Figure 2.

Representative EPR spectra generated using the spin trap DMPO. Spectra were determined in the presence of mitochondria of gastrocnemius (gastroc), heart, or liver from control or 2-month diabetic rats incubated in respiratory buffer under state 4 conditions with 5 mm succinate plus the additions indicated. The signals, which could represent either superoxide or the hydroxyl radical (because both react with the spin trap to generate the same spectrum), were abolished by addition of MnSOD (F), demonstrating specificity for superoxide. Note the scale difference for gastrocnemius mitochondria incubated in the presence of antimycin A (E) and the scale differences by tissue. Additions consisted of 5 μm rotenone, 80 nm stigmatellin, 1 μm antimycin A, or 200 μg/ml manganese superoxide dismutase (SOD).