Factors in the control of interdigestive and postprandial myoelectric patterns of canine jejunoileum: Role of extrinsic and intrinsic nerves

Our aim was to determine the roles of extrinsic and intrinsic (enteric) neural continuity to the jejunoileum in control of postprandial and fasting motility patterns. Four groups of dogs were prepared: control, neurally intact; intrinsic transection, distal duodenal transection to disrupt intrinsic myoneural continuity with jejunum; extrinsic transection, transection of all extrinsic nerves to jejunoileum; and intrinsic/extrinsic transection, disruption of both intrinsic myoneural and extrinsic neural continuity to jejunoileum. Duodenal and jejunal electrodes were placed to monitor motility. After 2 weeks, the dogs were studied while fasting, after meals, and during intravenous infusions of cholecystokinin octapeptide at 0.5 μg (kg · h) and pentagastrin at 2 μg (kg · h). During fasting, although the migrating motor complex (MMC) occurred in each region, coordination between duodenum and jejunoileum was disrupted in intrinsic/extrinsic transection dogs, but only partially in intrinsic transection dogs. Small meals (50 g of liver) interrupted the duodenal MMC in all groups and the jejunoileal MMC only in control dogs. A larger (500-g) meal disrupted the MMC in both regions for comparable durations in all groups. Cholecystokinin octapeptide and pentagastrin inhibited the MMC in duodenum and jejunoileum in all groups. Both intrinsic myoneural and extrinsic neural continuity play a role in regional coordination of interdigestive and digestive gut motility. Both hormonal and neural factors (central, enteric) participate in the regulation of onset of postprandial motor patterns.