Exercise and diet modulate cardiac lipid peroxidation and antioxidant defenses.

Free radical metabolism can be altered by several interventions, including dietary restriction (DR) and exercise. Most of the previous work has focused on the liver and skeletal muscle. The following experiments were performed to determine whether long-term DR and chronic exercise affect free radical metabolism and change the status of the antioxidant 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 fed and sedentary controls. Both DR and exercise decreased the malondialdehyde content of cardiac mitochondria, indicating a decrease in lipid peroxidation damage. The antioxidant enzymes in the cytosol, superoxide dismutase, selenium dependent glutathione peroxidase, and glutathione S-transferase were all increased by DR. Catalase activity was unaffected by DR but was increased by exercise. The following results demonstrate that long-term DR and exercise modulate the extent of free radical damage in the heart and enhance the antioxidant defense system.