Effect of 1-hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5) on the cytotoxic effect of 1 mM sodium nitroprusside (SNP) in human articular chondrocytes. Cell death was induced by treating chondrocytes with 1 mM SNP for 24 hours. To protect them from cell death, chondrocytes were treated with various concentrations of NOC-5 for 14 hours prior to 1 mM SNP treatment. Cell death was quantitated by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazdium bromide assay. Cell survival in control cultures was set at 100%. Data are the means and standard deviations of triplicate experiments on nine different donors. * P < 0.05 versus treatment with 1 mM SNP without NOC-5 pretreatment.