Evidence of oxygen radical injury in experimental otitis media.

Free radicals have been implicated in the pathogenesis of an increasing number of diseases and inflammatory states. They may cause tissue damage by their chemical modification of proteins, carbohydrates, nucleotides, and lipids. Lipid peroxidation occurs as a consequence of free radicals acting on the polyunsaturated fatty acids of cellular membranes. To determine if free radicals play a role in the pathogenesis of otitis media, lipid peroxides and their by-products were assayed in the mucosa of a guinea pig model of otitis media. Both lipid hydroperoxide (LPO) and malondialdehyde (MDA) were measured in the tissues of the middle ear mucosa. Comparisons were made between an infected and a control group. Both LPO and MDA were found to be significantly elevated (P < .01 and P < .05, respectively) in the infected mucosa. Correlation of the biochemical data was made with histologic studies. The significance of these findings as well as suggestions for future experimentation are addressed.