| ObjectivesAs the gas whose oxygen concentration is higher than the room air at 1 atm, hyperoxia is very useful in neonatal medicine, however, long-time hyperoxia inhalation maybe cause lung injury, which can result in respiratory failure and even death, and develop into BPD. At present, the pathogenesis of hyperoxic lung injury in neonate isn't understood completely, and when the doctors treat the neonatal patients, they haven't not only the safe critical value of the concentration and time of oxygen inhalation to consult, but also the proper measures to prevent from and treat hyperoxic lung injury. In order to explore the relation of lung injury in neonatal rats, degree of lung lipid peroxidation, TAOC,NO level and the expression level of eNOS and iNOS to provide methods for protecting from lung injury, and to explore the safe critical value of the concentration and time of neonatal rats' oxygen inhalation to provide evidence for selecting proper concentration and time of oxygen inhalation,the study has researched the pathologic alteration, TAOC, the MDA and NO level, and the expression level of eNOS and iNOS in lung of neonatal rats exposed to the different concentration oxygen for different time. Methods1. 160 clean Sprague-Dawley(SD) rats which were less than 12 hours old were enrolled in this study.2. The rats were divided into 4 groups randomly: â… .> 95%O2 group, â…¡.60%O2 group, â…¢.40%O2 group, â…£.normal air control group. Group â… , Group â…¡ and Group â…¢ were placed into oxygen cabins and were exposed to corresponding concentration oxygen. Group â…£ were placed in the room air. Lung samples were obtained at 12,24,48 and 72 hours.3. The MDA level of lung homogenates was measured by Thiobarbituric Acid Test.4. The NO level of lung homogenates was measured by Nitrate Reductase Test.5. The TAOC of lung homogenates was measured by Chemistry Colorimetry.6. The expression level of eNOS and iNOS of lung was measured by Immunohisto- chemisty Staining, and semi-quantitative analysis was performed by using MIG2000 ImageAnalysis Measured System.7. The pathologic alteration in lung was observed by using light microscope and transmission electron microscope.Results1. The MDA level of lung homogenates of Group â… was significantly higher than that of the other three Groups at all the time points(P<0.01). That of Group â…¡ was significantly higher than that of Group â…¢ and Group â…£ at 48 and 72 hours(P<0.01). That of Group â…¢ was significantly higher than that of Group â…£ at 48 and 72 hours(P<0.01,P<0.05). With the concentration of oxygen inhaled hoisting and the inhalation time prolonging, the MDA level increased gradually, and it correlated with the concentration of oxygen inhaled significantly positively at all the time points(P<0.01). 2. The NO level of lung homogenates of Group â… was significantly higher than that of the other three Groups at all the time points(P<0.05,P<0.01). That of Group â…¡ was significantly higher than that of Group â…£ at 24,48,and 72 hours(P<0.05,P<0.01), and was significantly higher than that of Group â…¢ at 72 hours(P<0.05). That of Group â…¢ was significantly higher than that of Group â…£ at 72 hours(P<0.01). The NO level correlated with the concentration of oxygen inhaled significantly positively at all the time points(P<0.01). 3. The TAOC of lung homogenates of Group â… was significantly lower than that of the other three Groups at all the time points(P<0.05,P<0.01). That of Group â…¡ was significantly lower than that of Group â…£ at 24,48,and 72 hours(P<0.05,P<0.01), and was significantly lower than that of Group â…¢ at 48 and 72 hours(P<0.01). That of Group â…¢ was significantly lower than that of Group â…£ at 48 and 72 hours(P<0.01). With the concentration of oxygen inhaled hoisting and the inhalation time prolonging, the TAOC decreased gradually. The TAOC correlated with the concentration of oxygen inhaled significantly negatively at all the time points(P<0.01).4. The expression level of eNOS of lung of Group â… was significantly higher than that... |
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