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Uptake of folates by rat and human brain endothelial cell lines
Author(s) -
Araújo João Ricardo,
Gonçalves Pedro,
Martel Fátima
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.604.9
Subject(s) - dids , biochemistry , cell culture , chemistry , microbiology and biotechnology , biology , genetics , membrane
The blood–brain barrier (BBB) is essential for central nervous system homeostasis. Folates are essential for the biosynthesis of purines, pyrimidines and methionine. Our aim was to characterize 3H‐folic acid (3H‐FA) and 14C‐methyltetrahydrofolic acid (14C‐MTHF) uptake by rat (RBE4) and human (hCMEC/D3) BBB endothelial cell lines. Uptake of 3H‐FA and 14C‐MTHF by RBE4 cells was time‐dependent and linear for the first 2 min of incubation. On the other hand, uptake of these substances by hCMEC/D3 cells showed less time‐dependency. Further experiments were performed in RBE4 cells. Uptake of 3H‐FA was found to be (1) stimulated at an acidic and at an alkaline pH, (2) Na+‐dependent and stimulated when F‐ substituted for Cl−, (3) energy‐independent, (4) inhibited by premetrexed (PTX) and stimulated by cytochalasin D (cyt D) and (5) not affected by MTHF, DIDS, SITS, methotrexate (MTX), monensin (MON) and FA. Uptake of 14C‐MTHF was found to be (1) pH‐independent, (2) Na+, Cl− and energy‐independent, (3) inhibited by PTX and MTX and stimulated by cyt D and (4) not affected by FA, DIDS, SITS, MON and MTHF. RT‐PCR analysis demonstrates mRNA expression of RFC (reduced folate carrier), but neither of FRα (folate receptor α) nor of PCFT (proton‐coupled folate transporter) in RBE4 cells and mRNA expression of both RFC and PCFT, but not of FRα, in hCMEC/D3 cells. Human and rat BBB cells show little capacity for folates uptake.