title: The effect of hydro-ethanolic extract of Achillea millefolium on muscarinic receptors of guinea pig tracheal smooth muscle.
abstract: OBJECTIVE
  To investigate one possible mechanism for the observed relaxant effect of A. millefolium (Achillea millefolium), in the present study the inhibitory effect of the extract of this plant on muscarinic receptors was examined.
  
  
  METHODS
  The effects of three concentrations of aqueous-ethanolic extract, 10 nM atropine, and saline on muscarinic receptors were tested in three conditions: In non incubated tracheal smooth muscle (group 1), tracheal chain incubated with propranolol and chlorpheniramine (group 2), and the one incubated with propranolol (group 3).
  
  
  RESULTS
  The EC₅₀ obtained in the presence of all three concentrations of the extract were significantly higher compared to saline in groups 2 and 3 (P < 0.001 and P < 0.01 in group 2 and 3 respectively). The EC₅₀ obtained in the presence of all concentrations of the extract in group 2 were significantly improved compared to groups 1 and 3 (P < 0.05 to P < 0.001). The maximum responses to methacholine in presence of only the higher concentration of the extract (0.8 mg/ml) was significantly lower than that of saline in groups 1 (P < 0.05). There was neither significant difference between slopes of methacholine-response curves obtained in the presence of different concentrations of the extract and that of saline nor between the three groups. The values of (CR-1), obtained in the presence of all concentrations of the extract, were significantly lower compared to atropine in the first group but were not significantly different in other groups. The values of (CR-1) obtained in the presence of all concentrations of the extract were significantly improved in groups 2, compared to groups 1 and 3 (P < 0.05 to P < 0.001).
  
  
  CONCLUSIONS
  These results showed an inhibitory effect for the extract of A. millefolium on muscarinic receptors of tracheal smooth muscle. A histamine (H₁) receptor blockade was also suggested for the extract.
authors.affiliation: Applied Physiology Research Centre and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Feizpour
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Boskabady
authors.forename: Goltaj
authors.initials: G
authors.lastname: Byrami
authors.forename: Zahra
authors.initials: Z
authors.lastname: Golamnezhad
authors.forename: Mohammad Naser
authors.initials: MN
authors.lastname: Shafei
mesh_terms: D031162:Achillea / Q000737:chemistry*; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014132:Trachea / Q000187:drug effects*
chemical_list: D010936:Plant Extracts; D011976:Receptors, Muscarinic
keywords: Achillea millefolium; guinea pig; hydroalcoholic extract; muscarinic receptors; trachea
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