Figure 6.

Concentration-response curves for the contractile effect of (+)-cis-Dioxolane alone and in combination with different concentrations of M₂ antagonist, methocramine (from 10^-8 mol/L to 10^-5 mol/L) on the rat antral circular smooth muscle strips. Each point represents the mean ± SE; n = 4, 9, 10 and 11 strips. First, cumulative concentration-effect curve was constructed for each strip for (+)-cis-Dioxolane, (10^-8 to 3 × 10^-5 mol/L). After washing, tissues were equilibrated in either the absence (control) or presence of methocramine for a 90 min. Subsequently, the second concentration-effect curve for (+)- cis-Dioxolane was constructed for each strip. Methocramine caused a significant inhibition of the contractile muscle response to (+)-cis-Dioxolane.