| Increases in transepithelial vectorial Na+ transport facilitates Na+-dependent L-DOPA transport in renal OK cells. | |
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MedLine Citation:
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PMID: 16600308 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The present study evaluated the hypothesis of whether increases in vectorial Na+ transport translate into facilitation of Na+-dependent L-DOPA uptake in cultured renal epithelial tubular cells. Increases in vectorial Na+ transport were obtained in opossum kidney (OK) cells engineered to overexpress Na+-K+-ATPase after transfection of wild type OK cells with the rodent Na+-K+-ATPase alpha1 subunit. The most impressive differences between wild type and transfected OK cells are that the latter overexpressed Na+-K+-ATPase accompanied by an increased activity of the transporter. Non-linear analysis of the saturation curve for l-DOPA uptake revealed a Vmax value (in nmol mg protein/6 min) of 62 and 80 in wild type and transfected cells, respectively. The uptake of a non-saturating concentration (0.25 microM) of [14C]-L-DOPA in OK-WT cells was not affected by Na+ removal, whereas in OK-alpha1 cells accumulation of [14C]-L-DOPA was clearly dependent on the presence of extracellular Na+. When Na+ was replaced by choline, the inhibitory profile of neutral l-amino acids, but not of basic and acidic amino acids, upon [14C]-L-DOPA uptake in both cell types, was significantly greater than that observed in the presence of extracellular Na+. It is concluded that enhanced ability of OK cells overexpressing Na+-K+-ATPase to translocate Na+ from the apical to the basal cell side correlates positively with their ability to accumulate L-DOPA, which is in agreement with the role of Na+ in taking up the precursor of renal dopamine. |
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Authors:
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E Silva; P Gomes; P Soares-da-Silva |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2006-03-06 |
Journal Detail:
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Title: Life sciences Volume: 79 ISSN: 0024-3205 ISO Abbreviation: Life Sci. Publication Date: 2006 Jul |
Date Detail:
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Created Date: 2006-07-10 Completed Date: 2006-08-16 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0375521 Medline TA: Life Sci Country: England |
Other Details:
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Languages: eng Pagination: 723-9 Citation Subset: IM |
Affiliation:
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Institute of Pharmacology and Therapeutics, Faculty of Medicine 4200-319 Porto, Portugal. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Biological Transport Cell Line Cell Membrane / metabolism Epithelial Cells / metabolism Ion Transport Kidney / cytology, metabolism* Kidney Tubules / cytology, metabolism Levodopa / metabolism* Opossums Rats Sodium / metabolism* Sodium-Potassium-Exchanging ATPase / metabolism* Transfection |
| Chemical | |
Reg. No./Substance:
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0/Levodopa; 7440-23-5/Sodium; EC 3.6.3.9/Sodium-Potassium-Exchanging ATPase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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