Cigarette smoke causes rapid lipid peroxidation of rat tracheal epithelium

Cigarette smoke-induced lipid peroxidation may be an important mechanism of smoke toxicity, but attempts to demonstrate peroxidation of pulmonary tissues after smoke exposure have yielded conflicting results. To examine this question, we exposed rat tracheal explants to whole smoke for 10 minutes followed by air recovery for periods up to 50 minutes (test), or to air alone (controls) and measured conjugated diene levels in the tissue. A dose-related increase in conjugated diene levels was seen in explants exposed to 1, 3 or 6 puffs of smoke. After exposure to 6 puffs of smoke, there was a progressive increase in conjugated diene levels during the first 10 minutes of air recovery; thereafter, test levels remained at about 1.5 times control. Pretreatment of the explants with superoxide dismutase, catalase, or deferoxamine prevented the increase in conjugated diene levels, and inactivation of the enzymes destroyed their protective effect. We conclude that cigarette smoke rapidly produces lipid peroxidation in tracheal segments in vitro, that the severity of the process is directly related to the amount of smoke exposure, and that inflammatory cells are not required for this effect. Lipid peroxidation in this system appears to be mediated by active oxygen species.