红霉素对小鼠海马神经元电压依赖性钾电流的影响

目的:研究红霉素对小鼠海马神经元电压依赖性钾电流的影响。方法:采用分离新生小鼠海马细胞和全细胞膜片钳技术的方法,观察给予红霉素前后海马神经元细胞电压依赖性钾电流的变化和电流-电压曲线的改变。结果:红霉素可抑制小鼠海马细胞电压依赖性钾电流,使电流峰值由(810.67±250.86)pA下降至(529.96±171.83)pA(P<0.05);给予系列去极化脉冲刺激海马神经元,随着刺激电压强度的增强,钾外向电流增加,电压-电流曲线右移,但不改变曲线的形态。结论:红霉素可抑制小鼠海马神经元电压依赖性钾电流,并可能通过中枢机制来影响其调节胃肠运动的效应。     

哮喘大鼠肺泡巨噬细胞电压依赖性钾通道的活性变化

目的探讨哮喘模型大鼠肺泡巨噬细胞(alveolar macrophage,AM)电压依赖性钾通道(Voltage-dependent potassiumchannel,KV)活性的变化及其对巨噬细胞功能的影响。方法利用卵蛋白(ovialbumin,OVA)致敏并激发大鼠建立哮喘模型,收集支气管肺泡灌洗液(bronchus alveolarlavagefluid,BALF)培养AM。利用全细胞电压钳模式记录AM细胞膜上的KV电流,观察比较哮喘模型组和对照组KV通道活性的变化。结果哮喘组支气管肺泡灌洗液(BALF)细胞总数显著增高,与对照组(n=7)比较差异显著(P<0.01);哮喘大鼠AM细胞KV电流幅度[(243.56±133.56)pA,n=11]较对照组[(656.23±162.34)pA,n=11]明显降低(P<0.01)。结论哮喘大鼠AM细胞KV通道活性降低,可能导致AM兴奋性增高易被激活分泌各种炎性介质和细胞因子,从而参与哮喘炎症的形成。     

大黄素对大鼠近端结肠平滑肌细胞电压依赖性钾通道的影响

目的研究大黄素对大鼠近端结肠电压依赖性钾离子通道的影响，以探讨其增强结肠运动的机制。方法 采用全细胞膜片钳技术测定电压依赖性钾离子通道快速激活型钾电流及延迟整流型钾电流。结果大黄素(1～30 μmol·L^-1)浓度依赖性地阻断延迟整流性钾通道，加快电流失活，其阻断作用不需要钾通道的开放。30 μmol·L^-1大黄素可抑制快速激活型钾电流。5 μmol·L^-1大黄素对钾通道的激活动力学及失活动力学没有影响，但30 μmol·L^-1大黄素使其激活动力学曲线明显右移，斜率常数由(13.0±0.6)上升至(19.6±2.5) mV，同时也使失活动力学曲线明显右移。结论大黄素可阻断延迟整流型钾通道及快速激活型钾通道，其阻断作用不是开放阻断。     

咪唑安定临床治疗浓度对海马神经元钠离子通道的作用

目的 :采用大鼠海马神经元作为研究对象 ,研究咪唑安定对神经元钠离子通道的影响 ,以探讨其临床遗忘作用的可能机制。方法 :在急性分离的大鼠海马锥体神经元上 ,利用全细胞膜片钳技术 ,记录钠离子通道的电流 ,研究咪唑安定对钠离子通道电流幅度和激活特性的影响。结果 :咪唑安定对海马钠离子通道电流具有可逆性抑制作用 ,0 .1和1 0 μmol·L- 1 的咪唑安定对钠离子通道分别抑制了(7.95± 7.46) %和 (2 5 .3 7± 8.3 1 ) % (P <0 .0 1 )。1 0 μmol·L- 1 的咪唑安定还可使钠离子通道的激活曲线右移。结论 :咪唑安定对海马神经元上的钠离子电流有较弱程度的抑制作用 ,但可能不是其主要的临床作用机制     

慢性孵育β淀粉样肽25-35对培养大鼠海马神经元电压依赖性外向钾通道亚型mRNA表达的影响

目的研究慢性孵育β淀粉样肽_25-35(β-AP_25-35)对海马神经元电压依赖性外向钾通道亚型mRNA表达的影响。方法用RT-PCR方法检测mRNA的表达,用光密度扫描法半定量测定表达变化。结果在正常培养的海马神经元上延迟整流(Kv2.1,Kv1.5),瞬间外向(A型)(Kv4.2,Kv1.4),钙激活的大电导(rSlo)钾通道亚型均有表达。β-AP_25-35 3 μmol·L^-1孵育细胞24 h后,Kv2.1 mRNA的表达明显上调,其它亚型则无显著性变化;β-AP_25-35上调Kv2.1 mRNA的作用主要发生在β-AP_25-35应用后48 h内;60 h后Kv2.1 mRNA表达水平显著下调。结论Kv2.1转录水平的上调可能参与β-AP_25-35选择性地增加海马神经元上延迟整流钾电流(I_K)的作用。     

