Cu-Zn superoxide dismutase inhibits lactate dehydrogenase release and protects against cell death in murine fibroblasts pretreated with ultraviolet radiation.
The effects of adding Cu-Zn superoxide dismutase (Cu-Zn SOD) to culture medium of the murine fibroblast cell line, L-929, pretreated with UV-B (312 nm, 480 mJ/cm(2)) have been investigated. Cell injury was monitored by the release of lactate dehydrogenase (LDH) into the medium, and cell death by the trypan blue exclusion test. UV-B radiation induced cell death by apoptosis, as demonstrated by DNA fragmentation. Over the range 0.1-0.3 microm Cu-Zn SOD, a significant dose-dependent protection against cell death was obtained of the UV-B exposed cells. Cell death correlated with the amount of LDH released into the medium, and Cu-Zn SOD treatment inhibited this. Heat-denatured Cu-Zn SOD did not affect either cell viability or the release of LDH from the cells. Endogenous Cu-Zn SOD activity, monitored by chemiluminescence, decreased by 20% in UV-B-irradiated cells; the addition of 0.3 microm exogenous Cu-Zn SOD to the medium did not affect intracellular Cu-Zn SOD activity. These results establish that Cu-Zn SOD added to extracellular medium can protect cells against injury caused by UV-B exposure.
Kimura
H
H
Department of Biological Sciences, Faculty of Engineering, Gunma University, Kiryu, Gunma, 376-8515, Japan.
Minakami
H
H
Otsuki
K
K
Shoji
A
A
D000818:Animals; D017209:Apoptosis; D053938:DNA Fragmentation; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology / Q000528:radiation effects*; D007739:L Cells; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008163:Luminescent Measurements; D051379:Mice; D013482:Superoxide Dismutase / Q000378:metabolism*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase