血管紧张素Ⅱ调控SK2通道参与犬心房颤动发生的研究

发布时间：2018-06-27 12:34

本文选题：血管紧张素Ⅱ + 小电导钙激活钾通道　；参考：《西南医科大学》2017年硕士论文

【摘要】：目的:心房颤动(Atrial fibrillation,AF)是临床最常见的心律失常之一,明显增加患者的死亡率及致残率,是一种与年龄密切相关的渐进性疾病,并可使潜在的心脏疾病恶化。AF的发病机制迄今为止不明,已经提出了许多假说,从AF局灶起源假说到多发子波折返假说再到局灶驱动伴颤动样传导、肺静脉触发起源假说,但没有一种学说能解释AF所有的现象[1-3]。尽管触发和折返作为AF的发生机制逐渐被接受,但AF的维持基质仍有许多尚未阐明的问题。新近发现的SK2通道为小电导钙激活钾通道(Small conductance Ca2+-activated K+channel,SK通道)的一个亚型,因具有心房选择性并且通道的改变与AF发生有关,成为近年大家研究的热点之一。该通道对钾离子具有选择性,对电压不敏感而对Ca2+高度敏感。业已证实AF的电重构涉及细胞内Ca2+超载,循环或组织血管紧张素Ⅱ(Angiotensin Ⅱ,AngⅡ)的增加可使细胞内钙进一步增多导致AF加重[4]。而SK2通道对细胞内钙高度敏感,因此我们推测AngⅡ导致AF加重可能涉及了对SK2通道的调控,然而通过文献的复习未见相关报道。因此本研究的目的是探讨AngⅡ对SK2通道的调控在AF发生中的作用机制。方法:健康成年比格犬25只随机分为5组(每组5只):分别为假手术组(Sham组)、起搏组(Pacing组)、起搏+血管紧张素Ⅱ组(Pacing+AngⅡ组)、起搏+缬沙坦组(Pacing+Valsartan组)、起搏+血管紧张素Ⅱ+缬沙坦组(Pacing+AngⅡ+Valsartan组)。实验各组用药前及用药后常规测量血压,每次测量3次取平均值。其中加药组于起搏前2周分别给予AngⅡ 110ng/kg/min皮下持续微量泵入或(和)Valsartan 30mg/kg/d口服。给药后所有犬经戊巴比妥钠麻醉后常规气管插管机械辅助通气,检测心电图变化,经右侧股静脉插入起搏电极至右心房,电极近端连接电生理起搏系统,除Sham组外其余各组均给予快速心房起搏(频率600次/分)8小时,起搏前及起搏后每小时测量心房有效不应期(atrialeffectiverefractoryperiod,aerp)和af发生频率及持续时间。起搏结束后抽取动物静脉血离心,检测血清angii浓度变化,开胸取左右心房组织检测组织angii浓度变化,westernblotting方法检测各组右心房组织sk2通道蛋白表达的变化。结果:1.血压的变化:angii预处理2周后,pacing+angii组血压上升45±3.53mmhg与sham组比较,差异明显(p0.01);其余各组与sham组比较差异无统计学意义(p0.05)。2.起搏后aerp的变化:与sham组比较,pacing组、pacing+angii组、pacing+angii+valsartan组aerp明显缩短(p0.01),pacing+angii组缩短最为显著,pacing+valsartan组无明显缩短(p0.05);与pacing组比较,pacing+angii组aerp缩短(p0.01),pacing+valsartan组、pacing+angii+valsartan组aerp延长(p0.01)。3.起搏后血清及左右心房组织angii浓度变化:与sham组比较,pacing组血清和ra组织angii浓度明显升高(p0.01),la组织angii浓度也升高(p0.05),pacing+valsartan组血清及左右心房组织angii浓度虽有所升高,但差异无统计学意义(p0.05)。4.各组burst刺激诱发af的频率和时间变化:与sham组比较,pacing组、pacing+angii组诱发af的频率和时间明显增加(p0.01),pacing+valsartan组无明显差异(p0.05);与pacing组比较,pacing+angii组诱发af的频率和时间增多(p0.01),而pacing+valsartan组、pacing+angii+valsartan组明显减少(p0.01)。5.westernblotting检测sk2通道蛋白相对表达量结果显示:与sham组比较,pacing组、pacing+angii组、pacing+angii+valsartan组蛋白表达明显下降(p0.01),其中pacing+angii组下降最为显著,pacing+valsartan组也有下降,但明显没有其余各组下降明显(p0.05);与pacing组比较,pacing+angii组蛋白表达下降(p0.01),pacing+valsartan组增多(p0.01),pacing+angii+valsartan组也有所上调(p0.05)。结论:1.快速起搏可导致心房发生电重构,其中AngⅡ可加重心房的电重构,而Valsartan可减轻心房的电重构减少AF的发生。2.快速起搏可导致血清及左右心房组织AngⅡ浓度增加,这是易于AF发生和维持的可能原因之一。3.SK2通道可能参与了心房的电重构过程,快速起搏可导致心肌组织SK2通道蛋白表达的下调,AngⅡ进一步下调SK2通道蛋白的表达,这可能是导致AF加重的原因之一。
[Abstract]:Objective: Atrial fibrillation (AF) is one of the most common arrhythmias in the clinic. It obviously increases the mortality and disability rate of the patients. It is a progressive disease closely related to age, and it can make the pathogenesis of the potential heart disease worse than that of.AF so far. Many hypotheses have been put forward, from the hypothesis of AF focal origin hypothesis. However, there is no one theory that can explain all AF phenomenon [1-3]., although triggering and reentry are gradually accepted as the mechanism of AF, but there are still many problems that have not been clarified in the AF maintenance matrix. The newly discovered SK2 channel is small conductance calcium. A subtype that activates the potassium channel (Small conductance Ca2+-activated K+channel, SK channel) has become one of the hotspots of recent research because of its atrial selectivity and changes in channels with AF. This channel is selective to potassium ions and is highly sensitive to voltage and is highly sensitive to Ca2+. It has been proved that the electrical reconfiguration of AF is involved. In cell Ca2+ overload, the increase of circulating or tissue angiotensin II (Angiotensin II, Ang II) increases the increase of intracellular calcium and causes AF to aggravate [4]. and SK2 channel is highly sensitive to intracellular calcium. Therefore, we speculate that Ang II leads to AF aggravation and may involve the regulation of SK2 channel. However, no related reports have been reported in literature review. Therefore, the purpose of this study is to explore the mechanism of Ang II regulation of the SK2 channel in the occurrence of AF. Methods: 25 healthy adult beagles were randomly divided into 5 groups (group Sham), pacing group (group Pacing), pacing + angiotensin II Group (group Pacing+Ang II), pacing + valsartan group (group Pacing+Valsartan), pacing +, and pacing + Angiotensin II + valsartan group (group Pacing+Ang II +Valsartan). The average blood pressure was measured 3 times before and after medication. The group was given Ang II 110ng/kg/min subcutaneous micropump or (and) Valsartan 30mg/kg/d orally at 2 weeks before pacing. All dogs were given pentobarbital sodium after administration. After anesthesia, the routine endotracheal intubation mechanical ventilation was used to detect the changes of electrocardiogram. The pacing electrode was inserted into the right atrium through the right femoral vein, and the electrophysiological pacing system was connected to the proximal end of the electrode. The other groups were given fast atrial pacing (frequency 600 / min) for 8 hours except the Sham group, and the atrial effective refractory period was measured every hour before and after pacing (atrial The frequency and duration of effectiverefractoryperiod, AERP) and AF. After the end of the pacing, the animal vein blood centrifugation was extracted, the serum AngII concentration was detected, the concentration of AngII in the left and right atrium tissue was detected by open chest, and the westernblotting method was used to detect the changes of SK2 channel protein expression in the right atrium tissue. Results: 1. the change of blood pressure: a After 2 weeks of ngii preconditioning, the blood pressure increased by 45 + 3.53mmhg in group pacing+angii compared with that in group sham, the difference was significant (P0.01). There was no significant difference between the other groups and sham group (P0.05) after.2. pacing. Compared with group pacing, AERP shortened (P0.01), pacing+valsartan group, and pacing+angii+valsartan group AERP lengthening (P0.01).3. pacing. Compared with group pacing, the concentration of serum and left and right atrial tissue in pacing+angii group was significantly higher than that in group pacing. The concentration of tissue AngII increased (P0.05), while the AngII concentration in serum and left and right atrium tissues in group pacing+valsartan increased, but there was no significant difference in the frequency and time of AF in.4. groups (P0.05). Compared with the sham group, the frequency and time of AF in pacing group and pacing+angii group increased significantly. There was no significant difference in the group (P0.05). Compared with the pacing group, the frequency and time of inducing AF increased in group pacing+angii (P0.01), but in group pacing+valsartan, pacing+angii+valsartan group decreased significantly (P0.01).5.westernblotting detection SK2 channel protein relative expression. The expression of histone decreased significantly (P0.01), in which the pacing+angii group decreased most significantly and the pacing+valsartan group decreased, but no other groups were obviously decreased (P0.05). Compared with the pacing group, the protein expression in the pacing+angii group decreased (P0.01), the pacing+valsartan group increased (P0.01), and the pacing+angii+valsartan group was also up (P0.05). 1. rapid pacing can lead to atrial electrical remodeling, in which Ang II can aggravate the electrical remodeling of the atrium, and Valsartan can reduce the electrical remodeling of the atrium and reduce the occurrence of AF,.2. rapid pacing can lead to the increase of the concentration of Ang II in the serum and the left and right atrium, which is one of the possible causes of the occurrence and maintenance of AF, and the.3.SK2 channel may be involved in the atrium. The rapid pacing can lead to the downregulation of SK2 channel protein expression in myocardial tissue, and Ang II further downregulation the expression of SK2 channel protein, which may be one of the reasons for the aggravation of AF.
【学位授予单位】：西南医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R541.75

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