海马脑片锥体细胞的膜电性质和突触反应

应用成年大鼠海马脑片锥体神经元细胞内记录技术,测得CA_1区锥体细胞的静息电位为-78±6mV(n=16),膜电阻69±18MΩ,时间常数5.7±2.1ms,由I-V曲线求得斜率电阻57±15MΩ(n=8)。I-F曲线表明锋电位发放频率随去极化电流增大而升高(n=4).刺激Schaffer侧支通路可透发潜伏期为5±2ms(n=7)的兴奋性突触后电位,其幅值呈等级性,为低钙高镁溶液取消,其迟后成分在无镁溶液中增大,提示兴奋性氨基酸可能为介导递质。     

miR-340对背根神经节神经元兴奋性和钠通道电流的作用

目的：观察miR-340对小鼠背根神经节神经元兴奋性和电压依赖性钠通道电流的作用。方法：采用全细胞膜片钳技术记录神经元放电和钠通道电流。结果：在给予miR-340-3p前DRG神经元的膜静息电位为-49.50±4.76 mV,灌流miR-340-3p后膜的静息电位为-52.13±5.32 mV,差异无统计学意义（P＞0.05）,提示miR-340未影响神经元静息膜电位。在给予miR-340-3p前诱发动作电位数为1.8±0.75个,灌流miR-340-3p后诱发动作电位数为5.6±0.51个,差异具有统计学意义（P＜0.05）,提示miR-340可增高神经元诱发放电频率。电流-电压曲线表明在激活电压从-30 mV至0 mV时,miR-340-3p明显增加钠通道电流密度,差异具有统计学意义（P＜0.05）。激活曲线也表明,miR-340-3p使钠通道激活曲线左移,半激活电压从-22.6 mV增加至-27.4 mV。结论：miR-340对背根神经节神经元的兴奋作用可能是介导坐骨神经损伤神经病理性疼痛的机制之一。     

心肌细胞肿胀激活氯离子通道的单通道特性

目的研究急性分离小鼠心肌细胞肿胀激活氯离子通道的单通道特征.方法采用膜片钳单通道(细胞贴附式和内面向外式)方法,记录急性分离的小鼠心肌细胞暴露于低渗溶液时出现的肿胀激活氯通道电流(ICl.swell).结果等渗状态下,用细胞贴附式记录,多数心肌细胞膜片无通道活动,用低渗溶液灌流细胞,在细胞容积增大的同时,出现单通道电流的激活.该肿胀激活单通道氯电压在-100mV~+100mV均有激活.在电压+100mV时,其单通道电导为(38.1±2.5)pS,开放概率为0.76±0.08,电流-电压曲线显示其反转电位(-34.5±2.8)mV,接近氯离子平衡电位的理论值(ECl=-38.6mV),且反转电位随氯离子浓度的改变而改变.氯通道阻断剂DIDS可逆性阻断该单通道电流.结论小鼠心肌细胞肿胀激活氯通道的单通道电导为(38.1±2.5)pS,电流呈外向整流特征并对DIDS敏感.     

法乐四联症儿童肥厚右心室细胞瞬间外向钾电流的研究

目的观察压力增高导致的人肥厚心室组织离子通道的特性.方法应用酶解分离技术从法乐四联症(F4)患儿的心脏右室得到单个细胞,应用膜片钳全细胞记录技术观察了细胞Ito1的特征.结果将钙电流阻断后,去极化至-20mV～+60mV时均可记录到Itn1,激活后电流衰减速度不随去极化程度的增强而改变,在0、20、40、60mV时分别为123ms±6ms、131ms±10ms、122ms±6ms、122ms±6ms,去极化至60mV时的电流密度为4.7pA/pF±0.8pA/pF,半数最大激活电位为4.1mV±2.8mV,半数最大失活电位出现在-41mV±4mV,失活后再激活的恢复时间常数为83ms±4ms.这种电流可被10mM4-AP基本抑制.结论肥厚的人右室细胞存在Itn1,通道动力学特征与成人心房肌细胞类似.     

