Vagal innervation modulates motor pattern but not initiation of canine gastric migrating motor complex

To determine the role of vagal nerves in initiation and modulation of the gastric migrating motor complex (MMC), motor activity was recorded in four dogs before and after total abdominal vagotomy during fasting, after exogenous intravenous motilin and insulin, and after feeding. After vagotomy, a temporally coordinated cyclic gastric and small bowel MMC persisted with an unchanged period. During gastric phase III, vagotomy decreased number of contractions (42 +/- 4 vs. 16 +/- 2), number of groupings of contractions (14 +/- 1 vs. 7 +/- 1), and motility index (12 +/- 1 vs. 10 +/- 1) and increased the duration between groupings (1 +/- 1 vs. 3 +/- 1 min) (P < 0.05 in each). Before and after vagotomy, motilin and insulin induced a premature MMC with minor changes in contractile pattern. A 200-g liver meal but not a 50-g liver meal inhibited the gastric MMC after vagotomy. A cyclic MMC persisted after vagotomy, but the contractile pattern during gastric phase III was altered. After a short recovery period, vagal innervation to the stomach modulates the pattern but not the presence of gastric interdigestive motility during phase III.