Quantitation of active pancreatic endopeptidases in the intestinal contents of germfree and conventional rats.

Trypsin, chymotrypsin, and elastase were measured in the intestinal contents of germfree and conventional laboratory rats. Active trypsin was highest in the lower part of the small intestine and fell abruptly in the cecum. Trypsin was present in the feces of germfree rats but not of conventional laboratory rats. Electrophoresis of supernatant fluids from intestinal contents, and functional assays with specific synthetic substrates confirmed these results. The concentrations of active elastase were very high in the upper small intestine but low elsewhere. Active elastase was present in contents from the large intestine of germfree, but not conventional laboratory rats. These results suggest that normal microbiological inhabitants of the intestinal tract of rats play a role in the inactivation of pancreatic enzymes.