Linked Life Data

8391316

Source:http://linkedlifedata.com/resource/pubmed/id/8391316

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1993-7-30
pubmed:abstractText
A cell line was derived from rabbit non-pigmented ciliary epithelium. The non-pigmented ciliary epithelium is one of the two cell layers which secrete aqueous humor into the eye and concentrate ascorbic acid in the newly-formed fluid. The cultured non-pigmented epithelial cells accumulated ascorbic acid at a rate of 3-5 pmol/micrograms protein per h. As in freshly-isolated native tissue, the ascorbate uptake mechanism was sodium-dependent and could be inhibited by phloretin (apparent Ki = 2-10(-5) M). Phorbol 12,13-dibutyrate (PDBu), a protein kinase C activator, reduced the ascorbate uptake rate. The PDBu effect was concentration-dependent; at a concentration of 10(-6) M, PDBu reduced the ascorbate uptake rate to 65% of the control value. PDBu reduced the maximal rate of ascorbate uptake (determined at 200-500 microM external ascorbate) but caused no detectable change in the Km for ascorbic acid (approx. 80 microM). The PDBu-induced inhibition of ascorbate uptake persisted in the presence of ouabain and in low sodium (25 mM Na) medium, suggesting that the effect is not secondary to a change in the sodium gradient. Furthermore, no detectable elevation of cell sodium content was seen in cells equilibrated with 22Na prior to PDBu treatment. The PDBu-induced inhibition of ascorbate uptake was apparently mediated by protein kinase C because the effect was not observed in the presence of staurosporine (10(-6) M), a protein kinase C inhibitor, or in cells in which protein kinase C was downregulated. These observations suggest that activation of protein kinase C causes inhibition of the ascorbate transporter in this cultured cell line.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
1149
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
102-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Studies on regulation of the ascorbic acid transporter in a cell line derived from rabbit non-pigmented ciliary epithelium.
pubmed:affiliation
Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Research Institute, University of Louisville School of Medicine 40292.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't