The plasma membrane is involved in the visible light-tissue interaction

Ronit Lavi, Rinat Ankri, Michael Sinyakov, Maor Eichler, Harry Friedmann, Asher Shainberg, Haim Breitbart, Rachel Lubart

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


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 data: 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 (400-800nm) 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.

Original languageEnglish
Pages (from-to)14-19
Number of pages6
JournalPhotomedicine and Laser Surgery
Issue number1
StatePublished - 1 Jan 2012
Externally publishedYes


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