Intracellular Ca2+ concentration change of T24 cell under irradiation in the presence of TiO2 ultrafine particles

Hideki Sakai, Etsuro Ito, Ru Xiong Cai, Toru Yoshioka, Yoshinobu Kubota, Kazuhito Hashimoto, Akira Fujishima

Research output: Contribution to journalArticlepeer-review

104 Citations (Scopus)


We respond that malignant cells are inactivated by photo-excited TiO2 particles (Cai, R.-X., et al. (1992) Cancer Res. 52, 2346-2348). In the present study, the process of cell death of a human bladder cell line T24 with the irradiated TiO2 was investigated by monitoring the time course change in intracellular calcium concentration ([Ca2+]i) under UV irradiation using calcium fluorescence indicator, fura-2. In the presence of photo-excited TiO2 particles (100 μg/ml), [Ca2+]i showed a rapid two-step increase, while in the absence of TiO2, it exhibited only a slight and monotonous increase or maintained a constant level. The rapid elevation of [Ca2+]i in the presence of photo-excited TiO2 particles was caused by the influx of extracellular Ca2+ through the plasma membrane and cell death occurred only after the second rapid elevation of [Ca2+]i. These results suggested that the cell membrane permeability to Ca2+ was promoted prior to cell death.

Original languageEnglish
Pages (from-to)259-265
Number of pages7
JournalBBA - General Subjects
Issue number2
Publication statusPublished - 1994 Nov 11


  • Fura-2
  • Intracellular Ca concentration
  • Photo-dynamic therapy
  • T24 cell
  • TiO
  • UV light

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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