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

Abstract
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 μM to 1 μM 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.