Linked Life Data

7548025

Source:http://linkedlifedata.com/resource/pubmed/id/7548025

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
39
pubmed:dateCreated
1995-11-8
pubmed:abstractText
The role of ascorbate transport and metabolism in the response of human erythrocytes to an extracellular oxidant stress was investigated. Rates of entry and exit of [14C]dehydroascorbate from erythrocytes were more than 10-fold greater than those of [14C]ascorbate. Both the reduced and oxidized forms of the vitamin were transported largely by the glucose transporter. Inside erythrocytes, dehydroascorbate was converted to ascorbate, increasing intracellular ascorbate concentrations 2-3-fold over those in the medium. In such ascorbate-loaded cells, the membrane-impermeant oxidant ferricyanide induced a transmembrane oxidation of intracellular ascorbate to dehydroascorbate. The latter escaped the cells on the glucose transporter, which resulted in a halving of the net entry of [14C]dehydroascorbate in the presence of ferricyanide. Treatment of ascorbate-loaded cells with H2O2 and Cu2+ also oxidized ascorbate and induced efflux of [14C]dehydroascorbate. Ferricyanide-dependent intracellular oxidation of ascorbate resulted in a corresponding reduction of extracellular ferricyanide, which served as an integrated measure of ascorbate recycling. Ferricyanide reduction was proportional to the loading concentration of dehydroascorbate and was enhanced when loss of dehydroascorbate from cells was decreased, either by blockade of the glucose transporter or by concentrating the cells. Selective depletion of cellular ascorbate lowered rates of ferricyanide reduction by two-thirds, suggesting that ascorbate rather than NADH is the major donor for the transmembrane ferricyanide oxidoreductase activity. On the basis of the ascorbate-dependent rate of ferricyanide reduction, erythrocytes at a 45% hematocrit can regenerate the ascorbic acid present in whole blood every 3 min. Erythrocyte ascorbate recycling may thus contribute more to the antioxidant reserve of blood than is evident from plasma ascorbate concentrations alone.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
3
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12721-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Ascorbic acid recycling enhances the antioxidant reserve of human erythrocytes.
pubmed:affiliation
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6303, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.