持续性钠电流与细胞缺血缺氧

持续性钠电流由可兴奋细胞膜上某些对河豚毒素敏感的电压依赖性钠通道持续开放产生，随着膜片钳技术的广泛应用，对其了解逐渐深入。近年来发现，持续性钠电流与细胞缺血缺氧关系密切。缺血缺氧时，持续性钠电流的幅度增大导致细胞内Na^＋浓度增高，进而引起细胞内Ca^2＋浓度增高、细胞外谷氨酸浓度增高以及细胞兴奋性改变，最终导致细胞不可逆性损伤甚至死亡。目前认为，持续性钠电流增大是缺血缺氧时细胞损伤的一种早期基础性病理学过程。     

急性缺血对单个窦房结起搏细胞起搏电流的影响

目的 探讨急性缺血对窦房结起搏细胞起搏电流(If)影响的机制.方法 将兔窦房结起搏细胞分为三组,均先灌流正常台式液,电流稳定后实验Ⅰ、Ⅱ组分别灌流含5.4、10mmol/L KCl的缺血样台式液,实验Ⅲ组灌流含10mmol/L KCl台式液,灌流5～8min,再用正常台式液冲洗;采用穿孔膜片钳技术记录If.结果 实验Ⅰ组If电流密度在舒张期膜电位(-60～-70mV)无显著变化;实验Ⅱ组If电流密度在测试电位(-60～-110mV)均显著增强(P<0.05);而实验Ⅲ组If电流密度亦显著增强(P<0.05).结论 急性缺血伴有细胞外高钾可显著增强兔窦房结起搏细胞If电流密度,其机制可能与细胞外高钾有关.     

心室快钠电流在不同模拟缺血时间的变化及阿托伐他汀的作用

目的观察不同模拟缺血时间下大鼠左室心肌细胞快钠电流(INa)的变化规律和阿托伐他汀对该过程的影响。方法 Wistar大鼠共30只,分离左室心肌细胞,分为缺血组(正常→模拟缺血)和他汀组(正常→模拟缺血+5μmol/L阿托伐他汀)。用全细胞膜片钳记录两组正常状态INa(对照),再从模拟缺血3~21 min,每2 min记录1次,检测标准化INa峰值;比较正常和模拟缺血3 min时INa的门控参数。结果①标准化INa峰值(测试电位-40mV):缺血组正常状态下为0.95±0.04,与正常状态比,缺血3 min时增至1.15±0.08(P<0.01)并达峰,9 min和11 min时分别降至0.98±0.12和0.92±0.12(均P>0.05),至21 min时减至0.56±0.13(P<0.01);他汀组在缺血3 min时和正常状态比无差别(分别为0.92±0.12和0.97±0.04,P>0.05)。②门控参数:由正常状态至缺血3min状态,缺血组半激活电压(V1/2,a)、激活曲线斜率(Ka)、半失活电压(V1/2,i)和恢复时间常数(τ)均减小(均P<0.01),失活曲线斜率(Ki)不变;组间比较,他汀组Ki值下降(P<0.05),τ值减小程度弱于缺血组(P<0.05)。结论模拟缺血对INa变化的作用呈时间依赖性;阿托伐他汀可通过改变门控特性来抑制这一达峰过程。     

阿托伐他汀对大鼠左室心肌细胞瞬时钠通道电流的作用

目的观察阿托伐他汀对正常和模拟缺血大鼠左室心肌细胞瞬时钠通道电流(INa)的作用。方法Wist-ar大鼠30只,用于分离左室心肌细胞。细胞按异体配对原则分为他汀组(阿托伐他汀5μmol/l+乙醇8.575mmol/L)和对照组(乙醇8.575 mmol/L)。采用全细胞膜片钳技术记录INa:测定正常和模拟缺血状态下,用药前和用药后3～5 min的数据;比较标准化INa峰值、半激活电压(V1/2)、激活曲线斜率(k)和衰减时间常数(τ)。结果正常状态下,他汀组用药后在-40 mV、-35 mV和-30 mV测试电位下的标准化INa峰值分别由0.93±0.14,0.92±0.06和0.88±0.08降低至0.68±0.16,0.68±0.17和0.65±0.18(P均<0.01);用药前后V1/2、k不变;用药后在-30 mV、-25 mV和-20 mV测试电位下的τ值(ms)分别由1.22±0.27,1.12±0.23和1.04±0.21延长至1.34±0.33,1.24±0.31和1.17±0.30(P均<0.05)。他汀组用药后对模拟缺血细胞INa的作用和正常细胞的作用相似。对照组对照液使用后不引起INa上述指标的变化。结论阿托伐他汀对正常和模拟缺血状态的大鼠左室心肌细胞的INa均有钠通道阻滞样作用。     

