effect of the hydroalcoholic extract from the leafy stems of waltheria indica l. (malvaceae) on acetylcholine and barium chloride-induced contractions on isolated rat tracheal tissue

A previous study has reported the interesting relaxant effect of the hydroalcoholic extract from waltheria indica l. (malvaceae) leafy stems, a plant with several therapeutic uses. the present study aimed to investigate the preventive effect of this plant using an ex vivo model of the rat trachea. two agonists, acetylcholine (10^-6 - 1.5×10^-5 m) and barium (10^-5- 10^-1 m) were used to induce contractions. the preventive effect was assessed on rat tracheal rings pretreated with hydroalcoholic extract (1.92 mg/ml), glibenclamide, atropine, and papaverine, all at 10 μm. acetylcholine and barium provoke contractions in a concentration-dependent manner, with a maximum contractile response of 3.953 ± 0.692 g and 2.999 ± 0.326 g, respectively. the ec50 values were 3.711 ± 0.823 μm and 9.502 ± 12.354 mm, respectively, for acetylcholine- and barium-induced contraction. glibenclamide caused a rightward shift of the acetylcholine-response curve, followed by a reduction of the maximum contraction (from 3.953 ± 0.692 g to 3. 116 ± 0.244 g). the hydroalcoholic extract, atropine (atrop), papaverine (pap), and their combinations induced a complete suppression of the contractile response to acetylcholine (p < 0.0001) and barium (p < 0.0001). the hydroalcoholic extract exhibited a potent relaxant effect comparable to that of atropine and papaverine. it can be concluded that the hydroalcoholic extract of w. indica can potently prevent acetylcholine-and barium chloride-induced contractions. the possible mechanisms by which the extract exerts its relaxant effect may involve the blockade of muscarinic receptors, the inhibition of phosphodiesterase activity, and/or the calcium channel.