beta-Amino acid transport in pig small intestine in vitro by a high-affinity, chloride-dependent carrier.
This study describes unidirectional influx of amino acids and D-glucose across the small intestinal brush-border membrane of fully weaned eight week old pigs. Influx is minimal in the duodenum and maximal in the distal and/or mid small intestine. Influx of beta-alanine, taurine and N-methyl-aminoisobutyric acid is chloride-dependent. The activation stoichiometry for taurine influx is 1.0 +/- 0.2 chloride/2.4 +/- 0.3 sodium/1 taurine. Influx of D-glucose, lysine, glycine and glutamate is chloride-independent. An ABC test demonstrates a common beta-amino acid carrier: (a) the apparent affinity constant K1/2Taurine is 44 +/- 13 microM (means +/- S.D.) and the inhibitory constant (KiTaurine) against beta-alanine influx is 41 +/- 5 microM (means +/- S.E.). (b) K1/2beta-alanine is 97 +/- 23 microM and Kibeta-alanine against taurine influx is 160 +/- 22 microM. (c) KiHypotaurine against taurine and beta-alanine influx is 43 +/- 4 (n = 7) and 22 +/- 5 microM (n = 7), respectively. In conclusion, a high affinity, low capacity, sodium- and chloride-dependent carrier of beta-amino acids is present in pig small intestine.
Munck
L K
LK
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
Grøndahl
M L
ML
Skadhauge
E
E
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002712:Chlorides / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D013552:Swine; D015091:beta-Alanine / Q000378:metabolism
D000596:Amino Acids; D002352:Carrier Proteins; D002712:Chlorides; D015091:beta-Alanine; D007930:Leucine; D005947:Glucose