Vagus-dependent disruption of interdigestive canine motility by gastric distension.

The purpose of this study was to determine the effect of proximal gastric distension on interdigestive patterns of canine gastrointestinal motility and to examine the role of extrinsic nerves in regulating such an effect. Serosal electrodes were placed on the antrum, duodenum, and jejunum. Animals were studied before and after transthoracic vagotomy or after neural isolation of the entire jejunoileum (extrinsic denervation). Proximal gastric distension for 5 h was provided by inflating with air a thin complaint bag placed into the proximal stomach after the onset of phase III of the migrating motor complex (MMC). Four volumes (0, 1.5, 12.5, and 25 ml/kg) were each tested four times in each animal. In neurally intact animals, gastric distension with volumes of 12.5 and 25 ml/kg consistently abolished the MMC in the antrum (100%), duodenum (96%), and proximal jejunum (greater than or equal to 62%), but less often in distal jejunum (greater than or equal to 25%). After vagotomy, gastric distension did not inhibit cycling of the MMC in the antrum, duodenum, or proximal or distal jejunum. After extrinsic denervation of the jejunoileum, gastric distension inhibited the MMC in the antrum and the duodenum but had no effect in the proximal or distal jejunum. These findings suggest that nonnutrient proximal gastric distension may contribute to postprandial changes in patterns of myoelectric activity in the upper gastrointestinal tract and that this effect is mediated by the vagus nerves.