In Vivo Characterization of a Red Light-Activated Vasodilation: A Photobiomodulation Study. Front Physiol 2022;13:880158
Date
05/20/2022Pubmed ID
35586710Pubmed Central ID
PMC9108481DOI
10.3389/fphys.2022.880158Scopus ID
2-s2.0-85130240732 (requires institutional sign-in at Scopus site) 4 CitationsAbstract
Nitric oxide dependent vasodilation is an effective mechanism for restoring blood flow to ischemic tissues. Previously, we established an ex vivo murine model whereby red light (670 nm) facilitates vasodilation via an endothelium derived vasoactive species which contains a functional group that can be reduced to nitric oxide. In the present study we investigated this vasodilator in vivo by measuring blood flow with Laser Doppler Perfusion imaging in mice. The vasodilatory nitric oxide precursor was analyzed in plasma and muscle with triiodide-dependent chemiluminescence. First, a 5-10 min irradiation of a 3 cm2 area in the hind limb at 670 nm (50 mW/cm2) produced optimal vasodilation. The nitric oxide precursor in the irradiated quadriceps tissue decreased significantly from 123 ± 18 pmol/g tissue by both intensity and duration of light treatment to an average of 90 ± 17 pmol/g tissue, while stayed steady (137 ± 21 pmol/g tissue) in unexposed control hindlimb. Second, the blood flow remained elevated 30 min after termination of the light exposure. The nitric oxide precursor content significantly increased by 50% by irradiation then depleted in plasma, while remained stable in the hindlimb muscle. Third, to mimic human peripheral artery disease, an ameroid constrictor was inserted on the proximal femoral artery of mice and caused a significant reduction of flow. Repeated light treatment for 14 days achieved steady and significant increase of perfusion in the constricted limb. Our results strongly support 670 nm light can regulate dilation of conduit vessel by releasing a vasoactive nitric oxide precursor species and may offer a simple home-based therapy in the future to individuals with impaired blood flow in the leg.
Author List
Keszler A, Lindemer B, Broeckel G, Weihrauch D, Gao Y, Lohr NLAuthors
Yan Gao PhD Assistant Professor in the Institute for Health and Equity department at Medical College of WisconsinAgnes Keszler PhD Research Scientist I in the Biophysics department at Medical College of Wisconsin
Dorothee Weihrauch DVM, PhD Research Scientist II in the Anesthesiology department at Medical College of Wisconsin
