【作者】 刘晓飞；

【导师】 曾秋棠；

【作者基本信息】 华中科技大学 ， 心血管病学， 2006， 博士

【摘要】 第一部分心肌梗死后大鼠钾通道Kv2.1基因表达的变化目的研究大鼠心肌梗死（MI）后钾通道Kv2.1的动态变化。方法通过结扎大鼠左前降支近端建立心肌梗死模型，手术后存活大鼠进入MI组（7，30天组）。同时，设立相应的假手术（SH）组。应用半定量RT-PCR方法和Western Blots方法检测左室心肌（MI者取梗死周边非梗死区左室心肌）钾通道Kv2.1mRNA及通道蛋白量。结果与SH组比较，MI组（7天组、30天组）Kv2.1mRNA和蛋白量明显下降（P＜0.05或P＜0.01）。MI组内30天组与7天组比较，Kv2.1mRNA和蛋白量显著下降（P＜0.05）。结论MI后钾通道Kv2.1基因表达呈时间依赖性下调，此可能是MI后易发心律失常的分子机制之一。第二部分缬沙坦对心肌梗死后大鼠钾通道Kv2.1表达变化的影响目的探讨缬沙坦对大鼠心肌梗死后梗死周边非梗死区左室心肌钾通道Kv2.1α-亚单位变化的影响。方法通过结扎大鼠左前降支近端建立心肌梗死大鼠模型，手术后存活大鼠随机分入心肌梗死组（7天组，30天组）和缬沙坦组(7天组，30天组：缬沙坦30mg．kg^-1．day^-1)，同时设立相应假手术组；心肌梗死组和假手术组对应给予等量盐水。应用半定量RT-PCR方法和Western Blots法检测非梗死左室心肌钾通道Kv2.1α-亚单位m RNA和通道蛋白量。结果与假手术组比较，心肌梗死后钾通道Kv2.1m RNA和通道蛋白量均明显下降[分别为P＜0.05（7天）；P＜0.01（30天）]。与心肌梗死组比较，缬沙坦组钾通道Kv2.1m RNA和通道蛋白量均明显升高[分别为P＜0.05（7天）；P＜0.01（30天）]。缬沙坦组与假手术组比较钾通道Kv2.1m RNA和通道蛋白量差异无显著性（P＞0.05）。结论缬沙坦可以明显逆转大鼠心肌梗死后钾通道Kv2.1的下调，这提示血管紧张素Ⅱ信号途径可能是心肌梗死后引起钾通道Kv2.1α-亚单位表达的下调的主要信号转导通路之一。第三部分缬沙坦对心肌梗死后大鼠蛋白激酶C异构体、Giα-2和β肾上腺受体激酶-1基因表达变化的影响目的研究缬沙坦对心肌梗死后梗死周边非梗死区左室心肌蛋白激酶C异构体（PKC—ε）、Giα—2和β肾上腺受体激酶—1基因表达变化的影响，初步探讨其调控心肌梗死后钾通道Kv2.1变化的分子机制。方法通过结扎大鼠左前降支近端建立心肌梗死大鼠模型，手术后存活大鼠随机分入心肌梗死组（7天组，30天组）和缬沙坦组(7天组，30天组：缬沙坦30mg．kg^-1．day^-1)，同时设立相应假手术组；心肌梗死组和假手术组对应给予等量盐水。应用半定量RT-PCR方法检测非梗死左室心肌蛋白激酶C异构体PKC—ε、Giα—2和β肾上腺受体激酶—1m RNA量。结果与假手术组比较，心肌梗死组蛋白激酶C异构体PKC—ε、Giα—2和β肾上腺受体激酶—1m RNA量明显升高[分别为P＜0.05（7天）；P＜0.01（30天）]；与心肌梗死组比较，缬沙坦组蛋白激酶C异构体PKC—ε、Giα—2和β肾上腺受体激酶—1m RNA量明显减低[分别为P＜0.05（7天）；P＜0.01（30天）]。与假手术组比较，缬沙坦组蛋白激酶C异构体PKC—ε、Giα—2和β肾上腺受体激酶—1m RNA量差异无显著性（P＞0.05）。结论缬沙坦可明显正常化蛋白激酶C异构体PKC—ε、Giα—2和β肾上腺受体激酶—1基因表达的上调，此可能是缬沙坦调控心肌梗死后钾通道Kv2.1变化的分子机制。更多还原

