title: Resistance of the histamine H2 receptor in guinea-pig heart to blockade by phenoxybenzamine.
abstract: Phenoxybenzamine is a potent irreversible H1 receptor antagonist in a variety of tissues. In order to assess the ability of this agent to antagonise the H2-receptor, we have examined the effects of phenoxybenzamine on the histamine-induced positive inotropic effect in electrically driven strips of guinea-pig right ventricle. Even at concentrations as high as 10(-4)M no significant change in the responses to histamine was observed. It is concluded that the histamine H2 receptor is unexpectedly resistant to antagonism by 2-haloalkylamines.
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*; D010643:Phenoxybenzamine / Q000494:pharmacology*; D011968:Receptors, Histamine / Q000187:drug effects*; D011970:Receptors, Histamine H2 / Q000187:drug effects*
chemical_list: D011968:Receptors, Histamine; D011970:Receptors, Histamine H2; D010643:Phenoxybenzamine