Abstract
The effects of crude methanolic extract of Tylophora hirsuta (Th.cr) were studied for possible cholinomimetic and calcium channel blocking activities in rabbit's jejunum preparations at different doses. Maximum spasmogenic response (26.6 +/- 1.6% of A Ch Max.) was shown by the extract at a dose of 1mg/ml. In a series of atropinized preparations, the spasmogenic activity was blocked and the relaxant effect was observed at dose of 0.1-0.5 mg/ml, a left shift in the inhibitory response curve. The K+ induced contractions were also inhibited by the Th.cr extract suggesting the calcium channel blocking activity. The calcium channel blocking activity was confirmed by the right shift in the dose response curves of the tissues in calcium free tyrode's solution. Moreover, the dose response curves of the Th.cr resemble the curves produced by verapamil, a standard calcium channel blocker. The results confirm the presence of both cholinomimetic and calcium channel blocker(s) in the extract and the plant specie could be a potential target for activity-guided isolation of pure compound.