MIGRATING MOTOR COMPLEX RECORDED SPONTANEOUSLY AND INDUCED BY MOTILINAND ERYTHROMYCIN IN AN EX-VIVO RABBIT INTESTINAL PREPARATION

We investigated basal motility and the motor effects of motilin, eryth romycin, and prostigmine on segments of rabbit gastrointestinal tract removed from extrinsic neural and vascular pathway and immersed in an oxygenated organ bath. Motility was recorded by means of four strain g auges sutured on the serosal surface of the segment. During basal reco rding, clusters of duodenal contractions that propagated distally, res embling phase III activity of migrating motor complex, were seen. Moti lin (10(-6) M) and erythromycin (10(-6) M) induced a propagated cluste r of contractions similar to the phase III recorded during the basal p eriod. Prostigmine (10(-6) M) induced a simultaneous increase in gastr ic and small intestinal motility. Atropine (10(-5) M) prevented the mo tor effect of motilin, erythromycin, and prostigmine. Thus, MMCs do no t appear to require central input for initiation and propagarion. Moti lin and erythromycin stimulate MMCs through an enteric cholinergic mec hanism; therefore, the previously reported smooth muscle receptors for both substances were not apparent in the ex vivo preparation.