Document Detail

Neutral amino acid transport by isolated small intestinal cells from guinea pigs.
MedLine Citation:
PMID:  1767844     Owner:  NLM     Status:  MEDLINE    
Neutral amino acid transport was examined by using isolated enterocytes. Cells transport L-alanine by at least three different mechanisms: two Na(+)-dependent systems (A and ASC) and one Na(+)-independent mechanism (system L), in addition to passive entry. System A was characterized acterized by measuring the Na(+)-dependent alpha-(methylamino)isobutyric acid (MeAIB) uptake. Na(+)-dependent MeAIB uptake was concentrative and saturable. Vmax was obtained at 80mM Na+ in the incubation medium and Kt app for Na+ was 21.5 mM. Kt app for MeAIB was 6.75 +/- 0.37 mM and the Vmax was 14.2 +/- 0.3 System ASC was studied by evaluating the Na(+)-dependent L-alanine uptake, insensitive to MeAIB and inhibitable by L-serine and L-cysteine. Uptake by this mechanism was also concentrative and saturable. Maximal uptake was obtained with 80 mM Na+ in the incubation medium and Kt app for Na+ was 29.7 mM. Kt app for L-alanine was 7.02 +/- 0.61 mM and Vmax was 5.44 +/- 0.19 The Na(+)-independent system L was studied by measuring cycloleucine uptake in Na(+)-free medium. It had a saturable and a nonsaturable component. Only the saturable component was concentrative; it was inhibited by 2-amino-2-norbornanecarboxylic acid and was capable of mediating exchange diffusion. Kt app for cycloleucine was 4.05 +/- 0.72 mM and the Vmax was 31.9 +/- 1.3 These results confirm the existence of Na(+)-dependent systems A and ASC and Na(+)-independent system L in isolated enterocytes.
J R Del Castillo; R Muñiz
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  261     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1991 Dec 
Date Detail:
Created Date:  1992-02-14     Completed Date:  1992-02-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  G1030-6     Citation Subset:  IM    
Laboratorio de Fisiología Gastrointestinal Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
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MeSH Terms
Alanine / metabolism
Amino Acids / metabolism*
Biological Transport
Cell Separation
Guinea Pigs
Intestine, Small / cytology,  metabolism*
Sodium / metabolism
Reg. No./Substance:
0/Amino Acids; 56-41-7/Alanine; 7440-23-5/Sodium

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