PTHALOCYANINE-INDUCED PHOTODYNAMIC CHANGES OF CYTOPLASMIC FREE CALCIUM IN CHINESE-HAMSTER CELLS

Exposure to light of Chinese hamster cells preloaded with chloroaluminum phthalocyanine causes an immediate increase of cytoplasmic free calcium, [Ca2+]i, from about 0.2-mu-M to 1-mu-M within 5 min after illumination. This increase was dose-dependent within the biological dose range, reaching a plateau at a dose that kills 99.5% of the cells. Fluoride addition prior to light exposure protected against cell killing and reduced the increase of [Ca2+]i. These findings raise the possibility that changes in [Ca2+]i after photodynamic treatment may be relevant to cell killing and/or other biological responses of the cells, e.g. release of eicosanoids.