莱菔提取物对大鼠结肠运动影响的研究

目的莱菔提取物(crude extract of raphanus,Ecr)对结肠运动的影响的探讨将为临床治疗结肠动力障碍提供理论依据。方法采用免疫荧光化学和电生理学方法,通过观察莱菔提取物对结肠黏膜上Cajal间质细胞(Interstitial cells of Cajal,ICCs)的超极化激活性环核苷酸门控性阳离子非选择性通道的亚型1(The tape 1 of hyperpolarization-activated cyclic nucleotide-gated cation nons-elective channel,HCN1)通道的激活,以及采用结肠离体肌条,在给予Ecr及HCN1特异性阻断剂情况下,观察结肠离体肌条收缩情况。结果给予一定剂量的Ecr情况下,结肠黏膜ICCs上的HCN1通道呈现显著激活状态,离体肌条的收缩显著增加,而在给予HCN1通道的特异性阻断剂ZD7288干预下,再给予相同剂量Ecr,结肠离体肌条收缩力显著降低。结论 Ecr促进结肠收缩,与其激活结肠黏膜ICCs上的HCN1通道密切相关,HCN1通道参与Ecr对结肠运动的调节作用。     

pHCN4-DsRed Express2慢病毒载体的构建和鉴定

目的构建超极化激活环核苷酸门控阳离子通道基因亚型4启动子（HCN4）重组慢病毒载体并进行鉴定。方法采用Gateway克隆技术,通过attBxattP反应,构建穿梭质粒pup—HCN4,而后将pLV／Des2-Puro、pUP—HCN4、pDown—DsRed Express2三个质粒通过attLxattR反应,构建成pLV／EXPN2-Puro-HCN4-DsRed Express2质粒,再转染感受态细胞stb13,孵育扩增,离心纯化。采用PCR方法对重组慢病毒载体进行鉴定。结果基于位点特异性重组原理,应用Gateway克隆技术构建了多基因共表达的pHCN4-DsRed Express2慢病毒载体,通过提取DNA测序,证明该序列与理论值一致。结论应用Gateway克隆技术成功构建了pHCN4-DsRed Express2慢病毒载体。     

兔窦房结HCN2通道蛋白表达的不均一性和增龄性变化

目的检测窦房结起搏电流(If)基因HCN2通道蛋白在窦房结增龄性中的变化,探讨病态窦房结综合征的病因及发病机制。方法采用SABC-FITC技术,利用激光共聚焦显微镜测定幼年兔组(1~2周龄)、成年兔组(5~6月龄)和老年兔组(40~70月龄)窦房结组织不同区域HCN2通道蛋白荧光强度。结果光镜下,幼年兔组的窦房结组织细胞最密集,成年兔次之,老年兔最少,老年兔有细胞核固缩、裂解现象,幼年组、成年组和老年组细胞数分别为:26.40±3.27,15.60±2.88,11.10±1.91,其中两两比较,差异有统计学意义;幼年、成年和老年3个年龄组的兔窦房结组织的HCN2通道蛋白荧光强度在外周区与中心区差异有统计学意义;在SAN各区域,幼年组的HCN2通道蛋白荧光强度均高于成年组和老年组(幼年组与成年组:中心区60.10±12.82对43.87±9.95,交界区66.48±14.38对51.55±10.80,外周区79.49±18.63对53.52±9.16,P<0.01;幼年组与老年组:中心区60.10±12.82对33.72±3.25,交界区66.48±14.38对40.08±4.17,外周区79.49±18.63对46.58±7.59,P<0.01)。结论兔窦房结组织细胞数随年龄增加而逐渐减少,并且在老年兔组出现核固缩、裂解现象;兔窦房结表达的HCN2通道蛋白具有不均一性;随着年龄增长,兔窦房结组织各区域表达的HCN2通道均逐渐降低。     

The cardiac pacemaker current

In mammals cardiac rate is determined by the duration of the diastolic depolarization of sinoatrial node (SAN) cells which is mainly determined by the pacemaker I_f current. f-channels are encoded by four members of the hyperpolarization-activated cyclic nucleotide-gated gene (HCN1-4) family. HCN4 is the most abundant isoform in the SAN, and its relevance to pacemaking has been further supported by the discovery of four loss-of-function mutations in patients with mild or severe forms of cardiac rate disturbances. Due to its selective contribution to pacemaking, the I_f current is also the pharmacological target of a selective heart rate-reducing agent (ivabradine) currently used in the clinical practice. Albeit to a minor extent, the I_f current is also present in other spontaneously active myocytes of the cardiac conduction system (atrioventricular node and Purkinje fibres). In working atrial and ventricular myocytes f-channels are expressed at a very low level and do not play any physiological role; however in certain pathological conditions over-expression of HCN proteins may represent an arrhythmogenic mechanism. In this review some of the most recent findings on f/HCN channels contribution to pacemaking are described.     

