title: Transport of 5-formyltetrahydrofolate into primary cultured rat astrocytes.
abstract: Transport of 5-formyltetrahydrofolate (5-FTHF) into primary cultured rat astrocytes was studied. Uptake of 5-FTHF into astrocytes was linear in the first 60 min and is saturable with K(m)=3.3 microM and V(max)=27.5 pmol/mg protein/45 min in pH 7.4 medium. Uptake of 5-FTHF displayed the characteristics of countertransport. Uptake of 5-FTHF was inhibited by the structural analogs 5-methyltetrahydrofolate, methtrexate, and folic acid (K(i)=3.8, 2.7, and 18.4 microM, respectively). Uptake was significantly decreased by sodium azide but was increased by high concentration of sodium cyanide and low concentration of sodium arsenate. Uptake was also inhibited by p-chloromercuriphenylsulfonate and by the anions probenecid and 4,4(')-diisothiocyanostilbene-2,2(')-disulfonic acid. Acute exposure of the cells to ethanol (100mM) inhibited the uptake for 90 min of the experimental duration. It is concluded that astrocytes have a system for the uptake of 5-FTHF and folate analogs which is carrier mediated, this system is sensitive to energy inhibitors and alcohol exposure.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Songmin
authors.initials: S
authors.lastname: Cai
authors.forename: Donald W
authors.initials: DW
authors.lastname: Horne
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000818:Animals; D001149:Arsenates / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002021:Buffers; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005492:Folic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D002955:Leucovorin / Q000378:metabolism* / Q000493:pharmacokinetics; D008727:Methotrexate / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012966:Sodium Cyanide / Q000494:pharmacology; D013763:Tetrahydrofolates / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D001149:Arsenates; D002021:Buffers; D004791:Enzyme Inhibitors; D013763:Tetrahydrofolates; D000431:Ethanol; D002731:4-Chloromercuribenzenesulfonate; C009277:sodium arsenate; D005492:Folic Acid; D012966:Sodium Cyanide; D011339:Probenecid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002955:Leucovorin; C005984:5-methyltetrahydrofolate; D008727:Methotrexate