Development of resistance of the outer membrane of brain and liver mitochondria.

The outer membrane resistance of brain and liver mitochondria to the action of digitonin was studied in 5- and 60-day-old rats. Disintegration of the outer membrane was evaluated by means of cytochrome oxidase activity. The mitochondria were isolated by the Ficoll gradient method. Brain mitochondria were found to be significantly more resistant to digitonin than liver mitochondria. It was also demonstrated that the resistance of the outer membrane of both brain and liver mitochondria rose approximately 1.3- to 1.4-fold during ontogenesis.