DARU Journal of Pharmaceutical Sciences131Relaxant effects of Ocimum basilicum on guinea pig tracheal chains and its possible mechanism(s)2833Mohammad Hossein BoskabadySahar KianiBehnia Haghiri20151006Therapeutic effects of Ocimum basilicum on respiratory diseases especially dyspnea have been reported in Iranian ancient medical books. In the present study, the relaxant effects of macerated and soxhlet extracts of this plant on tracheal chains of guinea pigs were evaluated. The relaxant effects of 4 cumulative concentrations of macerated and soxhlet extracts (0.25, 0.5, 0.75 and 1.0 W/V) in comparison with saline as negative control and 4 cumulative concentrations of theophylline (0.25, 0.5, 0.75, and 1.0 mM) as positive control were examined on precontracted tracheal chains of two groups of 6 guinea pig by 60 mM KCl (group 1) and 10 µM methacholine (group 2). Decrease in contractile tone of tracheal chains was considered as relaxant effect. In group 1 experiments only the last two higher concentrations of theophylline showed significant relaxant effect compared to that of saline (phttps://daru.tums.ac.ir/index.php/daru/article/view/229https://daru.tums.ac.ir/index.php/daru/article/download/229/229