NO2 accumulation in supernatants of normal chondrocytes treated with different NO donors depend ing on time and concentration. Effect of NO on cell death of normal human articular because chondrocytes NO donors damage the nuclear DNA of human articular chondrocytes in very different ways. By means of flow cyto metry with PI, we could observe that the percentage of death cells was much higher with SNP than NOC 12, with 1 mM SNP at 24 hours, 25. 9 23. 3 versus 0. 8 0. 5 compared with 1 mM NOC 12 at 24 hours, 4. 3 1. 9 versus 0. 8 0. 5. However, with higher concentrations of NOC 12, the percentage of apoptosis reached 21. 6 8. 5%. Besides this, when the cells were stained with DAPI we could see that the only NO donor able to induce the fragmentation of the nucleus and the formation of apoptotic bodies was SNP.

The only effect of NOC 12 on the nucleus of chondrocytes was the Inhibitors,Modulators,Libraries acquisi tion of a globule like aspect. NOC 12 alters the activity of the complexes of the mitochondrial respiratory chain in articular chondrocytes Previous results obtained in our laboratory showed that the activity of the complex IV is significantly lower in normal chondrocytes Inhibitors,Modulators,Libraries stimulated with 1 mM SNP at 5 hours than in control cells. In relation with the enzymatic activity of the MRC of normal chon drocytes treated with the diazeniumdiolate compound NOC 12, the activities of all complexes were signifi cantly lower than in control cells, except complex II. Enzyme activities were referred to the specific activity of CS to correct for mitochondrial volume.

NO causes depolarization of the mitochondria in normal chondrocytes Inhibitors,Modulators,Libraries The relative ratio of red green fluorescence intensity values showed that in normal human chondrocyte cultures 1 mM SNP at 24 hours decreased the ratio of red green fluorescence in Inhibitors,Modulators,Libraries compar ison with untreated cells. In addition, 1 mM SNP caused an increase in the cell population with mitochondrial depo larization. On the other hand, NOC 12 induced mito chondrial depolarization, as the percentage of cells with normal polarization diminished, with 1 mM NOC 12 at 24 hours, 27. 7 17. 9 versus 14. 1 3. 6, P 0. 05, and the percentage of cells with depolarization increased, 12. 2 6. 6 versus 18. 8 11. 3, P 0. 05. This finding also can be observed with decreasing ratio of red green fluorescence in comparison with untreated cells.

However, the NO donor that induced the strongest changes in the mitochondrial membrane potential was SNP. NO abolishes ATP generation by chondrocytes in culture NO has a detrimental effect on the generation of Inhibitors,Modulators,Libraries ATP by normal chondrocytes. meanwhile With NOC 12, the intracellular ATP levels were significantly lower than in control cells, with 1mM NOC 12 at 24 hours, 0. 40 0. 16 versus 0. 57 0. 19. Again, the NO donor that induced the most dramatic changes was SNP, as it reduced the intracellular ATP levels practi cally to zero.