SIN-1-induced DNA damage in isolated human peripheral blood lymphocytes as assessed by single cell gel electrophoresis (comet assay).
Human lymphocytes were exposed to increasing concentrations of SIN-1, which generates superoxide and nitric oxide, and the formation of single-strand breaks (SSB) in individual cells was determined by the single-cell gel electrophoresis assay (comet assay). A dose- and time-dependent increase in SSB formation was observed rapidly after the addition of SIN-1 (0.1-15 mM). Exposure of the cells to SIN-1 (5 mM) in the presence of excess of superoxide dismutase (0.375 mM) increased the formation of SSB significantly, whereas 1000 U/ml catalase significantly decreased the quantity of SSB. The simultaneous presence of both superoxide dismutase and catalase before the addition of SIN-1 brought the level of SSB to that of the untreated cells. Moreover, pretreatment of the cells with the intracellular Ca(2+)-chelator BAPTA/AM inhibited SIN-1-induced DNA damage, indicating the involvement of intracellular Ca(2+) changes in this process. On the other hand, pretreatment of the same cells with ascorbate or dehydroascorbate did not offer any significant protection in this system. The data suggest that H2O2-induced changes in Ca(2+) homeostasis are the predominant pathway for the induction of SSB in human lymphocytes exposed to oxidants.
Doulias
P T
PT
Laboratory of Biological Chemistry, University of Ioannina Medical School, Ioannina, Greece.
Barbouti
A
A
Galaris
D
D
Ischiropoulos
H
H
D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004277:DNA, Single-Stranded / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D008860:Microscopy, Ultraviolet; D008981:Molsidomine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009566:Nitrates / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism
D002614:Chelating Agents; D004277:DNA, Single-Stranded; D009566:Nitrates; D020030:Nitric Oxide Donors; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C039642:peroxynitric acid; D004533:Egtazic Acid; C002385:linsidomine; D008981:Molsidomine; D002374:Catalase; D013482:Superoxide Dismutase; D001205:Ascorbic Acid; D002118:Calcium