抄録
Cytochrome oxidase activity in rat metaphyseal bone cells was determined by enzyme cytochemistry. Factors such as fixation, incubation time and permeability of diaminobenzidine and cytochrome c, which might affect cytochemical reactivity of the enzyme, were evaluated. Three levels of cytochrome oxidase reactivity were observed in the mitochondria of each type of bone cell. These were 1) staining of the entire membrane system of mitochondria (type I), 2) partial staining in which only cristae were stained (type II) and 3) no staining (type III). In most osteoclasts, type I mitochondria predominated, and types II and III were few in number. Osteoblasts possessed mixed populations of mitochondria consisting mainly of types I and II, but some osteoblasts appeared to be in a functional transition and contained mitochondria weak in activity. Osteocytes had largely type III and few type II mitochondria. The results indicate that heterogeneity of cytochrome oxidase activity exists in bone cell mitochondria and that osteoclasts have the most active aerobic metabolism among bone cells, whereas osteoblasts favor oxidative metabolism and osteocytes are anaerobic.
