Analysis of neutral amino acid transport systems in the small intestine: a study of brush border membrane vesicles.
Transport of L-proline, L-leucine and L-cysteine was studied in brush border membrane vesicles prepared from guinea pig ileum. Concentrative transport of L-proline, L-leucine and L-cysteine was obtained in the presence of an Na+ gradient from, outside to inside of the vesicles, which indicated contribution of either system A (alanine-preferring) or system ASC (alanine-, serine- and cysteine-preferring) to the transport. When Na+ was replaced by Li+, L-leucine and L-cysteine maintained the same concentrative transport. However, the concentrative transport of L-proline was markedly decreased by Li+ -for-Na+ substitution. Strong exchange properties of L-leucine transport via system L (leucine-preferring) was observed with brush border membrane vesicles, in which preloaded L-methionine could be exchanged with labeled L-leucine added outside the vesicles. These results suggest that the small intestine of the guinea pig possesses classical neutral amino acid transport systems such as systems A, ASC and L.
Hayashi
K
K
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Dojo
S
S
Nakashima
K
K
Nishio
E
E
Kurushima
H
H
Saeki
M
M
Amioka
H
H
Hirata
Y
Y
Ohtani
H
H
Hiraoka
M
M
D000409:Alanine / Q000493:pharmacokinetics; D000596:Amino Acids / Q000493:pharmacokinetics*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D003470:Culture Media; D003545:Cysteine / Q000493:pharmacokinetics; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism* / Q000648:ultrastructure; D066298:In Vitro Techniques; D007930:Leucine / Q000493:pharmacokinetics; D008871:Microvilli / Q000378:metabolism*; D011392:Proline / Q000493:pharmacokinetics; D012694:Serine / Q000493:pharmacokinetics
D000596:Amino Acids; D003470:Culture Media; D012694:Serine; D011392:Proline; D007930:Leucine; D003545:Cysteine; D000409:Alanine