ABSTRACT
<p><b>OBJECTIVE</b>To establish an animal model of lung injury in SD rats using intratracheal instillation of unknown polymer and to provide the base for exploring the molecular mechanism of lung tissue injury induced by occupational exposure.</p><p><b>METHODS</b>One hundred forty SD rats were randomly divided into seven groups, including the control group 1 which was exposed to normal solution, the control group 2 which was not exposed to any one and five treatment groups which were exposed to 1 ml unknown polymer (0.5 ml for each lung) at the doses of 40, 30, 20, 10 and 5 mg/ml, respectively by intratracheal instillation. The rats were sacrificed on the 1st, 3rd, 7th, 10th, 14th, 21th and 28th day after exposure, then the lung tissues were examined pathologically and the blood bio-chemical analysis was conducted.</p><p><b>RESULTS</b>The results of blood biochemical analysis indicated that ALT and AST levels in rats exposed to 30 and 40 mg/ml unknown polymer were significantly higher than those in control groups. Intratracheal instillation of unknown polymer can causes PLF in experimental animals on the 14th days after exposure. The results of pathological examination exhibited that the lung tissue injury in rats exposed to unknown polymer for 14 days or more was found and the dose-effect relationship was observed.</p><p><b>CONCLUSION</b>An animal model of lung injury in SD rats induced by unknown polymer with intratracheal instillation was established successfully. The results of pathological examination showed that the types of rat lung injury were similar to the clinical lung injury after exposure to unknown polymer, which provided a base for studying the mechanism of lung injury caused by occupational exposure to unknown polymer.</p>