Low intensity light stimulates nitrite-dependent nitric oxide synthesis but not oxygen consumption by cytochrome c oxidase: Implications for phototherapy.
Cytochrome c oxidase (Cco) has been reported to be a receptor for some of the beneficial effects of low intensity visible and near-infrared light on cells and tissues. Here, we have explored the role of low intensity light in affecting a newly described function of Cco, its ability to catalyze nitrite-dependent nitric oxide (NO) synthesis (Cco/NO). Using a new assay for Cco/NO we have found that both yeast and mouse brain mitochondrial Cco produce NO over a wide range of oxygen concentrations and that the rate of NO synthesis increases as the oxygen concentration decreases, becoming optimal under hypoxic conditions. Low intensity broad-spectrum light increases Cco/NO activity in an intensity-dependent fashion but has no effect on oxygen consumption by Cco. By using a series of bandpass filters and light emitting devices (LEDs) we have determined that maximal stimulation of Cco/NO activity is achieved by exposure to light whose central wavelength is 590 ± 14 nm. This wavelength of light stimulates Cco/NO synthesis at physiological nitrite concentrations. These findings raise the interesting possibility that low intensity light exerts a beneficial effect on cells and tissues by increasing NO synthesis catalyzed by Cco and offer a new explanation for the increase in NO bioavailability experienced by tissue exposed to light.
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA.
Kerri A
KA
Ball
Pablo R
PR
Castello
Robert O
RO
Poyton
D000818:Animals; D055162:Biocatalysis; D001921:Brain / Q000166:cytology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D003576:Electron Transport Complex IV / Q000378:metabolism*; D008027:Light; D051379:Mice; D008928:Mitochondria / Q000378:metabolism / Q000528:radiation effects; D009569:Nitric Oxide / Q000096:biosynthesis*; D009573:Nitrites / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010789:Phototherapy; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000528:radiation effects; D014867:Water / Q000378:metabolism
D009573:Nitrites; D014867:Water; D009569:Nitric Oxide; D003576:Electron Transport Complex IV; D010100:Oxygen