Rossignoli, Patrícia de S. [UNESP]Rodrigues, Andréa D.Tinti, ThaísPereira, Oduvaldo C. M. [UNESP]Ellinger, FredChies, Agnaldo B.2014-05-272014-05-272008-11-07Journal of Smooth Muscle Research, v. 44, n. 3-4, p. 129-141, 2008.0916-8737http://hdl.handle.net/11449/70630The present study evaluated the effects of histamine 10 -2 M on longitudinal preparations of rat portal vein. It was observed that histamine 10 -2 M induced relaxation of rat portal vein preparations pre-contracted with phenylephrine 10 -4 M. On the other hand, no pharmacological effects were observed in preparations not pre-contracted. The observed histamine-induced relaxing effect was absent in preparations pre-contracted with KCl (120 mM) or in the presence of depolarizing nutritive solution. However, the histamine-induced relaxation was still present in the endothelium-removed preparations. The histamine-induced relaxation also was not prevented by astemizole (10 -6 M, 10 -5 M and 10 -4 M), cimetidine (10 -5 M, 10 -4 M and 10 -3 M) or thioperamide (10 -6 M, 10 -5 M and 10 -4 M), selective antagonists H 1, H 2 and H 3, respectively. The presence of L-NAME 10 -4 M or L-NAME 10 -4 M plus indomethacin 10 -5 M also did not prevent the histamine-induced relaxation observed in rat portal vein. Thus, the histamine-induced relaxation observed in rat portal vein appears to involve a non-endothelial hyperpolarizing mechanism independent of H 1, H 2 and H 3 receptors.129-141engEndotheliumHistamineHyperpolarizing mechanismPortal veinRelaxationastemizoleenzyme inhibitorhistaminehistamine agonisthistamine H1 receptorhistamine H1 receptor antagonistn(g) nitroarginine methyl esterphenylephrinepotassium chloridevasoconstrictor agentanimalanimal modeldose responsedrug effectmalephysiologyportal veinratvasodilatationWistar ratAnimalsAstemizoleDose-Response Relationship, DrugEnzyme InhibitorsHistamine AgonistsHistamine H1 Antagonists, Non-SedatingMaleModels, AnimalNG-Nitroarginine Methyl EsterPhenylephrinePortal VeinPotassium ChlorideRatsRats, WistarReceptors, Histamine H1Vasoconstrictor AgentsVasodilationArtigo10.1540/jsmr.44.12Acesso aberto2-s2.0-552491089212-s2.0-55249108921.pdf26229754535630850000-0001-6946-1145