充血性心衰病人心房肌细胞瞬间外向钾电流和超快延迟整流钾电流的特征

目的:研究充血性心衰病人心房肌细胞瞬间外向钾电流(I_(to))和超快延迟整流钾电流(I_(Kur))的特征.方法:全细胞膜片箝技术.结果:心衰病人心房肌细胞上的I_(to)的激活和失活具有电压依赖性及时间依赖性.其半数最大激活电位(V_(1/2))和半数最大失活电位(V_(1/2))分别为(15±12)mV和(-45±4)mV.当膜电位从-40mV升至 60mV时,激活时间常数均值从(6.9±2.3)ms降至(1.40±0.20)ms,失活时间常数均值从(69±17)ms降至(21±14)ms,两者均随着膜电位的增加而减小.此外,该通道从失活状态下的恢复也很快.当保持电位为-80mV时,其恢复时间常数为(125±65)ms,但在此条件下通道的恢复不完全.当测试脉冲频率为0.2-2 Hz时,此通道电流未表现出明显的频率依赖性.与I_(to)相比,I_(Kur)的激活只具有电压依赖性但无时间依赖性.当测试电位为 60mV时,其电流密度平均为(3.4±0.7)pA/pF.半数最大激活电位(V_(1/2))为(23±14)mV.在测试脉冲频率为0.2-2Hz的范围内,通道电流也无明显的频率依赖性.结论:I_(to)和I_(Kur)是充血性心衰病人心房肌细胞上主要的外向电流,其大小和动力学特征可显著地影响心房肌细胞的电生理特性.     

常咯啉对豚鼠和家兔单个心肌细胞钾电流的影响(英文)

目的:研究常咯啉是否对心肌细胞的钾电流有影响作用。方法:采用高阻抗密封膜片箝全细胞技术,记录分离的豚鼠和家兔心肌单个细胞的钾电流。结果:在临床用量常咯啉50μmol·L~(-1)抑制家兔心房肌细胞的瞬间外向钾电流(I_(TO))17.7％±2.4％(n=8)。但并不影响电压依赖性通道。同一剂量的常咯啉对单个家兔心室肌细胞的内向整流钾电流(I_(Kl))和单个豚鼠心室肌细胞的延迟整流钾电流(I_K)并不产生任何作用。结论:提示常咯啉具有阻制(I_(TO))的作用,而对(I_K)和(I_(Kl))无任何作用。     

槟榔碱对大鼠心室肌细胞瞬时外向钾电流的影响

目的：研究槟榔碱(Are)对大鼠心室肌细胞瞬时外向钾电流(I_(to))的影响。方法：利用全细胞膜片钳技术测定大鼠心室肌细胞的I_(to)。结果：10.0μmol·L~(-1) Are可以降低I_(to),使I_(to)幅值从(10.6±s 1.2)pA·pF~(-1)降至(6.2±0.9)pA·pF~(-1)(P＜0.01,n=20)。在1～100μmol·L~(-1)范围内Are的作用呈浓度依赖性,IC_(50)为8.2μmol·L~(-1)。10.0μmol·L~(-1)Are使稳态激活曲线右移,半激活电压(V_(1/2))从(-11.6±0.6)mV移至(-2.3±0.1)mV,但曲线斜率基本不变。Are对失活曲线影响不大,但10.0μmol·L~(-1)Are使通道失活后恢复时间常数从(88±16)ms延长为(152±24)ms(P＜0.01,n=18)。结论：Are浓度依赖地阻滞大鼠心室肌细胞的I_(to)。     

1—（2，6—二甲基苯氧基）—2—（3，4—二甲氧基苯乙氨基）丙烷盐酸盐抑制豚鼠心室肌细胞内向整流和延迟整流钾电流

目的:研究1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐(DDPH)对心室肌细胞动作电位(AP)、内向整流钾通道电流(I_(K1))及延迟整流钾通道电流(I_K)的影响。方法:全细胞膜片箝技术。结果:DDPH 10,100μmol·L~(-1)使豚鼠心室肌细胞AP时程APD_(50)明显缩短;但DDPH(>1μmol·L~(-1))延长APD_(90)。DDPH浓度依赖性地抑制I_K尾电流(I_(K·tail)),EC_(50)为13.3(11.6.6-16.7)μmol·L~(-1)。DDPH(>1.0μmol·L~(-1))明显抑制I_(Kl);同时,DDPH使I_(Kl)翻转电位向正电位方向移动。结论:DDPH对豚鼠心室肌细胞I_(Kl)和I_K具有明显的抑制作用。     

