1. In this study, the effect of cisapride on the isolated guinea pig gall bladder (GB) and common bile duct (CBD) motility was investigated. 2. Cisapride, up to a certain concentration, produced an increase in tone of the GB (EC501.35 x 10-8M) and the CBD (EC502.75 x 10-9M), whereas, at concentrations higher than 3 x 10-5M for the GB and 5 x 10-6M for the CBD, it produced a transient increase in tone followed by a sustained decrease in tone or in the contraction amplitude or in both. 3. The cisapride-induced increase in tone was antagonized by atropine on both the GB and the CBD. 4. Cisapride up to 2 x 10-5M for the GB and 3 x 10-6M for the CBD did not modify, whereas, at concentrations higher than 2.8 x 10-5M for the GB and 4 x 10-6M for the CBD, it antagonized, noncompetitively, the concentration-response curve to exogenously applied acetylcholine. The IC50values for cisapride on the EC50of acetylcholine on the GB and the CBD were 9.4 x 10-5M and 8.2 x 10-6M, respectively. 5. In conclusion, on the guinea pig GB and CBD, low concentrations of cisapride produce a stimulating effect, probably of cholinergic origin, whereas higher concentrations produce a transient stimulating effect, probably of cholinergic origin, followed by a sustained relaxing effect, which may involve both cholinergic and noncholinergic pathways.
Koutsoviti-Papadopoulou, M., Kounenis, G., Batzias, G., & Elezoglou, V. (1997). Effect of cisapride on the isolated guinea pig gall bladder and common bile duct. General Pharmacology, 29(5), 863–867. https://doi.org/10.1016/S0306-3623(97)00010-4