EFFECT OF MOTILIN AND ERYTHROMYCIN ON CALCIUM-ACTIVATED POTASSIUM CHANNELS IN RABBIT COLONIC MYOCYTES

Background & Aims: Motilin and erythromycin are prokinetic agents that act on the same receptor in gastrointestinal smooth muscle to cause c ontraction. Both agonists may also cause an increase in outward curren t. The aim of this study was to determine whether motilin and erythrom ycin activate calcium-activated potassium (K-Ca) channels. Methods: Fr eshly dispersed longitudinal smooth muscle cells of the rabbit colon w ere used to measure whole-cell outward current and single-channel acti vity using patch clamp recording methods. Results: Erythromycin and mo tilin increased a calcium-dependent outward potassium current and incr eased the open probability of K-Ca channels of cell-attached patches. Conclusions: Erythromycin and motilin activate K-Ca channels via an in tracellular second messenger system. This effect may modulate the incr ease in contractility caused by these agonists.