The effect of gravity on gastric emptying with various test meals

Abstract

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. METHODSThe subjects were eight healthy adults of whom seven were medical students. They came to the laboratory without breakfast at about 8 a.m. Their stomachs were washed out through a rubber tube with a 3 mm bore with 250 ml. of tap water at room temperature. After the subjects had taken up their experimental position for the day the meals were instilled into the stomach. The positions were either sitting, or lying supine and horizontal, or lying supine with the whole body tipped to 450 head down on a tilted table. When the meal had been given the tube was occluded until it was used for withdrawing the gastric contents after varying periods on different days. The experimental position was maintained until the gastric contents had been withdrawn and the stomach washed out with 250 ml. of tap water.Three types of meal were used: (a) 750 ml. of 50 mrN trisodium citrate; (b) 750 ml. of 35 mnw hydrochloric acid; (c) 750 ml. of 560 m glucose (100 g./l.). These solutions were chosen in the expectation that they would leave the stomach at different rates, the trisodium citrate solution the most rapidly, (Hunt & Knox 1962), and the glucose solution the most slowly

Effects of Posture on Gastric Emptying, Transpyloric Flow, and Hunger After a Glucose Drink in Healthy Humans

“…Our current observations and those reported previously [1,2,4] can be explained by the interplay of propulsive forces generated by intragastric volume/gravity with inhibitory feedback arising from the small intestine. The overall gastric emptying of nutrients, such as glucose, is known to be highly regulated, so that caloric loads to the duodenum remain relatively constant over a wide range of intragastric concentrations [31][32][33]; the extent of small intestinal feedback is dependent on the length of the small intestine exposed to nutrient [34,35].…”

“…These observations add significantly to existing information about the effects of posture/gravity on gastric emptying. Gravity has been shown to influence gastric emptying of lownutrient liquids, so that emptying is substantially faster in the erect than the supine position [1,2,4], as well as to modify he intragastric distribution [4]. In contrast, posture has been reported to have no effect on overall emptying of highnutrient liquids, measured by intubation techniques [1,2] or scintigraphy [3].…”

“…While a number of studies have evaluated the effects of posture on overall rates of gastric emptying of liquids [1][2][3][4] as well as solids [5], there is no information about the effects of posture/gravity on short-term patterns of transpyloric flow, including those which occur during and immediately after ingestion of liquids. The latter cannot be measured using intubation or radionuclide techniques, whereas Doppler ultrasound is ideally suited to this purpose [6,7].…”

Influence of posture on pharmacokinetics

“…In the trial cited above, BurnMurdoch et al did not find any significant influence of posture on the emptying rate of 750 ml of a glucose drink. Despite the force of gravity being the same for both kinds of liquids, corresponding studies confirmed this difference [6,7]. Whereas intragastric volume and gravity appear to be the driving forces controlling gastric emptying of nonnutrient liquids [2,5,8], for nutrient liquids, feedback from small intestinal "nutrient" receptors is the decisive factor.…”

Evaluation of Motility Changes after Laparoscopic Sleeve Gastrectomy Using Magnetic Resonance Imaging

“…This can explain the lower antral speed detected in our controls compared to that referred by the authors in the presurgical assessment [1,2]. In this regard, we would like to warn the authors about the use of water that could produce a drawback in quantitative assessment due to influence of posture and gravity for liquids in gastric emptying [3,4]; furthermore, steady-state imaging with a semisolid homogeneous food (like pudding) could be more achievable for gastric function evaluation, because of the marked contrast between stomach and neighboring structures produced by this kind of food [5]. Another limitation, in our opinion, concerns the need to evaluate the reproducibility of data extrapolation from imaging over all for antral speed assessment.…”