心房IKur动作电位的控制和心房收缩力对慢性房颤的影响

背景:IKur快速外流是心房复极过程中的主要电流,也是治疗房性心律失常电位靶点。在窦性心律(SR)和慢性房颤(AF)患者中,以低剂量的4-氨基吡啶或二苯基衍生物AVE0118选择性阻滞IKur后,观察右心房小梁部位动作电位(AP)的变化。方法和结果:复极90%(APD90)时,AF的AP时程较SR的短(300±16ms,n=6vs414±10ms,n=15),然而AF的APD20却比SR的长(AF35±9msvsSR5±2ms,P<0.05)。4-氨基吡啶(5μmol/L)使SR的平台期电位从-21±3mV升至-6±3mV,而使AF的平台期电位从0±3mV升至+12±3mV。二苯基衍生物AVE0118的作用结果也与4-氨基吡啶相似…     

藻酸双酯钠对豚鼠心室肌细胞离子电流的作用

目的:观察藻酸双酯钠(Polysaccharide sulfate,PSS)对豚鼠单个心室肌细胞离子流的影响。方法:采用Ⅰ型胶原酶分离单个豚鼠心室肌细胞的方法,利用全细胞膜片箝记录技术,在不同箝制条件下,记录并分析了PSS对L-型Ca2+电流(ICa,L)、内向整流K+电流(IK1)的影响。结果:①PSS使ICa,L的激活时间常数变大,电流幅度减小,Ⅰ-Ⅴ曲线上移。在箝制电位为+10 mV时,PSS在6-9 min内使ICa,L的激活时间常数从(0.92±0.10)ms增加到了(1.15±0.11)ms(n=5,P<0.052);ICa,L的电流幅度从(16.80±1.71)pA/pF下降至(13.86±1.67)pA/pF(n=5,P<0.01)。②PSS可使IK1的内向成分和外向成分均增加。当箝制电位在-170 mV时,PSS能使IK1内向电流幅度从(224±16.17)pA／pF增加至(257±17.36)pA／pF(n=7,P<0.01);箝制电位在-50 mV时,PSS使IK1的外向电流幅度从(8.89±0.86)pA／pF增加至(10.38±1.18)pA／pF(n=7,P<0.05)。在反转电位附近时(-70--120 mV),PSS的作用不明显。PSS能使IK1的激活时间常数减小,当箝制电位在-160 mV时,激活时间常数从加药前的(1.05±0.11)ms减小到了加药后的(0.78±0.90)ms(n=7,P<0.01);同时,IK1的电导值变大,从(2.53±0.17)nS／pF增加到了(2.82 ±0.20)nS／pF(n=7,P<0.05)。结论:PSS对L-型Ca2+电流有抑制作用,对内向整?     

异丙酚对离体新生大鼠脊髓运动神经元的抑制作用

目的　研究脊髓运动神经元是否是新型静脉全麻药异丙酚 (propofol)作用的靶位 ,并观察异丙酚对离体新生大鼠运动神经元 (MN)的作用 ,分析其可能机制。方法　应用新生大鼠脊髓切片MN细胞内记录技术。结果　实验中记录到的 2 9个神经元 ,其基本电生理参数为静息电位 (-67.8± 6.8)mV ,斜率电阻 (66.3±3 1 .8)MΩ ,时间常数 (4 .9± 1 .7)ms,动作电位 (AP)幅度 (70± 9.3 )mV、超射 (2 .1± 8.9)mV、阈电位(-49.3± 7.5 )mV及半幅时程 (1 .4± 0 .6)ms。对 1 2个细胞进行 0 .1～ 1mmol/L异丙酚灌流 ,结果 0 .1mmol/L的异丙酚对其电生理性质的影响无显著意义 (n =1 2 ,P >0 .0 5 ) ;而在 9个测试细胞中 ,0 .3mml/L异丙酚提高了细胞内去极化诱发AP的阈值 (P <0 .0 5 ) ;1 .0mmol/L的异丙酚还在 7/ 8的测试细胞中 ,完全可逆地抑制AP的产生。同时进行电流强度 放电频率关系曲线分析 ,显示异丙酚(0 .3和 1 .0mmol/L)呈浓度依赖性、可逆地抑制MN的AP发放。另外 ,异丙酚 (0 .1～ 1mmol/L)对由背根电刺激引发的兴奋性突触后电位 (EPSP) ,也有浓度依赖性、可逆的抑制作用 (n =4)。但对照试验显示 ,脂肪乳剂对脊髓MN的基本电生理性质均没有影响。结论　异丙酚对离体新生大鼠脊髓运动神经元的活动 ,可能存在直接的抑?     

