钠/钙和钠/氢交换蛋白与心肌缺血再灌注损伤

Ca2+超载与缺血/再灌注损伤有密切关系,钠/钙交换蛋白和钠/氢交换蛋白是缺血/再灌注Ca2+超载过程中两个至关重要的因素。目前已有很多钠/钙交换蛋白(NCX)抑制剂和钠/氢交换蛋白(NHE)抑制剂用来防止Ca2+超载引起的缺血再灌注损伤。     

二甲基-氨氯吡咪和牛黄酸对大鼠心室肌细胞Na+/Ca2+交换电流的影响

利用全细胞膜片钳技术 ,采用胶原酶B急性分离的大鼠心室肌细胞 ,研究了牛黄酸和二甲基 -氨氯吡咪对心肌细胞膜Na /Ca2 交换电流的影响。结果表明 ,10 μmol,2 0 μmol和 4 0 μmol的二甲基 -氨氯吡咪可使Ni2 敏感电流浓度依赖性地增加 ;膜电位为 5 0mV时分别增加 ( 2 7± 7) % ,( 12 1± 4 3 ) % ,和 ( 173± 68) % ;膜电位为 - 10 0mV时分别增加 ( 110±5 2 ) % ,( 2 2 1± 88) %和 ( 2 81± 80 ) %。牛黄酸对Na /Ca2 交换的内向和外向电流均无影响     

Na+ /H+交换阻滞剂Cariporide对离体大鼠心肌梗死范围的影响

目的:探讨Na+/H+交换阻滞剂Cariporide对离体大鼠心肌梗死范围的影响。方法:用离体大鼠双冠脉分别灌流心肌缺血模型,将大鼠心脏进行45 min的低流量缺血(用原灌流量的5％进行灌流),再灌注2h。药物在缺血及再灌注的不同时期应用。结果:在缺血及再灌注时和缺血再灌注时联合应用1μmol/L Cariporide,心肌梗死范围分别是(7±1)％,(7±2)％,(2±1)％,较对照组(20±4)％明显缩小。在缺血后0,10,30 min时分别应用,其心肌梗死范围分别是(7±2)％,(10±1)％,(17±3)％,较对照组(22±3)％明显缩小。在再灌注0,10 min时分别应用,其心肌梗死范围分别是(6±2)％,(15±2)％,而对照组为(19±3)％。结论:Na+/H+交换阻滞剂Caripo-ride在缺血及再灌注早期应用有明显的缩小心肌梗死范围作用。     

鹌鹑心室肌细胞电生理特性的研究

目的　建立鹌鹑单个心室肌细胞的分离方法 ,观察鹌鹑心室肌细胞的电生理特性 ,并探讨不同离子通道在鹌鹑心肌电活动中的作用。方法　采用酶解法分离单个心室肌细胞 ,应用全细胞膜片钳技术记录心室肌细胞动作电位和L型钙电流。结果　鹌鹑单个心室肌细胞的静息电位 (RP)为 ( 6 2 .2 8± 2 .6 4 )mV ,超射值 (OS)为 (5 9.38±3.81 )mV ,5 0 %复极时间 (APD50 )和 90 %复极时间 (APD90 )分别为 (80 .4 0± 1 9.1 0 )ms和 (1 2 1 .95± 38.72 )ms。在实验电压 +1 0mV时 ,L型钙电流的峰值为 ( 1 3.2 7± 3.70 )pA pF(n =4 )。结论　鹌鹑心室肌细胞上存在着L型钙电流 ,此电流为构成鹌鹑心室肌细胞动作电位的重要电流之一     

延胡索碱预处理对缺血再灌注心肌细胞膜L型Ca~(2+)通道动力学的影响

【目的】观察延胡索碱预处理对缺血再灌注心肌细胞膜L型Ca2+通道动力学的影响,并探讨其防治再灌注损伤的作用机制。【方法】将清洁级成年SD大鼠48只随机分为6组:延胡索碱高、中、低剂量预处理组(剂量分别为1.0、0.5、0.2 g.kg-1.d-1),缺血预处理组,模型组和假手术组,结扎左冠状动脉前降支近段30 min后再灌注60 min,之后断头放血取心脏。采用酶解技术分离大鼠心室肌细胞,应用膜片钳细胞吸附式单通道电流记录与分析方法,观察记录心肌细胞膜L型Ca2+通道平均开放概率、平均开放时间及平均电流幅值。【结果】与模型组比较,缺血预处理组和延胡索碱预处理各组心肌细胞L型Ca2+通道平均开放概率显著降低(均P0.01),但平均开放时间比较差异无显著性意义(均P0.05);与缺血预处理组比较,延胡索碱预处理中、低剂量组可降低L型Ca2+通道电流幅值(P0.05)。【结论】延胡索碱预处理防治再灌注损伤的可能作用机制与其能减少心肌细胞膜上L型Ca2+通道的开放概率,降低钙内向电流,避免细胞内钙超载,从而保护心肌细胞有关。     

