Effects Of Mixed Air Pollutants On The Oxidative Damage In Pulmonary Tissue Of Rats

Since the last century, after the industrial revolution, regional and global atmospheric chemical composition has a very great change. In the past 20 years, with the number of the world's population rose annually, instead of matching the modern industry and the rapid development of coal, oil, fuel use and the rapid increase in volume from Asia, Africa, South America, the impact on air quality in developing countries of the emission of pollutants has been a great extent disrupted the regional and global atmosphere, leading to air pollution has become increasingly serious. As the role of atmospheric pollutants, the environmental system has changed the structure of the various elements of the ecological environment and the impact of loss of balance, which directly affect people's health. However, the pathogenic mechanism of air pollution is not very clear at present, that many Oxides cause the injury in cells is considered one of the mechanisms.We treated Wistar rats with the analogue of atmospheric pollution as animal models to study the effect of mixed air pollutants on pulmonary oxidative damage in rats. 96 Wistar rats,200~240g,were purchased from China Medical University. They were randomly divided into three experimental groups (low, middle and high dose) and a control group, 24 rats / group. Each group included 1d, 15d, and 30d group. The rats were exposed to PM10 of 7.5, 15, 22.5mg in 1 ml NS respectively by intratracheal instillation under etherization, and then were respectively exposed to mixed gases of SO2 (7.5, 15, and 22.5 mg/m3), NO2 (6, 12, and 18 mg/m3), and CO (200, 400, and 600 mg/m3) , which equal to 50, 100, 150 times of secondary level of daily air standard set by national environmental quality standard (GB3095-1996). The exposure lasted for 1 day, 15days, and 30 days respectively, 2 hours/day. The rats of control group were instilled 1ml NS at the same time inhaled room air. We detected the activity of glutathione (GSH), glutathione peroxides (GSH-Px), super oxide dismutase (SOD) and the content of malondialdehyde (MDA) in the serum or the bronchoalveolar lavage fluid (BALF) as well as the histological changes of lung at different time to identify the changes in antioxidant capacity and the lesion of atmospheric pollutant on the body's antioxidant capacity, so that provided the evidence for the pathogenesis of atmospheric pollution. These provide a scientific basis for atmospheric particles sanitation standards in China.Through the different time of exposure in BALF MDA in the determination of the results were significantly higher (P <0.05), especially in one day was significantly. It shows that Oxidative damage have taken place in the lungs under the experimental conditions, The main pollutants from the mixed atmosphere is particulate matter, SO2, and NO2. They can generate free radicals and reactive oxygen species.Through the different exposure time of serum in the determination of SOD activity, compared with the control group were significantly different (P<0.05). Exposure 1 and 15 days decline, when the 30 days of exposure increased significantly. It shows that the consumption of antioxidant enzyme activity leads to its decline as oxidative damage occurred. However, their antioxidant capacity gradually restored and maintains a long time with extension of the exposure time;Through the determination of serum GSH, exposure in a slight decrease in 1 day, 15 days and 30 days increased, difference between the groups was significant (P<0.05). Activity of antioxidant is sensitive and maintains a long time. Rats exposed to one day in the GSH BALF were significantly higher (P<0.05). Exposure 15 days and 30 days in GSH decline was significantly lower than one day group (P<0.05). GSH in serum have high the ability to remove the low quality free radicals.The activity of GSH-Px in Serum in 1 day and 30 day was significantly lower than the control group. The activity reached a peak in 15 day, significantly higher than the other three groups. It shows that the enzyme in early stage of oxidative damage plays its role in anti-oxidation, and quickly reached a peak, but maintains a shorter time.With rats exposed to pollutants, serum antioxidant activity reached the peak i n 15 day or 30 day. Antioxidants and lipid per oxidation product in BALF is the highest in 1 day. It shows that oxidative damage in the lung tissue of Rats occurred in the early stage, antioxidants play a role at this time. With time extension, antioxidant enzyme system is launched, antioxidant activity increased. With rats exposed to the pollutants, inflammatory injury in lung epithelial occured, the injury increased gradually as the pollutants dose increased. The result shows that atmospheric pollutants can result in the oxidative damage in pulmonary tissue. The oxidative damage is associated with exposure time. For the performance, the serum antioxidant activity reached the peak i n 15 day or 30 day. Antioxidants and lipid per oxidation product in BALF is the highest in 1 day. It shows that oxidative damage in the lung tissue of Rats occurred in the early stage, antioxidants play a role at this time. With time extension, antioxidant enzyme system is launched, antioxidant activity increased.Under the electron microscope, we can see the dose-dependent inflammatory injury in the alveolar epithelium of experimental group rats. In our experimental conditions, the relationship is not very clear between the oxidative damage and experimental dose. Also need further elaboration.