title: A marked H1-receptor-mediated vasodilator effect of histamine in the isolated perfused rat heart.
abstract: Infusion of histamine into the coronary circulation of the isolated perfused rat heart produced a marked and concentration-dependent fall in perfusion pressure. A similar effect was obtained with 2-pyridylethylamine, a histamine H1-receptor agonist. Impromidine, a potent H2-receptor agonist, however, was found to be ineffective. Mepyramine but not cimetidine competitively inhibited the fall in perfusion pressure induced by histamine and 2-pyridylethylamine. Propranolol, a non-selective beta-adrenoceptor blocker, failed to abolish the coronary vasodilator effect of both histamine and 2-pyridylethylamine. From these results it was concluded that although the rat is known to be insensitive to histamine, this amine has a marked H1-mediated vasodilator effect in the isolated perfused coronary vasculature of this species.
mesh_terms: D000818:Animals; D005260:Female; D006321:Heart / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010477:Perfusion; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011968:Receptors, Histamine / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D011725:Pyridines; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D006632:Histamine; C006183:2-(2-aminoethyl)pyridine