Figure 4. .

Respiration assays. (A) Average rates of endogenous O₂ consumption per cell measured in different cell lines. A total of four determinations were performed on each of the lymphoblastoid cell lines. (B) Polarographic analysis of O₂ consumption in digitonin-permeabilized cells of the various cell lines using different substrates and inhibitors. The activities of the various components of the respiratory chain were investigated by measuring, on 1 × 10⁷ digitonin-permeabilized cells, the respiration dependent on malate/glutamate, succinate/G3P, and TMPD/ascorbate. A total of four determinations were performed on each of the lymphoblastoid cell lines: mal/glu, malate/glutamate-dependent respiration; succ/G3P, succinate/G3P-dependent respiration; TMPD/asc, TMPD/ascorbate-dependent respiration. The average of three to six determinations for each cell line is shown. The error bars indicate 2 SE of the mean; P indicates the significance, according to the t-test, of the difference between mutant mean and control mean.