Pathological Changes in the Sinoatrial Node Tissues of Rats Caused by Pulsed Microwave Exposure

To observe microwave induced dynamic pathological changes in the sinus nodes, wistar rats were exposed to 0, 5, 10, 50 mW/cm^2 microwave. In 10 and 50 mW/cm^2 groups, disorganized sinoatrial node cells, cell swelling, cytoplasmic condensation, nuclear pyknosis, and anachromasis, swollen, and empty mitochondria, and blurred and focally dissolved myofibrils could be detected from 1 to 28 d, while reduced parenchymal cells, increased collagen fibers, and extracellular matrix remodeling of interstitial cells were observed from 6 to 12 months. In conclusion, 10 and 50 mW/cm^2 microwave could cause structural damages in the sinoatrial node and extracellular matrix remodeling in rats.

Effect of simulated ischemia-reperfusion on I_f in sinoatrial node cells and the intervention of KATP channel opener

Objective: To study the effect of simulated ischemia-reperfusion (I/R) on If of sinoatrial node (SAN) cells and the intervention of KATP channel opener Pinacidil. Methods: The SAN cells of the neonatal rats were detached and purified 2 d before the experiment. The experimental animals were randomly divided into the control group, group of simulated I/R, group intervened with KATP channel opener Pinacidil (P+ I/R) and group intervened with KATP channel blocking agent 5-HD (5-HD + P + I/R & 5-HD + I/R). The If density of each group was measured by technique of routine whole cell patch clamp and multiple-catheter perfusion system and the If activated curve in each group was drawn. Results: ①Under different directive potentials, the If density of the SAN cells in I/R group increased significantly, compared with that in the control group ( P < 0.01); that in P + I/R group decreased significantly, compared with that in I/R group ( P < 0.01); the If density values in 5-HD + P + I/R group and 5-HD + I/R group increased significantly, compared with that in P + I/R group, but showed no significant difference with that in I/R group. ②Compared with that in the control group, the If activated curve of the SAN cells moved rightwards under ultimate activating potential, half of which was from - 108.0 ± 12.4 to - 89.5 ± 7.2 mV ( P <0.01); compared with that in I/R group, If activated curve of the SAN cells moved leftwards under ultimate activating potential, half of which was the range from -99.5± 10.8 mV (P<0.05); KATP channel blocking agent 5-HD could block the effect of Pinacdil on If activated curve. Conclusion: KATP channel opener Pinacidil can antagonize the effect of simulated I/R on the If of SAN cells, which may be beneficial to the maintenance of the relative stability of ion steady state and electrophysiological activities under condition of simulated I/R.

Junctional Pacemaker May Replace the Sinoatrial Node

Junctional rhythm is usually seen in the clinic with different causes.We report a case of bicuspid aortic valve accompa-nied by sinoatrial node dysfunction.The junctional escape beat could accelerate with physiological needs and provided for the normal needs of daily life when dysfunction of the sinoatrial node occurred,which provides a new way for the treatment of sinoatrial node dysfunction.Our fi ndings could be potentially signifi cant for identifying causes and choos-ing appropriate treatment strategies by using ECG monitoring in the clinic in the future.

Protective effect and mechanism of K_(ATp) channel opener on the sinoatrial node cells of neonatal rat cultured in simulated ischemia-reperfusion

