A cytosolic source of calcium unveiled by hydrogen peroxide with relevance for epithelial cell death

J. Castro, C. X. Bittner, A. Humeres, V. P. Montecinos, J. C. Vera, L. F. Barros

Research output: Contribution to journalReview articlepeer-review

30 Citations (Scopus)


Oxidative stress releases intracellular calcium, which plays a pathogenic role in mammalian cell death. Here we report a search for the source of oxidative calcium in HeLa cells based on confocal epifluorescence microscopy. H2O2 caused a rapid increase in cytosolic calcium, which was followed by mitochondrial Ca2+ loading. Combined mitochondrial uncoupling with full depletion of thapsigargin-sensitive stores abrogated inositol 1,4,5-trisphosphate-mediated calcium release but failed to inhibit H2O2-induced calcium release, observation that was confirmed in MDCK cells. Prevention of peroxide-induced acidification with a pH clamp was also ineffective, discarding a role for endosomal/lysosomal Ca2+/H+ exchange. Lysosomal integrity was not affected by H2O2. Mature human erythrocytes also reacted to peroxide by releasing intracellular calcium, thus directly demonstrating the cytosolic source. Glutathione depletion markedly sensitized cells to H2O2, an effect opposite to that achieved by DTT. Iron chelation was ineffective. In summary, our results show the existence of a previously unrecognized sulfhydrylsensitive source of pathogenic calcium in the cytosol of mammalian cells.

Original languageEnglish
Pages (from-to)468-478
Number of pages11
Issue number4
Publication statusPublished - 1 Apr 2004
Externally publishedYes


  • Endoplasmic reticulum
  • Glutahione necrosis
  • HeLa cells
  • Human erythrocytes
  • Lysosomes
  • MDCK cells
  • Mitochondria


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