Fig. 5. Mitochondrial oxygen uptake as a function of myoglobin concentration using NADH (1 mmol l^–1) as the sole substrate. For this experiment mitochondria were prepared by a less stringent procedure, making the mitochondria able to use exogenous NADH. Polarographically determined specific oxygen uptakes of this mitochondrial preparation were 134 and 412 mol O₂ (mol cytochrome aa₃)^–1 min^–1 using glutamate/malate or NADH (1 mmol l^–1), respectively, as substrate. The latter may be compared to the rate exhibited by mitochondria fully uncoupled by exposure to carbonyl cyanide m-chlorophenylhydrazone (CCCP), 700 mol O₂ (mol cytochrome aa₃)^–1 min^–1.