Near-infrared light at 810 nm increases mitochondrial ATP synthesis up to +253% at 6h post-irradiation in cultured muscle cells (in vitro), mechanism demonstrated via cytochrome c oxidase.
This study by Ferraresi et al. (2023), published in the Journal of Photochemistry and Photobiology, elucidates the fundamental mechanism by which near-infrared (NIR) light produces its biological effects: stimulation of cytochrome c oxidase (complex IV) of the mitochondrial respiratory chain.
The researchers used primary cell cultures and ex vivo muscle tissue models to precisely quantify the effects of irradiation at 810 nm on mitochondrial bioenergetic parameters, in particular membrane potential (ΔΨm) and ATP production.
The study provides robust mechanistic confirmation of the scientific efficacy of PBM, by showing that the observed effects are not non-specific but result from a precise photochemical interaction with an identified mitochondrial chromophore.
In vitro study on skeletal muscle cells (C2C12 myotubes, immortalized murine cell line). Standard DMEM culture medium, myogenic differentiation prior to experimentation. Classic model for studying cellular effects of photobiomodulation on muscle.
Light source: 810 nm laser (near-infrared). Energy doses tested (J/cm²): dose-response analysis. Single irradiation application on cells in culture. Control groups: non-irradiated cells under same culture conditions.
Mitochondrial ATP synthesis measured at 1h, 3h, 6h and 24h post-irradiation by luminescent assay (standard ATP kit). Mitochondrial membrane potential evaluated by fluorescence (JC-1 or TMRE probes). ATP production expressed in nmol/well.
Activation of cytochrome c oxidase (Complex IV of respiratory chain) by dissociation of inhibitory nitric oxide (NO). Increased electron flow, mitochondrial membrane potential (ΔΨm) and ATP synthesis. Maximum effect observed at 3-6h post-irradiation.
This mechanistic study is fundamental to understanding why photobiomodulation produces such varied effects, from muscle recovery to cognitive optimization. Everything rests on a single mechanism: stimulation of cytochrome c oxidase and increased ATP production in all exposed cells.
Confirmation of the biphasic dose-response curve is critical for our scientific practice. It justifies our approach of precise dosimetry: a dose that is too low is ineffective, a dose that is too high may become inhibitory. Our protocols are calibrated to systematically remain within the optimal therapeutic window identified (1–5 J/cm² depending on the target tissue).
The release of nitric oxide by CCO explains the vascular effects of PBM: improved microcirculation, reduced blood pressure, better tissue oxygenation. These effects particularly benefit patients with circulatory disorders or chronic fatigue of metabolic origin.
The discovery that the effect is abolished by specific CCO inhibitors (azide, cyanide) definitively confirms the specificity of the light-mitochondria interaction, ruling out any placebo or thermal effect in the scientific results obtained.