Abstract

In our previous studies, pharmacological actions of Senegalese plants on the modulation of tracheal contractile responses induced by acetylcholine were demonstrated. Here, we aim to demonstrate whether the pharmacological effects previously observed, could be obtained with other contractile agonists, such as histamine and potassium chloride (KCI), in the isolated trachea after treatment with the same extracts. For this purpose, changes in contractility of isolated trachea from male Wistar rats were assessed in organ chambers. Rings were first exposed to methanolic plants extracts or solvent. After a short-term incubation period, they were contracted with acetylcholine, histamine or KCl in a cumulative manner. Salvadora persica crude extract did not alter the contractile responses of tracheal smooth muscle. Those of Hymenocardia acida persistently and significantly attenuate the contractile responses of the three agonists.Cymbopogon giganteus crude extract, in contrast, significantly potentiates the contractile responses to histamine and KCl and has no effect on contractions induced by acetylcholine. The responses obtained with the extract of Gossypium barbadense depend on the agonist used. Similarly, Guiera senegalensis crude extract significantly increases the contractile responses to low concentrations of KCl and histamine and significantly reduces those induced by acetylcholine. Altogether, these results clearly indicate that the potential benefit of medicinal plants depends on the asthmatic disease component, especially mediated by contractile agonists for which the efficacy of bioactive compounds varies considerably.

Key words: Agonists, smooth muscle, trachea, asthma, medicinal plants.