蝙蝠葛碱对豚鼠心室肌细胞钾电流的阻断作用(英文)

目的:研究蝙蝠葛碱对豚鼠心室肌细胞快激活(I_(Kr))和慢激活(I_(Ks))延迟整流钾电流及内向整流钾电流(I_(K1))的作用。方法:酶解法制备单个心室肌细胞。电压箝制方式下全细胞记录豚鼠单个心室肌细胞钾通道电流。结果:蝙蝠葛碱1-100μmol·L~(-1)浓度依赖性阻断I_(Ks),I_(Ks-tail)[IC_(50)=33(95 ％可信限:24-46)μmol·L~(-1)]及I_(Kr),I_(Kr-tail)[IC_(50))=16 (95％可信限:13-22)μmol·L~(-1)]。对I_(Ks-tail),I_(Kr-tail)的去激活过程无明显影响,给药前的时间常数分别为(92±18)ms和(140±38)ms,给药后分别为(84±16)ms和(130±26)ms(P>0.05)。蝙蝠葛碱对I_(Ks)的抑制作用具有电压依赖性。 蝙蝠葛碱20μmol·L~(-1)对I_(K1)的内向部分具有阻断作用。结论:蝙蝠葛碱对I_(Kr)和I_(Ks)具有阻断作用,但不影响此两种成分的去激活过程. 蝙蝠葛碱同时具有阻断I_(K1)的作用。     

RP58866对哺乳动物心室肌细胞跨膜钾电流的作用(英文)

目的:研究RP58866对于豚鼠或犬分离心室肌细胞I_K,I_(to),和I_(Kl)的影响。方法:采用全细胞膜片箝技术。结果:在-100 mV时,RP58866以浓度依赖方式明显减少了豚鼠心室肌细胞I_(kl),其IC_(50)为(3.4±0.8)μmol·L~(-1)(n=6)。在犬心室肌细胞,RP58866可明显抑制I_(to),其IC_(50)为(2.3±0.5)μmol·L~(-1)。RP58866 100μmol·L~(-1)阻断豚鼠的心室肌细胞I_K,在 40mv时使I_(Kstep)减少(58±13)％,其IC_(50)为(7.5±0.8)μmol·L~(-1),I_(Ktail)减少(86±17)％,其IC_(50)为(3.5±0.9)μmol·L~(-1)。尾电流分析表明,RP58866对I_(Kr)和I_(Ks)均有阻断作用。结论:RP58866对心肌细胞的I_(Kl)和I_(to),I_K均有抑制作用,而不是一种特殊的I_(Kl)抑制剂。     

苄基四氢巴马汀对豚鼠和大鼠心室肌细胞钾电流的作用

目的:研究苄基四氢巴马汀(BTHP)对心室肌细胞快激活(I_(Kr))和慢激活(I_(Ks))延迟整流钾电流、内向整流钾电流(I_(Kl))和瞬时外向钾电流(I_(to))的作用.方法:采用全细胞膜片箝技术记录豚鼠及大鼠心室肌细胞钾电流.结果:BTHP在 1-100 μmol/L的范围内以浓度依赖性方式阻滞I_(Kr)和I_(Ks),其中对I_(Kr)的IC_(50)为 13.5 μmol/L(95％可信限:11.2-15.8 μmol/L)而对 I_(Ks)的 IC_(50)则为 9.3 μmol/L(95％可信限:7.8-11.8 μmol/L).BTHP 30μmol/L时可使 I_(Kr)及I_(Kr,tail)分别降低31％±4％和36％±5％(n=6,P<0.01);使I_(Ks)及I_(Ks,tail)分别降低40％±6％和45％±15％(n=7,P<0.01);BTHP 5μmol/L可抑制大鼠心室肌细胞I_(to)电流,使电流幅值降低63％±6％(n=6,P<0.01),BTHP1-100μmol/L以浓度依赖性方式阻滞入I_(to),其 IC_(50)为 3.6 μmol/L(95％可信限:2.9-4.3μmol/L).但BTHP 200 μpmol/L对I_(Kl)基本无影响.结论:BTHP对I_(Kr)、I_(Ks)、I_(to)均有抑制作用,且其阻滞作用呈现出浓度依赖性特征.     

