Figure 4. Mitochondrial respiration as a function of age.

Mitochondrial respiration rates (states 3 and 4) of Dm4_Control C3 and Dm4_SOD/OCAT E1 flies were measured using pyruvate+proline as substrates, and expressed as nmol of O₂·min⁻¹·mg of protein⁻¹. Results are means±S.D. for three independent experiments at each age. (A) State 3 respiration (in the presence of excess substrate and ADP) was the same in both groups at 10 days of age, but it was lower in experimental versus control flies at 20 and 40 days of age. (B) State 4 respiration (in the presence of excess substrate after exhaustion of ADP) was well maintained at all ages tested.