【Abstract】 Part IAn experimental study of the dynamic changes of expression ofpotassium channels Kv2.1 in post- myocardial infarction rat heart.Objective To investigate the dynamic changes of the expression of potassium channel Kv2.1 in post-myocardial infarction （MI） rat heart.Methods Using a rat model of MI, induced by the left anterior descending coronary artery （LAD） ligation in female Sprague-Dawley rats, the living rats were enrolled into post-MI group. Accordingly, the sham-operation group （sham-group） was established. According to the time of getting sample, the living rats in each group were divided into two subgroups （7 days group and 30 days group）. Using semi-quantitative reverse transcriptase-polymerase chain reaction （RT-PCR） and western blots, we measured mRNA and channel protein of Kv2.1 in each group. Results Compared to the sham-group, Kv2.1 mRNA and channel protein in the post-MI group remarkably decreased regardless of 7 days or 30 days （P<0.05 or P<0.01）. Compared to the 7 days post-MI group, Kv2.1 mRNA and protein in the 30 days post-MI group remarkably reduced （P<0.05）.Conclusion The expression of potassium channels Kv2.1 after myocardial infarctionexhibits the time-dependent downregulation, which may be one of the molecularmechanisms that are able to cause the arrhythmia after myocardial infarction.Part IIEffects of valsartan on the changes of expression of potassium channels Kv2.1 in post-myocardial infarction ratObjective To study the effects of valsartan on the changes of the expression of potassium channels Kv2.1a-subunit of left ventricular non-infarcted myocardiums in post-myocardial infarction （post-MI） rats.Methods Using a rat model of MI, induced by the left anterior descending coronary artery （LAD） ligation in female Sprague-Dawley rats, the living rats were randomly divided into post-MI group（ 7 days group[n=10]; 30 days group[n=11]） or valsartan group(7 days group[n=10]; 30 days group[n=10]; valsartan 30mg.kg^-1.day^-1). Accordingly, the sham-operation group （sham-group） was established. Using semi-quantitative reverse transcriptase-polymerase chain reaction （RT-PCR） and western blots, we measured the contents of Kv2.1 mRNA and protein in each group. Results Compared to sham-groups, the expression levels of Kv2.1 mRNA and protein in the post-MI group prominently reduced on 7 days （P<0.05） or 30 days （P＜0.01）. Compared to Post-MI groups, the expression levels of Kv2.1 mRNA and protein in the valsartan groups increased remarkably on 7 days （P<0.05） or 30 days （P<0.01）. There were no differences between the sham-groups and the valsartan groups （P>0.05）.Conclusion Valsartan may reverse the downregulation of expression of potassium channels Kv2.1 in post-myocardial infarction rat markedly, which suggests that angiotensin II signaling pathway can be one of major signaling-transduction pathway bringing potassium channel Kv2.1 α-subunit downregulation.Part IIIEffects of valsartan on the gene expression of protein kinase Cisoform, Giα-2, and β-adrenergic receptor kinase-1 inpost-myocardial infarction ratObjective To study the effects of valsartan on the gene expression of protein kinase C isoforms （PKC-ε）, Giα-2, and β-adrenergic receptor kinase-1 and to explore the molecular mechanism of valsartan modulating the changes of potassium channel Kv2.1 in post-myocardial infarction rat heart.Methods Using a rat model of MI, induced by the left anterior descending coronary artery （LAD） ligation in female Sprague-Dawley rats, the living rats were randomly divided into post-MI group（ 7 days group[n=10]; 30 days group[n=11]） or valsartan group(7 days group[n=10]; 30 days group[n=10]; valsartan 30mg.kg^-1.day^-1). Accordingly, the sham-operation group （sham-group） was established. Using semi-quantitative reverse transcriptase-polymerase chain reaction （RT-PCR）, we measured the contents of protein kinase C isoforms （PKC-ε）, Giα-2, and β-adrenergic receptor kinase-1 mRNA in each group.Results Compared to sham-groups, the expression levels of protein kinase C isoforms （PKC-ε）, Giα-2, and β-adrenergic receptor kinase-1 mRNA in the post-MI group prominently increased on 7 days （P＜0.05） or 30 days （P<0.01）. Compared to Post-MI groups, the expression levels of protein kinase C isoforms （PKC-ε）, Giα-2, and β-adrenergic receptor kinase-1 mRNA in the valsartan groups reduced remarkably on 7 days （P＜0.05） or 30 days （P<0.01）. There were no differences between the sham-groups and the valsartan groups （P>0.05）.Conclusion The gene expressions of protein kinase C isoforms （PKC-ε）, Giα-2, and β-adrenergic receptor kinase-1 are up-regulated remarkably in Post-MI rat heart; Valsartan may normalize these changes prominently, which can be the molecular mechanism of valsartan modulating the changes of potassium channel Kv2.1 in post-myocardial infarction rat.更多还原