The difference in acute lung injury caused by intratracheal instillation or intraperitoneal injection of LPS

Objective：To investigate the difference in acute lung injury caused by pulmonary and extrapulmonary factor.Methods：A rat model of ALI was induced by intratracheal（IT） instillation or intraperitoneal（IP） injection of LPS with a dose of 10mg/kg.54male SD rats were randomly divided into control group、IT group and IP group，every group included 18 rats（6 rats at 2h、6h and 24h respectively）. the arterial gas analysis、the total protein concentration、the total cell counts and classification、the level of TNF-αin BALF、lung pathology of rats were examined.Results：Comparision with IP group，in IT group the PaO₂ was decreased sharply（P＜0.001），the total protein concentration、the total PMN in BALF、the level of TNF-αin BALF were greatly increased（P＜0.001 or P＜0.05），lung pathology showed severe polymorphonuclears infiltration with bleeding and hyaline membranes.Conclusion：①PaO₂ of rats in IT group decreased progressively，intraperitoneal injection of LPS has no effcct on PaO₂ of rats.②Overwhelming PMN infiltration was found in rats of IT group and was more severe than IP group.