title: Amino acid transport across the hen colon: interactions between leucine and lysine.
abstract: Several neutral amino acids such as leucine added on the mucosal side stimulate the mucosal-to-serosal flux (Jm----s) of cationic amino acids such as lysine. We show here in the colon of the NaCl-loaded hen that this is a result of interactions at the basolateral membrane. The hen colon was used because it tolerates prolonged incubation and has a relatively short tip of villus-to-muscularis mucosa distance. Two models have been proposed for the interpretation of the effect of mucosal-side addition of leucine on Jm----s of lysine: 1) one of an allosteric effect of cytoplasmic leucine on lysine efflux across the basolateral membrane; and 2) one of asymmetric heteroexchange of leucine from outside the basolateral membrane for cytoplasmic lysine. These two models were tested by measurements of influx across the brush-border membrane, of Jm----s and serosal-to-mucosal flux, and of steady state epithelial uptake of leucine and lysine. The data favor the model of allosteric interaction and are inconsistent with the model of asymmetric heteroexchange.
authors.affiliation: Panum Institute, University of Copenhagen, Denmark.
authors.forename: B G
authors.initials: BG
authors.lastname: Munck
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002645:Chickens; D003106:Colon / Q000378:metabolism*; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism* / Q000494:pharmacology; D008239:Lysine / Q000378:metabolism* / Q000494:pharmacology; D008871:Microvilli / Q000378:metabolism*
chemical_list: D007930:Leucine; D008239:Lysine