Fig. 4

Mitochondrial adaptations following 6 weeks of voluntary wheel training. a Representative Western blots of COXI, COXII, COXIV and TFAM expression on isolated mitochondria from untrained and trained skeletal muscle of Parkin KO and WT animals. b Graphical representation of mitochondrial COXI expression (n = 8). c Quantification of mitochondrial COXII content (n = 4). d Mitochondrial yield of mixed hindlimb muscles of Parkin KO and WT animals (n = 4). e Skeletal muscle cytochrome c oxidase (COX) activity following training in quadriceps muscle of Parkin KO and WT animals (n = 5). f Mitochondrial state 4 and state 3 respiration rates in KO compared with WT animals (n = 8). g Mitochondrial ROS emission expressed per natom of oxygen consumed in Parkin KO and WT mice (n = 8; ¶P < 0.05, vs state 4 trained WT). Values are means ± SEM. *P < 0.05, main effect of training; #P < 0.05, main effect of genotype; †P < 0.05, interaction effect of genotype and training. Voltage-dependent anion channel (VDAC) was used as a mitochondrial loading control. WT, wild type; KO, Parkin knockout; UT, untrained; T, trained; COX1, cytochrome c oxidase subunit 1; COXII, cytochrome c oxidase subunit 2; COX4, cytochrome c oxidase subunit 4; TFAM, mitochondrial transcription factor A; ROS, reactive oxygen species; A.U., arbitrary units