Figure 5.

Concentration-response curves for the contractile effect of (+)-cis-Dioxolane alone and in combination with different concentrations of M1 antagonist, pirenzepine (10^-8 mol/L to 10^-5 mol/L) on the rat antral circular smooth muscle strips. Each point represents the mean ± SE, n = 6, 6, 7 and 8 strips. Cumulative concentration-effect curve was constructed for each strip for (+)-cis-Dioxolane, (10^-8 to 3 × 10^-5 mol/L). After washing, strips were equilibrated in either the absence (control) or presence of pirenzepine for 90 min. Subsequently, the second concentration-effect curve for (+)-cis-Dioxolane was constructed for each strip. Pirenzepine caused a significant inhibition of the contractile muscle response to (+)-cis-dioxolane.