FIGURE 4.

Both peroxisomes and mitochondria are potential sources of increased H₂O₂ production during high fat feeding. Protein concentrations of ACOX1 and ACADVL were determined by mass spectrometry analysis of whole heart lysates from mice maintained on either a high fat or a low fat control diet. Rate of H₂O₂ production was determined using isolated cardiac mitochondria. A and B, ACOX1 and ACADVL protein concentration, as determined by mass spectrometry, in mice maintained on either a high fat (closed bars) or a low fat control (open bars) diet for 1–3 days (d). C, representative trace of H₂O₂ production (see under “Experimental Procedures”) from mitochondria, isolated from low fat-fed mice, respiring on either palmitoylcarnitine or pyruvate. D, mean rate of H₂O₂ production, during pyruvate- (Pry) (open bar) or palmitoylcarnitine (PC) (closed bar)-supported respiration, from mitochondria isolated from mice maintained on a low fat diet for 2 weeks. Values are presented as the mean ± S.D. (n ≥5), where * indicates a significant increase (2-tailed t test) in high fat-fed mice versus low fat-fed controls within each diet duration (p < 0.01).