马桑内酯对大鼠海马锥体神经元钙激活钾通道的影响

目的　了解致痫剂马桑内酯 (CL)对培养的大鼠海马锥体神经元细胞膜钙激活钾通道 (KCa)的调节作用及癫痫的发病机理。方法　采用膜片钳单通道电流记录技术进行定量研究。结果　 1在内面向外式膜片下 ,KCa(12 0 .34± 2 5 .12 ) p S表现出钙离子浓度依赖性 (n=6 )、电压依赖性 (n=17)和四乙基胺 (TEA)阻断特点 ;2在细胞贴附式膜片下 ,浴液中加入 CL 可明显激活 KCa(P<0 .0 1) ;3在对称性高钾溶液中 ,使浴液 [Ca2 + ]i 为 10 - 8m ol/L,维持神经元膜电位为 2 0 m V,当 CL 为 0 μl/ m l和 1.0 μl/ m l时 ,可分别使 KCa开放概率从 0 .0 2 5增加到 0 .5 5 3(P<0 .0 1) ,通道活动的平均开放时间 (ms)从 1.875± 0 .4 12增加到 6 .82 9± 0 .136 ,平均关闭时间 (m s)从 179.342±13.831降低到 6 .4 12± 1.383(n=2 5 ,P<0 .0 1)。结论　在 CL 诱导的癫痫发病中 ,钙激活钾通道活化可能起重要的负反馈调节作用。     

丹参酮ⅡA磺酸钠对原代培养猪冠脉平滑肌ATP敏感钾通道、钙激活钾通道的影响

目的 :探讨丹参酮ⅡA磺酸钠 (DS 2 0 1)对原代培养猪冠脉平滑肌上ATP敏感的的钾通道 (KATP)、钙激活钾通道 (KCa)的作用。方法 :采用膜片钳单通道电流记录技术进行定量研究。结果 :KATP(33 15pS)可被 30 μmol/L优降糖特异性阻断 ,而KCa(2 46 .5 3pS)则表现出明显的钙离子依赖性和TEA阻断作用等特点。内面向外式膜片下 ,浴液中加入DS 2 0 1可激活KATP及Ca。膜电位为 5 0mV时 ,5、10、15 μmol/LDS 2 0 1分别使KATP开放概率 (NPo)从0 0 0 4± 0 0 0 1增加到 0 44 9± 0 0 0 4(n =5 ,P <0 0 1)、0 6 0 2± 0 0 32 (n =5 ,P <0 0 1)、0 90 4± 0 10 5 (n =5 ,P <0 0 1) ,2 0 μmol/LDS 2 0 1使KCa的NPo从 0 0 0 0增加到 0 0 11± 0 0 0 2 (n =3,P <0 0 1)。结论 :DS 2 0 1对KATP和KCa均有直接激活作用。     

ATP敏感性钾通道开放剂的脑保护作用研究

细胞上存在两种三磷酸腺苷敏感性钾(KATP)通道,一是位于细胞膜上的ATP敏感的钾通道;二是位于线粒体膜上的ATP敏感的钾通道。KATP通道广泛存在于各种脑区,若给予KATP开放剂则可以使其开放发挥对脑的保护作用。越来越多的研究表明,KATP通道在脑缺氧缺血等病理状态下被激活开放,使大量K+外流,细胞膜超极化,从而使Na+、Ca2+内流减少,避免或减轻钙超载、减少能耗、减轻兴奋性氨基酸及氧自由基释放,保护脑细胞。     

