Iranian Journal of Pharmaceutical Research (2004): Supplement 2:
Possible mechnisms of relaxant effect of Portulaca oleraceae on tracheal chains of guinea pig
Boskabady M.H., Broshaki M.T., Aslani M.R., Malek F.
Department of Physiology and Pharmacology, Ghaem Medical Centre, Mashhad University of Medical Sciences, Mashhad, Iran
Therapeutic effect of Portulaca oleraceae on respiratory diseases is indicated in Iranian ancient medical books. The relaxant effect of this plant also observed on smooth muscles in previous studies. Therefore, in the present study, the possible mechanism (s) for the relaxant effects of boiled and aqueous extracts of Portulaca oleraceae on tracheal chains of guinea pigs were examined.
The relaxant effects of 5 volumes of boiled (0.25, 0.5, 0.75, 1.0, and 1.25 ml of 5% W/V) and aqueous (0.125, 0.25, 0.375, 0.5, and 0.625 ml of 10%W/V) extracts were examined by their relaxant effects on pre-contracted tracheal chains of guinea pigs by 1 10 µM methacholine on: 1) non incubated tissues, and 2) incubated tissues with propranolol and chlorpheniramine in comparison with the effects of saline, theophylline, (n=6 for both groups).
In groups 1 and 2 experiments both boiled and aqueous extracts and theophylline showed concentration dependent relaxant effect compared to that of saline (p<0.05 to p<0.001). There were no significant differences between relaxant effects of boiled and aqueous extracts with those of theophylline in group 1 experiments. The effects of extracts between group 1 and 2 were not statistically significant.
These results showed a potent relaxant effect of Portulaca oleraceae on tracheal chains of guinea pigs that was comparable and even greater than theophylline at concentration used. However, the stimulatory property of the plant on beta-adrenegic receptor or inhibitory on histamine (H1) receptor was not contribute on its relaxant effect.