Different mechanisms mediate uptake of lead in a rat astroglial cell line

Jae Hoo Cheong, Desmond Bannon, Luisa Olivi, Yongbae Kim, Joseph Bressler

Research output: Contribution to journalArticle

Abstract

The mechanism by which lead (Pb) enters astrocytes was examined in a rat astroglial cell line in order to characterize specific pathways for transport. Pb uptake was saturable at pH 5.5 and 7.4, although quantitative differences existed in the Michaelis-Menten constants. At pH 7.4, the Vmax and Km were 2700 fmoles/mg protein/min and 13.4 μM, respectively, whereas the Vmax and Km were 329 fmoles/mg and 8.2 μM in the buffer at pH 5.5, respectively. The presence of extracellular iron inhibited uptake in a buffer at pH 5.5 but not at pH 7.4. Cells treated with the iron chelator deferoxamine displayed higher levels of the iron transporter divalent metal transporter 1 (DMT1) mRNA and protein, and consistent with increased DMT1 expression, the treated cells displayed greater uptake of Pb in the buffer at pH 5.5 but not at pH 7.4. Alternatively, at pH 7.4, the transport of Pb was blocked by the anion transporter inhibitor 4,4′-diisothiocyanatodihydrostilbene-2,2′-disulfonic acid (DIDS), which bound to cell surface proteins at concentrations that were similar to those that blocked Pb uptake. DIDS did not inhibit uptake of Pb in the buffer at pH 5.5. Greater uptake of Pb was observed in a buffer containing sodium bicarbonate, which was abrogated in the presence of DIDS. In summary, the astroglial cell line displays two distinct pH-sensitive transport mechanisms for Pb.

Original languageEnglish (US)
Pages (from-to)334-340
Number of pages7
JournalToxicological Sciences
Volume77
Issue number2
DOIs
StatePublished - Feb 2004

Fingerprint

Rats
Buffers
Cells
Cell Line
Iron
Acids
Sodium Bicarbonate
Deferoxamine
Chelating Agents
Anions
Membrane Proteins
Proteins
Lead
Messenger RNA
Astrocytes
solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2

Keywords

  • Anion
  • Astrocytes
  • Divalent metal transporter 1
  • Lead

ASJC Scopus subject areas

  • Toxicology

Cite this

Different mechanisms mediate uptake of lead in a rat astroglial cell line. / Cheong, Jae Hoo; Bannon, Desmond; Olivi, Luisa; Kim, Yongbae; Bressler, Joseph.

In: Toxicological Sciences, Vol. 77, No. 2, 02.2004, p. 334-340.

Research output: Contribution to journalArticle

Cheong, Jae Hoo ; Bannon, Desmond ; Olivi, Luisa ; Kim, Yongbae ; Bressler, Joseph. / Different mechanisms mediate uptake of lead in a rat astroglial cell line. In: Toxicological Sciences. 2004 ; Vol. 77, No. 2. pp. 334-340.
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