雌二醇抑制豚鼠心室肌细胞内向整流和延迟整流钾通道电流

目的:研究雌二醇(Estradiol,Est)对心室肌细胞动作电位(AP)、内向整流钾通道电流(I_(K1))及延迟整流钾通道电流(I_K)的影响。方法:全细胞膜片箝技术。结果:EST 10μmol·L~(-1)使豚鼠心室肌细胞AP时程明显缩短,APD_(50)由给药前(474±71)ms缩短至(330±75)ms(P<0.05),Est 100μmol·L~(-1)使APD_(50)缩短至(229±67)ms(P<0.01),使APD_(90)由(587±60)ms缩短至(418±79)ms(P<0.05)。Est浓度依赖性地抑制I_K尾电流(I_K·tail),10μmol·L~(-1)浓度下,I_K·tail减少53％(P<0.05),100μmol·L~(-1)浓度下,I_K·tail减少80％(P<0.05)。10μmol·L~(-1)以上浓度Est明显抑制I_(K1),在-100mV刺激电压下,内向电流最大抑制为49％(P<0.01);在-40mV刺激电压下,外向电流最大抑制为72％(P<0.01)。同时,Est使I_(K1)翻转电位向负电位方向移位(由-70mV变为-76mV)。结论:Est对豚鼠心室肌细胞I_(K1)和I_K通道具有明显的抑制作用。     

胍丁胺对大鼠心室肌细胞L—钙通道电流的影响

目的:观察胍丁胺(Agm)对大鼠心室肌细胞L-型钙通道电流(I_(Ca-L))的影响.方法:以酶解法制备单个心室肌细胞.应用全细胞膜片箝技术记录大鼠单个心室肌细胞钙通道电流.结果:(1)Agm(0.5,1,2mmol/L)可浓度依赖性地降低电压依赖性激活I_(Ca-L)(pA)峰值,其值从1451±236 (对照组)到937±105(n=8,P<0.05),585±74(n=8,P<0.01),和301±156(n=8,P<0.01).(2)Agm 1 mmol/L使用依赖性地阻滞I_(Ca-L)·1 Hz时抑制率为53％±12％(P<0.05),3Hz时为69％±11％(P<0.01).(3)Agm使I-V曲线上移,但对I_(Ca-L)的电压依赖特征、最大激活电压以及I_(Ca-L)稳态激活无明显影响.在Agm 1 mmol/L作用下,半数激活电压(V_(0.5)和斜率参数(k)与对照组相比均无显著性差异.V_(0.5)分别为(-20.2±2.5)mV和(-20.5±2.7)mV,k分别为(3.2±0.4)mV和(3.0±0.5)mV.(4)Agm 1 mmol/L可明显使钙电流稳态失活曲线左移,加速钙通道电压依赖性稳态失活.V_(0.5)分别为(-32±6)mV和(-40±5)mV,k分别为(7.6±O.9)mV和(12.5±1.1)mV(P<0.05).(5)Agm 1mmol/L还使I_(Ca)从失活状态下恢复明显减慢.结论:Agm抑制I_(Ca-L),并主要作用于L-型钙通道的失活状态,表现为钙通道失活加速和从失活状态下恢复减慢.     

赛庚啶对豚鼠心室肌细胞钙电流的影响

应用全细胞记录式膜片钳技术研究了赛庚啶(Cyp)对豚鼠心室肌细胞慢钙电流(I_(Ca))的影响,Cyp 3和8μmol·L~1对I_(Ca)的电流-电压关系曲线(I-V曲线)之各电流均有降低作用,使I-V曲线上抬;在指令电位0 mV时,I_(Ca)为次最大值,Cyp 0.3～10μmol·L~1使该I_(Ca)呈浓度依赖性降低,IC_(50)值为1.98μmol·L~1,还观察到Cyp 1μmol·L~1明显增加外向电流(I_(out)),且四乙基铵(TEA)1 mmol·L~1对其有显著的拮抗作用,但对控制电位从80 mV跃升至-40 mV时所出现的瞬时快内向电流,无明显影响.以上结果直接证明了Cyp对心室肌细胞钙跨膜转运有明显降低作用,还可能增加钾外流。     

