| Backgroud The relations between Endothlin-l(ET-l),Nitric oxide(NO) and acute lung injury are getting more and more attention.ET-1 plays a major role in acute lung injury.The role of NO in paraquat(PQ) poisoning is controversy. In the present study,we measured malondialdehyde(MDA),ET-l and NO content in lung homogenates and in the blood to investigate their roles in the pathogenesis of acute lung injury of rats induced by PQ.Method Male wistar rats were randomly assigned to PQ poisoning groupand control group. Rats in the PQ group were each given a single intraperitoneal injection of paraquat(16mg/kg body weight),while normal saline was injected to the rats in the control group.The rats were sacrificed at 6, 12, 24 and 72 hours after the administration of paraquat or normal saline.The performance of the rats were observed,the pathological changes of the lung were studied. MDA, ET-1and NO levels in lung homogenates were measured, as well as the blood levels of ET-1 and NO.Result The PQ poisoned rats had apparent dyspnea, accompanied withmarked decrease in activities.Microscopic examination reviewed lung tissue damage with alveolar edema and bleeding. MDA levels in the lung homogenate of PQ group rose significantly along with time. ET-1 levels in the lung homogenate and blood of PQ group were significantly higher than in the control group(P<0.05). The NO levels in lung homogenate and blood serum remained constant.Conclusion In paraquat induced acute lung injury ,although the NO level in blood and in lung homogenate remained constant,the level of ET-1 in blood and in lung homogenate were elevated. The level of NO is relatively insufficient, so the balance between ET-1 and NO was upset. The imbalance between ET-1 and NO activated NADPH oxidase both directly and indirectly, which promoted the production of active oxygen species,thereby aggravated lung injury. Inhalation of appropriate NO may has protection against acute lung injury induced by PQ.
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