Vascular actions of histamine H1- and H2-receptor agonists in dogs and cats.
Systemic and pulmonary vascular responses to infusions of histamine, 2-methylhistamine (2-MeH), and 4-methylhistamine (4-MeH) were determined. In dogs, H1-receptor stimulation with 2-MeH induced pulmonary vasoconstriction, and a decrease in cardiac output. H2-receptor stimulation with 4-MeH induced pulmonary and systemic vasodilation, tachycardia, and an increase in cardiac output. In cats, 2-MeH caused slight pulmonary vasoconstriction and 4-MeH caused vasodilation. Both H1- and H2-receptors mediated the systemic vasodilation, tachycardia, and increase in cardiac output observed in cats.
D000818:Animals; D002415:Cats; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology; D008761:Methylhistamines / Q000494:pharmacology; D011968:Receptors, Histamine / Q000187:drug effects*; D011969:Receptors, Histamine H1 / Q000187:drug effects*; D011970:Receptors, Histamine H2 / Q000187:drug effects*; D013268:Stimulation, Chemical; D013997:Time Factors
D008761:Methylhistamines; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D006632:Histamine