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P‐glycoprotein expression in rat brain endothelial cells:
evidence for regulation by transient oxidative stress
Author(s) -
Felix Robert A.,
Barrand Margery A.
Publication year - 2002
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.0022-3042.2001.00660.x
Subject(s) - p glycoprotein , oxidative stress , intracellular , hypoxia (environmental) , flow cytometry , efflux , endothelial stem cell , viability assay , microbiology and biotechnology , chemistry , cell , messenger rna , biology , biochemistry , multiple drug resistance , oxygen , gene , in vitro , organic chemistry , antibiotics
During ischaemia/reperfusion, cells of the blood–brain barrier are subjected to oxidative stress. This study uses primary cultured rat brain endothelial cells to examine the effect of such stresses on expression of multidrug transporters. H 2 O 2 up to 500 µ m applied to cell monolayers caused a concentration‐dependent increase in expression of P‐glycoprotein (Pgp) but not of multidrug resistance‐associated protein (Mrp1). Concentrations > 250 µ m H 2 O 2 decreased cell viability. Application of 100 µ m H 2 O 2 caused a significant increase after 48 h in Pgp functional activity, as assessed from [ 3 H]vincristine accumulation experiments. At this concentration, H 2 O 2 produced a transient increase within 10 min followed by a sustained decrease in levels of intracellular reactive oxygen species (iROS), detectable by flow cytometry. Reoxygenation of cell monolayers after 6 h hypoxia gave rise to a similar transient increase in iROS and this also led to increased Pgp expression by 24 h. Increases were also observed within 4 h after both H 2 O 2 and hypoxia/reoxygenation treatments in mdr1a and mdr1b mRNA. Evidence suggests this was due to enhanced transcription rather than mRNA stabilization. Therefore, oxidative stress, by changing Pgp expression, may affect movement of Pgp substrates in and out of the brain.