1. The spontaneous contraction of the isolated colon was inhibited by mebeverine at doses greater than 1×10^-7g/ml. The effect of mebeverine was stronger than that of papaverine or buscopan. Two kinds of movement occur in the rabbit colon, peristaltic movement and the local tonic wave. The local tonic wave is produced mainly by the ring muscle. Papaverine mainly inhibited the peristaltic contractions but the effect of mebeverine and that of buscopan were the inhibition of tonic contractions. These drugs showed greater inhibitory effects on the colonic activity than on the small intestinal one.
2. The antispasmodic properties of mebeverine against the evoked contractures yb acetylcholine 10^-5 g/ml or BaCl₂ 10^-3g/ml were stronger than those of papaverine and buscopan.
3. When mebeverine 10^-5g/ml was applied on the isolated colon the spontaneous contractions were enhanced about 50% of the cases. The phasic and tonic contractions were enhanced with the increase of spike discharge. The mechanisn of this phenomenon is obscure.
4. When 5mg/kg mebeverine was induced intravenously, the movement of the colon was slightly inhibited. But sometimes colonic movement enhanced, tachycardia appeared, respiration became irregular, tonic convulsion appeared and the animal died. But when mebeverine was given orally no significant alteration of colonic motility was observed.