title: The plasma membrane is involved in the visible light-tissue interaction.
abstract: OBJECTIVE
  The aim of the present study was to determine whether the plasma membrane is also involved in the light-tissue interaction because of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase electron chain, which can serve as a photosensitizer.
  
  
  BACKGROUND
  It has been suggested that the mechanism of photobiostimulation involves light-induced low levels of reactive oxygen species (ROS) that serve as signal transduction messengers. Production of ROS following visible-light irradiation was verified by the electron paramagnetic resonance (EPR) spin-trapping technique, and the mitochondrial cytochromes were suggested as the main cellular target for visible-light absorption.
  
  
  METHODS
  Isolated sperm membranes were illuminated with visible light and the increase in oxygen radical production was measured using the EPR spin-trapping technique coupled with the probe 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). A broadband visible light source (400-800 nm) at 40-130 mW/cm(2) with appropriate filters provided the illumination. In order to determine whether the light-induced ROS production is a result of a photo-accelerated electron transfer in the enzyme-catalyzed reaction with oxygen in the plasma membrane, or resulted from a photochemical reaction of the chromophores alone with oxygen, denatured membranes were irradiated as well.
  
  
  RESULTS
  Visible-light-induced oxyradicals were detected in isolated sperm membranes. Blue light was found to be more effective than red. Illuminated denatured membranes produced the same amount of ROS as non-denatured membranes.
  
  
  CONCLUSIONS
  Visible-light illumination, especially in the blue region, increases ROS levels in isolated plasma membranes. The mechanism of ROS formation is probably a photochemical reaction of the membranal chromophhores, for example, cytochromes or flavins with oxygen, and not an enzyme-catalyzed photochemical reaction.
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Lavi
authors.forename: Rinat
authors.initials: R
authors.lastname: Ankri
authors.forename: Michael
authors.initials: M
authors.lastname: Sinyakov
authors.forename: Maor
authors.initials: M
authors.lastname: Eichler
authors.forename: Harry
authors.initials: H
authors.lastname: Friedmann
authors.forename: Asher
authors.initials: A
authors.lastname: Shainberg
authors.forename: Haim
authors.initials: H
authors.lastname: Breitbart
authors.forename: Rachel
authors.initials: R
authors.lastname: Lubart
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism* / Q000528:radiation effects*; D003497:Cyclic N-Oxides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D008027:Light; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012756:Sheep; D013094:Spermatozoa / Q000648:ultrastructure; D019097:Spin Trapping
chemical_list: D003497:Cyclic N-Oxides; D017382:Reactive Oxygen Species; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D019255:NADPH Oxidases