Abstract
The gastrointestinal contents of rats given 20% casein diets containing either sucrose or α-corn starch as a carbohydrate source and 1% polyethylene glycol were analyzed. Ingested carbohydrates were rapidly digested and absorbed in the proximal intestine. Delay of stomach emptying occurred when dietary carbohydrate was suddenly changed from starch to sucrose. Digestibility of protein in the stomach was reduced and the stomach emptying was delayed with sucrose feeding. Protein was absorbed in the mid or distal part of the small intestine. Different carbohydrates did not modify the absorptive site for protein. The intestinal soluble fraction contained predictable amounts of proteins with molecular weight of around 30, 000, presumably of endogenous origin.
