title: Relaxant effects of the essential oil of Eucalyptus tereticornis and its main constituent 1,8-cineole on guinea-pig tracheal smooth muscle.
abstract: The effects of the essential oil of Eucalyptus tereticornis Sm. (EOET) on guinea-pig tracheal smooth muscle were investigated. EOET (10 - 1000 microg/mL) relaxed the tracheal basal tonus with an EC (50) value of 125.3 [52.2 - 300.9] microg/mL. Its maximal relaxation (40 +/- 6 %) was significantly lower than that evoked by aminophylline (209 +/- 34 %). The K (+)-(60 mM)-induced contractions were significantly reduced by both EOET (200 - 1000 microg/mL) and its main constituent 1,8-cineole (600 - 1000 microg/mL). Acetylcholine (1 microgM)-induced contractions were significantly enhanced by 1,8-cineole (10 - 1000 microg/mL). However, they were significantly enhanced and reduced by lower (200 - 400 microg/mL) and higher (800 - 1000 microg/mL) concentrations of EOET, respectively. Electrical field stimulation-induced contractions were significantly increased by EOET (100 - 600 microg/mL). In conclusion, EOET produces myorelaxant effects on guinea-pig isolated trachea, an effect that seems to result from a complex interaction between its monoterpenoid constituents.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, Brasil.
authors.forename: Lívia Noronha
authors.initials: LN
authors.lastname: Coelho-de-Souza
authors.forename: José Henrique
authors.initials: JH
authors.lastname: Leal-Cardoso
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: de Abreu Matos
authors.forename: Saad
authors.initials: S
authors.lastname: Lahlou
authors.forename: Pedro Jorge
authors.initials: PJ
authors.lastname: Magalhães
mesh_terms: D000818:Animals; D003511:Cyclohexanols / Q000737:chemistry / Q000494:pharmacology*; D000077591:Eucalyptol; D005052:Eucalyptus / Q000737:chemistry*; D006168:Guinea Pigs; D039821:Monoterpenes / Q000737:chemistry / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009822:Oils, Volatile / Q000737:chemistry* / Q000494:pharmacology*; D010938:Plant Oils / Q000737:chemistry / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects*
chemical_list: D003511:Cyclohexanols; D039821:Monoterpenes; D009822:Oils, Volatile; D010938:Plant Oils; D000077591:Eucalyptol