ABSTRACT
Lipid peroxidation was measured by release of thiobarbituric acid-reactive substances (TBARS) into the supernatant of cultured human skin fibroblasts. This process is triggered by ultraviolet A (UVA) and ultraviolet B (UVB) radiations. For UVA irradiances and irradiation times up to 40 W.m-2 and 90 min, respectively, the peroxidation response is linear and obeys the reciprocity law. Corresponding values for UVB are 12 W.m-2 and 30 min, respectively. The action spectrum of the peroxidation process shows a continuously increasing response from about 425 to 275 nm. Whereas the UVB to UVA effectiveness ratio lies in the range of 10(3) to 10(4) for most in vitro or in vivo UV-induced responses, the ratio is only 10 to 100 for the peroxidation process. Given the solar spectral distribution, solar UVA radiation is by far the most effective in triggering the peroxidation response.
Subject(s)
Lipid Peroxidation/radiation effects , Skin/radiation effects , Ultraviolet Rays , Breast , Cells, Cultured , Female , Fibroblasts/metabolism , Fibroblasts/radiation effects , Humans , Kinetics , Skin/metabolism , Thiobarbituric Acid Reactive Substances/analysis , Time FactorsSubject(s)
Lipid Peroxidation/radiation effects , Oxygen/metabolism , Skin/metabolism , Skin/radiation effects , Ultraviolet Rays/adverse effects , Azides/pharmacology , Cells, Cultured , Deuterium Oxide/pharmacology , Fibroblasts/metabolism , Fibroblasts/radiation effects , Humans , Singlet Oxygen , Thiobarbituric Acid Reactive Substances/metabolismABSTRACT
UVA-induced lipid peroxidation in cultured human skin fibroblasts, as measured by the release in the supernatant of thiobarbituric acid-reactive substances, is found to be linear with increasing irradiation dose (up to about 250 kJ m(-2)). Concomitantly, within this dose range catalase is strongly inactivated by UVA radiation according to an exponential process (k≈0.01 kJ(-1) m(2)). This suggests that catalase is not involved in modulating the peroxidation process. Inactivation of catalase by 3-amino-1,2,4-triazole can be efficiently achieved prior to irradiation. This inactivation has no consequence on the extent of peroxidation triggered by subsequent exposure to UVA radiation. It may be therefore strongly suggested that catalase is not, via H2O2 removal, a key enzyme in the cellular defence equipment towards UV A-peroxidative stress. An alternative interpretation may be formulated which supports the view that H2O2 produced upon exposure to UVA has no or very little role in triggering the lipid peroxidation process.
