Evidence for increased degeneration of mitochondria in old rats. A brief note.

An isotonic density gradient technique for separating mitochondria into two major components was applied to mitochondria isolated from young and old rats. Respiratory measuremtns indicate that the depression of state 3 respiration rates observed in the mitochondria from old rats when glutamate--malate is used as a substrate is due primarily to the faster sedimenting mitochondrial component.