The Effects of Protein Kinase C (PKC) on the Tension of Normal and Passively Sensitized Human Airway Smooth Muscle and the Activity of Voltage-dependent Delayed Rectifier Potassium Channel (Kv)

The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.

Differential Effects of d, l-Sotalol and d-Sotalol on Isoproterenol-Increased Delayed Rectifier Outward Potassium Current in Guinea Pig Single Ventricular Myocytes

The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier K+ outward currents were measured in isolated guinea pig single myocytes using the whole-cell configuration of the patch-clamp technique. Currents were measured in response to 300 ms depolarizing pulses from a holding potential of -40 mV in three experimental protocols [control, isoproterenol (10^(9)mol/L - 10^(-6) mol/L ), and isoproterenol (10^(-9)mol/L - 10^(-6)mol/L ) plus either d, l-Sotalol (10^(-4) mol/L) or d-Sotalol (10^(-4) mol/L)]. IK tail currents were measured upon repolarization to -40 mV. It was found that Ik was significantly amplified in the presence. of isoproterenol (10^(-9) mol/L- 10^(-6) mol/L) plus d-Sotalol. At 10-8 mol/L isoproterenol, Ik was increased by 92. 7%±17. 1 % (P<0. 05) and 54. 3 %±13. 4 % after d-Sotalol addition (P<0. 05). In contrast, d, l-Sotalol completely conteracted the increase of iK by isoproterenol (<10^(-8) mol/L), and compared to control, Ic was decreased by 35. 6 % ±8. 1% at 10^(-8) mol/L isoproterenol plus d, l-Sotalol (P<0. 05). It is concluded that the β-adrenergic blocking property of d, l-Sotalol but not that of dSotalol maintains the delayed rectifier K+ outward current blockade in the presence of isoproterenol in guinea pig myocytes. This might contribute to a superior antiarrhythmic efficacy as compared to d-Sotalol.

Effects of allocryptopine on outward potassium current and slow delayed rectifier potassium current in rabbit myocardium

Objective Allocryptopine （ALL） is an effective alkaloid of Corydalis decumbens （Thunb.） Pers. Papaveraceae and has proved to be an- ti-arrhythmic. The purpose of our study is to investigate the effects of ALL on transmural repolarizing ionic ingredients of outward potassium current （Ito） and slow delayed rectifier potassium current （IKs）. Methods The monophasic action potential （MAP） technique was used to record the MAP duration of the epicardium （Epi）, myocardium （M） and endocardium （Endo） of the rabbit heart and the whole cell patch clamp was used to record/to and IKs in cardiomyocytes of Epi, M and Endo layers that were isolated from rabbit ventricles. Results The effects of ALL on MAP of Epi, M and Endo layers were disequilibrium. ALL could effectively reduce the transmural dispersion of repolarization （TDR） in rabbit transmural ventricular wall. ALL decreased the current densities of/to and IKs in a voltage and concentration dependent way and narrowed the repolarizing differences among three layers. The analysis of gating kinetics showed ALL accelerated the channel activation ofIto in M layers and partly inhibit the channel openings of/to in Epi, M and Endo cells. On the other hand, ALL mainly slowed channel deactivation of IKs channel in Epi and Endo layers without affecting its activation. Conclusions Our study gives partially explanation about the mechanisms of tmnsmural inhibition of/to and IKs channels by ALL in rabbit myocardium. These findings provide novel perspective regarding the anti-arrhythmogenesis application of ALL in clinical settings.

The Effect of Benzyltetrahydropalmatine (BTHP) on Action Potentials and the Two Components of Delayed Rectifying Potassium Currents in Guinea Pig Ventricular Myocytes

The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp technique. BTHP 30 μmol·L -1 significantly prolonged APD 90 from 143±16 ms to 184±21 ms ( P 【0.01, n=5) without affecting either the RP or APA, and the APD prolonging effects of BTHP were independent of extracellular Ca 2+ . BTHP inhibited both I kr (IC 50 =7 9 μmol·L -1 ) and I ks (IC 50 =22 4 μmol·L -1 ) in a concentration dependent fashion. The results demon strated that BTHP had no obvious selectivity for I kr and I ks .

