The effects of trimebutine maleate (TM) on spontaneous contractions of colonic longitudinal muscle were investigated in guinea pigs. The contractile responses of smooth muscle strips were recorded by an isometric force transducer. Membrane and action potentials were detected by an intracellular microelectrode technique. The whole-cell patch clamp recording technique was used to record the changes in large conductance $Ca^{2+}$-activated $K^+$ ($BK_{ca}$) and L-type $Ca^{2+}$ currents in colonic smooth muscle cells. At high concentrations (30, 100, and $300{mu}M$), TM inhibited the amplitude of spontaneous contractions. At low concentrations (1 and $10{mu}M$), TM attenuated the frequency and tone of smooth muscle strips, whereas TM had no influence on the amplitude of spontaneous contractions. TM depolarized the membrane potentials, but decreased the amplitude and frequency of action potentials at high concentrations. TM inhibited $BK_{ca}$ and L-type $Ca^{2+}$ currents in a dose-dependent manner. In the presence of the $BK_{ca}$ channel opener, NS1619, TM also inhibited $BK_{ca}$ currents. Bayk8644, a L-type $Ca^{2+}$ channel opener, increased L-type $Ca^{2+}$ currents. This augmentation was also attenuated by TM. These results suggest that TM attenuates intestinal motility through inhibition of L-type $Ca^{2+}$ currents, and depolarizes membrane potentials by reducing $BK_{ca}$ currents. Thus, TM may be a multiple-ion channel regulator in the gastrointestinal tract.