[Differences in the photodestruction parameters of flavin fluorescence in normal and tumor cells at a decreased pH of the incubation medium].

Further investigation of the peculiarities of flavin fluorescence photodestruction in malignant cells was made. In normal cells incubated in low pH (3.0-3.2) physiological solutions, the decrease in the oxidized flavoprotein fluorescence intensity under irradiation is the same as in normal pH condition, whereas in tumor cell in low pH solutions a significant increase in the photodestruction level was noticed. The cells isolated from foci of transformation, following treatment of 3T3 NIH fibroblasts with the carcinogen N-methyl-N'-nitro-N-nitrosoguanidine, displayed the photodestruction parameters similar to those in tumor cells. A two-step analysis of cells is proposed for distinguishing between the normal and malignant cells.