Mapping of mitochondrial metabolic competence by cytochrome oxidase and succinic dehydrogenase cytochemistry

To map the mitochondrial capacity to provide adenosine triphosphate (ATP), the activities of cytochrome oxidase (COX) and succinic dehydrogenase (SDH) were respectively evidenced by diaminobenzidine (DAB) and copper ferrocyan ide cytochemical techniques in the cerebellar cortex of adult rats. Samplin g of the positive mitochondria was carried out by the disector procedure. T he ratio (R) overall area of the precipitates due to COX activity within th e single mitochondrion/area of the same organelle was automatically calcula ted to estimate enzyme activity vs mitochondrial size. The number of SDH-po sitive mitochondria/mum(3) of tissue (numeric density, Nv) was morphometric ally calculated. Cytochemistry of key enzymes of the respiratory chain enab les measurement of the actual capacity of individual mitochondria to provid e ATP. This quantitative estimation allows morphofunctional mapping of the mitochondrial metabolic competence in discrete tissue and/or cellular compa rtments.