title: Relaxant action of histamine on rabbit trachea: possible existence of third histamine receptor subtype.
abstract: The carbachol contracted rabbit trachea relaxes to isoproterenol, PGE1, E2, histamine and bradykinin. Histamine-induced relaxations were resistant to mepyramine (an H1-antagonist), burimamide, cimetidine, metiamide (H2-antagonists), propranolol (a beta-adrenoceptor blocker), indomethacin (a potent inhibitor of prostaglandin synthesis), trasylol (an inhibitor of kallikreins), aminophylline (a purinergic receptor blocker) and dibenzyline (a "D"-tryptamine receptor antagonist). The evidence achieved with these pharmacological agents appears to suggest that the chemical mediator responsible for the relaxant response to histamine is unlikely to be: catecholamines, prostaglandins, 5-HT, adenosine or ATP or kinins. The existence of H2-(iso or H3) histamine receptor subtype in rabbit trachea is postulated.
mesh_terms: D000403:Airway Resistance / Q000187:drug effects*; D000818:Animals; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D011817:Rabbits; D011968:Receptors, Histamine / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects
chemical_list: D011968:Receptors, Histamine; D006632:Histamine; D007545:Isoproterenol