Relative rates of gastric emptying of glucose vs. fat in rats fed nonliquid meals.

Abstract

Sprague-Dawley rats were briefly starved, fed various test meals, and killed at measured intervals, and the average fractional emptying (disappearance from stomach) rates for glucose (Kgl) and for fat (Kfat) were determined. The Kgl/Kfat ratio was calculated as a measure of the degree to which the stomach emptied glucose preferentially to fat. The size of the meal affected this ratio, which was 7.6 for a small (0.5 g) meal and 2.4 for a large (2.0 g) meal of a nutritionally complete diet. When test meals contained one of two levels of fat (0.4 and 0.1 g) and of glucose (1.2 and 0.3 g), the high level of fat depressed Kgl and Kgl/Kfat, whereas the high level of glucose depressed Kgl and particularly Kfat and, therefore, raised Kgl/Kfat. Kgl/Kfat was also affected by strain of rat and was reduced almost to 1.0 by mixing the meal into a viscous gel of xanthan gum. In the absence of this gel, the percentage of water existing in stomach contents shortly after the test meals varied between 53 and 79% and was suspected of influencing Kgl/Kfat.