伊布利特对兔心房细胞快钠电流活性的影响

目的观察不同浓度伊布利特对心房细胞快钠通道的影响。方法新西兰纯种大耳白兔40只,随机分为正常对照组(Con),伊布利特10-7mol/L、10-6mol/L和10-5mol/L浓度组。利用胶原酶酶解法分离心房肌细胞,应用膜片钳全细胞记录方法,记录对照组及伊布利特3种浓度组心房细胞INa活性,并与正常对照组进行比较分析。结果INa峰值电流密度在对照组为-87.12±4.67pA/pF;伊布利特10-7mol/L、10-6mol/L和10-5mol/L组分别为-68.82±4.43,-45.26±3.46和-33.46±3.11pA/pF,伊布利特组较对照组有明显下降(P<0.05或0.01),伊布利特3组之间也有显著差异且呈浓度依赖性(P<0.05)。伊布利特组的INa稳态失活曲线浓度依赖性左移,INa再恢复明显减慢。结论伊布利特浓度依赖性的抑制心房细胞0相快钠电流,这可能是伊布利特治疗房性心律失常的部分离子通道机制。     

豚鼠左心室不同区域细胞Iks电流对缺血反应的差异

目的：研究缺血时豚鼠左心室心内、外膜细胞及M细胞缓慢激活延迟整流钾通道电流（Iks)的变化特性。方法：利用全细胞膜片钳技术观察豚 鼠左心室心内、外膜细胞及M细胞Iks变化，利用不同成分浴槽液模拟细胞正常及缺血环境，观察Iks尾电流锋值的变化情况。结果：缺血时，三层细胞Iks均小于正常状态；指令电压小于0mV时，三层细胞Iks同步减小，减少率无显性差异，P＞0．05。指令电压≥0mV时，M细胞Iks减少程度明显高于心内、外膜细胞，P＜0．05；而心内、外膜细胞减少率无显性差异，P＞0．05。结论：缺血时左心室心内、外膜细胞及M细胞Iks减弱，而M细胞Iks减弱更为明显，这可能会增加心室壁电活动不均一性，诱发心律失常。     

黄芪对兔急性心肌梗死心室肌细胞钠通道电流的影响

目的 :研究黄芪对兔急性心肌梗死 （AMI）后心室肌细胞钠通道电流 （INa）的影响。方法 :采用结扎兔冠状动脉左前降支的方法建立 AMI动物模型 ,应用膜片钳全细胞记录方法 ,观察 AMI后 1周心外膜梗死区心肌细胞 INa的变化。结果 :AMI后 1周 INa的 I- V曲线明显上移。对照组 INa电流密度峰值 （- 30 m V）为 4 5 .5 0± 5 .33p A/ p F（n=12 ） ,AMI组为 2 2 .4 8± 4 .6 2 p A/ p F（n=14 ） ,显著低于对照组 （P<0 .0 1） ;黄芪组为 37.14± 3.79p A / p F（n=15 ） ,与 AMI组相比 ,显著增大 （P<0 .0 5 ）。结论 :AMI后 1周梗死区心室肌细胞 INa明显下降 ,黄芪可以使 AMI后下降的 INa趋于正常 ,逆转 AMI后形成的电重构。     

缺血后处理对大鼠心室肌细胞内向整流钾电流和动作电位的影响

目的探讨缺血后处理（IPC）对大鼠心室肌细胞内向整流钾电流（IKI）和动作电位的影响及机制。方法实验分IPC组、缺血／再灌注（I／R）组、单纯灌流（SP）组，利用大鼠心脏建立离体灌注模型，采用胶原酶酶解法分离得到大鼠单心室肌细胞，采用膜片钳全细胞技术分别记录三组心室肌细胞电流和动作电位的变化。结果在-120mV和-30mV刺激电压水平，IKI电流密度：IPC组低于I／R组，I／R组高于SP组（P均〈0．05），IPC组同SP组无差异（P〉0．05）。与SP组和IPC组比较，I／R组静息电位明显升高（P〈0．05）；而动作电位幅度、20％动作电位时程、50％动作电位时程、90％动作电位时程均明显下降（P〈0．05）。而IPC组各值与SP组无差异（P〉0．05）。结论IPC可以降低大鼠缺血／再灌注心肌细胞IKI延长缺血／再灌注心肌细胞APD。     

