Ethane production rate in rats exposed to high oxygen concentration

Production rates for ethane gas, a hydrocarbon byproduct of lipid peroxidation, measured from the ethane present in the exhaled breath of rats, were used to determine changes in oxygen-free radical activity. Rates of ethane production were measured in rats housed in metabolic chambers and exposed to room air and to high oxygen concentrations. Expired ethane, adsorbed onto activated charcoal and then liberated by heating, was measured by gas chromatography. Ethane production rates in groups of 8 rats increased during 8 h of 100% oxygen exposure from a mean (± SE) room air value of 11.30 ± 1.15 to 27.85 ± 2.93 pmol/min/100 g rat (p < 0.005). The mean (± SE) percent increase in ethane production after exposure to 100% oxygen in 8 rats pretreated iwth 0.1 mg/100 g of vitamin E in corn oil vehicle (0.1 ml/100 g) injected intraperitoneally and in a group of 5 rats injected with vehicle alone averaged 157.16 ± 37.83% and 150.98 ± 25.19%, respectively. The percent changes noted were not significantly different as measured by analysis of variance. These data indicate that lipid peroxidative activity, hence oxygen-free radical activity, increases in normally fed rats exposed to hyperoxia at a time prior to the previously reported neutrophil influx into the lungs of similarly exposed rats and that it is not attenuated by pretreatment with vitamin E.