The effects of H2-receptor antagonists on anaphylaxis in the guinea-pig.
Histamine has been shown to inhibit a variety of immune responses including the antigen-induced, IgE mediated, release of histamine from sensitized human leucocytes and from sensitized monkey and dog mast cells. The inhibitory action of histamine appears to be mediated by action at a histamine H2-receptor. In in vitro experiments the H2-receptor antagonist metiamide has been shown to block this histamine effect and it has been suggested that H2-receptor antagonists could intensify immediate hypersensitivity reactions in vivo. The effects of the H2-receptor antagonist metiamide and cimetidine have been studied in in vitro and in vivo models of anaphylaxis in the guinea-pig. The amount of extracellular histamine found after antigen challenge is greater when an H2-receptor antagonist is present during the incubation of mast cells with antigen. Bronchoconstriction induced by antigen in sensitized guinea-pig is exacerbated only by high doses of cimetidine. Possible explanations for the mechanism of action involved are discussed.
D000403:Airway Resistance / Q000187:drug effects; D000707:Anaphylaxis / Q000503:physiopathology*; D000818:Animals; D001986:Bronchial Spasm / Q000276:immunology / Q000503:physiopathology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008297:Male
D006635:Histamine H2 Antagonists; D006632:Histamine