Gastric emptying of indigestible solids--a rat model

The effects of ingestion of digestion of digestible solids and liquids on gastric emptying of indigestible solids were studied. Thirty rats were allocated to one of five groups; in four groups, rats had been fasted for 24 h before the experiment, whereas in the fifth group, they had not been fasted. In all groups, ten steel balls (1.0 mm in diameter) were inserted through an orogastric cannula into the stomach under brief halothane anesthesia. In the four groups of fasted rats, one of the following substance was then given into the stomach: (1) 0.5 g digestible solids; (2) 1.0 ml saline; (3) 1.0 ml contrast medium (45% wv sodium diatrizoate); (4) no substance (control group). Three hours later, the number of balls which had passed into the intestine was counted. Ingestion of 0.5 g meal in fasted rats significantly delayed gastric emptying of steel balls (P < < 0.001), whereas there was no difference in gastric emptying of steel balls between fasted rats and fully fed rats. Ingestion of the contrast medium (P < < 0.001), but not that of saline, significantly delayed the emptying of the balls. Therefore, ingestion of digestible solids or liquids may delay gastric emptying of indigestible solids. Clinical implications of gastric emptying of indigestible solids are discussed.