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.
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.
de Siqueira
Rodrigo José Bezerra
RJ
Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife, PE, Brazil.
Macedo
Francisco Igor Bulcão
FI
Interaminense
Leylliane de Fátima Leal
Lde F
Duarte
Gloria Pinto
GP
Magalhães
Pedro Jorge Caldas
PJ
Brito
Teresinha Silva
TS
da Silva
Joyce Kelly Rosário
JK
Maia
José Guilherme Soares
JG
Sousa
Pergentino José da Cunha
PJ
Leal-Cardoso
José Henrique
JH
Lahlou
Saad
S
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
C541822:1-nitro-2-phenylethane; D001286:Atropine Derivatives; D001555:Benzene Derivatives; D009822:Oils, Volatile; D010656:Phenylephrine; D017294:Ondansetron; C006649:methylatropine; C071423:capsazepine; D002211:Capsaicin