HISTAMINE

INTRODUCTION: Histamine is formed from histidine by decarboxylation, catalysed by histidine decarboxylase. The effects of histamine are; Smooth muscle contraction, enhanced vascular permeability, increased acid secretion are the important actions. So histamine causes fall in blood pressure.

PRODUCTION: The major cells producing histamine are platelets, mast cells and basophils. Certain antigens such as penicillin will elicit IgE antibodies that are fixed on the mast cells. When the next dose of penicillin is injected, it reacts with the antibodies; and degranulation of mast cells takes place. Histamine and slow reacting substance (SRS) are released. This leads to peripheral vasodilatation, fall in blood pressure and anaphylaxis.

ANTIHISTAMINES: These are drugs which block histamine receptors. They are used to control allergic and anaphylactic reactions. The stimulant effect of histamine on gastric acid secretion is by acting on H2 receptors. Hence H2 receptor antagonists are used in the treatment of acid peptic ulcers of stomach.

RELATED;

1. PEPTIC ULCERS  

2. ANTIHISTAMINES

3.  BIOCHEMISTRY

REFERENCES