牛磺酸对低氧-复氧乳鼠心肌细胞内游离钙浓度的影响

目的:研究低氧-复氧对心肌细胞内Ca2+浓度([Ca2+]I)的影响,以及牛磺酸减轻模拟心肌缺血-再灌过程中钙超载的作用. 方法: 采用SD大鼠乳鼠进行心肌细胞培养,建立模拟心肌缺血-再灌注模型. 实验分3组:①正常对照组;②模拟缺血-再灌注组:细胞低氧30 min-复氧30 min; ③牛磺酸+缺血-再灌组:先加入终浓度为20 mmol*L-1的牛磺酸,再行低氧30 min-复氧30 min. 以Fluo-3/AM荧光指示剂负载, 应用激光共聚焦显微镜技术检测心肌细胞 [Ca2+]I变化. 结果: 对照组心肌细胞[Ca2+]I荧光强度(650±41) U和荧光光密度较低. 低氧30 min后复氧即刻,[Ca2+]I荧光强度开始增加,复氧30 min后[Ca2+]I荧光强度(2537±187) U和光密度显著增高(P<0.01 vs对照组). 而牛磺酸组细胞内荧光强度和光密度较模拟缺血-再灌组显著降低[(895±50) U vs (2537±187) U, P<0.01]. 结论: 心肌细胞低氧-复氧导致钙超载;而牛磺酸有明显减轻心肌细胞低氧-复氧时Ca2+超载的作用.     

模拟缺血对豚鼠心室肌细胞Na~+/K~+泵电流的影响

目的 观察模拟缺血对心室肌细胞Na+/K+泵电流的影响.方法 采用胶原酶酶解法分离豚鼠心室肌细胞,以全细胞膜片钳方法记录心室肌细胞的Na+/K+泵电流(Ip).采用代谢抑制剂2-脱氧葡萄糖和碳酸氰-4-三氟甲氧基苯腙模拟缺血灌流,造成细胞的模拟缺血,观察模拟缺血对心室肌细胞Ip的影响,并探讨模拟缺血对双氢哇巴因(DHO)高亲和力Ip和DHO低亲和力Ip的影响.结果 模拟缺血2.5 min时Ip抑制率为(30.15±0.05)%,与4.0 min时的(49.33±0.02)%比较差异有统计学意义(P<0.05);6.0 min时Ip抑制率为(62.27±0.04)%,与4.0 min时的比较差异有统计学意义(P<0.05);Ip抑制程度随缺血时间延长而增加(r=0.82,P<0.05).模拟缺血特异性抑制DHO低亲和力Ip,而不影响DHO高亲和力Ip.结论 模拟缺血对DHO低亲和力Ip的特异性抑制作用,可能是缺血所致心室肌细胞内Na+浓度升高的主要因素之一.     

银杏叶提取物对家兔心室肌细胞瞬时外向钾电流和动作电位的影响

目的:探讨银杏叶提取物(Egb761)对家兔心室肌细胞瞬时外向钾电流(Ito)和动作电位的作用,揭示其抗心肌缺血及缺血引起的心律失常的离子机制。方法:酶解法分离家兔的心室肌细胞。全细胞膜片钳技术记录心肌细胞的Ito和动作电位及其被Egb761作用后的变化。结果:①在电压钳制方式下,60μg/L Egb761作用心室肌细胞5 min后,各个钳制电位下的Ito均明显增大,在钳制电位为+50 mV时,Egb761使Ito的电流密度由对照组的(7.59±0.19)pA/pF增加到(11.18±0.89)pA/pF(P<0.01,n=8),Egb761还使Ito的I-V曲线比对照组Ito的I-V明显抬高,但I-V曲线方向没有发生改变,表明Egb761引起了心肌细胞Ito的明显外流。②在电流钳制下,对照组心室肌细胞动作电位都具有从0期到4期的动作电位形态,60μg/L Egb761使心肌细胞动作电位形态呈三角形尖锥锋形,动作电位时程(APD)明显缩短,其复极化50%时程(APD50)和复极化90%时程(APD90)分别由(83.6±4.3)ms缩短为(51.3±3.2)ms和由(168.7±4.1)ms缩短为(93.8±4.4)ms(分别与对照组相比,P<0.01,n=8),尽管Egb761使动作电位幅度(APA)和静息电位(RP)降低,但与对照组相比,没有显著性差异(P>0.05)。结论:Egb761可使心室肌细胞Ito显著增加和APD明显缩短,从而减轻心肌缺血时细胞内阳离子超载对心肌造成的损伤和心肌缺血引起的心律失常的发生,以及增加心脏泵血功能。     

