title: Possible Mechanisms for Functional Antagonistic Effect of Ferula assafoetida on Muscarinic Receptors in Tracheal Smooth Muscle.
abstract: BACKGROUND
  The contribution of histamine (H1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of Ferula assa-foetida. (F. asafoetida) was examined in the present study.
  
  
  METHODS
  We evaluated the effect of three concentrations of F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H1) (group 1), and only β-adrenergic (group 2) receptors antagonists.
  
  
  RESULTS
  EC50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001, P = 0.0477, and P = 0.0008 in group 1 and P < 0.0001, P = 0.0438, and P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and P < 0.0001 for other extract concentrations in both groups).
  
  
  CONCLUSIONS
  Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of F. asafoetida in tracheal smooth muscle.
authors.affiliation: Neurogenic Inflammation Research Centre and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Post Code 9177948564, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Kiyanmehr
authors.affiliation: Neurogenic Inflammation Research Centre and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Post Code 9177948564, Iran.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Boskabady
authors.affiliation: Pharmaciutical Research Center and Department of Physiology School of Medicine, Mashhad University of Medical Sciences, Mashhad, Post Code 9177948564, Iran; Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Khazdair
authors.affiliation: Neurogenic Inflammation Research Centre and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Post Code 9177948564, Iran.
authors.forename: Milad
authors.initials: M
authors.lastname: Hashemzehi
keywords: Ferula extract; muscarinic receptors; muscle relaxation