17β-雌二醇舒张人肠系膜动脉与钙激活钾通道及ATP敏感钾通道的关系

目的 研究17β-雌二醇(17β-estradiol,E2)是否通过钙激活钾通道(Kca)、ATP敏感钾通道(KATP)途径快速舒张人肠系膜动脉(human mesenteric artery,HMA).方法 采用离体血管环灌流方法,观察17β-雌二醇(E2)对内皮完整和去内皮HMA的舒张作用,以及左旋硝基精氨酸甲酯(L-NAME)、IBTX及格列苯脲(GLY)对这一过程的影响.结果 E2(5×10-7～2×10-5mol/L)可剂量依赖性地快速舒张HMA;在低浓度(5×10-7～5×10-6mol/L)时,该舒张作用在内皮完整组明显大于去内皮组(P<0.05),且在内皮完整组E2的舒张作用可分别被一氧化氮合酶(NOS)选择性抑制剂L-NAME、大电导钙激活钾通道(Bkca)阻断剂IBTX、ATP敏感钾通道(KATP)选择性抑制剂GLY减弱(P<0.05);在高浓度(10-5～2×10-5 mol/L)时,去内皮组与内皮完整组E2的舒张反应差异无显著性(P>0.05),且阻断剂L-NAME、IBTX、GLY均不能削弱E2的舒张反应(P>0.05).结论 E2可以快速舒张人体阻力小血管--人肠系膜动脉,在低浓度时具有内皮依赖性,其舒张效应与刺激内皮释放NO和激活Bkca、KATP有关,而在高浓度时E2舒张HMA是非内皮依赖的.     

福辛普利对缺氧复氧豚鼠心室肌细胞动作电位及其离子通道的影响

目的 观察福辛普利预处理对缺氧复氧豚鼠心室肌细胞动作电位(AP)、L-型钙通道电流(ICa-L)和ATP敏感钾通道电流(IK-ATP)的影响,探讨其抗再灌注性心律失常的电生理机制.方法 采用全细胞电流钳和膜片钳技术分别记录AP和ICa-L,IK-ATP.结果 缺氧复氧使心室肌细胞AP时程(APD50,APD90)缩短;ICa-L峰值降低,I-V曲线上移,激活曲线右移,半数激活电压(V1/2)增大,失活曲线左移,失活V1/2减低;ATP敏感钾通道由正常关闭状态到完全开放.与缺氧复氧组相比,福辛普利预处理使APD50,APD90相对延长;ICa-L峰值增加,I-Ⅴ曲线上移幅度减小,激活曲线左移,失活曲线右移,激活与失活V1/2均接近正常,ATP敏感钾通道进一步开放,电流明显增加.结论 福辛普利预处理能显著改善缺氧复氧状态下L-钙通道的抑制状态,促进动作电位参数的恢复,减少有效不应期的离散度及折返形成;通过药物预适应机制,进一步开放ATP敏感钾通道,增加ATP敏感钾电流,而发挥抗再灌注心律失常的作用.     

钙激活钾通道及ATP敏感性钾通道在海马神经元缺氧超极化中的作用

研究缺氧超极化缺氧海马神经元中的电生理机制,以提示缺氧超极化在脑损伤中的作用。方法：应用膜片钳制技术的细胞贴附式膜片记录缺氧海马神经元的单通道电流活动,经p-CLAMP软件进行采样储存数据和数据的分析处理。结果：缺氧引起钙激活钾通道（KCa通道）和ATP敏感性通道（KATP通道）的激活,增加通道的开放概率。结论：缺氧超极化可能是缺血性脑损伤早期的重要代偿机制。     

钙离子致神经细胞损伤中钙激活钾通道的应用研究

目的:采用膜片钳单通道记录法,对新生SD大鼠的皮层神经元中,钙激活钾通道(KCa)特征,及胞内不同游离钙水平,开放动力学的调节。结果:培养SD大鼠皮层神经元中,KCa以大电导活动占优势,胞内游离钙为10-8 mol/L时,通道几乎不开放,在10-6 mol/L时达最大激活。结论:神经元上KCa通道开放概率,依赖于胞浆中钙离子膜电位,KCa对胞内钙离子浓度敏感。钾通道的开放剂,有一定神经细胞保护作用。     

