Intracellular ATP level increases in lymphocytes irradiated with infrared laser light of wavelength 904 nm.

Objective: Red and near-infrared laser irradiation is reported to have a range of biological effects on cultured cells and different tissues, leading to the hypothesis that laser light can affect energy metabolism. Increased adenosine triphosphate (ATP) synthesis has been reported in cultured cells and rat brain tissue after irradiation at 632.8 nm and 830 nm, respectively. This study investigated whether diode pulsed laser irradiation enhances ATP production in lymphocytes. Materials and Methods: Aliquots (500 μL) of an extract of cultured lymphocytes of the Molt-4 cell line were irradiated with diode laser light (λ = 904 nm, pulsed mode, 6 kHz frequency) with an average emission power of 10 mW for 60 min. A Spectra Physics M404 power meter was used to measure light intensity. Controls were treated similarly but not irradiated. The amount of ATP was measured by the luciferin-luciferase bioluminescent assay. Results: The amount of ATP in irradiated cell cultures was 10.79 ± 0.15 μg/L (SD; n = 10), and in non-irradiated cell cultures it was 8.81 ± 0.13 μg/L (SD; n = 10). The average percentage increase of irradiated versus control cell cultures was about 22.4% ± 0.56% SD (p < 0.001). Conclusion: This significant increase is probably due to laser irradiation; it cannot be attributed to any thermal effect, as the temperature during irradiation was maintained at 37.0° ± 0.5°C. Thus the therapeutic effects of the biostimulating power of this type of laser are identified and its indications may be expanded. © 2008 Mary Ann Liebert, Inc.