| Objective:To study the toxic effects of PM2.5in Shijiazhuang on the heart and lung of rats after 28 days repeated exposure via intracheal instillation.Methods:1 Acquisition,preparation and observation of PM2.5The large flow air sampler and PTFE filter were used.The PM2.5.5 was extracted by ultrasonic extraction-freeze drying method.Particles size and morphology of PM2.5.5 were observed by TEM.The hydrodynamic particle size distribution and Zeta potential of PM2.5.5 were measured by nano-particle size and Zeta potential analyzer.2 Establishment of of exposured model in ratsThirty-two male SD rats were randomly divided into 4 groups,the treatment dosages were 5mg/kg,10mg/kg and 20 mg/kg respectively.The rats were treatment for 4 weeks,2/week,intervals of 2.5 days.The rats were killed24 hours after the last infusion.3 Measurement of lung damagesThe organ coefficient was calculated.The metals in lung were detected by ICP-MS.Pathological changes of lung were observed through Hematoxylin-esosin?HE?staining.ROS levels in lung were detected by flow cytometry and the DNA damages of lung cells were detected by SCGE.4 Measurement of heart damagesThe organ coefficients,pathological changes,ROS levels and DNA damages were detected as same as the“3”.The ECG was monitored by the physiological recorder of small animals.The blood pressure of rats was detected by animal non-invasive blood pressure analysis system and the echocardiography of heart was monitored by small animal sonograph.Results:1 Acquisition,preparation and observation of PM2.5The extraction efficiency was 65.15%.PM2.5.5 was an irregular aggregation of circular particles in the present study.The hydrodynamic particle size was 1.12-1.98?m.Zeta potential of PM2.5.5 was-26.4±0.29mv.2 Establishment of exposured model in ratsThere was no accidental death and the model via intracheal instillation in rats were established successfully.3 Measurement of lung damagesThere was no significant difference in organ coefficient?P>0.05?.The contents of 12 metals in lungs of the exposed groups were significantly higher than those in the control group?P>0.05?.In the exposed group,gray and black particles were found in the lungs.The inflammatory cell infiltration and interstitial thickening were observed.The levels of ROS in each exposed group were significantly higher than that in the control group?P<0.05?,and the Tail DNA%and OTM were significantly increased?P<0.05?.4 Measurement of heart damageThere was no difference in organ coefficient between groups?P>0.05?,but there were pathological changes such as myocardial disorder in heart.The levels of ROS in each exposed group was significantly higher than that in the control group?P<0.05?.The Tail DNA%and OTM were increased?P<0.05?.ST segment elevation was found in high dose group?P<0.05?.There was no significant difference in blood pressure and ultrasound?P>0.05?.Conclusions:1 The particle size distribution of PM2.5.5 extracted by ultrasonic extraction and freeze-drying method is concentrated.The dispersion system is stable,which is according with the experimental requirements.2 The model of PM2.5.5 intracheal instillation in rats was established successfully.3 The levels of metals in PM2.5exposed lung tissue were increased,pathological changes,oxidative stress and DNA damages were occured.4 28 days repeated PM2.5.5 tracheal dripping could induce pathological changes,oxidative stress and DNA damages in the heart.ST elevation of ECG was found in the high dose group. |
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