Effect of passive sensitization by serum from allergic asthmatic patients on the activity and expression of voltage-dependent delayed rectifier potassium channel in human bronchial smooth muscle cells

Background Potassium (K +) channels are important in regulating cell membrane potential and excitability. Although bronchial myocytes from asthmatic rats show a significant reduction in voltage-dependent delayed rectifier potassium channel (Kv) current density and higher excitability, the activity and expression of Kv in human bronchial smooth muscle cells (HBSMCs) have never been studied. The ob jective of this study was to investigate the effect of passive sensitization by asthmatic serum on the activity of Kv and the expression of Kv isoform Kv1.5 in HBSMCs.Methods HBSMCs were randomly divided into two groups: control group (containing 10% serum from nonatopic individuals) and sensitized group (containing 10% asthmatic serum), then cultured for 24 hours. Whole-cell patch clamp, immunofluorescence staining, reverse transcription-polymerase chain reaction and Western blot techniques were used to study the effect of passive sensitization on the activity of Kv and the expression of Kv1.5 in HBSMCs.Results The membrane potential in passively sensitized HBSMCs was significantly depolarized to -(26.7±5.2) mV compared with -(41.3±6.4) mV in the cont rol group (P<0.01). Passive sensitization caused a significant inhibition of Kv currents in HBSMCs, resulting in a downward shift in the current-voltage (Ⅰ-Ⅴ) relationship curve. At +50mV, the peak Kv current density of passively sensitized HBSMCs was significantly decreased from (54.6±8.7) picoamperes per picofarad ( pA/pF) to (32.1±7.1) pA/pF (P<0.01). The expression level of Kv1.5 mRNA in passively sensitized HBSMCs was significantly lower than that in the control group (0.76±0.07 vs 1.04±0.13, P<0.05). The expression of Kv1.5 protein of passively sensitized HBSMCs was also significantly reduced compared to that from the control group (984±168 vs 2200±380, P<0.05).Conclusions The activity and expression of Kv were all decreased in HBSMCs passively sensitized by asthmatic serum compared with nonsensitized cells. These changes might be involved in the mechanisms of formation and development of asthma.

黄连素对结肠平滑肌细胞膜钙激活钾通道和延迟整流钾通道的影响

目的 研究黄连素对结肠平滑肌细胞膜钙离子激活钾通道 (IK(Ca) )和延迟整流钾通道 (IK(V) )的影响以初步探讨其治疗运动性腹泻的机制。方法 酶解法急性分离单个豚鼠结肠平滑肌细胞 ,运用膜片钳方法检测 10、5 0、10 0 μmol·L-1的黄连素对结肠平滑肌细胞膜IK(Ca) 和IK(V) 的影响。结果 10、5 0、10 0 μmol·L-1的黄连素可抑制豚鼠单个结肠平滑肌细胞膜IK(Ca) (P <0 0 1) ,当阶跃刺激为 +80mV时 ,其IK(Ca) 分别为生理盐水对照组的 (6 8 2 0± 5 17) % ,(5 5 89± 1 6 1) % ,(4 8 0 8± 2 4 5 ) % (P <0 0 1) ;10、5 0、10 0 μmol·L-1的黄连素可抑制豚鼠单个结肠平滑肌细胞膜IK(V) (P <0 0 1) ,当阶跃刺激为 +80mV时 ,其IK(V) 分别为生理盐水对照组的 (77 0 6± 6 4 2 ) % ,(6 8 6 7± 6 79) % ,(6 1 0 7±7 72 ) % (P <0 0 1)。结论 Ber能抑制豚鼠结肠平滑肌钙离子激活钾通道和延迟整流钾通道的开放 ,这可能是其治疗运动性腹泻的机制之一。

3种钾通道在哮喘豚鼠气道高反应中的作用

目的:探讨钙激活钾通道(KCa)、延迟整流型钾通道(Kdr)和ATP敏感型钾通道(KATP)在哮喘豚鼠气 道高反应中的作用。方法:采用离体气管环张力实验,观察加入特异性钾通道阻断剂后,与不加阻断剂相比气管环 对组胺反应的量效曲线的差异。结果:(1)加入KCa阻断剂TEA后,对照组气管环对组胺的反应变化不显著,而哮喘 组气管环对10-4mol／L、10-3mol／L组胺的收缩反应均显著低于不加TEA的气管环(P<0．01),量效曲线明显下移; (2)加入Kdr阻断剂4-AP后,对照组气管环对10-3mol／L组胺的最大收缩反应明显下降(P<0．05),组胺的量效曲线 下移,哮喘组气管环对10-4mol／L、10-3mol／L组胺的收缩反应均低于不加4-AP的气管环(P<0．01),且下降程度较 对照组大(P<0．05),量效曲线明显下移;(3)加入KATP阻断剂glibenclamide后,对照组和哮喘组气管环对组胺的量效 曲线与不加glibenclamide的气管环相比变化均无明显差异。结论:在豚鼠哮喘模型中,KCa和Kdr活性的降低在气道高 反应的发生中起介导作用,KATP作用不明显。

