Motilin-independent ectopic fronts of the interdigestive myoelectric complex in dogs

Abstract

In 4 conscious dogs, the relationship between circulating concentrations of motilin and the activity front (phase III) of the interdigestive myoelectric complex was studied. [Motilin, a 22-amino acid polypeptide, plays a role in the interdigestive motility of the small intestine.] During fasting, cyclic peaks of motilin secretion were concomitant in every instance with the initiation of activity fronts that began in the stomach or duodenum. When somatostatin was administered at doses of 5, 2.5, or 0.625 .mu.g .cntdot. kg-1 .cntdot. h-1 for 3 h, motilin concentrations were stabilized at lowered levels and no activity fronts occurred in the duodenum. Somatostatin also inhibited the stimulatory effects of exogenous motilin on the entire small intestine. During somatostatin infusion, however, ectopic fronts began in the jejunum and were propagated to the cecum despite low motilin concentration. After a 100 g meat meal, the cyclic increase of motilin was interrupted and no activity fronts were observed in the duodenum, but ectopic fronts started lower in the small intestine. Motilin probably induces activity fronts in the canine duodenum. Ectopic fronts are apparently not controlled by motilin.