Figure 4.

Biochemical assessments on brain purified mitochondria from control and homozygous mito-G93ASOD1 mice. A, Representative graph showing the sensitivity of brain mitochondria respiration to successive additions of 2 nm SF6847, in one non-transgenic and one mito-G93ASOD1 mouse. B, Graph representing the amount of SF6847 required to totally uncouple mitochondria respiration, determined by the respiration rate, in nanomoles of O₂ per minute per picomole of SF6847. Means ± SEM are shown for 4 individual brain mitochondria preparations per group. Samples were run in duplicates. NS, not significant; *p = 0.0387 after one-tailed, unpaired, Student's t test versus non-transgenic mitochondria. Mito-G93ASOD1 brain mitochondria are more sensitive to the uncoupling effect of SF6847 than are non-transgenic ones. C, Kinetic traces of mitochondrial Ca²⁺ uptake in brain mitochondria from 12-month-old mice monitored by Fura 6 fluorescence ratio (340/380 nm excitation, 510 nm emission). The peaks correspond to sequential bolus additions of 25 nmol of CaCl₂ (Ca²⁺). The downward deflections reflect mitochondria Ca²⁺ uptake. Non-transgenic and mito-WTSOD1 mitochondria took up 4 additions of Ca²⁺, whereas mito-G93ASOD1 showed loss of Ca²⁺ uptake after 3 additions. D, Brain mitochondrial Ca²⁺ capacity expressed in nanomoles of Ca²⁺ per milligram of protein. Mean ± SEM is shown for 3–7 independent brain mitochondrial preparations. Samples were run in duplicates. *p = 0.019 versus non-transgenic mitochondria. Mito-G93ASOD1 brain mitochondria take up less Ca²⁺ than mito-WTSOD1 and non-transgenic mitochondria. E, F, COX and CS enzymatic activities measured in spinal cord lysates from 12-month-old non-transgenic and mito-G93ASOD1 mice. Means ± SEM are shown for n = 7–8 mice per group. Samples were run in duplicates or triplicates. *p = 0.05 and 0.007 for COX and COX/CS, respectively, versus non-transgenic mice. Mito-G93ASOD1^tg/tg mitochondria have significantly lower COX activity than non-transgenic ones. Mito-WTSOD1 and mito-G93ASOD1 mitochondria were compared with their respective matched non-transgenic controls.