title: [Opposite effect of lipofuscin granules and melanosomes from human retinal pigment epithelium of eye on photooxidation of cardiolipin].
abstract: The influence of lipofuscin granules and melanosomes from human retinal pigment epithelium on the light-induced photooxidation of cardiolipin liposomes and the generation of superoxide radicals was studied. Lipofuscin granules were able to stimulate, while melanosomes inhibited, the cardiolipin photooxidation. The visible light irradiation of both melanosomes and lipofuscin granules generated superoxide radicals with mean rates of 1.5 nmole/min/10(7) and 38 nmole/min/10(7) granules, accordingly. However, melanosomes but not lipofuscin granules reacted readily with superoxide radicals. Moreover, the rate constant of degradation of superoxide radicals in the presence of melanosomes was about five orders of magnitude higher than the rate constant of its photogeneration. Therefore, we propose that melanosomes in retinal pigment epithelium cells have a photoprotective role whereas lipofuscin granules may stimulate photodestructive reactions.
authors.affiliation: Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia.
authors.forename: A E
authors.initials: AE
authors.lastname: Dontsov
authors.forename: N L
authors.initials: NL
authors.lastname: Sakina
authors.forename: M A
authors.initials: MA
authors.lastname: Ostrovskiĭ
mesh_terms: D000328:Adult; D000368:Aged; D002308:Cardiolipins / Q000378:metabolism / Q000528:radiation effects*; D003594:Cytoplasmic Granules / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008062:Lipofuscin / Q000502:physiology*; D008081:Liposomes; D020460:Melanosomes / Q000502:physiology*; D008875:Middle Aged; D010084:Oxidation-Reduction; D010777:Photochemistry; D010857:Pigment Epithelium of Eye / Q000166:cytology*
chemical_list: D002308:Cardiolipins; D008062:Lipofuscin; D008081:Liposomes