Photobiological basis of laser biostimulation

Quantitative studies of the action of low-power visible monochromatic light on various cells (E.coli, yeasts, HeLa) were performed to find irradiation conditions (wavelength, dose, intensity) conducive to vital activity stimulation. The action spectra of visible light on DNA and RNA synthesis in HeLa cells have maxima near 404, 620, 680, 760, and 830 nm. Growth stimulation of E.coli is at maximum when irradiated at 404, 454, 570, 620, and 750 nm, and biomass accumulation stimulation in yeasts has maxima at 404, 570, 620, 680, and 760 nm. Absorption of quanta is only a trigger for the rearrangement of cellular metabolism, with photosignal transduction being effected by standard cellular means such as changes in the cAMP level. Respiratory chain components are discussed as primary photoacceptors. It is concluded that laser biostimulation is of a photobiological nature and that low-power laser effects can be related to well-known photobiological phenomena