The effects of motilin on periodic myoelectric spike activity in intact and transected canine small intestine.

The effects of motilin infusions on periodic myoelectric spike activity were studied in conscious dogs with an intact small intestine and in dogs with established jejunal Thiry-Vella loops (T-V loops). Myoelectric activity was recorded from chronically implanted electrodes on the intact intestine, the anastomosed intestine and on the jejunal T-V loop. During fasting, migrating myoelectric complexes (m.m.c.s) were present in the intact and anastomosed intestine and in the T-V loop; in the latter, intervals between m.m.c.s were significantly shorter (P less than 0.05). Infusion of motilin induced premature m.m.c.s in the intact and anastomosed intestine, reducing the interval between successive m.m.c.s (P less than 0.05). In contrast, in the T-V loop, motilin significantly reduced the number of m.m.c.s (P less than 0.01) and the interval between two m.m.c.s was prolonged. After an infusion of motilin, the number of m.m.c.s in the intact and anastomosed intestine was significantly reduced (P less than 0.01), with a corresponding increase in the intervals between m.m.c.s; no further changes were observed in the T-V loop. These results demonstrate that m.m.c.s are induced by motilin in the proximal gut, suggesting a humoral mechanism for m.m.c. initiation in this region. In contrast, the genesis of m.m.c.s in jejunal T-V loops is delayed by motilin.