title: Absorption measurements of a cell monolayer relevant to phototherapy: reduction of cytochrome c oxidase under near IR radiation.
abstract: Phototherapy uses monochromatic light in the optical region of 600-1000 nm to treat in a non-destructive and non-thermal fashion various soft-tissue and neurological conditions. This kind of treatment is based on the ability of light red-to-near IR to alter cellular metabolism as a result of its being absorbed by cytochrome c oxidase. To further investigate the involvement of cytochrome c oxidase as a photoacceptor in the alteration of the cellular metabolism, we have aimed our study at, first, recording the absorption spectra of HeLa-cell monolayers in various oxygenation conditions (using fast multichannel recording), secondly, investigating the changes caused in these absorption spectra by radiation at 830 nm (the radiation wavelength often used in phototherapy), and thirdly, comparing between the absorption and action spectra recorded. The absorption measurements have revealed that the 710- to 790-nm spectral region is characteristic of a relatively reduced photoacceptor, while the 650- to 680-nm one characterizes a relatively oxidized photoacceptor. The ratio between the peak intensities at 760 and 665 nm is used to characterize the redox status of cytochrome c oxidase. By this criterion, the irradiation of the cellular monolayers with light at lambda=830 nm (D=6.3 x 10(3)J/m(2)) causes the reduction of the photoacceptor. A similarity is established between the peak positions at 616, 665, 760, 813, and 830 nm in the absorption spectra of the cellular monolayers and the action spectra of the long-term cellular responses (increase in the DNA synthesis rate and cell adhesion to a matrix).
authors.affiliation: Institute of Laser and Information Technologies of Russian Academy of Sciences, Troitsk, Pionerskaya Street 2, Moscow Region 142190, Russian Federation. tkaru@isan.troitsk.ru
authors.forename: Tiina I
authors.initials: TI
authors.lastname: Karu
authors.forename: Lydmila V
authors.initials: LV
authors.lastname: Pyatibrat
authors.forename: Sergei F
authors.initials: SF
authors.lastname: Kolyakov
authors.forename: Natalya I
authors.initials: NI
authors.lastname: Afanasyeva
mesh_terms: D003576:Electron Transport Complex IV / Q000378:metabolism / Q000528:radiation effects*; D006367:HeLa Cells; D006801:Humans; D007259:Infrared Rays; D010789:Phototherapy
chemical_list: D003576:Electron Transport Complex IV