Photoreactivity of aged human RPE melanosomes: A comparison with lipofuscin

Małgorzata Rózanowska, Witold Korytowski, Bartosz Rózanowski, Christine Skumatz, Mike E. Boulton, Janice M. Burke, Tadeusz Sarna

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

PURPOSE. To determine whether aging is accompanied by changes in aerobic photoreactivity of retinal pigment epithelial (RPE) melanosomes isolated from human donors of different ages, and to compare the photoreactivity of aged melanosomes with that of RPE lipofuscin. METHODS. Human RPE pigment granules were isolated from RPE cells pooled into groups according to the age of the donors. Photoreactivity was determined by blue-light-induced oxygen uptake and photogeneration of reactive oxygen species. Short-lived radical intermediates were detected by spin-trapping, hydrogen peroxide by an oxidase electrode, singlet oxygen by cholesterol assay, and lipid hydroperoxides by iodometric assay. RESULTS. Blue-light photoexcitation of melanosomes resulted in age-related increases in both oxygen uptake and the accumulation of superoxide anion spin adducts. The efficiencies of these processes, however, were still significantly lower than that induced by photoexcited lipofuscin. During irradiation of melanosomes, a substantial amount of oxygen was converted into hydrogen peroxide, whereas for lipofuscin, hydrogen peroxide accounted for not more than 3% of oxygen consumed. In contrast to lipofuscin, photoexcited melanosomes did not substantially increase the rate of oxidative reactions in the presence of polyunsaturated lipids or albumin. However, oxygen uptake was significantly elevated in the presence of ascorbate. Thus, the rate of photo-induced oxygen uptake in samples containing both ascorbate and melanosomes approached that observed in lipofuscin samples. CONCLUSIONS. Blue-light-induced photoreactivity of melanosomes increases with age, perhaps providing a source of reactive oxygen species and leading to depletion of vital cellular reductants, which, together with lipofuscin, may contribute to cellular dysfunction.

Original languageEnglish (US)
Pages (from-to)2088-2096
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Volume43
Issue number7
StatePublished - 2002
Externally publishedYes

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Melanosomes
Lipofuscin
Retinal Pigments
Oxygen
Hydrogen Peroxide
Light
Reactive Oxygen Species
Spin Trapping
Singlet Oxygen
Lipid Peroxides
Reducing Agents
Superoxides
Albumins
Oxidoreductases
Electrodes
Epithelial Cells
Lipids

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Rózanowska, M., Korytowski, W., Rózanowski, B., Skumatz, C., Boulton, M. E., Burke, J. M., & Sarna, T. (2002). Photoreactivity of aged human RPE melanosomes: A comparison with lipofuscin. Investigative Ophthalmology and Visual Science, 43(7), 2088-2096.

Photoreactivity of aged human RPE melanosomes : A comparison with lipofuscin. / Rózanowska, Małgorzata; Korytowski, Witold; Rózanowski, Bartosz; Skumatz, Christine; Boulton, Mike E.; Burke, Janice M.; Sarna, Tadeusz.

In: Investigative Ophthalmology and Visual Science, Vol. 43, No. 7, 2002, p. 2088-2096.

Research output: Contribution to journalArticle

Rózanowska, M, Korytowski, W, Rózanowski, B, Skumatz, C, Boulton, ME, Burke, JM & Sarna, T 2002, 'Photoreactivity of aged human RPE melanosomes: A comparison with lipofuscin', Investigative Ophthalmology and Visual Science, vol. 43, no. 7, pp. 2088-2096.
Rózanowska M, Korytowski W, Rózanowski B, Skumatz C, Boulton ME, Burke JM et al. Photoreactivity of aged human RPE melanosomes: A comparison with lipofuscin. Investigative Ophthalmology and Visual Science. 2002;43(7):2088-2096.
Rózanowska, Małgorzata ; Korytowski, Witold ; Rózanowski, Bartosz ; Skumatz, Christine ; Boulton, Mike E. ; Burke, Janice M. ; Sarna, Tadeusz. / Photoreactivity of aged human RPE melanosomes : A comparison with lipofuscin. In: Investigative Ophthalmology and Visual Science. 2002 ; Vol. 43, No. 7. pp. 2088-2096.
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abstract = "PURPOSE. To determine whether aging is accompanied by changes in aerobic photoreactivity of retinal pigment epithelial (RPE) melanosomes isolated from human donors of different ages, and to compare the photoreactivity of aged melanosomes with that of RPE lipofuscin. METHODS. Human RPE pigment granules were isolated from RPE cells pooled into groups according to the age of the donors. Photoreactivity was determined by blue-light-induced oxygen uptake and photogeneration of reactive oxygen species. Short-lived radical intermediates were detected by spin-trapping, hydrogen peroxide by an oxidase electrode, singlet oxygen by cholesterol assay, and lipid hydroperoxides by iodometric assay. RESULTS. Blue-light photoexcitation of melanosomes resulted in age-related increases in both oxygen uptake and the accumulation of superoxide anion spin adducts. The efficiencies of these processes, however, were still significantly lower than that induced by photoexcited lipofuscin. During irradiation of melanosomes, a substantial amount of oxygen was converted into hydrogen peroxide, whereas for lipofuscin, hydrogen peroxide accounted for not more than 3{\%} of oxygen consumed. In contrast to lipofuscin, photoexcited melanosomes did not substantially increase the rate of oxidative reactions in the presence of polyunsaturated lipids or albumin. However, oxygen uptake was significantly elevated in the presence of ascorbate. Thus, the rate of photo-induced oxygen uptake in samples containing both ascorbate and melanosomes approached that observed in lipofuscin samples. CONCLUSIONS. Blue-light-induced photoreactivity of melanosomes increases with age, perhaps providing a source of reactive oxygen species and leading to depletion of vital cellular reductants, which, together with lipofuscin, may contribute to cellular dysfunction.",
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T2 - A comparison with lipofuscin

