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Ca 2+ INFLUX INDUCED BY PHOTODYNAMIC ACTION IN HUMAN CEREBRAL GLIOMA (U‐87 MG) CELLS: POSSIBLE INVOLVEMENT OF A CALCIUM CHANNEL
Author(s) -
Joshi Preeti G.,
Joshi Kunju,
Mishra Sudha,
Joshi Nanda B.
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb05098.x
Subject(s) - extracellular , diltiazem , hematoporphyrin , biophysics , chemistry , calcium , intracellular , calcium channel , glioma , membrane , photodynamic therapy , calcium channel blocker , channel blocker , calcium in biology , cell membrane , membrane potential , biochemistry , biology , cancer research , organic chemistry
The plasma membrane has been implicated as a critical target of photodynamic action on cells. We have observed that the photosensitization of human cerebral glioma (U‐87 MG) cells by hematoporphyrin derivative (HpD) causes a large increase in intracellular calcium [Ca 2+ ]. This increase in [Ca 2+ ] i was solely due to the influx of extracellular Ca 2+ through the plasma membrane and showed a dependence on HpD concentration, light dose and concentration of calcium in the extracellular medium. The magnitude of the Ca 2+ influx decreased with increasing postirradiation time, which suggests that the cell membrane partially recovers from the photodynamic injury. The photoinduced Ca 2+ influx was inhibited by the Ca 2+ channel blocker diltiazem and the reducing agent dithioerythritol. These findings are discussed in terms of possible activation of a Ca 2+ channel as a result of photosensitization.