Gastric emptying and intestinal transit of hyperosmolar solutions in relation to indomethacin and certain gut polypeptides in the rat

The present study in the rat demonstrates an inhibitory mechanism of gastric emptying, sensitive to the osmolality of a liquid meal. Gastric emptying and intestinal transit were studied in groups that differed with regard to the osmolality of the gastric or duodenal instillation, experimental time, and indomethacin treatment. By intragastric instillation animals were fed an aqueous solution containing the nonabsorbable marker 51CrO2-4. After certain fixed time intervals the rats were killed and the stomach and small intestine were dissected out en bloc. The distribution of the isotope along the gastrointestinal canal was then determined. Intestinal transit was evaluated in a similar manner. The marker solution was introduced into the duodenum. A hyperosmolar solution, 1200 mOsm kg-1, was emptied from the stomach significantly more slowly than was an iso-osmolar solution, 300 mOsm kg-1. Of the iso- and hyper-osmolar solutions 87% and 74%, respectively, were emptied in 1 h. The isotope distribution along the intestinal canal after intraduodenal instillation was not affected by the osmolality of the installation. The osmotic inhibition of gastric emptying was not affected by indomethacin treatment (4 mg kg-1) or related to elevated plasma levels of gastrin, neurotensin, somatostatin, or gastric inhibitory polypeptide.