title: Oxygen tension influences DNA fragmentation and cell death in glucocorticoid-treated thymocytes.
abstract: Internucleosomal DNA fragmentation and cell death induced by dexamethasone in rat thymocytes were inhibited when cells were cultured in 95% N2/5% CO2 atmosphere, in which oxygen was rapidly reduced to under 0.5%. DNA fragmentation was delayed by a less severe hypoxia in 5% oxygen whilst in cell cultured in high oxygen atmosphere (95% O2) cell death was increased. On the other hand, prolonged oxygen deprivation caused an increase of spontaneous apoptotic cell death. Hypoxia also inhibited DNA fragmentation induced by calcium ionophore A23187, but not by topoisomerase inhibitor camptothecin. These data support the hypothesis of the involvement of oxygen reactive species in calcium-mediated apoptosis and suggest a complex role of oxygen in the modulation of programmed cell death.
authors.affiliation: Dipartimento di Biochimica G. Moruzzi, Universita' di Bologna, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Stefanelli
authors.forename: I
authors.initials: I
authors.lastname: Stanic
authors.forename: F
authors.initials: F
authors.lastname: Bonavita
authors.forename: C
authors.initials: C
authors.lastname: Muscari
authors.forename: C
authors.initials: C
authors.lastname: Pignatti
authors.forename: C
authors.initials: C
authors.lastname: Rossoni
authors.forename: C M
authors.initials: CM
authors.lastname: Caldarera
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D000001:Calcimycin / Q000494:pharmacology; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D004587:Electrophoresis, Agar Gel; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: D018808:Transcription Factor AP-1; D016159:Tumor Suppressor Protein p53; D000001:Calcimycin; D003907:Dexamethasone; D004247:DNA; D007770:L-Lactate Dehydrogenase; D010100:Oxygen