Myostimulating Effect of the Aqueous Extract of Khaya senegalensis (Desr) A. Juss.(Meliaceae) in Isolated Taenia caeci Contractile Activity

The effects of the aqueous extract of Khaya senegalenis (Desr) A. Juss. (Meliaceae) (EAKS) were evaluated on the contractile activity of the guinea-pig Taenia coli. EAKS in a range of concentrations from 10-8mg/ml to 10-2mg/ml induced an increase of the spontaneous rhythmic contractions and of basal muscular tone, in a concentration-dependent manner (EC50: 6.10-4 mg/ml). With 10- 2mg/ml of the extract, maximal stimulation was obtained. The effects of EAKS were comparable to those induced by acetylcholine (ACh). Moreover, the cholinoceptor antagonist, atropine, applied at a concentration of 10-6 mg/ml inhibited the stimulating effects of ACh. However, atropine did not inhibit the myostimulant action induced by EAKS. In calcium-free solution containing EDTA, a bivalent chelator, at a concentration of 10-3 mM, EAKS had no effect on the guinea-pig isolated Taenia coli. In the same conditions, ACh induced an increase of basal muscular tone. In conclusion, EAKS exerted a stimulating effect in the intestinal smooth muscle. Cholinergic mechanisms may not be involved. The myostimulating action of EAKS could be due to a mobilization of bivalent, mainly calcium flux.