Objective: To study the effect of KATp channel opener and its possible mechanism on the sinoatrial node cells of neonatal rats which were cultured under simulated ischemia-reperfusion. Methods: Freshly isolated sinoatrial node (SAN) cells of neonatal rats were purified and cultured for 2 d, and then they were randomly divided into the control, simulated ischemia-reperfusion group (I/R group) , group intervened with KATp channel opener pinacidil (P + I/R group), KATP Channel blocking agent 5-HD (5-HD + I/R group) , and group with the 2 agents at same time (5-HD + P + I/R group) . The survival rate of cells was measured by flow cytometry and the content of intracellular calcium in the cells of each group was detected with laser confocal microscopy. Results: ① The survival rate of SAN cells in I/R group [ (51. 79±6. 28)% ] was remarkably significantly lower than in control [ (95. 08±10. 48)% ] (P < 0.001), and very significantly lower than in P + I/R group [ (63. 77±5. 35) % ] (P<0.01), however, those of 5-HD + P + I/R group [(52. 88±6. 25)% ] and 5-HD+I/R group [ (53. 16±5. 35)% ] was significantly lower compared with that in P + I/R group (P <0. 01) ; ② When the average fluorescence intensity of sinoatrial node cells in the control was regarded as 100% , the relative fluorescence intensities of each group were: ( 374±52) % in I/R group, significantly higher than that of control (P <0. 01) ; ( 162±20)% in P + I/R group, declining significantly than that of I/R group (P<0.01); (385?6)% in 5-HD+ P + I/R group and (379±44)% in 5-HD + I/R group, increasing significantly than that of I/R group (P<0.01). Conclusion: ① Simulated ischemia-reperfusion can significantly reduce the survival rate of SAN cells, and can also lead to the overload of intracellular calcium in them.② KATp channel opener, pinacidil, exerts protective effect on the cells under simulated ischemia-reperfusion, which may be associated with the decrease of intracellular calcium loading in them.

超极化激活环核苷酸门控通道4和钙依赖性蛋白激酶Ⅱ在心源性猝死患者窦房结中的表达情况及其法医学意义

目的探讨心源性猝死(SCD)患者窦房结组织超极化激活环核苷酸门控通道4(HCN4)和钙依赖性蛋白激酶Ⅱ(CaMKⅡ)蛋白表达情况及其法医学意义。方法收集2018年1月至2022年12月川北医学院司法鉴定中心尸检心脏标本200份,其中SCD100份(SCD组),非SCD100份(非SCD组)。两组均进行常规苏木精-伊红(HE)染色,采用免疫组织化学方法检测两组标本窦房结组织中HCN4和CAMKⅡ蛋白表达,图像处理软件计算目的蛋白的AOD值。结果SCD以成年男性为主且在死因中以冠心病占比最多。SCD组中HCN4的AOD值低于非SCD组,CAMKⅡ的AOD值高于非SCD组,差异有统计学意义(P<0.05)。结论窦房结中HCN4、CaMKⅡ异常表达可能是心源性猝死的机制,HCN4、CaMKⅡ有望成为心源性猝死的分子标记。

窦房结节律调控的动力学机制综述

窦房结是包埋在右心房的一小片可以自发电位振荡的组织,是整个心脏搏动的发起点.其节律失常会诱发一系列的综合征.窦房结节律的发起和调控,是心脏电生理和医学在窦房结研究领域的关注点.随着近几十年来非线性动力学被引入心律失常领域,心脏疾病与物理学的结合研究为这一医学范畴的问题带来了重要的理论发展.旨在综述从非线性动力学的角度研究窦房结节律所取得的一些重要成果,比较详细地介绍窦房结数值模型、节律调控的分岔机制、信号传导条件、心率变异等方面的研究进展.从目前的发展趋势来看,非线性动力学有可能成为一个有效解释窦房结节律调控的理论框架,因此,建议在多尺度建模和基于多尺度模型进行基础动力学理论分析方面做进一步的研究工作.

兔窦房结切片制作方法的探究和形态学特点的观察

目的:建立兔窦房结(SAN)的快速取材和切片标本制作方法,观察其形态学结构。方法:健康大白兔10只,取其心脏上腔静脉与右心房交界处的界沟组织,常规处理后进行连续切片,采用HE染色法和改良Masson三色染色法显示兔心脏SAN的形态学结构。结果:兔SAN主要位于上腔静脉与右心房界沟的静脉窦侧,SAN区域组织结构较为疏松,染色比较浅淡,主要由P细胞、T细胞、少量心房肌细胞以及包绕细胞的胶原纤维构成,有SAN动脉1~3条。常规HE染色法除细胞核蓝染以外,其余组织均红色,胶原纤维等成分不易观察,改良Masson三色染色中,胶原纤维被苯胺蓝染成蓝色,肌纤维被酸性品红染成红色,胞核呈黑蓝色,对于成分结构复杂的结缔组织分类显示,清晰明了,更好地显示了SAN结构。结论:该取材及染色方法适用于兔SAN切片标本的制作,有助于SAN结构的观察。该方法能够为心脏传导系统的研究提供技术保障,同时能更好地服务教学。