NPA抑制大鼠DRG分离神经元ATP-激活电流

目的　本研究主要探讨多巴胺D2受体的选择性激动剂R(- ) -NPA对ATP -激活电流的调制。方法　在大鼠新鲜分离的DRG神经元标本上应用全细胞膜片钳技术 ,观察了NPA对ATP -激活电流的作用。结果　大部分受检细胞 (87.3% ,48/ 5 5 )对ATP敏感 ,10 -6～ 10 -3 mol/LATP可引起剂量依赖性呈明显去敏感的内向电流。在此45个细胞中 ,预加NPA可引起三类反应 :(1)外向电流 (6 .3% ,3/ 48) ;(2 )内向电流 (2 5 .0 % ,12 / 48)和 (3)无反应 (6 8.8% ,33/ 48)。与ATP -激活电流相比 ,NPA -激活电流幅值小 ,无明显去敏感现象。预加NPA 30～ 6 0s对ATP -激活电流的影响如下 :在 91.7% (4 4/ 48)的细胞产生抑制作用 ,其余的无明显作用 (8.3% ,4/ 48)。此种抑制作用与NPA本身是否引起或引起的是内向或外向电流无关。在浓度 10 -7～ 10 -5mol/L范围NPA对 10 -4 mol/LATP -激活电流的抑制作用依赖于NPA的浓度。胞内透析GDP - β -s上述抑制作用可完全被取消。 结论　NPA对ATP -激活电流的抑制作用可能是由于D2受体激活后经G蛋白偶联及相应胞内转导途径而使ATP受体磷酸化所致。     

褪黑激素对新生大鼠海马神经元延迟整流钾电流的影响

目的 用膜片钳技术观察褪黑激素对电压门控性延迟整流钾电流(Ik)的影响,探讨褪黑激素在中枢神经系统的作用机制及其生物学意义.方法 选择7～12 d原代培养的新生Wistar大鼠海马锥体神经元,用膜片钳电压钳全细胞记录模式观察Ik的基本电生理特点,并观察不同浓度褪黑激素,包括1、10、100 nmol/L、1、10、100 μmol/L和1 mmol/L对Ik的幅度及动力学特性的影响.结果 利用海马锥体神经元的钾电流对4-AP、TEA的敏感性及电生理特性的不同可分离出激活、失活缓慢,具有强烈外向整流特性的延迟整流钾电流.褪黑激素对海马锥体神经元Ik的影响是快速、可逆、呈电压依赖性的,但对其激活曲线没有影响.褪黑激素对Ik的作用具有浓度依赖性.1～100nmoI/L的褪黑激素可逐渐递增地增加Ik幅度;1～100 μmol/L褪黑激素对Ik的增加程度随浓度增加而增大,而1 mmol/L褪黑激素的增加程度却减小.结论 褪黑激素可逆地增强体外培养新生大鼠海马神经元的Ik电流,这或许参与了神经元损伤和记忆损害的某些环节.     

线粒体K+ ATP通道介导麻醉药异氟烷的心肌预处理

0 引言研究表明吸入麻醉药异氟烷可模拟缺血预处理发挥心肌保护作用,减轻缺血再灌注期心肌功能抑制和心肌坏死程度,其机制可能与激活心肌细胞膜腺苷受体、通过蛋白激酶C开放肌膜ATP敏感的钾离子通道(K+ATP)有关[1]. 由于激活线粒体K+ATP通道也可减轻缺血再灌注损伤,我们利用选择性线粒体K+ATP通道阻断剂(5-hydroxydecanoate, 5-HD)探讨线粒体KATP通道在异氟烷预处理中的作用.     

ATP sensitive K+ channel may be involved in the protective effects of precon ditioning in isolated guinea pig cardiomyocytes

Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensiti ve K(+) (K(ATP)) channel is involved in ischemic precond itioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs.The expe rimental chamber allowed the cells to be exposed to low O(2)pressure.During h ypoxic preconditioning, the cells were equilibrated with normaxic solution for 1 0 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of re oxygenation.The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation.Ionic currents were studied with the patch clamp technique in w hole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell i n jury in subsequent hypoxia-reoxygenation.After a latency of more than 15 minu tes, hypoxia induced a time-independent outward K(+) current which could be blo cked by 5 μmol/L glibenclamide.At 10 mV, the current increased from 78 ±1 5 pA to 1581±153 pA (P&lt;0.01, n=18).However, the latency to develop K(ATP) channel currents (I(KATP)) was greatly shortened in preconditioned c ells, and the current was increased acceleratively.At 10 mV, the current more than 4 nA was recorded in preconditioning cells.In the single channel record ings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells.Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia.This hypoxic preconditioning may modify the K(ATP) channel, and make the channel open more readily during the second hypoxia.     