过氧化氢对培养大鼠海马神经元瞬时外向钾电流的影响

目的　研究过氧化氢对海马神经元上瞬时外向钾电流的影响。方法　采用全细胞膜片钳技术记录培养大鼠海马神经元瞬时外向钾电流的变化。结果　 3 0 μmol·L-1H2 O2 孵育 12h后 (1)明显抑制IA,电流密度由 (5 3 8±15 8) pA·pF-1变为 (18 5± 6 2 ) pA·pF-1(n =10 ,P <0 0 1) ;(2 )明显抑制IA 激活作用 ,半数最大激活电压由 (-15 2± 3 6)mV左移至 (- 18 2± 2 7)mV(n =10 ,P <0 0 1) ;(3 )明显抑制IA 失活作用 ,失活常数由 (42 2± 10 1)ms变为 (81 9± 3 5 0 )ms(n =10 ,P <0 0 5 ) ,半数最大灭活膜电位V1/ 2 由 (- 87 5± 12 6)mV变为 (- 99 8± 2 1)mV(n =10 ,P <0 0 1) ;(4)明显抑制IA 电流失活后复活作用 ;恢复时间常数由 (2 7 9± 14 1)ms变为 (5 8 6± 10 0 )ms(n=10～ 11,P <0 0 1) ;(5 )降低静息膜电位 ,由 (- 64 9±9 4)mV变为 (- 46 0± 12 8)mV(n =6～ 11,P <0 0 1) ,延长动作电位时程 ,由 (8 7± 3 4)ms增至 (16 0± 6 2 )ms(n =6～ 11,P <0 0 5 )。结论　H2 O2 对IA 的抑制作用可能参与其对神经元的氧化应激损伤毒性     

东莨菪碱致记忆障碍大鼠中枢电压依赖性钾通道亚型的表达

目的研究东莨菪碱致记忆障碍大鼠模型中枢电压依赖性钾通道亚型mRNA表达的差异。方法Morris水迷宫实验检验大鼠空间学习记忆能力,用RT-PCR方法检测大脑皮层和海马中5种电压依赖性钾通道Kv1.4,Kv1.5,Kv2.1,Kv4.2及Kv4.3 mRNA的表达。结果注射东莨菪碱大鼠的学习记忆能力明显下降,大脑皮层中Kv4.2的表达比对照组降低28.8%;海马中Kv1.4的表达升高111.7%,Kv2.1的表达升高64.3%,而Kv4.2的表达降低33.9%。其它电压依赖性钾通道表达的变化不大。结论东莨菪碱致大鼠学习记忆障碍的同时可诱发中枢电压依赖性钾通道亚型的表达改变。     

水杨酸钠抑制大鼠螺旋神经节神经元电压门控钾通道的研究

目的研究水杨酸钠对大鼠螺旋神经节神经元电压门控钾通道电流(Ik)的影响。方法采用全细胞膜片钳技术分析水杨酸钠对急性分离大鼠SGN电压门控钾通道电流的影响。结果水杨酸钠抑制电压门控钾通道电流幅值,其抑制强度与水杨酸钠浓度呈正相关,1mmol/L水杨酸钠可导致Ik激活曲线向超级化方向移动10.5885mV。结论水杨酸钠对大鼠SGN电压门控钾通道电流具有抑制作用,使其电流峰值减低、激活曲线向超级化方向移动。     

他克林对培养大鼠海马神经元延迟整流钾电流和瞬间外向钾电流的影响

目的研究他克林对培养大鼠海马神经元上延迟整流钾电流(I_K)和瞬间外向钾电流(I_A)的影响。方法 大鼠海马神经元原代培养,全细胞膜片钳记录培养大鼠海马神经元上电压依赖性外向钾电流和瞬间外向钾电流变化。结果他克林明显抑制海马神经元延迟整流钾电流和瞬间外向钾电流,呈浓度依赖性,对延迟整流钾电流的敏感性高于瞬间外向钾电流。30 μmol·L^-1他克林显著影响I_K和I_A稳态激活曲线,使所有电流的V_1/2左移。结论他克林明显抑制延迟整流钾电流和瞬间外向钾电流,对延迟整流钾电流的敏感性高于瞬间外向钾电流。     