未成年人心房肌细胞瞬间外向钾电流和内向整流钾电流的特性

AIM: To study the properties of transient outward K+ current (Ito) and inward rectifier K+ current (IKl) in immature human heart. METHODS: Ito and IKl were recorded using whole-cell patch-clamp technique in atrial myocytes isolated from 12 immature (aged from 6 months to 5 a) human hearts. RESULTS: Ito was voltage-dependent, activated and inactivated rapidly. The IC50 (95% confidence limits) of 4-AP on Ito was 0.64 (0.48-0.87) mmol.L-1. 4-AP 1 mmol.L-1 shifted V1/2 of activation from (6.6 +/- 2.0) mV to (19.8 +/- 3.0) mV (n = 4-10, P < 0.01). 4-AP 0.3 mmol.L-1 changed V1/2 of inactivation from (-49 +/- 4) mV to (-61.4 +/- 2.1) mV (n = 3, P < 0.01), but there were no obvious influence on voltage-dependent activation of Ito (P > 0.05). At the same concentration, the recovery time constant (tau value) was prolonged from (108 +/- 16) ms to (220 +/- 67) ms (n = 3-12, P < 0.01). IKl was also voltage-dependent. Its reverse potential was -40 mV. CONCLUSION: Both Ito and IKl are important K+ channel currents in immature human atrial myocytes. 4-AP can affect the inactivation and recovery of Ito at low concentration (0.3 mmol.L-1) and affect its activation at high concentration (1 mmol.L-1).     

N-甲基小檗胺对人心房肌细胞瞬时外向钾电流和延迟整流钾电流的作用(英文)

目的　动物实验表明N 甲基小檗胺 (NMB)通过抑制豚鼠心室肌细胞ATP敏感性钾电流和钙电流来发挥抗心律失常和抗心肌缺血作用 ,故进一步研究NMB对人心肌细胞电流的作用。方法　膜片钳制技术全细胞记录模式研究NMB对人心房肌细胞瞬时外向钾电流 (Ito)和延迟整流钾电流 (IK)的作用。结果　指令电位为 +60mV时 ,NMB 0 .1 ,1 ,1 0 μmol·L-1 分别使Ito幅值下降 (1 6± 4) % ,(2 5±4) %和 (49± 3) % ,使IK 幅值下降 (42± 6) % ,(47±7) %和(65± 3) %。结论　NMB对人心房肌细胞Ito和IK 均有抑制作用。     

Calcium-activated potassium current in single Novikoff cell

The electrophysiological properties of the hemichannels of the gap junction in a single Novikoff cell was studied using patch-clamp whole-cell recording techniques. During the experiments, a transient outward current (peak current, Ip) was found to be evoked by the increment of depolarized pulses. Ip was voltage-dependent and could be inhibited partly by CsCl and tetraethylammonium (TEA), but was blocked completely by quinidine. When the intracellular free Ca2+ concentration ([Ca2+]i) was increased, the amplitude of Ip was enhanced. Adding 10 mmol/l EGTA in the pipette solution, Ip disappeared. When the cells were bathed in symmetrical high-K+ solution, Ip also completely disappeared. These results suggest that Ip is a calcium-activated potassium current, although it cannot be blocked by apamin.     

Effects of aluminum chloride on sodium current, transient outward potassium current and delayed rectifier potassium current in acutely isolated rat hippocampal CA1 neurons.

The effects of aluminum chloride (AlCl3) on sodium current (INa), the transient outward potassium (IA) and delayed rectifier potassium currents (IK) in hippocampal CA1 neurons of rats were studied using the whole cell patch-clamp technique. AlCl3 decreased INa, IA, and IK in a partly reversible, dose and voltage-dependent manner. AlCl3 prolonged the time to peak of INa, and increased the inactivation time constants of INa and IA . In addition, 1000 microM AlCl3 shifted the voltage dependence of steady-state activation of INa, IA and IK toward positive potential, and the voltage dependence of steady-state inactivation of INa, IA toward negative potential. These results imply that AlCl3 could affect the activation and inactivation courses of sodium current and potassium current of rat hippocampal CA1 neurons, which may contribute to damage of the central nervous system by aluminum.     

