Effect of enzymatic digestion on phenylalanine transport across the small intestine.

Phenylalanine accumulation in mucosal strips isolated from rat small intestine was significantly inhibited (P less than 0.01) after preincubation with trypsin, chymotrypsin, phospholipase D and neuraminidase. Unidirectional phenylalanine influx across the small intestine was significantly reduced (P less than 0.01) when the mucosal strips were preincubated with the above mentioned enzymes. Intestinal cell water and volume were not significantly changed (P greater than 0.6) when the intestinal tissues were preincubated with these enzymes.