Effects of procaine on the oxidative phosphorylation of brain mitochondria from senescent rats

Senescence affects cerebral metabolic functions. Various drugs have been tested to counteract the effects of aging on the brain. In this paper, we studied the influence of treatment using procaine, 1 mg per 100 g body weight, injected over a period of 3 days, to both young and old rats, on the phosphorylative oxidation properties of cerebral mitochondria. Respiratory activity decreased significantly in the brain of old rats. This reduction of oxygen consumption measured in the presence of glutamate, reached 31% in state 4, 25% in state 3 and, in the presence of succinate, 23% in state 4 without significant changes in state 3. The injection of procaine into young rats induced a significant increase of oxygen consumption rate with both glutamate and succinate as substrates. The same treatment administered to old rats was followed by a rise in respiratory activity, with values close to those observed in young control rats. Although the mechanism of action of procaine is not yet clear, there is some evidence that it interacts with membrane phospholipid sites. Therefore, it may be concluded that procaine facilitates oxygen transport towards the mitochondrial matrix by modifying the membrane structure in both old and young rats, although, in the latter case, this increase is not intended to improve the energetic properties of the mitochondrion.