PM_2.5致动脉粥样硬化大鼠心肌梗死及心律失常的实验研究

【作者】 王彩霞；

【导师】 吕吉元；

【作者基本信息】 山西医科大学 ， 心血管内科学， 2008， 博士

【摘要】 第一部分PM_2.5对正常及动脉粥样硬化大鼠离体心脏心律及冠脉血流的影响研究目的:通过研究PM_2.5对正常及动脉粥样硬化大鼠离体心脏心率、心律及冠脉血流的影响,探讨PM_2.5对动脉粥样硬化大鼠心脏毒性作用的可能机制。研究方法:36只雄性Wistar-kyoto（WKY）大鼠,随机分为:正常对照组和动脉粥样硬化组。正常对照组大鼠给予基础饲料和普通自来水;动脉粥样硬化组给予动脉粥样硬化饲料（4%胆固醇,0.5%胆酸钠,0.2%丙基硫氧嘧啶,10%猪油,维生素D₃1.25×10U/kg和85.3%基础饲料）和普通自来水,肌注维生素D₃30万U/kg,共喂养12周,12周后动脉粥样硬化大鼠模型制作成功。两组大鼠制备离体灌注的Langendorff心脏,分别给予0.25%、0.5%、1%的PM_2.5酸溶性成份（ASC）溶液及硝苯地平10mg灌注,记录心电图（ECG）,分析心率（HR）和心律失常的发生情况;分别测量两组大鼠基础状态下、PM_2.5ASC灌注后、硝苯地平灌注后的冠脉血流（CF）。研究结果:1、PM_2.5引起实验大鼠HR明显减慢,呈剂量依赖性。其中0.25%、0.5%、1%PM_2.5分别使正常对照组大鼠的HR由（268.50±10.58）、（269.67±7.01）、（269.33±7.94）次/分分别减慢为（229.17±12.27）、（180.67±8.17）、（140.33±8.36）次/分;使动脉粥样硬化组大鼠的HR由（274.83±13.27）、（275.17±9.41）、（273.50±7.79）次/分分别减慢为（223.17±10.82）、（170.67±9.75）、（135.50±7.94）次/分。给予PM_2.5前后HR比较具有显著性差异（P＜0.001）,两组间HR比较无统计学差异,浓度与组间交互作用有显著性（P＜0.001）。硝苯地平灌注后各组HR与灌注前比较无显著性变化（P＞0.05）。2、PM_2.5引起CF明显下降,呈剂量依赖性。0.25%、0.5%、1%PM_2.5分别使正常对照组大鼠的CF由（8.82±0.87）、（8.90±0.81）、（8.83±0.89）ml/min分别下降到（7.02±0.86）、（5.25±0.87）、（4.32±0.81）ml/min;使动脉粥样硬化组大鼠的CF由（7.95±0.92）、（7.92±0.81）、（7.98±1.41）ml/min下降到（6.30±1.06）、（3.73±0.79）、（3.23±0.72）ml/min。给予PM_2.5前后CF比较具有显著性差异（P＜0.001）,给予0.25%、1%PM_2.5的两组间CF比较无统计学差异,浓度与组间交互作用无显著性。给予0.5%PM_2.5的两组间CF比较有显著性差异,浓度与组间交互作用有显著性。硝苯地平干预后两组CF均有所恢复（P＜0.001）。3、PM_2.5引起室性心律失常,其发生率和严重程度呈剂量依赖性。动脉粥样硬化组大鼠室性心动过速（VT）的发生时间提前（7.19±2.48）vs（12.83±2.79）分（P＜0.05）,而且明显延长了动脉粥样硬化组大鼠的VT累加时间（109.50±18.51）vs（57.67±12.96）秒（P＜0.05）。