Relationship of cytochrome oxidase activity to vertebrate total and organ oxygen consumption

1. 1. Cytochrome oxidase activity shows a precise exponential relationship to total O 2 consumption among various vertebrate species with different O 2 , consumptions. A similar relationship between cytochrome oxidase activity and organ O 2 consumption has been demonstrated in a single species (rabbit). 2. 2. These findings suggest that cytochrome oxidase activity may represent a quantitative biochemical marker for functional mitochondrial mass. 3. 3. The regulation of cytochrome oxidase activity may represent a long-term regulatory mechanism involving mitochondrial O 2 uptake in different species and different tissues.