title: 1-Nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, elicits a vago-vagal bradycardiac and depressor reflex in normotensive rats.
abstract: Previously, it was shown that intravenous (i.v.) treatment with the essential oil of Aniba canelilla (EOAC) elicited a hypotensive response that is due to active vascular relaxation rather than to the withdrawal of sympathetic tone. The present study investigated mechanisms underlying the cardiovascular responses to 1-nitro-2-phenylethane, the main constituent of the EOAC. In pentobarbital-anesthetized normotensive rats, 1-nitro-2-phenylethane (1-10mg/kg, i.v.) elicited dose-dependent hypotensive and bradycardiac effects which were characterized in two periods (phases 1 and 2). The first rapid component (phase 1) evoked by 1-nitro-2-phenylethane (10mg/kg) was fully abolished by bilateral vagotomy, perineural treatment of both cervical vagus nerves with capsaicin (250 microg/ml) and was absent after left ventricle injection. However, pretreatment with capsazepine (1mg/kg, i.v.) or ondansetron (30 microg/kg, i.v.) did not alter phase 1 of the cardiovascular responses to 1-nitro-2-phenylethane (10mg/kg, i.v.). In conscious rats, 1-nitro-2-phenylethane (1-10mg/kg, i.v.) evoked rapid hypotensive and bradycardiac (phase 1) effects that were fully abolished by methylatropine (1mg/kg, i.v.). It is concluded that 1-nitro-2-phenylethane induces a vago-vagal bradycardiac and depressor reflex (phase 1) that apparently results from the stimulation of vagal pulmonary rather than cardiac C-fiber afferents. The transduction mechanism of the 1-nitro-2-phenylethane excitation of C-fiber endings is not fully understood and does not appear to involve activation of either Vanilloid TPRV(1) or 5-HT(3) receptors. The phase 2 hypotensive response to 1-nitro-2-phenylethane seems to result, at least in part, from a direct vasodilatory effect since 1-nitro-2-phenylethane (1-300 microg/ml) induced a concentration-dependent reduction of phenylephrine-induced contraction in rat endothelium-containing aorta preparations.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Rodrigo José Bezerra
authors.initials: RJ
authors.lastname: de Siqueira
authors.forename: Francisco Igor Bulcão
authors.initials: FI
authors.lastname: Macedo
authors.forename: Leylliane de Fátima Leal
authors.initials: Lde F
authors.lastname: Interaminense
authors.forename: Gloria Pinto
authors.initials: GP
authors.lastname: Duarte
authors.forename: Pedro Jorge Caldas
authors.initials: PJ
authors.lastname: Magalhães
authors.forename: Teresinha Silva
authors.initials: TS
authors.lastname: Brito
authors.forename: Joyce Kelly Rosário
authors.initials: JK
authors.lastname: da Silva
authors.forename: José Guilherme Soares
authors.initials: JG
authors.lastname: Maia
authors.forename: Pergentino José da Cunha
authors.initials: PJ
authors.lastname: Sousa
authors.forename: José Henrique
authors.initials: JH
authors.lastname: Leal-Cardoso
authors.forename: Saad
authors.initials: S
authors.lastname: Lahlou
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects; D001286:Atropine Derivatives / Q000494:pharmacology; D001555:Benzene Derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001919:Bradycardia / Q000139:chemically induced*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D031369:Cryptocarya; D004305:Dose-Response Relationship, Drug; D041743:Herb-Drug Interactions; D007022:Hypotension / Q000139:chemically induced*; D066298:In Vitro Techniques; D008297:Male; D009822:Oils, Volatile / Q000302:isolation & purification / Q000494:pharmacology*; D017294:Ondansetron / Q000494:pharmacology; D010656:Phenylephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects*; D014630:Vagus Nerve / Q000187:drug effects* / Q000601:surgery; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: C541822:1-nitro-2-phenylethane; D001286:Atropine Derivatives; D001555:Benzene Derivatives; D009822:Oils, Volatile; D010656:Phenylephrine; D017294:Ondansetron; C006649:methylatropine; C071423:capsazepine; D002211:Capsaicin