CONTROL OF GASTRIC-EMPTYING BY GASTRIC TONE

During ingestion of food, the stomach relaxes to accommodate the meal and, subsequently, a progressive gastric contraction parallels gastric emptying. Intestinal nutrients trigger feedback relaxatory mechanisms that regulate gastric tone and, hence, the nutrient load delivered into the small intestine. This regulation of gastric tone is mediated, at least in part, via the vagus. Defective gastric tone is associated with impaired gastric emptying, as seen in patients with postsurgical gastroparesis. However, increased intragastric pressure, corresponding with defective gastric accommodation, induces abdominal symptoms, but does not alter the gastric emptying pattern. These data indicate that gastric emptying is controlled by complementary mechanisms: gastric tone exerts an emptying force, but gastric outlet resistance is also an important regulator.