histamine shock


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his·ta·mine shock

the shock state produced in animals by the injection of histamine; characterized by bronchiolar spasm in the guinea pig and constriction of hepatic veins in the dog.

histamine

an amine, C5H9N3, produced by decarboxylation of histidine, found in all body tissues.
It induces capillary dilatation, which increases capillary permeability and lowers blood pressure; contraction of most smooth muscle tissue; increased gastric acid secretion; and acceleration of the heart rate. It is also a mediator of immediate hypersensitivity. There are two types of cellular receptors of histamine: H1-receptors, which mediate contraction of smooth muscle and capillary dilatation; and H2-receptors, which mediate acceleration of heart rate and promotion of gastric acid secretion. Both H1- and H2-receptors mediate the contraction of vascular smooth muscle. Histamine may also be a neurotransmitter in the central nervous system. It is used as a diagnostic aid in testing gastric secretion and in the diagnosis of pheochromocytoma.
There are two types of histamine antagonists that act at either the H1- or the H2-receptors. Drugs such as diphenhydramine and chlorpheniramine are referred to as antihistamines or H1-blockers; they block the effects of histamine on vascular, bronchial and gastrointestinal smooth muscle and on capillary permeability. They are used for relief of allergic and gastrointestinal disorders. Drugs such as cimetidine (Tagamet) are referred to as H2-blockers; they block the stimulation of gastric acid secretion and are used to treat gastrointestinal ulceration.

histamine-containing foods
some food sources, particularly some species of fish, have high levels of histamine; increased levels can also occur from improper storage which permits conversion of histidine to histamine, and an excessive carbohydrate content may promote bacterial growth, fermentation and production of histamine.
histamine-releasing foods
some foods can cause release of histamine from mast cells; these include egg white, shellfish and fish.
histamine shock
manipulation and particularly surgical trauma to large mast cell tumors may lead to decreased blood pressure and persistant bleeding caused by the release of histamine and vasoactive amines.
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