EXERCISE AND DIET MODULATE CARDIAC LIPID-PEROXIDATION AND ANTIOXIDANTDEFENSES

Free radical metabolism can be altered by several interventions, inclu ding dietary restriction (DR) and exercise. Most of the previous work has focused on the liver and skeletal muscle. The following experiment s were performed to determine whether long-term DR and chronic exercis e affect free radical metabolism and change the status of the antioxid ant defenses of the heart. Rats were subjected to DR and/or endurance exercise for 18.5 months and were sacrificed along with their ad lib f ed and sedentary controls. Both DR and exercise decreased the malondia ldehyde content of cardiac mitochondria, indicating a decrease in lipi d peroxidation damage. The antioxidant enzymes in the cytosol, superox ide dismutase, selenium dependent glutathione peroxidase, and glutathi one S-transferase were al. increased by DR. Catalase activity was unaf fected by DR but was increased by exercise. The following results demo nstrate that long-term DR :ind exercise modulate the extent of free ra dical damage in the heart and enhance the antioxidant defense system.