心室流出道室性心动过速的电生理学基础

目的研究心室流出道的电生理特性及其与室性心动过速的关系.方法利用细胞内微电极记录技术,观察豚鼠左心室流出道组织的电活动特性.结果 (1)在32例豚鼠左室流出道组织标本中6例(18.75%)未经电刺激即可记录到自律性电活动,23例(71.88%)在常规电刺激诱导下也可出现自律性电活动.(2)在左心室流出道记录到的动作电位形态呈多样性,可分为3大类①上升支缓慢、幅值小且4相自动去极化明显的自律性慢反应电位,其特征与窦房结慢反应自律细胞动作电位相似[APA(50.23±13.56)mV,Vmax(10.03±6.32)V/s,VDD(33.36±6.38)mV/s],记录部位为紧靠瓣膜下及流出道光滑部的局部区域;②非自律性慢反应电位,其上升支缓慢、幅值小无4相自动去极化[APA(63.26±17.33)mV,Vmax(18.27±8.33)V/s],分布在慢反应自律细胞的周围及相邻的局部区域;③非自律性快反应电位,其特征与普通心室肌细胞动作电位相似[APA(88.32±6.86)mV,Vmax(109.60±8.62)V/s],流出道的大部分组织为此类电位.各类型动作电位的0相去极化速度、幅度及动作电位时程均变异较大.结论心室流出道组织的电生理特性与普通心室肌不同,具有明显的自律性和电生理各向异性,我们认为这可能与临床上起源于流出道的室性心动过速有关,这一观点将为临床诊断和治疗室性心动过速提供新的思路,值得临床工作者进一步研究和关注.     

乳鼠窦房结细胞、心房肌细胞及心室肌细胞动作电位比较

目的研究乳鼠窦房结细胞、心房肌细胞及心室肌细胞的动作电位。方法选12只新生24 h内的Wistar大鼠乳鼠,分离培养窦房结细胞、心房肌细胞和心室肌细胞,运用全细胞膜片钳技术记录动作电位。结果窦房结细胞体积小,细而长,呈长梭形,搏动频率为（152.1±10.9）min-1;心房肌细胞体积亦较小,梭形或三角形,搏动频率为（116.3±8.6）min-1;心室肌细胞体积较大,可伸出伪足并交织成网,呈短梭形、多角形或不规则形,搏动频率为（92.4±9.3）min-1,3种细胞的搏动频率差别均有统计学意义（P＜0.01）。3种细胞的静息电位分别为（-41.3±4.0）,（-50.7±2.9）及（-59.8±2.1）mV,差别无统计学意义（P＞0.05）。心室肌细胞的APD20,APD50和APD90均较心房肌细胞延长,差别具有统计学意义（P＜0.05）。结论3种细胞形态各异,窦房结细胞具有自发性搏动,心室肌细胞动作电位时程较心房肌细胞长。     

促甲状腺素释放激素对离体新生大鼠运动神经元的直接和间接作用

<正> 对离体新生大鼠脊髓切片腹角神经元进行细胞内记录,发现灌流促甲状腺素释放激素(TRH,5～10μmol/L)使52％(n=64)的经逆行激活鉴定的运动神经元(MN)出现缓慢,且伴有膜电阻增大的去极化反应,并有大量峰电位发放,去极化幅度随膜电位超极化而减小,外推法计算的翻转电位为-88±6mV(n=3),在含TTX(0.3μmol/L)或低Ca~(2+)/高Mg~(2+)溶液中去极化持续存在。另外,TRH还同时使背根刺激在MN诱发的EPSP增大或转为峰发放(n=7),手动拑制     

大鼠海马脑片锥体神经元的细胞内记录

从成年大鼠分离海马结构并用震动切片机制备500μm 厚的海马脑片,应用玻璃微电极技术进行海马锥体层神经元的细胞内记录.对 CAl 锥体神经元的被动膜电性质、I-V 关系曲线、动作电位等进行了观察,发现灌流 Immol/L 的谷氨酸钠或乙酰胆碱均引起去极化,并伴有强烈放电.结果证明海马脑片神经元的细胞内记录是中枢神经电生理和药理学研究的一种稳定可靠的方法.     

