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

Abstract

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 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.