THE PHOTODYNAMIC EFFECTS ONV–79 CHINESE HAMSTER CELLS

Abstract— Holding of acriflavine sensitizedV–79 cells in growth medium before visible light exposure decreases inactivation by visible light. The decrease depended upon the period of holding, indicating that there was release of cellular dye during this period. Exposures to visible light were done in two conditions: (a) with no dye in the medium during visible light exposure (washed) and (b) with dye in the medium during exposure (unwashed). Caffeine was found to slightly increase the sensitivity of the cells to visible light in the washed condition, whereas, in the unwashed condition no such effect was observed. Interaction studies with far UV did not reveal any correlation between photodynamic damage and UV damage. Visible light exposure of acriflavine sensitized cells was found to be mutagenic, as studied from the induction of 8-azaguanine resistant mutants. Inhibition of singlet oxygen production by sodium azide suppressed the induction of mutants. All these, taken together, have been discussed with respect to the relative importance of DNA and non-DNA damage in the photodynamic action of acriflavine.