INDIRECT EXAMINATION OF EXOCRINE PANCREATIC FUNCTION IN-VIVO BY DETERMINATION OF CHYMOTRYPSIN ACTIVITY IN ANIMAL INTESTINE USING A SYNTHETIC SUBSTRATE

Using the substrate N-acetyl-L-tyrosyl-p-aminobenzoic acid, we determi ned chymotrypsin activity in the small intestine of calf, pig, and pou ltry. Orally administered N-acetyl-L-tyrosyl-p-aminobenzoic acid is en zymatically cleaved in vivo, and the released p-aminobenzoic acid is d etermined by HPLC. We found that the p-aminobenzoic acid concentration in plasma and urine was significantly influenced by the feeding of so ya flour. After soybean flour feeding, the p-aminobenzoic acid concent ration significantly increased in the plasma of calves and hens, in co ntrast to pigs, where the p-aminobenzoic acid concentration significan tly decreased. This shows that the oral administration of N-acetyl-L-t yrosyl-p-aminobenzoic acid with subsequent determination of p-aminoben zoic acid is suitable for the estimation of exocrine pancreatic functi on and for determination of changes in intestinal proteolytic activity caused by antinutritive substances.