Relaxant effects of Rosa damascena on guinea pig tracheal chains and its possible mechanism(s).

Several therapeutic effects including hypnotic, antispasmodic, treatment of abdominal and chest pain and strengthening the heart have been described for the flowers of Rosa damascena. Therefore in the present study, the relaxant effects of ethanolic extract and essential oils of Rosa damascena on tracheal chains of guinea pigs were examined. The relaxant effects of four cumulative concentrations of ethanolic extract (0.25, 0.5, 0.75, and 1.0g%) and essential oils (0.25, 0.5, 0.75, and 1.0vol.%) in comparison with saline as negative control and four cumulative concentrations of theophylline (0.25, 0.5, 0.75, and 1.0mM) were examined by their relaxant effects on precontracted tracheal chains of guinea pig by 60mM KCl (group 1, n=5) and 10microM methacholine in two different conditions including: non-incubated tissues (group 2, n=8) and incubated tissues with 1microM propranolol and 1microM chlorpheniramine (group 3, n=5). In group 1 experiments two final concentrations of essential oil and theophylline and only final concentration of ethanolic extract showed relaxant effects compared to that of saline (p<0.01-0.001). In group 2 three higher concentrations of ethanolic extract and theophylline and all concentrations of essential oil showed concentration dependent relaxant effects compared to that of saline (p<0.05-0.001). In addition, the effect of 0.25 and 0.5g% of essential oils in group 2 was significantly higher than those of theophylline and ethanolic extract (p<0.01 for all cases). However, in group 3 experiments the extract and essential oil of Rosa damascena did not show any significant relaxant effect. There were significant correlations between the relaxant effects and concentrations for ethanolic extract and essential oil and theophylline in groups 1 and 2. These results showed a potent relaxant effect of Rosa damascena on tracheal chains of guinea pigs that was comparable to that of theophylline at concentrations used.