心肌梗死后心室肌细胞内钙离子浓度变化及比索洛尔对其的影响

目的　观察心肌梗死 (MI)后应用比索洛尔的保护作用与心室肌细胞内钙离子 ([Ca2 +]i)的关系 .方法　建立兔MI模型 ,采用钙敏感性荧光探针 Fluo- 3为 [Ca2 +]i 指示剂 ,应用激光扫描共聚焦技术测定 MI后急性分离的非梗死区心室肌 [Ca2 +]i 及比索洛尔对其影响 .结果　对细胞负载 Fluo-3/AM后的细胞内游离 Ca2 +图像观察发现 ,MI心室肌细胞荧光强度、密度明显强于 Sham组及 β- B组 (P<0 .0 0 1及 P<0 .0 5 ) .Sham组、MI组及 β- B组心室肌细胞的平均荧光强度分别为 2 93± 72 ,6 70± 131,40 2± 92 .结论　 MI后非梗死心室肌细胞内 Ca2 +超载 ,比索洛尔治疗 3wk可减轻心室肌细胞内 Ca2 +超载 .     

匹那地尔对大鼠缺血心肌钙调控的作用

目的 :探讨大鼠缺血心肌再灌注 (I- R)损伤的钙调控机制及匹那地尔对心肌 I- R损伤的保护作用机理。方法 :取 SD大鼠 ,心室肌细胞酶解分离 ,心肌细胞静息 1～ 2 h后随机分为 4组 :对照组、高钾停搏液组、匹那地尔强化组、格列苯脲拮抗组。 4组细胞在 2 4℃下保存 2 h后 ,复氧、复灌 2 0 min同时测定 [Ca2 + ]i 瞬态变化、肌浆网内贮钙释放功能。结果 :经匹那地尔强化处理的心肌细胞在 I- R过程中 [Ca2 + ]i 瞬态变化恢复率明显高于高钾停搏液组 (90 .2 7%～ 95 .5 7% vs6 7.0 5 %～ 80 .11% ,P<0 .0 1)。肌浆网内贮钙释放能力 (173.15 %± 2 6 .0 1% )明显高于高钾停搏液组 (112 .0 0 %± 16 .93% ) (P<0 .0 1)。经匹那地尔强化处理的心肌细胞在咖啡因诱导的钙释放后 ,胞内钙离子浓度从高水平回复到舒张末静息水平的时间为 (3.2 0± 0 .71) ms,显著短于高钾停搏液组 (3.93± 0 .4 6 ) ms(P<0 .0 5 )和对照组 (4 .6 8± 0 .77) ms(P<0 .0 1)。结论 :匹那地尔通过肌浆网和细胞膜 Na+ /Ca2 +交换体功能来调节钙瞬态变化 ,减少细胞内钙超载使心肌细胞在 I- R过程中保持较好的钙调控功能。     

HEK293细胞内源性电压门控钾离子通道电生理学特性研究

目的探讨人胚胎肾细胞(HEK293细胞)内源性电压门控钾通道的电生理特性,避免HEK293细胞上内源性离子通道对外源性离子通道表达时的干扰。方法利用全细胞膜片钳技术分析了HEK293细胞内源性电压门控钾通道的电生理特性。结果在HEK293细胞上去极化电压从-80 mV开始可触发1个外向电流。在+100 mV时电流为(422.78±68.87)pA,电流密度为(21.91±3.20)pA/pF。钾通道阻断剂四乙胺(tetraethylammonium,TEA)、4-氨基吡啶(4-aminopyri-dine,4-AP),在将细胞外液钾浓度由4 mmol/L提高到40 mmol/L时,对外向电流有影响。结论正常培养的HEK293细胞本身有内源性的钾通道。该外向电流可能包括了IK、IK1、IKur和Ito。     

体外培养视网膜神经元电压门控钾离子通道特性的研究

目的探讨体外培养不同时期新生小牛视网膜神经元电压门控钾离子通道的特性。方法分别取培养2、4、6周的视网膜神经元,进行全细胞膜片钳记录,并进行统计学分析。结果去极化刺激可诱导3组细胞产生IK电流,各组检出率差异无统计学意义(P>0.05);随培养时间延长,IK电流平均峰值增高(P<0.05)。超极化刺激可诱导培养6周的部分细胞产生内向整流钾电流。结论体外培养新生小牛视网膜神经元表达不同电压门控钾电流。某些神经元的电生理学特性在不同培养阶段发生变化。     

11,12-EET对大鼠心脏缺血/再灌注损伤保护作用研究

目的观察不同质量浓度11,12-EET对心肌缺血/再灌注损伤的影响及给药后不同时间11,12-EET保护作用的变化,以期了解11,12-EET对心肌保护作用的特点。方法复制大鼠心脏缺血/再灌注模型,给予不同浓度的11,12-EET,观察不同时间点的心功能变化。结果给予6.24×10-7.5mol/L、6.24×10-8mol/L 11,12-EET均可改善心肌缺血/再灌注损伤的大鼠心功能,6.24×10-9mol/L 11,12-EET作用较弱;给药24 h后11,12-EET拮抗大鼠心肌缺血/再灌注损伤的作用也减弱。结论11,12-EET的浓度及给予11,12-EET的时间对心脏保护作用有一定的影响。     

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).     

Effect of Nitric Oxide on Potassium Channels of Rat Airway Smooth Muscle Cells

Summary: The effect of nitric oxide donor sodium nitroprusside (SNP) on resting membrane potential (Em) and potassium currents of the bronchial smooth muscle cells from rats was investigated. All experiments were conducted in conventional whole-cell configuration. The changes of Em and potassium currents after addition of 0. 1 mmol/L SNP were measured under the current-clamp mode and the voltage-clamp mode respectively. Results showed that (1) SNP could decrease the Em from --33. 8±7.4 mV to -43. 7±6. 7mV (n=10, P＜0. 01); (2) SNP could increase the Ca2+-activated K+ channel peak currents under ramp protocol from 466.9±180. 1 pA to 597. 7±237. 6 pA (n= 7, P＜0. 01), and the currents under pulse protocol at +50 mV were increased from 544.2±145.4 pA to 678.1±206. 2 pA (n=6, P＜0.05); (3) SNP also could increase voltage-gated K+ channel peak currents under ramp protocol from 389. 6±84. 1 pA to 526. 7±98. 7 pA (n=7, P＜0. 01), the currents under pulse protocol at +50 mV were increased from 275.7±85.2 pA to 444.3±128.5 pA(n=6,P＜0. 01). It was concluded that SNP increases the activities of Ca2+-activated K+ channels and voltage-gated K+ channels and leads to K+ efflux and hyperpolarization of the cell membrane, resulting in a decrease of the cell excitement.     

α-突触核蛋白对N-甲基-D-天门冬氨酸所致细胞毒性作用的影响

目的研究α-突触核蛋白(α-Syn)对N-甲基-D-天门冬氨酸(NMDA)引起的多巴胺能神经细胞毒性作用的影响。方法在MES23.5多巴胺能神经细胞建立NMDA细胞毒模型,MTS法检测细胞活力,AO/PI荧光标记以及免疫印记测定caspase-3表达检测细胞凋亡,细胞外添加α-Syn蛋白,观察α-Syn对NMDA所致细胞毒性作用的影响。结果 NMDA(5mmol/L)引起明显的细胞内Ca2+升高以及细胞毒性作用,表现为细胞活力下降、凋亡细胞增加以及caspase-3表达升高。NMDA的细胞毒性作用可被NMDA受体特异性阻断剂MK801阻断。预先用α-Syn(2.5μmol/L,5μmol/L,10μmol/L)处理细胞明显抑制NMDA引起的细胞内Ca2+升高以及细胞毒性作用,其作用随α-Syn浓度增高而增强。结论α-Syn对NMDA所致多巴胺能神经元的细胞毒性作用具有抑制作用,其机制可能与其抑制与NMDA引起的Ca2+内流以及caspase-3激活有关。     

Expression of chemokine receptors CCR3, CCR5 and CXCR3 on CD4^＋ T cells in CBA/J×DBA/2 mouse model,selectively induced by IL-4 and IL-10, regulates the embryo resorption rate

Background Chemokines and their receptors have been a research focus in transplantation immunology. Chemokines and their receptors play a role in lymphocyte recruitment and differentiation process. This study aimed to observe whether IL-4 and IL-10 may regulate the expression of chemokine receptors CCR3, CCR5 and CXCR3 on CD4^＋ T cells in CBA/J×DBA/2 mouse model and to explore the role of CCR3, CCR5, CXCR3 in immune tolerance in pregnancy. Methods The mouse model of spontaneous abortion （CBA/J×DBA/2） and the normal pregnant mouse model （CBA/J×BALB/c） were used. CBA/J×DBA/2 mice were injected with IL-4 （CBA/J×DBA/2-IL-4）, IL-4 and IL-10 （CBA/J×DBA/2-IL-4＋IL-10）, or normal saline （CBA/J×DBA/2-NS） as a control. The expression of CCR3, CCR5 and CXCR3 on CD4^＋ T cells from mouse peripheral blood was measured by the double-labelled FCM method, and the embryo resorption rate was also examined. Results The embryo resorption rate in the CBA/J×DBA/2 group without any treatment was significantly higher than that in the CBA/J×BALB/c group （17.9% vs 3.7%, P 〈0.01）. The embryo resorption rate in the CBA/J×DBA/2 group immunized with IL-4 or IL-4 together with IL-10 was significantly decreased, compared with that in the control and NS groups respectively. CCR3 expression on CD4^＋ T cells in the CBA/J×DBA/2 group without any treatment was significantly lower than that in the CBA/J×BALB/c group （0.3738±0.3575 vs 1.2190±0.2772, P 〈0.01）; both CCR5 （3.0900±1.5603 vs 1.2390±0.6361, P〈0.01） and CXCR3 （2.4715±0.9074 vs 0.9200±0.5585, P 〈0.01） expressions on CD4^＋ T cells of the CBA/J×DBA/2 group without any treatment were significantly higher than those of the CBA/J×BALB/c group. Significant up-regulation of CCR3 and down-regulation of CXCR3 were found in the CBA/J×DBA/2 group treated with IL-4 （CCR3： 2.0360±0.6944, CXCR3： 1.3510±0.5263, P〈0.01） or IL-4 and IL-10 （CCR3： 1.8160±1.0947, CXCR3：1.0940±0.7168, P〈0.01）. Because of the CCR5, IL-4 and IL-10 （1.9400±0.8504 vs 3.0900±1.5603, P 〈0.05）, but IL-4 alone （2.5310±1.3595 vs 3.0900±1.5603, P 〉0.05） treatment significantly decreased the expression of CCR5 in CBA/J×DBA/2. Conclusions The abnormal expression of CCR3, CCR5 and CXCR3 on CD4^＋ T cells may play an important role in the pathogenesis of spontaneous abortion. The pregnancy immune tolerance may be induced through selective induction of CCR3, CCR5 and CXCR3 expressions by IL-4 together with IL-10.     

Early changes of CD4+CD25+Foxp3+ regulatory T cells and Th1/Th2, Tc1/Tc2 profiles in the peripheral blood of rats with controlled hemorrhagic shock and no fluid resuscitation

Background  Hemorrhagic shock induces immune dysfunction. Regulatory T cells (Tregs), T-helper (Th) cells, and cytotoxic T-lymphocytes (CTLs) can execute many crucial actions in immune and inflammatory responses. This study was conducted to investigate the early pathophysiological changes of CD4⁺CD25⁺Foxp3⁺ Treg and Th1/Th2, Tc1/Tc2 profiles in the peripheral blood of rats with controlled hemorrhagic shock and no fluid resuscitation.

Methods  A rat model of controlled hemorrhagic shock with no fluid resuscitation was established. Peripheral blood samples were taken before and four hours after hemorrhagic shock with no fluid resuscitation. Three color flow cytometry was used to detect Tregs, Th1, Th2, Tc1 and Tc2 cells in the samples.

Results  In the peripheral blood of rats, the percentage of Tregs four hours after hemorrhagic shock was significantly lower than before hemorrhagic shock (P=0.001). The ratios of Th1/Th2 and Tc1/Tc2 were changed from (23.08±8.98)% to (23.91±15.36)%, and from (40.40±21.56)% to (65.48±23.88)%, respectively.

Conclusions  At an early stage, the advent of hemorrhagic shock is related to an early decrease of Tregs, and a mild shift in the Th1/Th2, Tc1/Tc2 balance toward Th1 and Tc1 dominance. These changes are part of a hyper-inflammatory state of the host, and will deteriorate the maintenance of immune balance. Further influences and detailed mechanisms need to be investigated.