Abstract: Objective To evaluate the efficacy of a modified method of passive smoking and endotracheal instillation of LPS for establishment of chronic obstructive pulmonary disease (COPD) model in rats. Methods 30 Sprague-Dawley(SD) rats were randomly divided into three groups; normal, model and modification groups, 10 rats each. The rats in normal group received normal feeding. The rats of model group were endotracheal instilled LPS (lg/L, 0.2 ml) on the first and 15^th day (no passive smoking on the same days) and they received passive smoking from the 2nd day to 28th day. The rats undertook passive smoking for 3 times. Each time they received 10 cigarettes lasting for 30 minutes and the interval time was 2 hours. Except the adjustment of the dose of LPS to 0.1 ml on the 15th day, the dose of cigarettes to 5 from the 2nd day to the 7th day, other performances in the modification groups are the same as those in the model group. On the 29th day, the pulmonary function, histopathology changes, concentration of TNFa in bronchoalveolar fluid (BALF), success rate and mortality rate were compared among three groups. Results Compared with the rats in normal group, the latter groups rats，airway resistance and concentration of TKFa in BALF were much higher. Conclusion This modified method of passive smoking and endotracheal instillation of LPS for establishment of COPD models in rats is more economic, reliable and worthy of application.

Key words: Passive smoking, LPS, COPD, Model, animal