Biological action of low-intensity visible light on $HeLa$ cells as a function of the coherence, dose, wavelength, and irradiation regime. II.

An investigation was made of the action of low-intensity cw visible light of wavelengths in the range 313–860 nm on the rate of DNA synthesis in a culture of $HeLa$ cells. It was found that the synthesis of DNA was stimulated in three spectral ranges: 313–450 nm, 600–650 nm, and 750–840 nm. For a fixed dose the stimulation effect was very sensitive to the irradiation time (radiation intensity). The maximum increase in the rate of DNA synthesis occurred in $\lesssim$ 15 min from the beginning of irradiation and the effect was retained for several hours. The stimulation effect was less in the case of two-wavelength (dichromatic) irradiation of the cells with red and wide-band visible light.