Effect of Qiangxin Fumai Granule(强心复脉颗粒) on Electrophysiological Functions of the Sinoatrial Node during Ischemia-reperfusion of the Right Coronary Artery in Rabbits

Objective： To study the effect of the Chinese medicine Qiangxin Fumai Granule （强心复脉颗粒, QFG） on electrophysiological functions of the sinoatrial node during ischemia-reperfusion （IR） of the right coronary artery in rabbits. Methods： The right coronary artery IR model in rabbits was adopted. The modeled rabbits were randomly divided into 4 groups： the model group, the atropine group, the highdose QFG group, and the low-dose QFG group, with 8 animals in each group. In addition, twelve rabbits were selected for the sham-operative group. The drugs were administered once via duodenal perfusion after modeling had been stabilized for 10 min. The changes in AA interval, the sinoatrial conduction time （SACT）, the sinus node recovery time （SNRT）, the corrected sinus node recovery time （CSNRT） and the index of sinus node recovery time （ISNRT） at different time points during ischemia and reperfusion were measured. Results： The AA interval was prolonged for more than 40 ms in the model group during ischemia. Compared with the model group, the four electrophysiological parameters abovementioned in the high-dose QFG group and the low-dose QFG group were decreased to different extents at each time point （P〈0.01 or P〈0.05）, and no statistically significant differences were found between the QFG groups and the atropine group （P〉0.05）. Conclusion： QFG is beneficial for accelerating the recovery of sinus node autorhythmicity and conduction function, so as to protect electrophysiological functions of the sinoatrial node. Accelerating the recovery of autorhythmicity and conduction function in the sinus node is considered its electrophysiological mechanism in the treatment of sinoatrial node injury induced by ischemia.

Primary culture and identification of sinoatrial node cells from newborn rat

Objective To establish a reliable approach to primary culture and identification of sinoatrial node (SAN) cells. Methods The SAN cells were cultured from SAN tissue removed from neonatal Wistar rats and purified with differential attachment and 5'-bromodeoxyuridine (BrdU) treatment. The obtained cells were morphologically observed with inverted microscopy and transmission electron microscopy. Its action potential was recorded using electrophysiological methods.Results Three distinctly different cells were observed in the cultured SAN cells: spindle, triangle and irregular. Of these, the spindle cells comprised the greatest proportion, with their shape, structure and electrophysiological characteristics consistent with those of the pacemaker cells of SAN. The triangle cells were similar in features to the similarly shaped myocytes located in the atrial myocardium. Conclusions The culture method of differential attachment combined with BrdU treatment is a reliable approach to growing SAN cells. Of the cells cultured from SAN, the spindle cells appear to function as pacemaker cells.

Effects of Chinese Herbal Medicine Serum on the Apoptosis of Sinoatrial Node Cells Induced by Simulated Ischemia-reperfusion

Objective:To study the effect of Chinese herbal medicine Kangxin Fumai Granule(康心复脉颗粒 Granule for heart diseases) serum on the primary cultured sinoatrial node(SAN) cell apoptosis induced by simulated ischemia-reperfusion(IR).Methods:The SAN cells removed from SAN tissue of neonatal Wistar rats were cultured and purified with differential attachment and 5'-bromodeoxyuridine(BrdU) treatment.Simulated IR model was adopted.The obtained cells were morphologically observed with inverted microscopy.By using the method of serum pharmacology,the cell apoptosis was measured with TUNEL staining qualitatively and with flow cytometry quantitatively.Results:Three kinds of cells were observed in the cultured SAN cells:spindle,triangle and irregular.The spindle cells comprised the greatest proportion.The SAN cells in the model group showed moderate positive brown staining in the nucleus,and the apoptosis rate increased significantly compared to that in the control group(P<0.01).While the SAN cells in the Kangxin Fumai Granule high-dose group did not demonstrated positive staining in the nucleus,and the apoptosis rate decreased significantly compared to that in the model group(P<0.05).Conclusion:Of the cells cultured from SAN,the spindle cells were pacemaker cells of SAN in rats.Blockade and/or inhibition of the SAN cell apoptosis might be one of the important mechanisms of Kangxin Fumai Granule in preventing and treating sinoatrial injury induced by simulated IR.

