Responses of rabbit portal vein to histamine.
1 Histamine produced a dose-dependent contraction of the isolated portal vein of the rabbit. This contraction was not antagonized by atropine, methysergide, indomethacin, cocaine or 6-hydroxy-dopamine, nor by pretreatment of the rabbit with reserpine. 2 The response to histamine was blocked by H1-receptor antagonists only when the blocking agent was used in very high concentrations, and was not antagonized by the H2-receptor blocking agent, metiamide, H1-receptor antagonists did not block the effects of 5-hydroxytryptamine. 3 The contractions elicited by histamine, 5-hydroxytryptamine and noradrenaline were blocked by phentolamine. 4 Desensitization to high doses of 5-hydroxytryptamine caused a concomitant depression in the response to histamine but not to noradrenaline or acetylcholine. 5 The results suggest that the contractions of rabbit portal vein elicited by histamine are not mediated by receptors of the H1- or the H2-type, but may involve an action of histamine at a receptor which is also involved in the action of 5-hydroxytryptamine.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004347:Drug Interactions; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects*; D011817:Rabbits; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology
D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D012701:Serotonin; D001285:Atropine; D006632:Histamine; D012110:Reserpine; D007213:Indomethacin; D008784:Methysergide; D010646:Phentolamine