| Uptake and utilization of exogenous cystine by cystinotic and normal fibroblasts. | |
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MedLine Citation:
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PMID: 4815074 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The uptake of l-[(35)S]cystine was studied in six cystinotic and six normal fibroblast lines grown for five days either on cover slips or in 32-oz plastic flasks. Cystinotics showed greater uptake than normals. The apparent K(t) for cystine entry in both types of cells was 0.043 mM but cystinotic cells showed a higher maximum velocity of entry. A comparison of the fate of l-[(35)S]cystine incubated for 20 min with monolayers of cells showed 30% and 15% of the intracellular (35)S to be l-cystine in cystinotic and normal cells, respectively. The (35)S effluxed more slowly from cystinotic than from normal cells after a 20-min preloading with l-[(35)S]cystine. Identification of (35)S compounds in efflux media after 3 min showed 75% of the total (35)S was l-cystine with the remainder in cysteine and acidic sulfur metabolites of cystine with no essential difference between cystinotics and normals. In paired experiments, the specific activity of the effluxed l-[(35)S]cystine after both efflux periods was the same as that entering the cell, thus indicating that the free l-[(35)S]cystine had not exchanged with the pre-existing pool in the cystinotic cells. During 3 min efflux, the l-cystine pool in normal cells was depleted mainly by loss of free cystine. In cystinotic cells, a new steady state was attained after 21 min of efflux and the intracellular l-[(35)S]cystine had the same percentage of total radioactivity seen after the initial 20-min uptake. After the rapid efflux of l-[(35)S]cystine from normals, [(35)S]cysteine and other labeled cystine metabolites appeared in the efflux media. By the end of a 3-min efflux, cystinotic cells had incorporated more label into reduced glutathione than had normal cells. However, when the new steady state was attained in cystinotics, the amounts of (35)S in glutathione were not markedly different in the two types of cells. Approximately 95% of the total label could be accounted for in free sulfur compounds. The data show an increased uptake and decreased efflux of cystine from cystinotic cells. However, it is not possible to conclude if these differences are due to primary changes in membrane function or to the reflection of metabolic defects without further investigation. |
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Authors:
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B States; D Harris; S Segal |
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Publication Detail:
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Type: Comparative Study; In Vitro; Journal Article |
Journal Detail:
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Title: The Journal of clinical investigation Volume: 53 ISSN: 0021-9738 ISO Abbreviation: J. Clin. Invest. Publication Date: 1974 Apr |
Date Detail:
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Created Date: 1974-04-29 Completed Date: 1974-04-29 Revised Date: 2010-09-10 |
Medline Journal Info:
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Nlm Unique ID: 7802877 Medline TA: J Clin Invest Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1003-16 Citation Subset: AIM; IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adolescent Biological Transport Carbon Radioisotopes Cells, Cultured Child Child, Preschool Culture Media Cysteine / metabolism Cystine / metabolism* Cystinosis / metabolism* Fibroblasts / metabolism* Glutathione / metabolism Humans Infant Kinetics Methionine / metabolism Sulfur Radioisotopes Time Factors Tritium |
| Chemical | |
Reg. No./Substance:
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0/Carbon Radioisotopes; 0/Culture Media; 0/Sulfur Radioisotopes; 10028-17-8/Tritium; 52-90-4/Cysteine; 56-89-3/Cystine; 63-68-3/Methionine; 70-18-8/Glutathione |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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