Effects of external stimuli on the pacemaker function of the sinoatrial node in sodium channel gene mutations models

Loss of function and gain of function mutations of the sodium channel were investigated using an intact two-dimensional rabbit sinoatrial node (SAN) and atrial cell model. The effects of three external stimuli (acetylcholine secretion by the vagal nerve, acid-base concentration, and tissue temperature) on cardiac pacemaker function and conduction were studied. Our results show that these two groups of mutations have different effects on pacemaker function and conduction. Furthermore, we found that the negative effects of these mutations could be altered by external stimuli. The bradycardic effects of mutations were magnified by an increase in acetylcholine level. Changes in acid-base concentration and tissue temperature increased the ability of the SAN to recover its pacemaker function. The results of this study increase our understanding of sodium channel disorders, and help to advance research on the treatment of these conditions.

Sinoatrial node pacemaker cells share dominant biological properties with glutamatergic neurons

Activation of the heart normally begins in the sinoatrial node(SAN).Electrical impulses spontaneously released by SAN pacemaker cells(SANPCs)trigger the contraction of the heart.However,the cellular nature of SANPCs remains controversial.Here,we report that SANPCs exhibit glutamatergic neuron-like properties.By comparing the single-cell transcriptome of SANPCs with that of cells from primary visual cortex in mouse,we found that SANPCs co-clustered with cortical neurons.Tissue and cellular imaging confirmed that SANPCs contained key elements of glutamatergic neurotransmitter system,expressing genes encoding glutamate synthesis pathway(G/s),ionotropic and metabotropic glutamate receptors(Grina,Gria3,Grm1 and Grm5)t and glutamate transporters(Slc17a7).SANPCs highly expressed cell markers of glutamatergic neurons(Snap25 and S/-c17a7)t whereas Gad1,a marker of GABAergic neurons,was negative.Functional studies revealed that inhibition of glutamate receptors or transporters reduced spontaneous pacing frequency of isolated SAN tissues and spontaneous Ca2+transients frequency in single SANPC.Collectively,our work suggests that SANPCs share dominant biological properties with glutamatergic neurons,and the glutamatergic neurotransmitter system may act as an intrinsic regulation module of heart rhythm,which provides a potential intervention target for pacemaker cell-associated arrhythmias.

兔主动脉前庭自律细胞与窦房结电生理特性的比较

为进一步阐明左心室流出道(主动脉前庭)自律细胞的特性,及其与窦房结细胞的异同,本实验利用常规的玻璃微电极细胞内记录技术,观察了一些离子通道阻断剂分别对离体兔窦房结起搏细胞与左心室流出道慢反应自律细胞的电生理特性的影响,重点探讨了这两种自律细胞的0期、4期去极离子流的异同。结果表明:(1)用1μmol/L维拉帕米(verapamil,VER)灌流后,窦房结及主动脉前庭自律细胞的动作电位幅值(APA)、0相最大除极速率(V_(max))、最大舒张电位(MDP)绝对值、舒张期除极速率(VDD)、自发放电频率(RPF)均明显下降,复极90％时间(APD_(90))延长(P<0.05)。(2)用180μmol/L氯化镍(NiCl_2)灌流,两自律细胞的VDD均明显下降;APA、V_(max)和RPF也显著降低,且窦房结细胞的APD_(90)明显延长。(3)给予2 mmol/L 4-氨基吡啶(4-AP)后,窦房结及主动脉前庭自律细胞的VDD均明显增快,MDP绝对值、APA和V_(max)显著下降,APD_(90)明显延长(P<0.05)。(4)给予2 mmol/L氯化铯(CsCl),两自律细胞的VDD及RPF均明显变慢。结果提示:(1)主动脉前庭自发慢反应电位的0相、4相去极离子流及复极离子流均与窦房结优势起搏细胞相似。(2)主动脉前庭起搏细胞Ca^(2+)内流为其0相主要去极离子流,复极过程主要由K^+外流引起,4相自动除极以K^+外流衰减为主。

