Actions of NO and INOS on endotoxin induced rat acute lung injury and effect of rhubarb on them.

This study is to explore the actions of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) on endotoxin (lipopolysaccharide, LPS) induced rat acute lung injury (ALI) and effect of Rhubarb on them. LPS was injected into the sublingual vein of male Wistar rats to prepare ALI animal models. The rats were divided into 4 groups: LPS, control, Rhubarb, and dexamethasone. Macroscopic and histopathological examinations of the lung specimens were performed and the biological indexes of lung, including wet weight/dry weight, the rate of neutrophils and protein content in the pulmonary alveolar lavage fluid, pulmonary vascular permeability and pulmonary alveolar permeability were observed. In the mean time, the contents of serum NO and the activities of lung tissue homogenate iNOS were measured. The results showed that in the LPS group, the injury and celluar infiltration in the pulmonary stroma and alveoli were more prominent than that in the control group. Lung wet weight/dry weight, the rate of neutrophils, protein content, pulmonary alveolar permeability, pulmonary vascular permeability were significantly increased (P < 0.01); NO and iNOS were also markedly elevated (P < 0.01). In the groups of dexamethasone and Rhubarb, the histopathological changes were significantly milder, and all the above biological indexes of lung injury and the contents of NO and the activities of iNOS were correspondingly decreased (P < 0.05). The above data demonstrate that NO and iNOS play an important role in the onset of ALI; dexamethasone and Rhubarb interfering treatment can ameliorate lung injury and decrease the concentrations of NO and the activities of iNOS, showing that through inhibiting the levels of NO and the activities of iNOS, these 2 agents exert protective effect on ALI induced LPS.