Mechanisms regulating ruminant pancreatic exocrine function differ in some respects from those in nonruminants. This may affect the post-ruminal digestion of certain dietary nutrients such as starch. Ruminants do not exhibit clearly defined cephalic and gastric phases of pancreatic regulation, a likely consequence of the continuous nature of digesta flow from the rumen. Local neural reflexes and secretin-mediated exocrine responses may be more important than stimulation by cholecystokinin. Additionally, the ruminant pancreas may be stimulated by short-chain fatty acids produced in the rumen. A "ruminal phase" of pancreatic exocrine regulation has been proposed. The failure of cattle to digest efficiently starch in the small intestine may result from an asynchrony between delivery of starch to the intestines and pancreatic amylase release.

The effects of epidermal growth factor on intestinal glucose transport were examined in mice. Glucose transport measurements were performed using an in vitro assay system that estimated the rate of accumulation of [3H]3-O-methyl-D-glucose. In Experiment 1, two-mo-old male and female mice were subcutaneously injected once daily with 0, 150 or 300 micrograms epidermal growth factor/kg body weight for 3 d. Jejunal glucose active transport was increased in a dose-dependent manner. There were no gender-related differences in intestinal glucose transport or the response to exogenous epidermal growth factor. In Experiment 2, 2-, 10- and 18-mo-old mice were administered 0 or 300 micrograms epidermal growth factor/kg body weight using a treatment similar to that used in Experiment 1. Active intestinal glucose transport was 30% greater in response to epidermal growth factor in each of the three age groups. Ouabain-sensitive and -insensitive jejunal oxygen consumption was increased in response to epidermal growth factor such that total jejunal respiration was stimulated 15 to 31%. The epidermal growth factor related percentage increase in glucose absorption was similar to the percentage increase in oxygen consumption such that the apparent energetic efficiency of glucose transport was unaffected. In both experiments, the active component of glucose transport was increased by epidermal growth factor while passive transport was not affected. Jejunal morphology and mucosal DNA and protein concentration were not altered by epidermal growth factor treatment. Epidermal growth factor-induced increases in intestinal absorption was not attributable to mucosal hyperplasia.

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