[abstract] IN VIVO MEASUREMENT OF FREE RADICALS PRODUCED BY HYPEROXIA AND SMOKE INHALATION.

Abstract

Compounds such as those found in gases produced during combustion or high concentrations of inspired oxygen can cause direct lung damage because of the formation of oxygen- or carbon-centered free radicals. These free radicals can readily enter lung cells after inhalation and disrupt normal function when their concentrations rise to toxic levels. A number of studies have investigated the effects of free radicals from various sources but have used methods which do not directly quantify the type or amount of free radicals produced. In this study we employed an animal model and electron paramagnetic resonance (EPR) spectroscopy to investigate the free radicals found in intravascular fluids after exposure to cotton smoke or hyperoxia. After exposure to smoke or oxygen the animals were injected with the electron spin trap n-t butyl 1-alpha phenyl nitrone (PBN) which is altered in the presence of free radicals. We found that both smoke and oxygen exposures produce free radical adducts of PBN that are identifiable and quantifiable by EPR analysis. Hyperbaric oxygen at pressures of 2.5 ATA produces detectable free radicals that increase with longer exposures. Radicals appear very quickly after exposure to either smoke or hyperoxia (2.5 ATA but not 1.0 ATA) but are not detectable 2 hrs after exposure. This in vivo model has allowed our group to study free radicals with the aim of reducing toxicity.