Effect of acetylcholine on membrane potential in toad dorsal root ganglion neurons and its underlying ionic basis

Intracellular recordings were made to investigate the responses of membrane potential to acetylcholine (ACh) on neurons in isolated toad dorsal root ganglion (DRG). In the 73 neurons examined, 67 were of type A, and the remaining 6 of type C cell. The resting membrane potential of these two types of cells was −67.5±1.3 mV (× ±SE). During the application of ACh (4 × 10^-4–6 × 10^-4 mol/L), the changes in membrane potential were as follows: 1) hyperpolarization, with amplitude of 9.1±3.0 mV (X ± SE; n = 23); 2) depolarization, with amplitude of 12.9 ±2.2 mV (X ±SE; n = 20); 3) biphasic response, i.e., hyperpolarization with amplitude of 8.0±2.4 mV (X±SE) followed by depolarization with amplitude of 10.9±2.1 mV (X±SE) (n=24); no effect (n=6). The hyperpolarization induced by ACh was blocked by superfusion with atropine (1.3 × 10^-5 mol/L; n = 23), while ACh depolarization was blocked by the mixture of d-tubocurarine (1.4 × 10^-5 mol/L) and hexamethonium (1.4 ×10^-5 mol/L) (n = 18). When ACh caused hyperpolarization, the membrane conductance wascin reased by 13.8% and the reversal potential was about -96 mV (n=3). TEA (20 mmol/L) superfusion enhanced ACh depolarization amplitude by 48.2 ±3.2 % (× ± SE;n = 6), and depressed ACh hyperpolarization amplitude by 79.4 ±4.3 % (× ± SE; n= 8).MnCl₂ (4 mmol/l) superfusion decreased the amplitudes of ACh depolarization and hyperpolarization by 54.2 ±7.2 % (X ±SE; n= 5) and by 69.2±6.4 % (X±SE; n = 14) respectively. These results suggest that the depolarization and hyperpolarization induced by ACh are mediated by nicotinic and muscarinic receptors on the soma of toad DRG neurons separately, and it seems that ACh hyperpolarization involves activation of calcium-activated potassium conductance.     

下丘脑冠状切片视上核神经元的电生理特性

目的了解下丘脑冠状切片视上核神经元的电生理特性。方法在下丘脑冠状切片（厚５００μｍ）对视上核神经元进行细胞内生物电记录。结果测得静息电位（－５８±７） ｍＶ（ｘ± ｓ, ｎ＝４４）,膜斜率电阻（１９５±８３）ＭΩ,时间常数（１０．８± ５．０）ｍｓ,膜电容（６０±２０）ｐＦ,动作电位幅度（６７± ９）ｍＶ,阈电位（－４２ ±８）ｍＶ,半幅时程（２．１±１．１）ｍｓ,超射（１１±５）ｍＶ。在记录的１１３个细胞中,３１．９％的细胞有自发锋电位发放,其中５．５％为持续型（紧张型）放电,７０．６％为时相型放电,其余为不规则放电。在时相型放电的细胞可观察到自发的慢去极化电位。长时程去极化时锋电位发放呈明显的适应现象。顺行电刺激可诱发兴奋性突触后电位,并具有刺激强度依赖性。结论提示视上核神经元作为神经内分泌细胞具有与其他神经元不同的电生理特性。     

牛蛙球囊毛细胞电压依赖性钾通道电流的研究

目的 :研究牛蛙球囊毛细胞膜上钾通道的类型。方法 :全细胞膜片钳技术。结果 :1当钳制电位为 - 1 0 0 m V,以 1 0 m V的步距阶跃 ,阶跃从 - 70 m V至 + 2 0 m V,随着膜电位的去极化 ,可记录到一系列快速、瞬时的外向电流 ,4- Ap对其有特异性阻断作用。激活电压为 - 53.85± 7.8m V。2 A型钾通道的数量在牛蛙毛细胞间存在差异。 3当钳制电位为 - 70 m V,以 1 0 m V的步距阶跃去极化 ( - 50 m V～ + 4 0 m V) ,可产生一延迟整流性钾离子流 ,四乙基氯化氨 ( TEA)能使该电流幅度下降 59%± 1 1 %。结论 :牛蛙毛细胞膜上含有 A型钾通道和延迟整流性钾通道。     

大戟二萜醇酯对大鼠颈上神经节胆碱能传递的影响

应用细胞内生物电记录技术观察了两种大戟二萜醇酯对大鼠颈上神经节胆碱能传递的影响.灌流5或10μmol/L 的4β-大戟二萜醇-12,13-双丁酯(PDB)增大膜电阻而不影响膜电位,对刺激节前神经诱发的快兴奋性突触后电位(f-EPSP)及外源性乙酰胆碱(ACh)引起的 ACh电位均有浓度依赖性的增强作用,并诱导自发性 EPSP,表明 PDB 通过突触前、后机制易化交感神经节的胆碱能传递.4β-大戟二萜醇-12-肉豆蔻酯-13-乙酯(PMA,10μmol/L)灌流30min 对神经节细胞的电生理性质及其胆碱能传递无明显影响.     