HCN离子通道对Fontan循环下发生房性心动过速的作用

目的:探讨HCN离子通道对Fontan循环下发生房性心动过速的作用。方法:通过外科手术建立Fontan比格犬模型,术前及术后1周行心脏超声测量右心房大小,穿刺测量右心房和肺动脉压力,行右心房组织病理学检查观察右心房组织的纤维化程度。使用TaqMan实时定量PCR检测右心房肌细胞中HCN2和HCN4 mRNA表达水平,Western blot检测右心房肌细胞中HCN2和HCN4蛋白表达水平,全细胞膜片钳技术检测右心房肌细胞If通道电流。结果:共18只犬进行手术,其中存活5只,Fontan术后存活1周犬右心房内径较术前增加[(17.08±1.73)mm对(13.90±1.25)mm,P0.01],右心房压力增高[(17.80±2.39)mmHg对(8.40±1.14)mmHg,P0.01],肺动脉压力无明显变化[(12.60±2.41)mmHg对(13.00±2.74)mmHg,P0.05]。模型犬右心房组织纤维化程度较对照组增加(P0.05);模型犬术后右心房心肌细胞HCN2和HCN4 mRNA表达水平均较对照组升高(P均0.05),HCN2和HCN4的蛋白表达水平均较对照组升高(P均0.05);HCN通道电流较正常对照组增大,钳制电压为-140 mV时,模型组和对照组电流密度分别为(-1.98±0.14)pA/pF和(-1.09±0.09)pA/pF,P0.01。结论:Fontan循环下心房肌细胞HCN离子通道表达上调,HCN电流增大,可能参与房性心动过速的发生。     

大鼠急性心肌梗死后梗死周边区HCN通道蛋白表达的动态变化

目的 了解急性心肌梗死后梗死周边区心肌组织中HCN2和HCN4的mRNA和蛋白表达的动态变化.方法 通过结扎大鼠左冠状动脉前降支建立急性心肌梗死模型,将成功建模的大鼠随机分为24 h组、1周组、2周组和4周组,同时于各时间点均设立假手术组,每组5只.于各时间点末取左心室梗死周边区心肌组织样本(假手术组取左心室相应部位的心肌组织),用逆转录聚合酶链反应检测HCN2和HCN4 mRNA的表达,用免疫组织化学和免疫印迹法检测HCN2和HCN4蛋白的表达.结果 假手术组左心室心肌组织中存在HCN2和HCN4通道蛋白的表达,梗死周边区心肌组织中HCN2和HCN4的表达在梗死后24 h出现上升趋势,于梗死后1周表达达到峰值,之后逐渐下降,梗死后4周HCN2 mRNA和蛋白的表达仍高于对照组,而HCN4的表达已回落至假手术组水平.结论 急性心肌梗死后左心室梗死周边缺血区心肌组织HCN2和HCN4通道蛋白的表达呈动态变化趋势,梗死后1周表达明显增高.     

Various Electrocardiographic and Electrophysiologic Presentations of Normal and Abnormal Sinus Node

Electropbysiology of the Sinus Node. Differentiation of normal from abnormal sinus nodal function is frequently difficult because the electrocardiographic and electrophysiologic presentations of abnormal and normal sinus nodal function are quite diverse. The autonomic nervous system greatly influences sinus nodal function, making this differentiation even more complicated. Data obtained from the recording of sinus nodal electrogram in animals and humans have helped in elucidating changes in automaticity and conduction of the sinus node. In this review, we provide examples of rhythms related to normal and abnormal sinus nodal function. (J Cardiovasc Electrophysiol, Vol. 3, pp. 187–197, April 1992)     

The rationale for repurposing funny current inhibition for management of ventricular arrhythmia

