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 rupture, edema and hemorrhage, and may be fatal. Previous observations at the molecular level using the rat model, suggested that secondary free radical-mediated oxidative stress occurs post exposure resulting in antioxidant depletion and hemoglobin (Hb) oxidation. This study examined whether a short period of pre-exposure supplementation with antioxidants would protect Hb from the effects of BLAST exposure. Six groups of male Sprague-Dawley rats (8/group) were gavaged with 800 IU vitamin E (VE) in 2 ml corn oil, 1000 mg vitamin C (VC) in 2 ml distilled water or 25 mg or (-lipoic acid (LA) in 2 ml corn oil for 3 days. Matched control groups were gavaged with the respective vehicles. On day 4, rats were deeply anesthetized and exposed to a simulated BLAST wave with an average peak pressure of 62 +/- 2 kPa. Rats were euthanized one hour post exposure and blood samples were obtained by cardiac puncture and analyzed using a hemoximeter. Post exposure oxygenation states (HbO2, O2 saturation, and O2 content) were markedly decreased, while reduced-Hb was increased. Supplementation with VE and LA reversed the trend and increased Hb oxygenation, but VC did not. This suggests that a brief dietary loading with pharmacological doses of VE or LA, but not VC shortly before BLAST exposure may be beneficial. Moreover, measurement of blood oxygenation may function as a simple semi-invasive biomarker of BLAST-induced injury applicable to humans.