研究结论:1、PM_2.5可对正常及动脉粥样硬化大鼠心脏产生直接影响,而不依赖PM_2.5对肺的作用。2、PM_2.5可引起离体灌注的Langendorff心脏心率减慢、冠脉血流减少,诱发室性心律失常的发生。可以解释与PM_2.5暴露相关的缺血性心脏病发生率增加的原因。3、PM_2.5对动脉粥样硬化大鼠心脏毒性作用更强,PM_2.5可引起动脉粥样硬化病变进展。第二部分PM_2.5致动脉粥样硬化大鼠在体心脏心肌梗死的实验研究研究目的:通过PM_2.5短期暴露致正常及动脉粥样硬化大鼠心肌梗死的作用,探讨PM_2.5对动脉粥样硬化大鼠在体心脏的毒性作用及可能机制。研究方法:40只雄性WKY正常大鼠,随机分为两组:正常对照组和动脉粥样硬化组。12周造模成功后,两组分别进行腹腔内注射戊巴比妥钠（40mg/kg）麻醉后,气管滴入10mg/kg体重的PM_2.5ASC溶液。观察PM_2.5ASC暴露前、暴露后1小时的HR,暴露前、暴露后2小时的血压（BP）改变情况;观察PM_2.5ASC暴露前、暴露后24小时血清心肌肌钙蛋白T（cTnT）、血清高敏C反应蛋白（hs-CRP）、血浆D-二聚体（D-dimer）、血浆纤溶酶原激活物抑制剂-1（PAI-1）水平（酶联免疫吸附法）和血清白介素-6（IL-6）（放射免疫法）表达水平。研究结果:1、PM_2.5引起HR增快:正常组由基础状态的（282.10±10.52）次/分增加到（286.05±16.87）次/分,动脉粥样硬化组由基础状态的（291.10±9.70）次/分增加到（297.00±14.33）次/分。PM_2.5滴注后,两组HR均增快（P＜0.01）,组间有差别（P＜0.05）。2、PM_2.5引起BP升高:正常组由基础状态的（105.50±6.58/91.65±7.00）mmHg升高到（108.45±9.65/95.55±10.48）mmHg,动脉粥样硬化组由基础状态的（108.20±6.98/92.50±6.79）mmHg升高到（113.40±9.91/99.35±10.03）mmHg。PM_2.5滴注后,两组BP均升高（P＜0.001）,组间无差别（P＞0.05）。3、PM_2.5可诱发急性心肌梗死（AMI）的发作,正常对照组2/20只大鼠发生AMI,动脉粥样硬化组8/20只大鼠发生AMI。4、（1）PM_2.5引起正常大鼠及动脉粥样硬化大鼠血清IL-6（P＜0.001）、血清hs-CRP（P＜0.001）、血浆D-dimer（P＜0.01）、血浆PAI-1（P＜0.001）水平升高;（2）PM_2.5滴注前后血清IL-6（P＜0.001）、血清hs-CRP水平（P＜0.001）、血浆D-dimer（P＜0.01）、血浆PAI-1水平（P＜0.05）动脉粥样硬化组较正常对照组高。（3）PM_2.5滴注后动脉粥样硬化组中血浆D-dimer非梗死组vs梗死组为（4.44±1.80）ng/dl vs（16.98±7.26）ng/dl（P＜0.01）。PM_2.5滴注后动脉粥样硬化组中血浆PAI-1非梗死组vs梗死组为（73.67±32.88）ng/dl vs（142.50±28.70）ng/dl（P＜0.001）。研究结论:1、PM_2.5短期暴露可诱发急性心肌梗死的发作,动脉粥样硬化组大鼠急性心肌梗死的发生率高。提示动脉粥样硬化大鼠对PM_2.5的心血管毒性作用更敏感。2、PM_2.5对心血管系统产生毒性作用可能主要通过两条途径:一是通过引起炎症反应及继发的高凝状态,二是通过改变自主神经功能。更多还原

