title: Enzymatic inhibition of lysine transport across the small intestine in vivo.
abstract: 1. Trypsin, at different concentrations, significantly inhibited lysine absorption (P less than 0.05) in a dose-dependent pattern. 2. Maximum inhibition equivalent to 35% below control value was reached with 10 micrograms/ml (100 BAEE units) trypsin with a non-reversible inhibitory effect. 3. Chymotrypsin at 10 micrograms/ml produced a significant decrease (P less than 0.05) of lysine absorption although it did not exceed 5%. Perfusion of both enzymes did not show an additive inhibitory effect. 4. Lysine absorption showed a 39% decrease with 10 micrograms/ml trypsin and 1 X 10(-4) M ouabain, whereas ouabain alone produced 34% inhibition. 5. Lysine absorption showed a 71% decrease with 10 micrograms/ml trypsin in a sodium-free medium, and 70% inhibition with Na-free medium alone. 6. The inhibition of lysine absorption after trypsin treatment could be due to inhibition of the active component of lysine transport.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002918:Chymotrypsin / Q000494:pharmacology; D005260:Female; D007408:Intestinal Absorption / Q000187:drug effects; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014357:Trypsin / Q000494:pharmacology
chemical_list: D010042:Ouabain; D002918:Chymotrypsin; D014357:Trypsin; D008239:Lysine