POSTNATAL-DEVELOPMENT OF THE COMPLEXES OF THE ELECTRON-TRANSPORT CHAIN IN ISOLATED RAT-BRAIN MITOCHONDRIA

The postnatal development of the complexes of the electron transport c hain in isolated rat brain mitochondria were investigated. Nonsynaptos omal brain mitochondria were isolated from rats aged 1-60 days, and th e activities of mitochondrial complexes I, II-III, IV, V and citrate s ynthase were measured. There was a significant increase in the activit y of complex I from postnatal day 1 to day 21, and in the activities o f complex II-III, complex IV and citrate synthase from postnatal day 1 to day 60. In contrast, the activity of complex V increased significa ntly between postnatal day 1 and day 10 where it attained adult levels . These data are consistent with the increasing demand for mitochondri al ATP production as the brain develops and as aerobic glycolysis beco mes the major pathway for energy production.