【Abstract】 Part 1 Effects of PM_2.5 on Heart Rate,Rhythm and Coronary Flow in in-vitro Hearts of Normal and Atherosclerosis RatsObjective:To explore the possible mechanism of PM_2.5 inducing cardiatoxicity of atherosclerosis rats by observing effects of PM_2.5 on heart rate,arrhythmia and coronary flow in normal and atherosclerosis rats.Method:36 male Wistar-kyoto（WKY） rats were randomly divided into 2 groups:normal and atherosclerosis group.The rats in normal group were fed with basic food and water.The rats in atherosclerosis group were fed with atherosclerosis diets（4%cholesterol,0.5%sodium cholate,0.2%propylthiouracil,10%leaf fat,1.25×10U/kg body cholecalciferol,85.3%basic food） and were injected with 300,000 U/kg body cholecalciferol in right legs.The rats were fed 12 weeks.After 12 weeks of atherosclerosis diets,atherosclerosis rat model were successfully made.Isolated perfused Langendorff hearts were preparated.0.25%,0.5%,1%PM_2.5 acide-soluble components（ASC） solution and 10mg nifedipine were perfused respectively. Electrocardiogram（ECG） was recorded for analyzing heart rate（HR） and cardiac arrhythmias. Coronary flow（CF） was measured in baseline and after PM_2.5 ASC perfusion and after nifedipine perfusion.Results:（1） PM_2.5 dose-dependently decreased HR significantly.0.25%,0.5%and 1% PM_2.5 decreased HR to（229.17±12.27）、（180.67±8.17）、（140.33±8.36）BPM,respectively,from （268.50±10.58）、（269.67±7.01）、（269.33±7.94）BPM in normal group and decreased HR to （223.17±10.82）、（170.67±9.75）、（135.50±7.94）BPM,respectively,from（274.834±13.27）、（275.17±9.41）、（273.50±7.79）BPM in atherosclerosis group.There were significant changes of HR between before and after PM_2.5（P＜0.001）.There were no significant changes between the two groups.There were no significant changes of HR after nifedipine perfusion（P＞0.05）.（2） PM_2.5 dose-dependently reduced CF.0.25%,0.5%and 1%PM_2.5 reduced CF to（7.02±0.86）、（5.25±0.87）、（4.32±0.81）ml/min,respectively,from（8.82±0.87）、（8.90±0.81）、（8.83±0.89）ml/min in normal group and reduced CF to（6.30±1.06）、（3.73±0.79）、（3.23±0.72）ml/min,respectively,from（7.95±0.92）、（7.92±0.81）、（7.98±1.41）ml/min in atherosclerosis group.There were significant changes of CF between before and after PM_2.5 （P＜0.001）.CF of two groups restored after perfusing nifedipine（P＜0.001）.（3） PM_2.5 dose-dependently triggered cardiac arrhythmias.1%PM_2.5 made ventricular tachycardia（VT） occurrence ahead of time（7.19±2.48） minutes in atherosclerosis group vs（12.83±2.79） minutes in normal group and prolonged accumulated VT time to（109.50±18.51） seconds in atherosclerosis group vs（57.67±12.96） seconds in normal group.Conclusion:（1） PM_2.5 has a direct effect on cardiovascular system,independent of the effect of PM_2.5 on pulmonary circulation.（2） PM_2.5 decreases HR,reduces CF and triggers venticular arrhythmias in isolated perfused hearts,which may explain the increase in the incidence of ischemic heart diseases in clinic association with elevated PM_2.5 exposure.（3） PM_2.5 has bigger cardiotoxicity to atherosclerosis rats.PM_2.5 makes atherosclerosis progress.Part 2 Experiment investigation of PM_2.5 Inducing Acute Myocardial Infarction in in-vivo Atherosclerosis RatsObjiective:To explore the effects and the possible mechanism of PM_2.5 causing cardiotoxicity of atherosclerosis rats by triggering acute myocardial infarction（AMI） in normal and atherosclerosis rats.Methods:40 male Wistar-kyoto（WKY） rats were randomly divided into 2 groups:normal and atherosclerosis group.Atherosclerosis rat models were successfully established by fed with atherosclerosis diets for 12 weeks.After anaesthesia by intraperitoneally injected with pentobarbitone 40mg/kg body weight,two groups rats were exposed by intratracheal instillation of PM_2.5 solution 10mg/kg body weight.Heart rate（HR） was recorded in baseline(before instillation of PM_2.5) and after PM_2.5 exposure 1 hour.Blood pressure（BP） was measured in baseline and after PM_2.5 exposure 2 hours.Blood markers:serum cardiac troponin T（cTnT）, serum high sensitive C-reactive protein（hs-CRP）,serum interleukin-6（IL-6）,plasma D-dimer, plasma plasminogen activator inhibitor-1（PAI-1） were measured in baseline and after PM_2.5 exposure 24 hours by enzyme linked immunosorbent assay and radio-immunity assay.Results:1.PM_2.5 induced HR increase.HR increased to（286.05±16.87） BPM from （282.10±10.52） BPM in normal group and increased to（297.00±14.33） BPM from（291.10±9.70） BPM in atherosclerosis group.HR of two groups increased after instillating PM_2.5（P＜0.01）. There were significant changes of HR between two groups（P＜0.05）.2.PM_2.5 induced BP increase.BP increased to（108.45±9.65/95.65±10.48）mmHg from （105.50±6.58/91.65±7.00）mmHg in normal group and increased to （113.40±9.91/99.35±10.03）mmHg from（108.20±6.98/92.50±6.79）mmHg in atherosclerosis group.BP of two groups increased after instillating PM_2.5（P＜0.001）.There were no significant changes of BP between two groups（P＞0.05）.3.PM_2.5 triggered onset of AMI.2/20 rats occurred AMI in normal group and 8/20 rats occurred AMI in atherosclerosis group.4.（1） PM_2.5 increased serum IL-6（P＜0.001）,serum hs-CRP（P＜0.001）,plasma D-dimer（P＜0.01） and plasma PAI-1（P＜0.001） concentration.（2） The serum concentration of IL-6,hs-CRP and plasma D-dimer,PAI-1 were higher in atherosclerosis group both before and after PM_2.5 instillation.（3） After PM_2.5 instillation,the level of plasma D-dimer and PAI-1 were significantly higher in atherosclerosis rats with AMI.The level of plasma D-dimer is（4.44±1.80）ng/dl vs （16.98±7.26）ng/dl（P＜0.01） of non-AMI vs AMI group.The level of plasma PAI-1 is （73.67±32.88） ng/dl vs（142.50±28.70 ） ng/dl（P＜0.001） of non-AMI vs AMI group.Conclusion:（1） PM_2.5 short-term exposure triggers onset of AMI.AMI incidence is higher in atherosclerosis group.The atherosclerosis rats are more susceptible to PM_2.5 than normal rats. （2） PM_2.5 causes adverse effects on cardiovascular system by two passways:inflammation and changes of autonomic nervous function.更多还原