Previous experiments from our laboratory have shown that the vagus nerves mediate proximal gastric distention-induced disruption of interdigestive motor patterns in the upper gut of dogs. Our aim was to determine the role of vagal innervation of the proximal stomach in mediating the response to nonnutrient proximal gastric distention. Five dogs underwent proximal gastric vagotomy (PGV) and placement of electrodes and manometry catheters on the antrum nod the upper small intestine. Proximal gastric distention for 5 hr was achieved by inflating a thin, compliant bag in the proximal stomach. Four volumes of distention stimulus (0, 1.5, 12,5, and 25 ml/kg) were tested. As with total abdominal vagotomy, intragastric stimulus volumes of 12.5 and 25 ml/kg after PGV no longer inhibited cycling of the migrating motor complex in the stomach, duodenum, proximal jejunum, and distal jejunum. Volumes of 12.5 and 25 ml/kg did, however, on occasion, lead to the absence of phase III activity in the stomach or the duodenum when it would have been expected to precede phase III activity in the jejunum; this effect did not occur in the jejunum. These findings with a nonnutrient stimulus suggest that vagal branches to the proximal stomach might mediate, in part, the postprandial changes in upper gut motility in response to gastric distention by ingestion of a meal.
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