Source:http://linkedlifedata.com/resource/pubmed/id/12397600
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
4
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pubmed:dateCreated |
2002-10-24
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pubmed:abstractText |
Alkaline phosphatase (ALP) refers to a group of nonspecific phosphomonoesterases located primarily in cell plasma membrane. It has been described in different cell lines that ecto-ALP is directly or indirectly involved in the modulation of organic cation transport. We aimed to investigate, in Caco-2 cells, a putative modulation of 1-methyl-4-phenylpyridinium (MPP(+)) apical uptake by an ecto-ALP activity. Ecto-ALP activity and (3)H-MPP(+) uptake were evaluated in intact Caco-2 cells (human colon adenocarcinoma cell line), in the absence and presence of a series of drugs. The activity of membrane-bound ecto-ALP expressed on the apical surface of Caco-2 cells was studied at physiological pH using p-nitrophenylphosphate as substrate. The results showed that Caco-2 cells express ALP activity, characterized by an ecto-oriented active site functional at physiological pH. Genistein (250 micro M), 3-isobutyl-1-methylxanthine (1 mM), verapamil (100 micro M), and ascorbic acid (1 mM) significantly increased ecto-ALP activity and decreased (3)H-MPP(+) apical transport in this cell line. Orthovanadate (100 micro M) showed no effect on (3)H-MPP(+) transport and on ecto-ALP activity. On the other hand, okadaic acid (310 nM) and all trans-retinoic acid (1 micro M) significantly increased (3)H-MPP(+) uptake and inhibited ecto-ALP activity. There is a negative correlation between the effect of drugs upon ecto-ALP activity and (3)H-MPP(+) apical transport (r = -0.9; P = 0.0014). We suggest that apical uptake of organic cations in Caco-2 cells is affected by phosphorylation/dephosphorylation mechanisms, and that ecto-ALP activity may be involved in this process.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Alkaline Phosphatase,
http://linkedlifedata.com/resource/pubmed/chemical/Antioxidants,
http://linkedlifedata.com/resource/pubmed/chemical/Ascorbic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Cations,
http://linkedlifedata.com/resource/pubmed/chemical/Phosphoric Monoester Hydrolases,
http://linkedlifedata.com/resource/pubmed/chemical/Tretinoin,
http://linkedlifedata.com/resource/pubmed/chemical/Vanadates
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pubmed:status |
MEDLINE
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pubmed:issn |
0730-2312
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pubmed:author | |
pubmed:copyrightInfo |
Copyright 2002 Wiley-Liss, Inc.
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pubmed:issnType |
Print
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pubmed:volume |
87
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
408-16
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:12397600-Adenocarcinoma,
pubmed-meshheading:12397600-Alkaline Phosphatase,
pubmed-meshheading:12397600-Antioxidants,
pubmed-meshheading:12397600-Ascorbic Acid,
pubmed-meshheading:12397600-Caco-2 Cells,
pubmed-meshheading:12397600-Cations,
pubmed-meshheading:12397600-Cell Membrane,
pubmed-meshheading:12397600-Colonic Neoplasms,
pubmed-meshheading:12397600-Dose-Response Relationship, Drug,
pubmed-meshheading:12397600-Humans,
pubmed-meshheading:12397600-Phosphoric Monoester Hydrolases,
pubmed-meshheading:12397600-Protein Transport,
pubmed-meshheading:12397600-Tretinoin,
pubmed-meshheading:12397600-Tumor Cells, Cultured,
pubmed-meshheading:12397600-Up-Regulation,
pubmed-meshheading:12397600-Vanadates
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pubmed:year |
2002
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pubmed:articleTitle |
Modulation of uptake of organic cationic drugs in cultured human colon adenocarcinoma Caco-2 cells by an ecto-alkaline phosphatase activity.
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pubmed:affiliation |
Department of Biochemistry, Faculty of Medicine (U38-FCT), University of Porto, Porto, Portugal. ccalhau@med.up.pt
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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