Respiration and redox behavior of mitochondria in the presence of AF and/or DNCB. (A and B) Freshly isolated mitochondria from guinea pig heart were handled and assayed, as described in Materials and methods. Mitochondrial respiration (VO₂) was monitored under FET conditions in state 4 with G/M (A) and state 3 after addition of 1 mM ADP (B) in the absence or the presence of 50 nM AF or 10 µM DNCB or both together. The statistical significance of the differences between treatments was evaluated with ANOVA using Tukey’s multiple comparison test (*, p < 0.05; ***, p < 0.001). (C) The same mitochondrial preparation was analyzed in parallel by fluorometry for NADH and H₂O₂ emission (see Table 4), which were monitored simultaneously after preincubation, with the concentrations of AF and DNCB indicated. Arrows point to substrate (G/M and ADP) addition. In the whisker plots, the top and the bottom of the box represent the 75 and 25% percentile, respectively, whereas the line within the box is the median; the bars indicate the maximum and minimum values of the distribution. The numbers on top of the whisker plots correspond to the mean ± SEM (n = 12, with two experiments). prot., protein.