The Effect of Coriaria Lactone on NMDA Receptor Mediated Currents in Rat Hippocampal CAI Neurons

To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (Iasp) in rat hippocampal CAI neurons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (Iasp) at a holding potential (VH) of -40mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50,Hill coefficient as well as maximal-effect concentration and reversal potential of Iasp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]I of neurons by acting on Gly site, thereby inducing epilepsy.     

The effect of coriaria lactone on NMDA receptor mediated currents in rat hippocampal CA1 neurons

Epileptogenesis of (CL) has been verified bymany studies. We can establish an ideal animalmodel of epilepsy on the basis of these studiesll' ZJ.Homeostasis of cytoplasmic free Ca2 is the basisfor neuron to perform its normal functions. Theabnormal elevation of cytoplasmic free Ca2 is thekey step in the triggering of a series of pathologicalchanges"'. Our past findings showed that CLcould elevate LCa' j, of hippocampal neurons[4].But there was no report about the way thoughwhich CL ele…     

丹参对大鼠大脑缺血时神经细胞ATP敏感性钾通道的影响

目的探讨丹参对大脑缺血时神经细胞ATP敏感性钾通道的影响.方法利用膜片钳内面向内外式记录方法,观察了不同浓度(1、5、10 m/ml)丹参时对ATP敏感性钾通道的活性和敏感性的影响.结果丹参降低单个通道内向电流开放概率,激活通道的多级开放,降低通道对胞内ATP的敏感性.结论丹参有类似钾通道开放剂作用,具有保护脑缺血缺氧损伤作用.     

Protective effects of pinacidil hyperpolarizing cardioplegia on myocardial ischemia reperfusion injury by mitochondrial KATP channels

Background  Many studies have indicated that hyperpolarizing cardioplegia is responsible for myocardial preservation and researchers have suggested that the adenosine triphosphate-sensitive potassium channels (K_ATP) were the end effectors of cardio-protection. But whether mitochondrial K_ATP plays an important role in hyperpolarizing cardioplegia is not apparent. The present study investigated the effect of hyperpolarizing cardioplegia containing pinacidil (a nonselective K_ATP opener) on ischemia/reperfusion injury in rat hearts, especially the role of mitochondrial K_ATP in pinacidil hyperpolarizing cardioplegia.

Methods  Sprague-Dawley rat hearts were Langendorff-perfused for 20 minutes with Krebs-Henseleit buffer at 37°C before equilibration. Cardiac arrest was then induced in different treatments: there was no arrest and ischemia in the normal group, the control group were arrested by clamping the aorta, depolarizing caidioplegia (St. Thomas solution containing 16 mmol/L KCl) and hyperpolarizing cardioplegia groups used St. Thomas solution containing 0.05 mmol/L pinacidil and 5 mmol/L KCl to induce cardiac arrest in group hyperkalemic and group pinacidil, in group hyperkalemic + 5-hydroxydecanote (5HD) and Pinacidil + 5HD, 5HD (0.1 mmol/L) was added to the above two solutions to block mitochondria K_ATP channels. Global ischemia was then administrated for 40 minutes at 37°C, followed by 30 minutes of reperfusion. At the end of equilibration and reperfusion, hemodynamics, ultrastructure, and mitochondrial function were measured.

Results  In the control group, ischemia/reperfusion decreased the left ventricular developed pressure, heart rate, coronary flow, mitochondrial membrane potential, impaired mitochondrial respiratory function, increased reactive oxygen species and left ventricular end diastolic pressure. Damage to myocardial ultrastructure was also evident. Both depolarized arrest and especially hyperpolarized cardioplegia significantly reduced these lesions. 5HD partially blocked the beneficial effects of pinacidil cardioplegia but showing no effects on hyperkalemic arrest.

Conclusions  Pinacidil cardioplegia provides better cardioprotection with preservation of hemodynamics, ultrastructure, and mitochondrial function than traditional cardioplegia. The mitochondria K_ATP channels may play an important role in the protection mechanism.

     

大鼠肠肌间神经元胃动素受体的表达及胃动素引起神经元内钙信号的机制

目的观察大鼠肠肌间神经元胃动素受体(MTLR)的表达,并探讨胃动素引起神经元内钙信号的机制。方法采用免疫荧光双标技术观察大鼠肠肌间神经元MTLR的表达;应用激光共聚焦显微镜技术检测不同药物处理组胃动素引起的单个神经元内Ca2+荧光强度的变化。结果大鼠肠肌间神经元呈MTLR免疫反应阳性表达;在Hank's液中,10-6mol/L胃动素可引起神经元内Ca2+浓度的显著升高,其峰高(峰值减去静息值)为30.6±3.7,荧光强度相对变化百分比为(100.8±18.4)%。在D-Hank's液(去除细胞外Ca2+)中或用L型钙离子通道阻断剂维拉帕米预处理细胞后,胃动素可轻度升高胞内Ca2+浓度。与单独应用胃动素组相比差异有统计学意义(P<0.05)。当分别用G蛋白拮抗剂NEM和PLC抑制剂Compound48/80预处理细胞后再加入胃动素,胞内Ca2+浓度升高的程度明显降低,与单独应用胃动素组相比差异有统计学意义(P<0.05)。当用PKC抑制剂D-鞘氨醇预处理细胞后,再加入胃动素,其峰高和荧光强度相对变化百分比同单独应用胃动素组相比差异无统计学意义(P>0.05)。结论大鼠肠肌间神经元能自身表达MTLR。胃动素可明显升高神经元内Ca2+浓度,胞内Ca2+浓度的升高既源于外钙的内流又源于内钙的释放。外钙的内流主要通过L型Ca2+通道,G蛋白偶联型MTLR-PLC-IP3途径参与细胞内钙的释放。     

马桑内酯对大鼠海马神经元钠电流的影响

目的 研究马桑内酯(coriaria lactone,CL)对大鼠海马神经元钠离子通道电流的影响,探讨该影响在CL致痫中的意义.方法 利用全细胞膜片钳技术,在急性分离的大鼠海马神经元上记录钠电流,观察CL对电流幅度的影响.结果 经0.1 mg/mL、0.2 mg/mL的CL作用后,海马神经元钠电流有不同程度的增加[CL 0.1 mg/mL组的最大峰值电流密度为(-90.11±14.02) pA/pF,增幅为17.32%±8.52%;CL 0.2 mg/mL组的最大峰值电流密度为(-111.52±6.65) pA/pF,增幅为37.98%±4.91%];经与对照组相比,CL 0.2 mg/mL组(P＜0.05)的变化较CL 0.1 mg/mL组(P＞0.05)明显.结论 CL使海马神经元电压依赖性钠电流的幅度增大,从而改变细胞的兴奋性,引发异常放电.     

吗啡导致猕猴海马神经元自发放电节律转变

目的 分析吗啡对猕猴海马神经元自发放电节律的影响。方法 分析注射吗啡后猕猴海马神经元自发放电节律变化情况，并用数学方法加以验证。结果 在吗啡作用下海马神经元自发放电节律会发生转变，纳络酮可以逆转这种转变，共观察到种转变形式。为了研究这种转变的动力学机制，用数学模型模拟吗啡对神经元自发放电节律的影响，得到了与在体实验一致的结果。结论 在吗啡作用下海马神经自发放电节律发生转变。利用数学模型研究发现节律转变的原因是吗啡改变了膜上钠，钾，超极化电流等离子通道的功能所致，节律转变的过程存在着混沌规律。     

线粒体KATP在吡那地尔预处理后失血性休克大鼠组织血流灌注和线粒体功能保护效应中的作用

目的 观察吡那地尔(pinacidil)预处理对失血性休克大鼠血流灌注和线粒体功能的保护效应,及其与线粒体ATP激活钾通道[adenosine triphosphate(ATP)-activated potassium channels,KATP]的关系.方法 Wiser大鼠60只,随机数字表法分为:正常对照组、休克组...