Mitochondrial coenzyme Q content and aging.

The main objective of this study was to determine the nature of the relationship between aging and mitochondrial coenzyme Q (CoQ) content. Mitochondria in the heart, skeletal muscle, kidney and brain of the mouse varied in both the amount of total CoQ (CoQ9 + CoQ10) content as well as in the ratio of the CoQ9 to CoQ10. CoQ content declined with age only in the skeletal muscle. Caloric restriction (CR) resulted in an increase in the amount of CoQ9 in skeletal muscle mitochondria. This effect was partially reversible upon termination of the caloric restriction regimen. Results suggest that a decrease in mitochondrial CoQ content is an integral aspect of aging in skeletal muscle.