Light-induced nitric oxide release in the skin beyond UVA and blue light: Red & near-infrared wavelengths.

Nitric oxide (NO) is omnipresent in the body and synthesized by 3 isoenzymes (nNOS, eNOS and iNOS), all detected in human skin. NO can be stored in a pool of compounds readily converted to NO following skin irradiation by UVR and blue light. This non-enzymatic (without NOS involvement) photolytic reaction mobilizes cutaneous stores of NO derivatives to the bloodstream, lowering blood pressure. However, with the likelihood of skin deleterious effects caused by UVR/blue light, safer wavelengths in the red/near-infrared (NIR) spectrum are becoming potential contenders to release cutaneous NO, possibly via NOS temperature-dependent effects. The use of red/NIR light to mobilize NO stores from the body's largest organ (the skin) is auspicious. This review focuses on UVR, blue, red, and NIR spectra and their capacity to release NO in human skin. PubMed and Google Scholar were used as article databases to find relevant publications related to this particular field. [Display omitted] • This extensive review summarizes light-induced nitric oxide (NO) release mechanisms in the skin. • Established UVA and blue light spectra are capable of releasing NO in human skin through enzymatic and non-enzymatic pathways. • Alternatively, the use of safer non-ionizing wavelengths in the red / near-infrared spectra can also release cutaneous NO, presumably using enzymatic pathways. • A brief overview on rising polymeric NO donors promoting skin NO release explains potential medical applications. • Lastly, most recent light-induced therapeutic approaches and biomedical applications involving NO release are portrayed, with their potential local and distant effects in the body. [ABSTRACT FROM AUTHOR]