Abstract
In this study, we used NHIK (Norsk Hydro's Institutt for Kreftforskning) 3025 cells, derived from a human carcinoma of the cervix, to screen for phototoxicity. Previously, NHIK 3025 cells have been used in porphyrin research. A number of sulphonamide-derived oral anti-diabetics and diuretics were incubated together with the NHIK cells for one hour and irradiated with broad band UV and UVA radiation. Cell death was observed in the presence of two oral anti-diabetic drugs and ten diurectic drugs, and was dependent on UVA exposure and the concentration of the test substance. This model proved valuable for the detection of known phototoxic substances, and, in addition, phototoxic properties were demonstrated for a number of substances not previously shown to exert these effects. Electron microscopy of the cells, in the presence of the diuretic bemetizide, showed that biomembranes are the main target for phototoxicity, although nuclear damage was also demonstrated. The addition of antioxidants reduced the amount of phototoxic cell death, indicating the participation of reactive oxygen species in the process. These procedures show that this model can be useful both in screening procedures and in mechanistic investigations.
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