The role of intracellular free calcium in the cellular response to hyperthermia

E. D. Wieder, M. H. Fox

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The intracellular free calcium (Ca+plus;i) concentration was measured in several cell lines after heating at 45.0°C using flow cytometry with indo-1. Chinese hamster ovary 10B2 (CHO) cells do not stain well with indo-1, so a CHO mutant cell line (CHO IS1) isolated in our laboratory with much-improved stainability for indo-1 was used to study CA+plus;i changes in heated CHO cells. BALB-3T3 (mouse) and EJ30 (human) cells were also studied. Cells were heated in the sample holder of the cell sorter in order to measure Ca+plus;i within seconds after heating. Ca+plus;i increased rapidly within the first 5 min of heating at 45.0°C in all three lines, though the magnitude of the increase varied for each cell line. The Ca+plus;i returned rapidly to baseline after heating in CHO IS1 cells and BALB-3T3 cells. After 5 min of heating, the Ca+plus;i, plateaued in the EJ30 and IS1 cells, but decreased in the 3T3 cells. There was an inverse relationship between the Ca+plus;i after 10 min at 45°C and survival for the different cell lines. Thermotolerant cells experienced a similar change in Ca+plus;i during heating as non-thermotolerant cells, though the kinetics were somewhat different for the IS1 cells. A bimodal distribution of Ca+plus;i developed in EJ30 cells by 2 min after heating. Cells sorted from the near-normal Ca+plus;i region of the histogram had a 2-fold higher survival rate than the cells which had a high Ca+plus;i concentration. These data support the view that Ca+plus;i changes during heating are not the principal factor in heat-induced cell death.

Original languageEnglish (US)
Pages (from-to)733-742
Number of pages10
JournalInternational Journal of Hyperthermia
Issue number5
StatePublished - 1995
Externally publishedYes


  • Flow cytometry
  • Hyperthermia
  • Indo-1
  • Thermotolerance

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cancer Research


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