In vitro study on influence of nano particles of CuO on CA1 pyramidal neurons of rat hippocampus potassium currents

The effects of nano particles of CuO on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus using the whole-cell patch-clamp techniques. Nano particles of CuO had small effects on transient outward potassium current (I(A), no statistical significance) and mainly inhibited delayed rectifier potassium current (I(K)) in the concentration of 5 x 10(-5) g/mL. Nano particles of CuO didn't shift the steady-state activation curve of I(K) and I(A) but negatively shifted the inactivation curve of I(K). The effects on inactivation curve of I(A) had no statistical significance. These results suggested that blockades of K+ currents by nano particles of CuO could be preferential for I(k) for the first time. This may interfere with the normal function of nerve cells.     

Effects of carvedilol on delayed rectifier and transient inactivating potassium currents in rat hippocampal CA1 neurons

1. The aims of the present study were to investigate the mechanism(s) underlying the protective effect of carvedilol against neural damage. 2. The transient inactivating potassium current (I_A) and the delayed rectifier potassium current (I_K) in rat hippocampal CA1 pyramidal neurons were recorded using whole‐cell patch‐clamp techniques. 3. Carvedilol (0.1–3 μmol/L) significantly inhibited I_K with an IC₅₀ of 1.3 μmol/L and the inhibition was voltage independent. Over the same concentration range, carvedilol had no effect on the amplitude of I_A. At 1 μmol/L, carvedilol did not significantly change the steady state activation curves of I_A and I_K, but did negatively shift their steady state inactivation curves. Recovery from inactivation was slowed for both I_A and I_K. The inhibitory effect of carvedilol on I_K was not affected by the adrenoceptor agonists phenylephrine and prazosin or the adrenoceptor antagonist isoproterenol, but propranolol was able to shift the dose–response curve of carvedilol for I_K to the right. 4. Because I_K is the main pathway for loss of intracellular potassium from depolarized neurons, selective obstruction of I_K by carvedilol could be useful for neuroprotection.     

Effects of sodium metabisulfite on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus.

The effects of sodium metabisulfite (SMB), a food preservative mostly used in food and drug industries, on voltage-dependent potassium currents in acutely isolated hippocampal CA1 pyramidal neurons of rat were studied using the whole-cell patch-clamp techniques. SMB increased transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner. 10 microM SMB shifted the steady-state activation curve of IK to more negative potentials, and the steady-state inactivation curves of IA and IK to more positive potentials. Time to peak of IA was not affected, but the decay of IA was delayed by SMB. However, the activation and inactivation time constants of IK were both decreased by SMB. These results suggested that SMB differently affected IA and IK, and it would decrease the excitability of hippocampal neuron by increasing potassium currents.     

急性分离大鼠脑内神经元上由多巴胺引起的离子电流(英文)

目的:研究多巴胺(DA)诱发神经元的电流反应。 方法:制霉菌素打孔的膜片箝全细胞记录。 结果:在-20mV箝制电压下,DA(0.1—1mmol·L~(-1))对26％黑质神经元(5/19个)引起外向电流;对36％海马CA_1锥体细胞(25/69个)出现3种反应:外向电流伴有膜电导增加、缓慢内向电流伴随膜电导减小、外向—内向电流。DA引起的CA_1锥体细胞电流反应的阈剂量为3mmol·L~(-1),无电压依赖关系。翻转电位(E_(DA))接近K~ 平衡电位,为TEA抑制。结论:DA诱发海马CA_1锥体细胞的外向电流可能是K~ 电流。     

咪达唑仑对交感神经元电压门控性钾电流的影响

目的 :观察不同浓度咪达唑仑对交感神经元电压门控钾通道电流的影响 ,探讨临床浓度咪达唑仑对钾电流的作用是否与抑制交感神经系统有关。方法 :用酶消化法获得急性分离的SD大鼠 (7～1 0d)颈上交感神经节细胞 ,应用膜片钳技术记录不同浓度的咪达唑仑对电压门控钾电流的影响。结果 :在钳制电位 (Vh) -80mV ,刺激电压 (Vt) -1 0 0mV～ 3 0mV ,时程 1 60ms条件下 ,不同浓度的咪达唑仑对电压门控钾电流均有抑制作用 ,且呈浓度依赖性。临床相关浓度的咪达唑仑(0 .3 μmol·L-1)使钾通道电流峰值下降3 .89% (P =0 .88)。5 0 %钾通道电流峰值受抑制时的咪达唑仑浓度(IC50 )约为 70 .0 6μmol·L-1。结论 :咪达唑仑对交感神经元电压门控钾电流具浓度依赖性抑制作用 ,但临床浓度咪达唑仑对钾电流影响较小。     

