Increase in the nitric oxide release without changes in cell viability of macrophages after laser therapy with 660 and 808nm lasers.

Abstract

The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) with different parameters and wavelengths on nitric oxide (NO) release and cell viability. Irradiation was performed with Ga-Al-As laser, continuous mode and wavelengths of 660 and 808nm at different energy and power densities. For each wavelength, powers of 30, 50, and 100mW and times of 10, 30, and 60s were used. NO release was measured using Griess reaction, and cell viability was evaluated by mitochondrial reduction of bromide 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to formazan. LLLT promoted statistically significant changes in NO release and MTT value only at the wavelength of 660nm (p < 0.05). LLLT also promoted an increase in the NO release and cell viability when the energy densities 64 (p = 0.04) and 214J/cm2 (p = 0.012), respectively, were used. LLLT has a significant impact on NO release without affecting cell viability, but the significance of these findings in the inflammatory response needs to be further studied.