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高血压合并2型糖尿病患者心率震荡的研究

目的探讨窦性心率震荡(HRT)、静息心率(RHR)和心率变异性(HRV)时阈指标(SDNN)在单纯高血压及高血压合并2型糖尿病中的变化及相互关系。方法选择单纯高血压46例、高血压合并2型糖尿病22例和健康人50例,分别为单纯高血压组、高血压合并2型糖尿病组和对照组。根据24h动态心电图记录,分别计算各组HRT的两个参数震荡初始值(TO)和震荡斜率值(TS)以及HRV的全部NN间期的标准差(SDNN)和6:00时的RHR,比较各组间的差别,分析TO、TS与SDNN、RHR之间的相关性。结果高血压合并2型糖尿病组TO、TS、TO+TS、SDNN的阳性检出率均高于单纯高血压组及对照组,组间比较差异有显著意义;RHR值明显高于单纯高血压组及对照组,组间比较差异有显著意义。高血压合并2型糖尿病组TO与SDNN呈负相关,与RHR呈正相关;TS与RHR呈负相关,而与SDNN呈正相关。结论高血压患者特别是合并有2型糖尿病者,HRT减弱及HRV异常,RHR增加,提示HRT及RHR可以作为早期发现高血压或合并2型糖尿病患者心脏自主神经功能紊乱的一个有效的可靠无创指标。     

Intermittent sinus bigeminy as an expression of sinus parasystole: A case report

A case of sinus parasystole is reported. The diagnosis of sinus parasystole is relatively difficult because there is no difference between the basic sinus P wave and the parasystolic wave. Sinus parasystole is diagnosed according to the following electrocardiographic criteria: (1) premature P waves having contour identical to P waves of basic beats; (2) intervals between premature P waves mathematically related. In the case reported, the coupling intervals during long phases of intermittent sinus bigeminy were nearly fixed, because there was little variability in the returning cycles, making the diagnosis of sinus parasystole difficult.     

稳心颗粒对人超极化激活环核苷酸门控阳离子通道2电生理特性的影响

目的探讨稳心颗粒对人超极化激活环核苷酸门控阳离子通道2(HCN2)电生理特性的影响。方法将人HCN2的mRNA注射到非洲爪蟾卵母细胞,孵育1~2天后,采用双电极电压钳技术观察0.5,1,2,4 g/L稳心颗粒对HCN2通道电流的作用。结果①测试电位-90 mV时,0.5,1,2,4 g/L稳心颗粒分别使HCN2瞬时电流增加17.74%±6.04%,49.26%±8.74%,86.05%±16.15%和124.38%±11.62%,瞬时电流增加50%的药物浓度(EC50)为1.54±0.24 g/L(n=8)。②在测试电位-140 mV到-100 mV水平上,2 g/L稳心颗粒延长HCN2通道激活时间常数:(226.74±31.37 ms vs 143.68±21.45 ms;-140 mV,n=10,P<0.05)③2 g/L稳心颗粒延长HCN2通道去激活时间常数(1 293.54±95.03 ms vs 647.13±61.36 ms;-140 mV,n=10,P<0.05)。结论稳心颗粒呈浓度依赖性增强HCN2瞬时电流,减缓通道激活和去激活过程。     

Prevalence and One-year Outcome of Carotid Sinus Hypersensitivity in Unexplained Syncope: A Prospective Cohort Study from South India

Background

Carotid sinus syndrome accounts for one third of patients who presents with unexplained syncope. Prevalence of carotid sinus hypersensitivity (CSH) in Indians has not been studied till now.

HCN4通道基因过度表达的电生理实验研究

目的探讨腺病毒介导超极化激活环核苷酸门控通道（HCN4）在猪左心室过度表达的电生理效应。方法应用细菌内同源重组法构建携带人HCN4基因的重组腺病毒载体（Ad-HCN4）和绿色荧光蛋白的重组腺病毒载体（Ad-GFP）。实验动物随机分成3组：Ad-HCN4组（n=6），Ad-GFP组（n=5）和PBS组（n=3）。腺病毒或PBS注入到Yorkshire猪左心室游离壁，3-4d后行房室结消融造成完全性房室阻滞，记录体表心电图并进行心内起搏标测。注射部位心肌组织用酶分离后获得单个心肌细胞，膜片钳记录起搏电流（If）和内向整流钾电流（Ik1）。结果Ad-HCN4组室性心律频率显著快于Ad-GFP组和PBS组，心腔内起搏标测证实该心律起源于Ad-HCN4注射区且可被异丙肾上腺素所调节，无水乙醇消融Ad-HCN4注射区后该心律消失。Ad-HCN4转染心肌细胞表达较大的If;Ik1在3组间差异无统计学意义。结论腺病毒介导HCN4通道基因心室局部高表达发挥了生物起搏器的作用。