心肌梗死1周后梗死边缘区心室肌细胞快钠通道电流跨壁异质性的变化

目的 探讨心肌梗死1周后梗死边缘区心肌细胞快钠通道电流(INa )跨壁异质性的变化.方法 30只兔随机分为3组,其中两组结扎家兔左前降支建立心肌梗死动物模型,分别为心肌梗死组和假手术对照组,另一组为正常对照组.1周后,用膜片钳技术研究左心室梗死边缘区三层心肌细胞INa 的改变.结果 正常对照组左室三层细胞的钠电流存在异质性, M细胞的峰值INa 是心内膜和心外膜细胞的2倍多;M细胞的INa 失活最快;对照组与假手术组无明显差别.心肌梗死组三层细胞的INa I-V曲线均上移,以 M细胞变化最显著, INa 稳态失活曲线均左移,以心外膜细胞变化最显著.结论 左室心肌细胞的INa 存在跨壁异质性;心肌梗死对INa 的跨壁异质性有明显影响.     

心肌梗死1周后梗死边缘区心室肌细胞快钠通道电流跨壁异质性的变化

目的探讨心肌梗死1周后梗死边缘区心肌细胞快钠通道电流（INa）跨壁异质性的变化。方法30只兔随机分为3组,其中两组结扎家兔左前降支建立心肌梗死动物模型,分别为心肌梗死组和假手术对照组,另一组为正常对照组。1周后,用膜片钳技术研究左心室梗死边缘区三层心肌细胞INa的改变。结果正常对照组左室三层细胞的钠电流存在异质性,M细胞的峰值INa是心内膜和心外膜细胞的2倍多;M细胞的INa失活最快;对照组与假手术组无明显差别。心肌梗死组三层细胞的INa I—V曲线均上移,以M细胞变化最显著,INa稳态失活曲线均左移,以心外膜细胞变化最显著。结论左室心肌细胞的INa存在跨壁异质性;心肌梗死对INa的跨壁异质性有明显影响。     

Differential Sodium Current Remodelling Identifies Distinct Cellular Proarrhythmic Mechanisms in Paroxysmal vs Persistent Atrial Fibrillation

BackgroundThe cellular mechanisms underlying progression from paroxysmal to persistent atrial fibrillation (AF) are not fully understood, but alterations in (late) sodium current (I_Na) have been proposed. Human studies investigating electrophysiological changes at the paroxysmal stage of AF are sparse, with the majority employing right atrial appendage cardiomyocytes (CMs). We here investigated action potential (AP) characteristics and (late) I_Na remodelling in left atrial appendage CMs (LAA-CMs) from patients with paroxysmal and persistent AF and patients in sinus rhythm (SR), as well as the potential contribution of the “neuronal” sodium channel SCN10A/Na_V1.8.MethodsPeak I_Na, late I_Na and AP properties were investigated through patch-clamp analysis on single LAA-CMs, whereas quantitative polymerase chain reaction was used to assess SCN5A/SCN10A expression levels in LAA tissue.ResultsIn paroxysmal and persistent AF LAA-CMs, AP duration was shorter than in SR LAA-CMs. Compared with SR, peak I_Na and SCN5A expression were significantly decreased in paroxysmal AF, whereas they were restored to SR levels in persistent AF. Conversely, although late I_Na was unchanged in paroxysmal AF compared with SR, it was significantly increased in persistent AF. Peak or late Na_v1.8-based I_Na was not detected in persistent AF LAA-CMs. Similarly, expression of SCN10A was not observed in LAAs at any stage.ConclusionsOur findings demonstrate differences in (late) I_Na remodeling in LAA-CMs from patients with paroxysmal vs persistent AF, indicating distinct cellular proarrhythmic mechanisms in different AF forms. These observations are of particular relevance when considering potential pharmacologic approaches targeting (late) I_Na in AF.     

脑红蛋白与缺血缺氧性脑损伤

脑红蛋白(neuroglobin,Ngb)是携氧球蛋白家族成员之一,主要以单体形式存在于神经细胞中,与脑内氧供应密切相关.脑缺血缺氧能诱导Ngb高表达,并作为一种内源性神经保护因子保护神经元免受缺血缺氧性损害.文章对Ngb的分布、结构、功能及其在缺血缺氧性脑损伤中的保护作用和机制做了综述.     

Rapid Noninvasive Continuous Monitoring of Oxygenation in Cerebral Ischemia and Hypoxia

The brain is most sensitively dependent on oxygen to maintain its normal function. Methods to assess the degree of its oxygenation have generally been invasive and indirect. Rapid assessment of brain oxygenation is particularly vital during cerebrospinal ischemia and hypoxia. We have developed a noninvasive electro-optical method using pulsed near-infrared (NIR) light to quantify brain oxygenation during ischemia and hypoxia in anesthetized rabbits. Cerebral ischemia was induced through 30–40 s of bi-lateral carotid artery occlusion. Cerebral hypoxia was induced by varying inspired oxygen levels. The NIR light response to the interventions was expressed in terms of relative absorption (RA). Results showed that our pulsed NIR system could rapidly detect sudden alterations in oxygenation and blood flow to the brain. The response patterns during cerebral ischemia and hypoxia were significantly different, although both decreased brain oxygenation. The overall RA response to ischemia was much faster (in seconds) than during hypoxia (in minutes). These different response patterns can serve as early warning signal of low brain oxygenation and to discriminate the cause of the diminished oxygenation. The present pulsed NIR system is capable to provide a rapid, noninvasive and continuous monitoring of such decreases in brain oxygenation.     

