Age-dependent changes in the structure-function correlation of ADP/ATP-translocating mitochondrial membranes.

Morphological changes in rat heart mitochondria following mobilization of the adenine nucleotide binding sites from the matrix to the cytosolic face of the inner membrane have been documented in this paper by means of electron microscopy. Significant differences in the shape of cristae membranes could be established when rat heart mitochondria from 3- and 30-month-old animals were compared. Changes in structural organization of the inner membrane - an event associated with the function of the adenine nucleotide carrier - were found to be distinctly less marked in mitochondria from the aged group. Kinetic analysis of this process revealed that both the velocity and the extent of conformational membrane changes were reduced as the animal ages. These observations are discussed in relation to the finding, also described in this paper, that aging is linked to a drastic decrease in the activity of adenosine diphosphate/adenosine triphosphate exchange.