丙基丁基多巴胺对心肌内向整流钾电流的抑制作用(英文)

研究丙基了基多巴胺（ＰＢＤＡ）对内向整流钾电流（Ｉｋ１）的影响．方法：应用缓慢斜坡去极化脉冲程序测定离体豚鼠心室肌细胞准稳态电流－电压关系曲线．结果： ＰＢＤＡ ５, ５０和１００μｍｏｌ· Ｌ－１浓度依赖性地降低了心肌内向整流钾电流,表明该药对Ｉｋ１具有抑制作用ＰＢＤＡ对于Ｉｋ１的这种抑制效应不被多巴胺Ｄ２受体选择性阻断剂多潘立酮所阻断．结论：ＰＢＤＡ直接抑制Ｉｋ１,与多巴胺Ｄ２受体无关。     

鸡胚心肌细胞膜上外向钾电流的特征(英文)

目的:研究原代培养黄羽鸡胚心肌细胞上存在的外向钾电流特性,方法:膜片箝技术的“全细胞”记录,结果:此细胞模型上的钾电流动力学和药理学特征均不同于白羽鸡胚心肌细胞上的报道,钙通道阻断剂镉离子可消除此电流,异丙肾上腺素和cAMP通过磷酸化增加电流的峰值和缩短达到最大峰电流的时间,通道被磷酸化修饰后出现频率依赖性负性效应,结论:黄羽鸡胚心肌细胞上存在着钙激活的钾通道,磷酸化修饰不仅改变其开放速率还延长通道失活后再复活的时间,此结果也说明,同一种动物其细胞膜上离子通道的特性可因不同种系而各异。     

Purinergic facilitation of ATP-sensitive potassium current in rat ventricular myocytes

1. The effects of different purinergic agonists on the cardiac adenosine 5′-triphosphate (ATP)-sensitive potassium current (I_K(ATP)), appearing during dialysis of rat isolated ventricular myocytes with a low-ATP (100 μM) internal solution under whole-cell patch-clamp conditions, were examined in the presence of a P₁ purinoceptor antagonist.
2. The extracellular application of ATP in the micromolar range induced, besides known inward currents through cationic and chloride channels, the facilitation of I_K(ATP) once I_K(ATP) had already been partially activated during the low-ATP dialysis.
3. Analogues of ATP, α,β-methyleneadenosine 5′-triphosphate (α,βmeATP), 2-methylthioadenosine triphosphate (2MeSATP), adenosine 5′-O-3-thiotriphosphate (ATPγS) similarly facilitated I_K(ATP). UTP and ADP were very weak agonists while AMP and adenosine had no detectable effect.
4. The half-maximal stimulating concentration (C₅₀) of α,βmeATP, an analogue that did not elicite the interfering inward cationic current was 1.5 μM. Similar apparent C₅₀ (1–2 μM) were observed for ATP and analogues tested with somewhat less maximal effect of ATPγS.
5. Suramin, a nonselective P₂-purinoceptor antagonist, altered I_K(ATP) at the relatively high concentration required to inhibit purinoceptors. Pyridoxal-phosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS), a supposedly predominantly P_2X-purinoceptor antagonist, at micromolar concentration inhibited the transient inward current but did not block the facilitation of I_K(ATP).
6. Our results demonstrate that ATP and its analogues facilitate I_K(ATP) in rat ventricular myocytes by stimulation of non-P₁-, non-P_2X-purinoceptors.

     

丙基丁基多巴胺对心肌内向整流钾电流的抑制作用

研究丙基丁基多巴胺对内向整流钾电流的影响。方法：应用缓慢斜坡去极化脉冲程序测定离体豚鼠心室肌细胞准稳态电流－电压关系曲线。结果：ＰＢＤＡ５,５０和１００μｍｏｌ．Ｌ＾－１浓度依赖性地降低了心肌内向整流钾电流,表明该药对ＩＫ１具有抑制作用。     

ATP敏感性钾电流与蛋白激酶关系的研究

目的观察蛋白激酶A(PKA)及蛋白激酶C(PKC)抑制剂和蛋白脱磷酸化物质对大鼠心室肌细胞ATP敏感性钾电流 (IKATP)的影响 ,探讨克罗卡林 (cromakalim)开放ATP敏感性钾通道的作用机制。方法采用全细胞膜片钳技术记录心室肌细胞IKATP。结果在37℃时克罗卡林 (1μmol·L-1)可阻断ATP的抑制作用 ,诱导出IKATP。PKA抑制剂PKI(6～22)amide (1μmol·L -1),可模拟克罗卡林的作用 ,激活IKATP;而PKC抑制剂calphosticC无此作用。同时还观察到蛋白脱磷酸化物质butanedioemonoxime(BDM,5mmol·L -1)也可诱发出IKATP。结论克罗卡林开放IKATP 机制与抑制PKA的活性有关 ,而与PKC无关。