一种超声组织多普勒图像的定量分析新方法

目的研究通过二维B型超声组织多普勒图像 (DTI)序列分析获得组织机械运动定量参数的新方法 ,解决心脏生理研究中不能从图像中获得所关心区域内全部定量数据的问题 ;分析窦房结组织激动过程的图像序列。方法建立图像颜色信息同机械运动参数之间的关系 ,并从复合图像中得到多普勒信息 ;通过对DTI图像序列进行分析 ,获得用于定量描述窦房结组织运动的曲线。结果 ( 1 )通过DTI图像分析获取了所关心区域内全场的加速度值 ;( 2 )对窦房结组织多普勒图像序列的分析 ,得到了窦房结激动过程的加速度累积概率分布函数随时间变化的曲线。结论通过DTI图像序列分析可以获得组织运动的定量信息 ,为心脏生理研究提供新途径。

硫化氢对家兔窦房结起搏细胞的电生理效应(英文)

本研究应用细胞内微电极技术,观察硫化氢(hydrogen sulfide,H2S)对家兔窦房结起搏细胞的电生理效应。结果表明:(1)NaHS(H2S供体)50、100、200μmol/L浓度依赖地降低家兔窦房结起搏细胞4相去极化速率及起搏放电频率。(2)ATP敏感性钾(ATP-sensitive K+,KATP)通道阻断剂格列苯脲(glybenclamide,Gli,20μmol/L)阻断NaHS(100μmol/L)的电生理效应。(3)预先应用起搏离子流(pacemaker current,If)通道阻断剂氯化铯(CsCl,2mmol/L)对NaHS(100μmol/L)的电生理效应无影响。(4)胱硫醚-γ裂解酶(cystathionineγ-lyase,CSE)的不可逆抑制剂DL-propargylglycine(PPG,200μmol/L)对家兔窦房结起搏细胞的动作电位参数无影响。以上结果提示,H2S对家兔窦房结起搏细胞有负性变时作用,这些效应可能与其开放KATP通道,增加K+外流有关,与If无关。本实验没有发现窦房结起搏细胞内有CSE催化产生的内源性H2S的合成。

白藜芦醇对家兔窦房结起搏细胞的电生理效应(英文)

目的为探讨白藜芦醇是否能成为抗心律失常药,研究了其对窦房结起搏细胞的电生理效应.方法应用细胞内微电极方法记录家兔窦房结起搏细胞的动作电位.结果白藜芦醇(30～120 μmol·L-1)显著降低窦房结起搏细胞的动作电位幅度、零相最大上升速率(Vmax)、舒张期除极速率和起搏放电频率.而对最大舒张期电位和90%复极化的时间无明显作用.预先应用L型钙通道开放剂Bay-K-8644(0.5 μmol·L-1)灌流窦房结10 min可阻断白藜芦醇(60 μmol·L-1)对起搏细胞的上述电生理效应.而应用超极化激活电流阻断剂氯化铯(2 mmol·L-1)加钾通道阻断剂四乙铵(20 mmol·L-1)或应用一氧化氮(NO)合酶阻断剂L-NAME(0.5 mmol·L-1)灌流窦房结标本10 min对白藜芦醇(60 μmol·L-1)的电生理效应没有明显影响.结论白藜芦醇能抑制家兔窦房结起搏细胞的自发活动,此效应可能与其通过非NO依赖性途径抑制钙离子内流有关.

