Document Detail


Mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells: evidence for the involvement of sodium-dependent vitamin C transporter 2.
MedLine Citation:
PMID:  16769607     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To investigate the mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells and to functionally characterize the specific transporter involved in this translocation process.
METHODS: Uptake studies were carried out with SIRC (Statens Seruminstitut Rabbit Cornea) and rPCEC (rabbit Primary corneal epithelial cell culture) in 12-well plates using [14C] Ascorbic acid (AA). Uptake was done in the presence of L-ascorbic acid and D-isoascorbic acid to delineate stereospecificity. Inhibition studies were performed in the presence of D-glucose a substrate for GLUT and also para amino hippuric acid (PAHA) a substrate for organic anion transporter. Effects of pH and sodium on the uptake of AA were characterized. Concentration dependency studies were performed. Energy dependence of AA uptake was investigated with ouabain and sodium azide in rPCEC. Reverse Transcription-polymerase chain reaction (RT-PCR) was also performed.
RESULTS: Uptake of AA was inhibited by about 90% and 50% respectively in the presence of L-ascorbic acid and D-isoascorbic acid in both SIRC and rPCEC. Uptake was unaltered by D-glucose and PAHA. The process was sodium dependent and saturable at higher concentrations. Ouabain and sodium azide significantly diminished the uptake process. It also decreased with a reduction in pH. The RT-PCR results showed the presence of SVCT2 but not SVCT1.
CONCLUSIONS: Uptake of AA across rabbit corneal epithelial cells appears to be a carrier mediated active process. A saturable, sodium dependent, and pH sensitive transporter with high specificity for L-ascorbic acid was functionally characterized and was identified as SVCT2.
Authors:
Ravi S Talluri; Suresh Katragadda; Dhananjay Pal; Ashim K Mitra
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Current eye research     Volume:  31     ISSN:  0271-3683     ISO Abbreviation:  Curr. Eye Res.     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-06-13     Completed Date:  2006-08-08     Revised Date:  2011-01-21    
Medline Journal Info:
Nlm Unique ID:  8104312     Medline TA:  Curr Eye Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  481-9     Citation Subset:  IM    
Affiliation:
School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Ascorbic Acid / metabolism*
Biological Transport
Cell Line
Dose-Response Relationship, Drug
Epithelium, Corneal / cytology,  drug effects,  metabolism*
Fibroblasts / cytology,  drug effects,  metabolism
Glucose / pharmacology
Hydrogen-Ion Concentration
Organic Anion Transporters, Sodium-Dependent / genetics,  metabolism*
Ouabain / pharmacology
Rabbits
Reverse Transcriptase Polymerase Chain Reaction
Sodium Azide / pharmacology
Symporters / genetics,  metabolism*
p-Aminohippuric Acid / pharmacology
Grant Support
ID/Acronym/Agency:
R01 EY09171-10/EY/NEI NIH HHS; R01 EY10659-09/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Organic Anion Transporters, Sodium-Dependent; 0/Symporters; 0/sodium-dependent vitamin C transporter; 26628-22-8/Sodium Azide; 50-81-7/Ascorbic Acid; 50-99-7/Glucose; 61-78-9/p-Aminohippuric Acid; 630-60-4/Ouabain; 89-65-6/isoascorbic acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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