Effects of 3-benzidino-6-phenylpyridazine, as an acetylcholinesterase inhibitor, on outward potassium current in acutely isolated rat hippocampal pyramidal neurons

As an acetylcholinesterase (AChE) inhibitor, the effects of 3-benzidino-6-phenylpyridazine (BPP) on outward potassium current including delayed rectifier potassium current (I(K(DR))) and transient outward potassium current (I(K(A))) in acutely isolated rat hippocampal pyramidal neurons were studied, using the whole cell patch-clamp technique. BPP reversibly inhibited electric eel AChE as an inhibitor, with IC(50) of 1.43muM. BPP (0.10-100muM) decreased I(K(DR)) and I(K(A)) in a concentration-dependent, voltage-independent and partial reversible manner, with IC(50) of 0.47 and 0.31muM, respectively. 10muM BPP did not affect steady-state activation of I(K(DR)) and I(K(A)). In addition, 10muM BPP shifted the voltage dependence of steady-state inactivation of I(K(A)) towards negative potential. In conclusion, BPP potently inhibits I(K(DR)) and I(K(A)) in rat hippocampal pyramidal neurons, which may contribute to BPP's restoring the damaged central nervous system.     

The inhibitory effects of nano‐Ag on voltage‐gated potassium currents of hippocampal CA1 neurons

The application of the nano‐sized materials continues to grow at a rapid rate in the fields of medicine, biotechnology, and environmental technology. Voltage‐gated potassium currents play a key role in excitable cellular viability and function, especially in the central nervous system. The aim of this study was to investigate the actions of silver nano‐particles (nano‐Ag) on voltage‐activated potassium currents in hippocampal CA1 neurons using whole cell patch‐clamp technique. The hydrodynamic mean diameter of nano‐Ag (10^?5g mL^?1) was 223.9 nm in artificial cerebrospinal fluid (ACSF). Both types, transient potassium (I_A) and delayed rectifier potassium (I_K) current amplitudes were inhibited by the nano‐Ag (10^?5g mL^?1). The nano‐Ag particles produced a hyperpolarizing shift in the activation‐voltage curve of I_K and inactivation‐voltage curve of I_A and also delayed the recovery of I_A from inactivation. The results suggest that nano‐Ag may have potential to alter the excitability of neurons by depressing the potassium channels. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

Inhibitory effect of tungsten carbide nanoparticles on voltage-gated potassium currents of hippocampal CA1 neurons

The effects of tungsten carbide nanoparticles (nano-WC) on the properties of voltage-dependent potassium currents and evoked action potentials were studied in the hippocampal CA1 pyramidal neurons of rats at the ages of postnatal days 10-14 using the whole-cell patch-clamp technique. The results indicated that: (1) the amplitudes of transient outward potassium current (I_A) and delayed rectifier potassium current (I_K) were significantly decreased by 10⁻⁷ g/ml nano-WC, while the current-voltage curves of I_A and I_K were significantly decreased by nano-WC from +10 to +90 mV. (2) Nano-WC produced a depolarizing shift in the steady-state activation curve of I_A and I_K with increased slope factors, and delayed the recovery of I_A from inactivation, but no significant effects were found on the inactivation of I_A. (3) Nano-WC prolonged the evoked action potential duration and lowered the firing rate. These results suggest that 10⁻⁷ g/ml nano-WC can decrease the amplitudes of I_A and I_K currents by reducing the opening number of voltage-gated potassium channels and delaying the recovery of I_A from inactivation, which indicate that nano-WC has the potential neurotoxicity.     

莫达非尼对大鼠海马神经元I_(GABA)的抑制作用机制

目的研究新型促醒药莫达非尼对培养的大鼠海马神经元GABAA受体介导的电流(IGABA)的影响。方法在培养的海马锥体神经元上,进行全细胞膜片钳记录。结果GABA引起电流能被GABAA受体的竞争性阻断剂荷包牡丹碱阻断。单独给予莫达非尼时,明显地抑制了内向电流IGABA。而格列本脲预处理海马神经元后,再单独给予莫达非尼,发现莫达非尼对于IGABA的抑制作用被逆转。结论新型促醒药莫达非尼不同于传统的兴奋剂,莫达非尼对于神经元的保护作用可能与ATP敏感性钾离子通道的开放有关。