Relaxant effect of Satureja hortensis on guinea pig tracheal chains and its possible mechanism(s)

Background: In Iranian ancient medical books, the therapeutic effects of Satureja hortensison respiratory diseases have been reported. In order to verify these reports, the relaxanteffect of aqueous-ethanolic extract of Satureja hortensis on guinea pig trachea wasexamined.Methods: The relaxant effects of 6 cumulative concentrations of extract (0.15, 0.3, 0.45,0.6, 0.75 and 0.9 g %) in comparison with saline and 4 cumulative concentrations oftheophylline (0.15, 0.3, 0.45, and 0.6 mM) by their effects on precontracted tracheal chainsof guinea pig by 10 μM methacholine (group 1) or 60 mM KCl in two different conditionsincluding: non-incubated tissues (group 2) and incubated tissues with 1 μM propranolol, 1μM chlorpheniramine and 1 μM atropine (group 3, for each group n=6) were examined.Results: In group 1, the extract and theophylline showed concentration dependent relaxanteffects compared to that of saline (p 0.05 to p 0.001). In group 2, three last concentrationsof theophylline and four higher concentrations of extract showed significant relaxant effectscompared to that of saline (p 0.05 to p 0.001). The effects of four lower concentrations ofextracts in groups 1 and 2 were significantly lower than those of theophylline (p 0.05p 0.001). In group 3, the extract did not show any significant relaxant effect. There weresignificant correlations between the relaxant effects and concentrations of extract andtheophylline in groups 1 and 2 (p 0.001 for all cases).Conclusion: These results showed a potent relaxant effect of Satureja hortensis on guineapigs trachea which was comparable to that of theophylline.