Photobiomodulation and Nitric Oxide (NO)
Simply put: a gas that helps make everything better
Nitric oxide (NO) is a gas produced naturally by our bodies. Although it is invisible, it plays a very important role in our cells. In particular, it helps to:
- improve blood circulation (vasodilation),
- reduce inflammation,
- activate cellular repair.
How does light release NO?
In certain cells, NO is temporarily trapped inside an enzyme called cytochrome c oxidase. Red or infrared light releases it, allowing the cell to resume functioning more smoothly. This is one of the immediate effects of photobiomodulation.
Why is this useful?
This release helps improve oxygenation of the tissues, relieve pain, speed up recovery after exercise or an injury, and stimulate regenerative processes.
Nitric Oxide and Light: A Scientific Perspective
NO is a signaling gas found in many tissues. It acts both locally and at a distance, triggering a cascade of responses within the cell.
CCO and NO release
In photobiomodulation, NO is reversibly stored at cytochrome c oxidase (CCO), temporarily inhibiting mitochondrial respiration.
When red light (approximately 630–850 nm) strikes this complex, it causes:
- the dissociation of the CCO–NO complex,
- the restoration of the electron flow,
- an increase in ATP production,
- and the release of free NO into the cytoplasm.
Roles of NO After Its Release
- Vasodilation: By activating guanylate cyclase, NO increases cGMP, leading to relaxation of the smooth muscles in blood vessels.
- Modulation of inflammation: It inhibits the production of pro-inflammatory cytokines.
- Signaling: It is involved in the genetic transcription of growth factors and repair enzymes (NF-κB, Nrf2, etc.).
💡 The right amount of stimulation can produce powerful anti-inflammatory effectswithout causing any toxic effects.
Therapeutic Applications of Light-Induced NO
- Relief from muscle and joint pain,
- Post-exercise recovery in athletes,
- Improved tissue healing and oxygenation,
- Vascular effects on circulatory disorders,
- Protective and regulatory effect on nerve cells.
These benefits explain why photobiomodulation is used in sports medicine, dermatology, neurology, and cosmetic treatments.
LED Photobiomodulation and NO Activation Parameters
For this release of NO to occur, several conditions must be met:
- effective wavelength: between 630 and 850 nm,
- Controlled fluence: 1 to 8 J/cm² depending on the tissue,
- appropriate exposure time and frequency,
- a well-targeted area, to avoid a loss of efficacy or excessive inhibition.
These settings are defined by specific protocols for in-office or at-home self-treatment.
Frequently Asked Questions
What is nitric oxide (NO)?
NO is a gaseous molecule produced naturally by cells. It acts as an intracellular messenger, particularly to dilate blood vessels and improve circulation.
What is the connection between light and NO?
Red and infrared light releases NO stored in the mitochondria. This promotes better tissue oxygenation, helps regulate inflammation, and has a local vasodilatory effect.
Are there any risks associated with NO in photobiomodulation?
In small doses, NO is beneficial. But if it is overproduced or poorly regulated, it can inhibit the mitochondria. This is why it is important to adhere to the recommended doses in photobiomodulation.
Scientific sources cited
- Liu T.C.-Y. et al. (2009). Nitric oxide and photodynamic therapy.
Link to the study
→ Shows that red light releases nitric oxide (NO) from the mitochondria, which improves microcirculation and reduces inflammation. - Hamblin, M.R. (2017). Mechanisms and doses for photobiomodulation therapy.
Link to the study
→ Confirms the role of NO in red-light-induced vasodilation and its protective effect against cellular damage. - Brown, G.C. (1999). Nitric oxide and mitochondrial function.
Link to the study:
→ Analyzes the dual action of NO: beneficial at low doses, but inhibitory to mitochondria at excessive doses. - Karu T.I. (2005). Mitochondrial signaling in low-level light therapy.
Link to the study
→ Describes the role of NO as a secondary signaling molecule in photobiomodulation.
See also
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