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 g astric migrating motor complex (MMC), motor activity was recorded in four d ogs before and after total abdominal vagotomy during fasting, after exogeno us intravenous motilin and insulin, and after feeding. After vagotomy, a te mporally coordinated cyclic gastric and small bowel MMC persisted with an u nchanged period. During gastric phase III, vagotomy decreased number of con tractions (42 +/- 4 vs. 16 +/- 2), number of groupings of contractions (14 +/- 1 vs. 7 +/- 1), and motility index (12 +/- 1 vs. 10 +/- 1) and increase d the duration between groupings (1 +/- 1 vs. 3 +/- 1 min) (P < 0.05 in eac h). 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 persist ed after vagotomy, but the contractile pattern during gastric phase III was altered. After a short recovery period, vagal innervation to the stomach m odulates the pattern but not the presence of gastric interdigestive motilit y during phase III.