AU - Rózanowska, Małgorzata

AU - Korytowski, Witold

AU - Rózanowski, Bartosz

AU - Skumatz, Christine

AU - Boulton, Mike E.

AU - Burke, Janice M.

AU - Sarna, Tadeusz

PY - 2002

Y1 - 2002

N2 - PURPOSE. To determine whether aging is accompanied by changes in aerobic photoreactivity of retinal pigment epithelial (RPE) melanosomes isolated from human donors of different ages, and to compare the photoreactivity of aged melanosomes with that of RPE lipofuscin. METHODS. Human RPE pigment granules were isolated from RPE cells pooled into groups according to the age of the donors. Photoreactivity was determined by blue-light-induced oxygen uptake and photogeneration of reactive oxygen species. Short-lived radical intermediates were detected by spin-trapping, hydrogen peroxide by an oxidase electrode, singlet oxygen by cholesterol assay, and lipid hydroperoxides by iodometric assay. RESULTS. Blue-light photoexcitation of melanosomes resulted in age-related increases in both oxygen uptake and the accumulation of superoxide anion spin adducts. The efficiencies of these processes, however, were still significantly lower than that induced by photoexcited lipofuscin. During irradiation of melanosomes, a substantial amount of oxygen was converted into hydrogen peroxide, whereas for lipofuscin, hydrogen peroxide accounted for not more than 3% of oxygen consumed. In contrast to lipofuscin, photoexcited melanosomes did not substantially increase the rate of oxidative reactions in the presence of polyunsaturated lipids or albumin. However, oxygen uptake was significantly elevated in the presence of ascorbate. Thus, the rate of photo-induced oxygen uptake in samples containing both ascorbate and melanosomes approached that observed in lipofuscin samples. CONCLUSIONS. Blue-light-induced photoreactivity of melanosomes increases with age, perhaps providing a source of reactive oxygen species and leading to depletion of vital cellular reductants, which, together with lipofuscin, may contribute to cellular dysfunction.

AB - PURPOSE. To determine whether aging is accompanied by changes in aerobic photoreactivity of retinal pigment epithelial (RPE) melanosomes isolated from human donors of different ages, and to compare the photoreactivity of aged melanosomes with that of RPE lipofuscin. METHODS. Human RPE pigment granules were isolated from RPE cells pooled into groups according to the age of the donors. Photoreactivity was determined by blue-light-induced oxygen uptake and photogeneration of reactive oxygen species. Short-lived radical intermediates were detected by spin-trapping, hydrogen peroxide by an oxidase electrode, singlet oxygen by cholesterol assay, and lipid hydroperoxides by iodometric assay. RESULTS. Blue-light photoexcitation of melanosomes resulted in age-related increases in both oxygen uptake and the accumulation of superoxide anion spin adducts. The efficiencies of these processes, however, were still significantly lower than that induced by photoexcited lipofuscin. During irradiation of melanosomes, a substantial amount of oxygen was converted into hydrogen peroxide, whereas for lipofuscin, hydrogen peroxide accounted for not more than 3% of oxygen consumed. In contrast to lipofuscin, photoexcited melanosomes did not substantially increase the rate of oxidative reactions in the presence of polyunsaturated lipids or albumin. However, oxygen uptake was significantly elevated in the presence of ascorbate. Thus, the rate of photo-induced oxygen uptake in samples containing both ascorbate and melanosomes approached that observed in lipofuscin samples. CONCLUSIONS. Blue-light-induced photoreactivity of melanosomes increases with age, perhaps providing a source of reactive oxygen species and leading to depletion of vital cellular reductants, which, together with lipofuscin, may contribute to cellular dysfunction.

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