemical formula: C5H9N3