Properties of Mg2+-dependent cation channels in human leukemia K562 cells

Svetlana B. Semenova, Alla F Fomina, Irina O. Vassilieva, Yuri A. Negulyaev

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The endogenous Mg2+-inhibited cation (MIC) current was recently described in different cells of hematopoietic lineage and was implicated in the regulation of Mg2+ homeostasis. Here we present a single channel study of endogenously expressed Mg2+-dependent cation channels in the human myeloid leukemia K562 cells. Inwardly directed unitary currents were activated in cell-attached experiments in the absence of Ca2+ and Mg2+ in the pipette solution. The current-voltage (I-V) relationships displayed strong inward rectification and yielded a single channel slope conductance of ∼30 pS at negative potentials. The I-V relationships were not altered by patch excision into divalent-free solution. Channel open probability (Po) and mean closed time constant (τC) were strongly voltage-dependent, indicating that gating mechanisms may underlie current inward rectification. Millimolar concentrations of Ca2+ or Mg 2+ applied to the cytoplasmic side of the membrane produced slow irreversible inhibition of channel activity. The Mg2+-dependent cation channels described in this study differ from the MIC channels described in human T-cells, Jurkat, and rat basophilic leukemia (RBL) cells in their I-V relationships, kinetic parameters and dependence on intracellular divalent cations. Our results suggested that endogenously expressed Mg 2+-dependent cation channels in K562 cells and the MIC channels in other hematopoietic cells might be formed by different channel proteins.

Original languageEnglish (US)
Pages (from-to)372-378
Number of pages7
JournalJournal of Cellular Physiology
Volume205
Issue number3
DOIs
StatePublished - Dec 2005

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

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