title: Tracheal relaxation of five Ivorian anti-asthmatic plants: role of epithelium and K⁺ channels in the effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark.
abstract: BACKGROUND
  Leaves of Boerhavia diffusa (Nyctaginaceae), Baphia nitida, Cassia occidentalis, Desmodium adscendens (Fabaceae), and root bark of Dichrostachys cinerea (Fabaceae) are used in Ivory Coast for the treatment of asthma. The aim of this study was to evaluate the potential airway relaxant activity of different extracts of these plants.
  
  
  METHODS
  Extracts of different polarities (H(2)O, EtOH/H(2)O, MeOH and CH(2)Cl(2)) were obtained from these five plants. Their ex vivo relaxant activity was tested in mice isolated trachea precontracted with carbachol (1 μM).
  
  
  RESULTS
  Cumulative concentrations of most extracts induced moderate to strong relaxation, the methanolic extracts being the most potent and the polar extracts the most active at the concentrations used, supporting the traditional use of these five plants as anti-asthmatic remedies. We further investigated the molecular and cellular mechanisms of the mouse trachea relaxant effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark, the most potent extract. Its effect was not modified in the presence of β-adrenoceptor antagonists (propranolol or ICI 118,551) or a PKA inhibitor (H89). By contrast, it was decreased after depolarization-induced precontraction (with 80 mM KCl), in the presence of some K(+) channels blockers [4-aminopyridine as voltage-dependent K(+) (K(v)) channel blocker and tetraethylammonium chloride as large conductance Ca(2+)-activated K(+) (BK(Ca)) channel blocker, but not with glibenclamide, an ATP-sensitive K(+) (K(ATP)) channel blocker] or after epithelium removal.
  
  
  CONCLUSIONS
  The mouse tracheal relaxant effect of Dichrostachys cinerea EtOH/H(2)O extract was independent of β(2)-adrenoceptors activation and cAMP/PKA pathway, but dependent on epithelium and K(+) channels, namely K(v) and BK(Ca) channels. Further investigation will be required to identify the component(s) responsible for this airways relaxant activity.
authors.affiliation: Chimie des substances naturelles, CNRS UMR 8076 BioCIS, LabEx LERMIT, F-92296 Châtenay-Malabry, France. jemigrace@gmail.com
authors.forename: Geneviève
authors.initials: G
authors.lastname: Irié-N'guessan
authors.forename: Pierre
authors.initials: P
authors.lastname: Champy
authors.forename: Gisèle
authors.initials: G
authors.lastname: Kouakou-Siransy
authors.forename: Armand
authors.initials: A
authors.lastname: Koffi
authors.forename: Brou Jérôme
authors.initials: BJ
authors.lastname: Kablan
authors.forename: Véronique
authors.initials: V
authors.lastname: Leblais
mesh_terms: D000818:Animals; D018927:Anti-Asthmatic Agents / Q000494:pharmacology*; D007560:Cote d'Ivoire; D000431:Ethanol; D007887:Fabaceae / Q000737:chemistry*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009126:Muscle Relaxation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D015221:Potassium Channels / Q000502:physiology*; D014132:Trachea / Q000187:drug effects*; D014867:Water
chemical_list: D018927:Anti-Asthmatic Agents; D010936:Plant Extracts; D015221:Potassium Channels; D014867:Water; D000431:Ethanol