Protective Effect Of Perfluorocarbon On Rat’s Lung Oxidative Stress Induced By Hot Smoke Inhalation Injury

ObjectiveTo create a smoke inhalation injury model of the rat and then take a look at the variance of indicates which represent the oxidative stress of the lung such as myeloperoxidase (MPO),3-nitrotyrosine (3-NT), malondialdehyde (MDA) and so on in the bronchoalveolar lavage fluid and blood serum. At the same time, pathological sections and immunohistochemisty were also done to view the pathological change and the expression of the inducible nitric-oxide synthase (iNOS) in order to find a new method to cure smoke inhalation injury and explore the suitable dose of application.Methods1. Twenty rats were randomly divided into two groups:normal group and smoke inhalation injury group. We made the model by using the special box and follow the rules that had been done before. All the rats were killed after six hours when suffered the smoke inhalation. Arterial blood was taken from abdominal aortas of each rat and blood gas analysis was also detectived to observe the PaO2and PaCO2levels. At the same time, pathological sections were sampling from median lobe of each rat for knowing the pathological changes among every group. These interventions would assure the success of this model for the next step.2. Forty rats were randomly divided into five groups:normal control group(N group), smoke inhalation injury group(S group), smoke inhalation injury group treated with low dose of perfluorocarbon(S+L group), smoke inhalation injury group treated with medium dose of perfluorocarbon(S+M group), smoke inhalation injury group treated with high dose of perfluorocarbon(S+H group). All the treated groups were suffered smoke inhalation injury except N group. Perfluorocarbon was injected into trachea through the interspace of the third tracheal ring slowly with different dose of2ml/kg,4ml/kg and8ml/kg. All the rats were killed after six hours. The blood samples and the bronchoalveolar lavage fluid (BALF) were obtained from cardiac puncture and alveolar wash from left lung. These samples were centrifugated and were stored in vessel at-20. The content of MPO,3-NT and MDA were detected by enzyme linked immunosorbent assay (ELISA). The anterior lobe of right lung was used for W/D ratio and the median lobe was used for Pathology. The inferior lobe was prepared for immunohistochemisty to detect the expression of iNOS.Results1. The manifest of rats suffered smoke inhalation injury:the breathing frequency of injury group increased dramatically (100-125breath/min) with abdominal breathing. There was something like Carbo Medicinalis around the mouth and nose with scleral injection. The wheezing and moist rales could be heard through auscultation. The lung Pathology displayed diffuse injury, hemorrhagic spots in local sections were exist.Lots of neutrophilic granulocytes aggregated with alveolar septum was wided and alveolar space was full of erythrocytes. The numerus of arterial oxygen tension (PaO2) and Hydrogen ion concentration (PH) decreased, however arterial carbon dioxide tension (PaCO2) inceased compared with normal group.2. S+L group and S+M group could improve lung wet/dry ratio, reduce the content of MPO in BALF and MDA、3-NT in blood plasma (p<0.05), S+L group could inhibit MPO level better than S+M group (p>0.05)。Although S+H group reduce MDA level,but it have no effect on reducing lung W/D ratio and MPO level in blood plasma (ρ>0.05), also increase3-NT level.3. S+L group and S+M group could impress iNOS expression. S+L group done better, however, the expression of iNOS in S+H group seems higher than S group.Conclusion1. Our model of smoke inhalation injury in rats could be copied stabily from the comparison of the behave change as well as the numerus of index in arterial blood gas analysis and PH.2. The oxidative stress reaction could be prevented by injection of PFC slowly, but results showed no dose-response relationship. Low dose of PFC seems play a better role than other groups with no W/D ratio rose.The result of low dose PFC seems evidently compared with middle dose. However high dose have no ideal effect been found in this experiment.