Purchase this article with an account.
M.B. Rozanowska, M.E. Boulton, M. Davies, A. Pawlak, B. Rozanowski; Human Bruch's Membrane From Elderly Donors Is a Source of Light–Induced Reactive Oxygen Species and Is Susceptible to Photooxidation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2318.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine the susceptibility of human Bruch's membrane (BrM) to photooxidation and its ability to photogenerate reactive oxygen species and induce lipid peroxidation.
BrMs were isolated from human eyes from donors above 60 years old. Mechanically homogenized BrMs were subjected to chloroform/methanol extraction. Chloroform soluble components were used either for preparation of liposomes or were solubilized in an organic solvent. Electron spin resonance (ESR) oximetry, iodometric assay of lipid hydroperoxides, TBA–assay for detection of secondary poducts of lipid peroxidation, ESR spin trapping, laser flash photolysis combined with absorption spectroscopy and time–resolved detection of singlet oxygen phosphorescence were used to investigate the susceptibility of BrM extract to light–induced oxidation and determination of its photosensitizing properties.
Absorption spectrum of solubilized BrM extract exhibited a steep increase with decreasing wavelengths. The rates of photo–induced oxygen uptake in suspension of BrM liposomes exhibited an increasing efficiency with decreasing irradiation wavelengths within the range of 500 to 312 nm when normalized to equal number of incident photons. This action spectrum was similar to BrM absorption spectrum. Light–induced photooxidation was accompanied by loss of unsaturated lipids, accumulation of lipid hydroperoxides, and formation of TBA–reactive substances. Irradiation of BrM in the presence of a spin trap, DMPO led to the formation of DMPO–OOH radical adducts. Photoexcitation of solubilized BrM extract with 355 nm or 420 nm laser light led to photosensitized generation of singlet oxygen with quantum yields up to 16%.
Human BrM from elderly donors is susceptible to light–induced oxidation and contains potent photosensitizers generating superoxide, singlet oxygen, lidid hydroperoxides and secondary products of lipid peroxidation when excited with ultraviolet or blue light. It can be speculated that irradiation with blue light of BrM may prove toxic to cells of neighbouring retinal pigment epithelium and/or choroid.
This PDF is available to Subscribers Only