Myocardial Hypofunction Due to Ischemia and/or Hypoxia in Collateralized and Noncollateralized Hearts

The severity of coronary artery (CA) disease depends on the degree of CA stenosis possibly aggravated by an O₂ deficiency in the blood and the CA architecture. To analyze the functional response of the myocardium to hypoxia provoked by different methods, studies on dogs and domestic pigs were retrospectively evaluated. The left anterior descending coronary artery (LAD) was mechanically narrowed while the coronary blood flow (Q _LAD) and myocardial shortening fraction (MSF) of dependent left ventricular subendocardial wall segments were assessed. Myocardial oxygen delivery ( ) was calculated from Q _LAD and O₂ content. In dogs, MSF decreased to half that in the control when was lowered by about 50% irrespective of the mode of hypoxia (i) CA narrowing: Q _LAD = –51%. (ii) Hypoxemia by pump-controlled CA perfusion with venous blood: Q _LAD = –29%. (iii) O₂-transport capacity lowered by hemodilution: Q _LAD = +47%). In pigs, mechanically impeding Q _LAD and by 47% diminished MSF by 82%. MSF of –50% was achieved at a Q _LAD of –31%, with Q _LCx unaffected. In dogs in contrast, MSF of –54% in the LAD region was obtained at a Q _LAD of –53% while the LC_x flow rose by 22%. Consequently, local MSF lessened by 50% in dogs as well as in pigs when the sum flow through the LCA (LAD + LC_x) was reduced by about 30%. This might indicate an onset of collateral blood flow, which occurs in dogs but not in swine.     

奥扎格雷钠治疗短暂性脑缺血发作的疗效分析

目的探讨奥扎格雷钠(奥吉格)治疗短暂性脑缺血发作(TIA)的临床疗效。方法将76例患者随机分为治疗组和对照组,治疗组40例,给予奥吉格80mg,2次/d静脉滴注;对照组36例,给予阿司匹林50mg,3次/d,口服。两组疗程均为14d,并于治疗结束后随访60d,观察疗效。结果两组总有效率比较差异无统计学意义(P>0.05),而治疗组较对照组的基本治愈率明显提高(P<0.01)。结论奥吉格治疗TIA效果确切,尤其是其较高的基本治愈率,将大大降低TIA患者脑梗死的转归率。     

心肌缺血再灌注损伤相关细胞因子及细胞通路研究进展

心肌缺血再灌注损伤是心肌梗死急性治疗所不可避免的一种损害,它是由多种炎症因子及多细胞信号通路参与的复杂的炎症损伤反应,其具体机制涉及氧化应激、线粒体损伤及钙超载等,目前很多研究旨在探索其发生机制,以便尽可能减小这种损伤.新的因子和靶作用位点不断被发现,对未来临床治疗提供了新的方向.     

Critical Limb Ischemia: Current Approach and Future Directions

Patients with critical limb ischemia (CLI) represent the highest risk patients with peripheral artery disease (PAD), with high rates of death, amputation, and other cardiovascular events. Previously, nonsurgical options for patients with CLI were limited. However, advances in endovascular techniques such as angiosome-based revascularization and technologies such as drug-eluting balloon and stent platforms have dramatically improved the therapeutic outlook. Additionally, advances in stem cell-based therapy and angiogenic factors show promise as adjuvant medical therapy.     

心肌细胞晚钠离子流与心血管疾病

近年来的研究证明,心肌细胞膜钠通道晚钠离子流(晚/Na)与心血管疾病,尤其与缺血性心脏病及其相关疾病状态的发生、发展密切相关。晚/Na抑制剂雷诺嗪能有效抑制晚/Na内流,进而缓解心肌缺血,改善心脏舒缩功能和遏止相关心律失常的发生。目前为止,除众多基础研究的证据外,尚有雷诺嗪治疗慢性缺血性心脏病临床试验的证据。现就晚/Na与缺血性心脏病及其相关疾病,如稳定型心绞痛、心功能不全和心律失常的关系及雷诺嗪心血管保护作用的研究进展做一综述。