蛇床子素对心肌慢反应动作电位及右心房自搏频率的影响

用细胞内微电极技术，观察了蛇床子素（Ｏｓｔ）对离体豚鼠乳头状肌ＢａＣｌ２高ＫＣｌ除极化及家兔窦房结慢反应动作电位的影响。结果表明。Ｏｓｔ抑制Ｂａ２＋诱发的自发电活动：降低高Ｋ＋除极化慢反应动作电位的幅度（ＡＰＡ）及动作电垃最大上升速率（Ｖｍａｘ），并缩短５０％动作电垃时程（ＡＰＤ５０），延长９０％动作电位时程（ＡＰＤ９０）；对家兔离体窦房结优势起搏细胞窦搏周期（ＳＣＬ），ＡＰＡ及Ｖｍａｘ亦有抑制作用。此外，对离体豚鼠右房负性频率作用。似与激动Ｍ胆碱能受体或阻滞β肾上腺圭能受体无关，与钙拮抗剂维拉帕米相似．结果提示。Ｏｓｔ具有钙拮抗作用．

成人窦房结的透射电镜观察

目的 :了解成年人心脏窦房结的超微结构 ,为下一步探讨结构与功能的关系打基础。方法 :用透射电镜观察二例男青年的窦房结。结果 :(1 )成年人窦房结中结细胞、移行细胞线粒体丰富 ,嵴多 ,密集 ;2 )结细胞、移行细胞之间有中间形式 ;(3 )结细胞与移行细胞的主要区别在于前者肌丝束排列不规则 ,无完整肌节 ,后者有 ;(4 )有些结细胞含心钠素颗粒 ;(5 )结细胞环绕密布结内之毛细血管 ,细胞胞巢外层细胞与血管贴近 ,形成保障血液供给窦房结的特殊构筑 ;(6)许多地方成纤维细胞的板状突起包绕着毛细血管外围 ,另一侧细胞与成纤维细胞、毛细血管、神经末梢紧密相关 ,构成一与功能相结合的特殊构筑。

人窦房结胶原纤维比例与分型年龄变化的研究

目的 :了解窦房结的胶原纤维年龄变化及分型。方法 :采用 Masson三色染色网格测微器及苦味酸天狼猩红染色 ,分别作光镜、偏光显微镜观察 ,对 4 7例非心脏病变窦房结胶原纤维比例及分型进行检测。结果 :窦房结胶原纤维随年龄的增高有增高的趋势 ,发现胶原纤维以 1型为主 ,3型胶原纤维随年龄的增高有减少的趋势。结论

强心复脉颗粒对兔缺血再灌注窦房结细胞凋亡及Bax,Bcl-2,Fas-L蛋白表达的影响

目的:探讨临床有效中药复方强心复脉颗粒防治病窦综合征的分子作用机制。方法:采用兔右冠状动脉根部结扎/放松法制备兔窦房结缺血再灌注模型,运用原位末端标记(TUNEL)法观察强心复脉颗粒对兔右冠状动脉缺血再灌注致窦房结细胞凋亡的影响,并运用免疫组化的方法观察其对细胞凋亡相关基因Bax,Bcl-2,Fas-L蛋白表达的影响,用Imagepro Plus图象分析系统计算Bax,Bcl-2,Fas-L表达平均吸光度值。结果:兔右冠状动脉缺血再灌注所致窦房结损伤可明显诱导兔窦房结细胞发生凋亡,引发Fas-L基因蛋白表达增强,同时显著引发Bax基因蛋白表达增强,Bcl-2/Bax下降;强心复脉颗粒可显著下调Fas-L和Bax基因的蛋白表达,上调Bcl-2/Bax,明显抑制和阻断窦房结细胞发生凋亡。结论:通过调节缺血再灌注后窦房结Bax,Bcl,Fas-L基因的蛋白表达从而抑制和阻断细胞凋亡的发生,可能是中药复方强心复脉颗粒防治病窦综合征窦房结缺血再灌注损伤的分子作用机制。