In four dogs, gastric emptying of a digestible solid (50 g of liver tagged with [57Co]-cyanocobalamine and diced into 1-cm cubes), an indigestible solid (40 radiopaque plastic spheres, diameter 7mm), and a liquid (400 ml of either 1 or 10% dextrose tagged with polyethylene[1,2-3H]glycol were simultaneously assessed by quantitating the rate of appearance of the gastric markers in the duodenum. The rate of gastric emptying of cubed liver was similar whether the liver was given alone or with solutions of the rapidly emptying 1% dextrose, but its rate of emptying was slowed by the slower emptying 10% dextrose. Homogenization of the liver speeded its emptying. Moreover, the homogenized liver emptied even faster when dispersed in 1% dextrose and emptied more slowly when dispersed in 10% dextrose, but in both instances the liver emptied at the same rate as the solution in which it was mixed. Indigestible spheres were nearly all retained, whereas the liver and the dextrose were emptied. Our conclusion is that the stomach empties liquids and retains solids for reduction to a smaller size, after which they are discharged at the same rates as the liquid then present in the stomach.
