Figure 4

Activity of mitochondrial respiratory chain (MRC) complexes of osteoarthritic (OA) synoviocytes incubated with sodium nitroprusside (SNP). A) Confluent synoviocytes were incubated for 48 hours under basal conditions (RPMI only) or with SNP at 0.5 mM and MRC complex activities were measured as reported in Methods. Citrate synthase (CS)-corrected complex activity is expressed as nmol/min/mg protein/CS specific activity x100. Complex I = rotenone-sensitive NADH-coenzyme Q1 reductase; Complex II = succinate dehydrogenase; Complex III = antimycin-sensitive ubiuqinol cytocrome c reductase; Complex IV = cytocrome c oxidase. The values are the mean ± standard error of six experiments performed in duplicate (*p < 0.05). B) The activity of CS following stimulation with SNP at 0.5 mM was evaluated. The values are the mean ± standard error of six experiments performed in duplicate (*p < 0.05).