| Neutral amino acid transport by isolated small intestinal cells from guinea pigs. | |
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MedLine Citation:
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PMID: 1767844 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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 nmol.mg-1.min-1. 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 nmol.mg-1.min-1. 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 nmol.mg-1.min-1. These results confirm the existence of Na(+)-dependent systems A and ASC and Na(+)-independent system L in isolated enterocytes. |
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Authors:
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J R Del Castillo; R Muñiz |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The American journal of physiology Volume: 261 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1991 Dec |
Date Detail:
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Created Date: 1992-02-14 Completed Date: 1992-02-14 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: G1030-6 Citation Subset: IM |
Affiliation:
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Laboratorio de Fisiología Gastrointestinal Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Alanine
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metabolism Amino Acids / metabolism* Animals Biological Transport Cell Separation Guinea Pigs Intestine, Small / cytology, metabolism* Kinetics Male Sodium / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Amino Acids; 56-41-7/Alanine; 7440-23-5/Sodium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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