(C) Respiratory chain enzyme activities. Relative enzyme activities of respiratory chain enzyme C I (NADH coenzyme Q reductase), C I/III (NADH cytochrome c reductase), C II (succinate dehydrogenase), C II/III (succinate cytochrome c reductase) and C IV (cytochrome c oxidase) in mitochondrial extracts from wild type and Clpp knockout hearts. (n=5). Bars present mean levels ± SD. Statistical difference was calculated by Student's t-test and changes are presented in the figure (n=5). 