Correlation between cytosolic Ca2+ concentration and cytotoxicity in hepatocytes exposed to oxidative stress

Pierluigi Nicotera, David McConkey, Sten Åke Svensson, Giorgio Bellomo, Sten Orrenius

Research output: Contribution to journalArticlepeer-review

Abstract

To investigate the relationship between alterations of cytosolic Ca2+ concentration and development of cytotoxicity, isolated rat hepatocytes were loaded with the fluorescent indicator Quin-2 AM and then incubated with non-toxic or toxic levels of menadione (2-methyl-1,4-napthoquinone) or tert-butyl hydroperoxide (t-BH). The resulting changes in cytosolic Ca2+ concentration were compared to those seen upon exposure of the hepatocytes to an α1-adrenergic agonist, phenylephrine, as well as to those induced by menadione and (t-BH) in hepatocytes pretreated with agents that modify their toxicity. Exposure of hepatocytes to phenylephrine or non-toxic levels of menadione caused a moderate and transient increase in cytosolic Ca2+({slanted equal to or less-than}0.7 μM), whereas a toxic concentration of menadione produced a marked, sustained increase in Ca2+ which fully saturated the binding capacity of Quin-2 (>1.5 μM). Treatment of the hepatocytes with the protective agent, dithiothreitol, prevented both the increase in cytosolic Ca2+ and the cytotoxicity induced by menadione. On the other hand, pretreatment of cells with diethylmaleate to deplete intracellular glutathione made otherwise non-toxic concentrations of menadione cause both a sustained increase in cytosolic Ca2+ and cytotoxicity. Similarly, toxic concentrations of t-BH also caused a sustained increase in cytosolic Ca2+. The iron chelator, desferrioxamine, and dithiothreitol (DTT), which protected the cells from t-BH toxicity, also prevented the sustained elevation of cytosolic Ca2+. Our findings provide further support for the hypothesis that a perturbation of intracellular Ca2+ homeostasis is an early and critical event in the development of toxicity in hepatocytes exposed to oxidative stress.

Original languageEnglish (US)
Pages (from-to)55-63
Number of pages9
JournalToxicology
Volume52
Issue number1-2
DOIs
StatePublished - Nov 14 1988
Externally publishedYes

Keywords

  • Calcium
  • Hepatocytes
  • Menadione
  • Oxidative stress
  • Toxicity
  • tert-Butyl hydroperoxide

ASJC Scopus subject areas

  • Toxicology

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