title: Mechanisms of sodium nitroprusside-induced death in human chondrocytes.
abstract: The nitric oxide (NO) donor sodium nitroprusside (SNP) has been used to study NO-dependent cell death in human chondrocytes. This study compares SNP-induced chondrocyte death and SNP-activated signaling mechanisms with apoptosis induced by CD95 activation. Sodium nitroprusside increased cell death dose-dependently. Compared to CD95 stimulation, SNP induced only low levels of internucleosomal DNA fragmentation as measured by cell-death enzyme-linked immunosorbent assay (ELISA). However, SNP caused substantial nuclear DNA cleavage, as evidenced by terminal deoxynucleotidyltransferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL). Caspase-3 processing in response to SNP was not detected. The pancaspase inhibitor Z-VAD.FMK partially abrogated the TUNEL signal but did not block cell death or internucleosomal DNA fragmentation. The caspase-3-specific inhibitor Ac-DEVD-CHO did not inhibit the SNP-induced TUNEL signal or internucleosomal DNA fragmentation. DNA degradation was not blocked by the p38 inhibitor SB 202190 but by the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine. The results of this study support the hypothesis that the phenotype and mechanisms of SNP-induced chondrocyte death are distinct from apoptosis induction via CD95.
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D020169:Caspases / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects*; D053938:DNA Fragmentation / Q000187:drug effects; D006801:Humans; D020287:In Situ Nick-End Labeling; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects; D009336:Necrosis; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000187:drug effects; D019014:fas Receptor / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; D019014:fas Receptor; D009599:Nitroprusside; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases