Figure 6.

Scavenging peroxynitrite-derived radicals reverses the decrease of mitochondrial complex IV activity in human MD-Schwann cells. A, mitochondrial complex I, II + III, and IV activities were assessed in disrupted mitochondria of WT- and MD-Schwann cells isolated after 48 h incubation in the absence and presence of urate (100 μm). Complex activities are expressed as % inhibitor-sensitive complex activity respect to WT-Schwann cells. Columns represent the mean ± S.D. (n = 4–6). B, mitochondrial complex I, II + III, and IV activity was assessed by extracellular flux analysis in permeabilized mitochondria. On the left, representative OCR experiments (mean ± S.D. of 5 replicates). Cells were permeabilized during the first injection (Perm), and ADP was added to couple the activity of the complexes to ATP production. Malate-glutamate was added as substrate for complex I, succinate as substrate for complex II, and TMPD/ascorbate as substrate of complex IV. Azide was used to inhibit complex IV activity. Complex activities are expressed as % inhibitor-sensitive complex activity in respect to WT-Schwann cells (n = 3–4 with 5 replicates). *, p < 0.01 versus untreated WT- or MD-Schwann cells, and **, p < 0.01 versus untreated MD-Schwann cells by Kruskal-Wallis test followed by Dunn's post test.