K<Superscript>+</Superscript> channels and their effects on membrane potential in rat bronchial smooth muscle cells

Summary In order to investigate the K⁺ channels and their effects on resting membrane potential (Em) and excitability in rat bronchial smooth muscle cells (BSMCs), the components of outward K⁺ channel currents and the effects of K⁺ channels on Em and tension in rat bronchial smooth muscle were observed by using standard whole-cell recording of patch clamp and isometric tension recording techniques. The results showed that under resting conditions, total outward K⁺ channel currents in freshly isolated BSMCs were unaffected by ATP-sensitive K⁺ channel blocker. There were two types of K⁺ currents: voltage-dependent delayed rectifier K⁺ channel (K_v) and large conductance calcium-activated K⁺ channel (BK_Ca) currents. 1 mmol/L 4-aminopyridine (4-AP, an, inhibitor of K_V) caused a significant depolarization (from −8.7±5.9 mV to −25.4±3.1 mV,n=18,P<0.001). In contrast, 1 mmol/L tetraethylammonium (TEA, an inhibitor of BK_Ca) had no significant effect on Em (from −37.6±4.8 mV to −36.8±4.1 mV,n=12,P>0.05). 4-AP caused a concentration-dependent contraction in resting bronchial strips. TEA had no effect on resting tension, but application of 5 mmol/L TEA resulted in a left shift with bigger pD₂ (the negative logarithm of the drug concentration causing 50% of maximal effect) (from 6.27±0.38 to 6.89±0.54,n=10,P<0.05) in the concentration-effect curve of endothine-1, and a right shift with smaller pD₂ (from 8.10±0.23 to 7.69±0.08,n=10,P<0.05) in the concentration-effect curve of isoprenaline. It was suggested that in rat BSMCs there may be two types of K⁺ channels, K_v and BK_Ca, which serve distinct roles. K_v participates in the control of resting Em and tension. BK_Ca is involved in the regulation of relaxation or contraction associated with excitation. LIU Xiansheng, male, born in 1969, M. D., Ph. D. This project was supported by a grant from the National Natural Sciences Foundation of China (No. 30270583).     

Electrophysiological properties of neurons of guinea pig celiac ganglia

Summary The present study was carried out to investigate electrophysiological properties of neurons of guinea pig celiac ganglia in vitro. The mean value of resting membrane potential was-59.3 ±5.6 mV (n = 29). The mean values of membrane resistance, time constant and membrane capacity were 53.7±19.8mΩ, 18.4±8.5 ms, and 375.9±175.0 pF (n = 24) respectively. When depolarizing electrotonic potentials induced by application of depolarizing current pulses reached the threshold level, all of the neurons could be made to discharge action potentials. The mean values of amplitude, overshoot, duration of the spikes were 68.0±15.3 mV, 11.7 ±4.6mV, and 2.7±0.6ms (n = 29) respectively. 75% of the neurons tested (n = 29) produced tonic (slow adapting) firing in response to depolarizing current lasting 5 s. The remaining neurons (25%) produced phasic (fast adapting) firing. In addition, fast excitatory postsynaptic potentials or orihodromic action potentials were recorded from 80% of the neurons, antidromic action potentials were recorded from ihe remaining neurons during stimulation of the splanchnic nerves.     

Ionic basis of noradrenaline depolarization and hyperpolarization in toad dorsal root ganglia neurones

Summary The membrane conductance and reversal potential were estimated for neurones in toad dorsal root ganglia with intracellular recording technique during depolarization or hyperpolarization induced by noradrenaline (NA). The effects of blocking agents for potassium or calcium ion current on NA-induced membrane potential responses were observed as well. The NA depolarization was accompanied by a 32.6% decrease of membrane conductance. In a few neurones, the membrane conductance showed an initial increase and a following decrease. The NA hyperpolarization was associated with an increase of membrane conductance by 16.2%. The mean reversal potential of NA depolarization was -88.5 ± 0.9mV. The NA hyperpolarization responses were nullified at -89 to -92 mV of membrane potential. TEA superfusion enhanced NA depolarization amplitude by 73.7 ± 11.9% and depressed NA hyperpolarization amplitude by 40.5%. CsCl (intracelluar injection) increased phenylephrine depolarization by 34.5 %. MnCl₂ superfusion decreased the amplitudes of NA depolarization by 50.5 ± 9.9%, and of NA hyperpolarizalion by 89.5±4.9% respectively. The results suggest that depolarization or hyperpolarization induced by NA might be mediated by the alteration of K or Ca channels.