FIG. 6.

Mitochondrial function after chronic exercise. A: Active rates of respiration (state 3) were measured in saponin-skinned fibers in the presence of 5 mmol/l ADP and either 10 mmol/l pyruvate (Pyr) + 2 mmol/l malate or 10 mmol/l succinate (Succ) + 5 μmol/l rotenone. Rates of respiration are given as pmol O₂/second/mg wet weight. B: Effects on enzymatic activity of the respiratory chain complexes. Citrate synthase (CS) normalized complex I activity (rotenone-sensitive NADH:CoQ₁ oxidoreductase) is higher in the skeletal muscle of all trained mice (hatched columns) compared with the respective controls. CS normalized activity of complex IV is similar among the groups (numbers of animals as described in Fig. 1). Data are means ± SEM. *P < 0.05. C, controls; T, trained mice.