Document Detail

Characterization by flow cytometry of fluorescein-methotrexate transport in Chinese hamster ovary cells.
MedLine Citation:
PMID:  2917475     Owner:  NLM     Status:  MEDLINE    
We have studied by flow cytometry the transport of fluorescein-methotrexate in Chinese hamster ovary cells. Fluorescein-methotrexate appears to enter cells via a mechanism different from the carrier-mediated system for methotrexate. This conclusion is supported by the following observations: 1) Fluorescein-methotrexate is transported equally well into normal and mutant cells defective in the inward methotrexate uptake. 2) Folic acid and its reduced states, which competitively inhibit methotrexate uptake, do not alter fluorescein-methotrexate transport. 3) Fluorescein-methotrexate accumulation exhibits a low temperature coefficient (Q10 = 1.6) compared with the influx of methotrexate (Q10 = 6-8). 4) Initial rates of fluorescein-methotrexate uptake are concentration dependent but are not saturable. 5) Fluorescein-methotrexate uptake is very slow and reaches steady state after 8 h, whereas at an equimolar concentration methotrexate reaches saturation after 20 min. 6) Initial influx rates of fluorescein-methotrexate are not affected by the presence of methotrexate. 7) Sulfhydryl-reactive mercurials, which block methotrexate transport, do not reduce fluorescein-methotrexate influx, but rather stimulate it. Thus, based on the nonsaturability of fluorescein-methotrexate inward transport, its low temperature coefficient, and lack of inhibition with structural analogs, we conclude that fluorescein-methotrexate is accumulated in hamster cells by a passive diffusion process.
Y G Assaraf; L C Seamer; R T Schimke
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cytometry     Volume:  10     ISSN:  0196-4763     ISO Abbreviation:  Cytometry     Publication Date:  1989 Jan 
Date Detail:
Created Date:  1989-03-29     Completed Date:  1989-03-29     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8102328     Medline TA:  Cytometry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  50-5     Citation Subset:  IM    
Department of Biological Sciences, Stanford University, California 94305.
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MeSH Terms
Cells, Cultured
Flow Cytometry
Fluoresceins / metabolism*
Methotrexate / metabolism*
Ovary / cytology*,  metabolism
Grant Support
Reg. No./Substance:
0/Fluoresceins; 59-05-2/Methotrexate

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