Vitamin E and lipoic acid, but not vitamin C improve blood oxygenation after high-energy IMPULSE noise (BLAST) exposure

Exposure to high energy impulse noise (BLAST) caused by explosions, result in structural and functional damage to the hollow organs, especially to the respiratory and auditory systems. Lung damage includes alveolar wall ruptu re, edema and hemorrhage, and may be fatal. Previous observations at the mo lecular level using the rat model, suggested that secondary free radical-me diated oxidative stress occurs post exposure resulting in antioxidant deple tion and hemoglobin (Hb) oxidation. This study examined whether a short per iod of pre-exposure supplementation with antioxidants would protect Hb from the effects of BLAST exposure. Six groups of male Sprague-Dawley rats (8/g roup) were gavaged with 800 IU vitamin E (VE) in 2 ml corn oil, 1000 mg vit amin C (VC) in 2 mi distilled water or 25 mg or (-lipoic acid (LA) in 2 mi corn oil for 3 days. Matched control groups were gavaged with the respectiv e vehicles. On day 4, rats were deeply anesthetized and exposed to a simula ted BLAST wave with an average peak pressure of 62 +/- 2 kPa. Rats were eut hanized one hour post exposure and blood samples were obtained by cardiac p uncture and analyzed using a hemoximeter. Post exposure oxygenation states (HbO(2), O-2 saturation, and O-2 content) were markedly decreased, while re duced-Hb was increased. Supplementation with VE and LA reversed the trend a nd increased Hb oxygenation, but VC did not. This suggests that a brief die tary loading with pharmacological doses of VE or LA, but not VC shortly bef ore BLAST exposure may be beneficial. Moreover, measurement of blood oxygen ation may function as a simple, semi-invasive biomarker of BLAST-induced in jury applicable to humans. (C) 1998 Academic Press.