Antioxidant loading reduces oxidative stress induced by high-energy impulse noise (blast) exposure

Detonation of explosives, firing of large caliber weapons and occupational explosions, professional or accidental, produce high-energy impulse noise ( blast) waves characterized by a rapid rise in atmospheric pressure (overpre ssure) followed by gradual decay to ambient level. Exposure to blast waves causes injury, predominantly to the hollow organs such as ears and lungs. W e have previously reported that blast exposure can induce free radical-medi ated oxidative stress in the lung characterized by antioxidant depletion, l ipid peroxidation, and hemoglobin (Hb) oxidation. In this study, we examine d whether pre-loading, adequately fed rats, with pharmacological doses of a ntioxidants would reduce the response to blast. Sprague-Dawley rats weighin g 300-350 g were loaded with either 800 IU vitamin E (VE), 1000 mg Vitamin C (VC) or 25 mg lipoic acid (LA) for 3 consecutive days by gavage before ex posure to blast. Both VE, and LA were dissolved in 2 ml corn oil, but VC in 2 ml water. After the 3-day antioxidant loading, the rats were divided int o six groups (five rats per group), deeply anesthetized with sodium pentoba rbital (60 mg/kg body weight), then exposed to a low-level blast (62 +/- 2 kPa peak pressure and 5 ms duration). A matched number of groups were sham exposed and served as controls. One hour after exposure, all rats were euth anized then blood, and lung tissue was analyzed. We found that antioxidant loading resulted in restored Hb oxygenation, and reduced lipid peroxidation . Lung tissue VE content was elevated after loading but VC did not change p ossibly due to their different bioavailability and saturation kinetics. The se observations, suggest that brief antioxidant loading with pharmacologica l doses can reduce blast-induced oxidative stress, and may have occupationa l and clinical implications. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.