Objective To investigate the mechanism of effect of
trimebutine on the movement of colonic
smooth muscle of wrap restrain
stress (WRS) rats. Methods The tones of isolated longitudinal and circular muscle strips from colon in WRS rats were measured by transducer. Results In baseline condition, the tone of circular
smooth muscle strips increased after
trimebutine was added. But for longitudinal muscle strips, when the concentration of trimebutine was lower than 10 -7 g/ml, the tone increased; when the concentration of trimebutine was over 10 -6 g/ml, the tone decreased. In rich K + and acetycholine solution, trimebutine decreased the tone of smooth muscle strips. As its concentration increased, the tone tended to increase. In rich Ca 2+ solution, when the concentration of trimebutine was 10 -8 g/ml, the tone of smooth muscle strips increased; when the concentration of trimebutine was over 10 -7 g/ml, the tone decreased. Conclusion Trimebutine can either stimulate or inhibit spontaneous contractions of isolated both longitudinal and circular muscle strips of colon in WRS rats, depending on the previous contractile activity of muscle strips and the concentration of the drug and electrolytes in solution. Consequently, trimebutine may be used to relieve both atonic and irritable bowel syndrome.