Protective effect of low-concentration sodium nitroprusside (SNP) on 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 0.1 mM SNP or 1 mM dibutylyl guanosine-3',5'-cyclic monophosphate (DBcGMP) 14 hours prior to 1 mM SNP treatment. To inhibit cyclic guanylase, 1 μM Ly83583 was added with 0.1 mM of SNP. (a) Cell death was quantitated using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazdium bromide assay. Cell survival in control cultures was set at 100%. Data shown are the means and standard deviations of triplicate experiments from at least three different donors. * P < 0.05 versus control. (b) Cell death was verified by propidium iodide staining and fluorescence-activated cell sorting analysis. Chondrocytes were trypsinized after treatment and were sedimented. Cell pellets obtained were washed and stained in 100 μg/ml propidium iodide solution for 15 min. For each sample, 104 cells were analyzed. Data are representative of samples from four different donors. Percentage values denote propidium iodide positive (dead) chondrocytes.
Kim et al. Arthritis Research & Therapy 2005 7:R526-R535 doi:10.1186/ar1705