Respiration rates were measured in isolated mitochondria (A,B,C) and permeabilized fibers (D and E) with substrates targeting complex I (CI), complex I+II (CI+II), and complex II (CII). Non-mitochondrial oxygen consumption was measured in the presence of antimycin A (AA). In isolated mitochondria, respiration rates were expressed per tissue wet (A), mitochondrial protein content (B), and mitochondrial DNA copy number (C). In permeabilized muscle fibers, respiration rates were expressed per tissue wet (D) and mitochondrial DNA copy number (E).
(F and G) Respiratory control ratio (RCR, state 3/state 4) and phosphorylation efficiency (ADP:O) were measured in isolated mitochondria.
Bars represent means ± SEM for young ad libitum mice (YAL), old ad libitum mice (OAL), and old caloric restricted mice (OCR). * represents significant statistical differences from YAL (P<0.05, Tukey’s HSD). # represents significant statistical differences from OAL (P<0.05, Tukey’s HSD). N=6–8 per group.