Effect of age and caloric restriction on coenzyme Q and alpha-tocopherol levels in the rat.

Alterations in the amount of coenzyme Q and alpha-tocopherol during aging and in response to 40% reduction in caloric intake were determined in homogenates and mitochondria of liver, heart and kidney of the rat. A comparison among 4-, 19- and 28-month-old ad libitum fed (AL) rats indicated an age-related loss in the amount of CoQ9 and alpha-tocopherol in mitochondria of all the three tissues. Depletion of alpha-tocopherol, but not of CoQ, was also detectable in tissue homogenates, apparently due to the preferential sequestration of CoQ in the mitochondrial fraction. Comparison of 19-month-old AL and calorically restricted (CR) rats indicated that CR elevates the level of mitochondrial CoQ, but greatly diminishes the alpha-tocopherol content. Activity of DT-diaphorase, a quinone reductase, increased with age as well as in response to CR. Altogether, results are interpreted to suggest that the widely observed age-related increase in mitochondrial oxidative damage may be associated with depletion of CoQ and alpha-tocopherol, which are known to act in tandem to prevent oxidative damage to membranes.