The effect of gravity on gastric emptying with various test meals

The rates at which the gastric contents are usually passed into the duodenum are much less than the maximal rate which the stomach can achieve. The rates are submaximal because the propulsive mechanism of the stomach is usually partly inhibited through the excitation of duodenal receptors responding to the duodenal contents, recently transferred from the stomach. This being so, mechanical hindrance to the gastric propulsive mechanism might be expected to have little influence on the usual rate of gastric emptying, since the reduced rate of transfer of gastric contents resulting from the hindrance would be offset by the reduced inhibitory action of the duodenal receptors. On the other hand, if a test meal were specially selected to have minimal action on the duodenal receptors, mechanical hindrance of the stomach should significantly slow gastric emptying because there would in this instance be no possibility of reducing the inhibition playing on the stomach. In the experiments described below the stomach was mechanically hindered by tipping supine subjects feet up, head down. The results with test meals which emptied at different rates were consistent with gastric emptying being controlled by duodenal receptors as outlined above.