I_(Ks)复极储备下调对心肌肥厚豚鼠室性心律失常发生的影响

目的:观察心肌肥厚时快激活延迟整流钾电流(rapidly activated delayed rectifier potassium channel,I_(Kr))和慢激活延迟整流钾电流(slowly activated delayed rectifier potassium channel,IKs)的变化,并探讨I_(Kr)和IKs阻断剂对心肌肥厚豚鼠室性心律失常发生的影响。方法:豚鼠分为假手术组和左心室肥厚(left ventricular hypertrophy,LVH)组,制备LVH模型。采用全细胞膜片钳技术记录心室肌细胞I_(Kr)和IKs电流,观察I_(Kr)和IKs电流的变化;给予豚鼠分别静脉注射I_(Kr)阻断剂多非利特(0.04 mg/kg)和IKs阻断剂chromanol 293B(0.1 mg/kg),观察其对LVH豚鼠QTc及室性心律失常发生的影响。结果:豚鼠胸主动脉缩窄6周后,与假手术组相比,室间隔厚度,左室后壁厚度,QTc间期和细胞电容显著增加(P<0.05或P<0.01);LVH心室肌细胞IKs明显减少[+60 m V:(0.36±0.03)p A/p F vs(0.58±0.05)p A/p F,P<0.01];LVH对I_(Kr)无明显影响。I_(Kr)阻断剂可显著延长LVH豚鼠QTc间期(P<0.01),并增加室性心律失常的发生。IKs阻断剂对LVH豚鼠QTc间期及室性心律失常的发生无明显影响。结论:IKs复极储备下调是心肌肥厚诱发室性心律失常的重要机制之一。

柚皮素舒张大鼠肾动脉及其机制研究

[目的]探讨柚皮素对大鼠离体肾动脉血管环的舒张作用及其机制。[方法]通过DMT微血管张力记录仪和Powerlab张力换能器记录其张力变化。将肾动脉血管环用氯化钾(60mmol/L)或苯肾上腺素(10-5 mol/L)预收缩达平台后,用柚皮素(10-6 mol/L^10-4 mol/L)对肾动脉进行浓度依赖性的舒张,测定柚皮素对预收缩肾动脉的舒张百分比。观察柚皮素预孵(浓度选舒张实验中计算的RC50值)前后60mmol/L氯化钾或10-5 mol/L苯肾上腺素收缩肾动脉幅度的变化。用氯化钾或苯肾上腺素预收缩肾动脉达平台后,孵育Kir通道抑制剂氯化钡(BaCl210-4 mol/L)、KCa通道抑制剂四乙胺(TEA,10-3 mol/L)15min,达平台后,依次加入不同浓度的柚皮素(10-6mol/L^10-4 mol/L)对其进行舒张,观察BaCl2、TEA对柚皮素舒张肾动脉作用的影响。[结果]柚皮素在10-6 mol/L^10-4 mol/L内对氯化钾或苯肾上腺素预收缩大鼠离体肾动脉血管环均具有浓度依赖性的舒张作用;提前孵育柚皮素,使氯化钾或苯肾上腺素收缩大鼠离体肾动脉血管环的幅度发生一定程度的降低,分别降低了(53.10±2.43)%、(46.39±3.24)%;Kir通道抑制剂氯化钡(10-4mol/L)对柚皮素舒张60mmol/L氯化钾或10-5 mol/L苯肾上腺素预收缩肾动脉血管环的作用没有明显的影响,而KCa通道抑制剂四乙胺对柚皮素舒张60mmol/L氯化钾或10-5 mol/L苯肾上腺素预收缩肾动脉的最大舒张幅度均有一定程度的抑制作用。[结论]柚皮素对高钾或苯肾上腺素预收缩的离体大鼠肾动脉血管环均有浓度依赖性的舒张效果;柚皮素对肾动脉血管环的舒张作用与钙激活钾通道KCa有关。

人心肌细胞缓慢激活延迟整流钾电流细胞模型的建立

目的建立稳定表达人心肌细胞缓慢激活延迟整流钾电流(IKs)的细胞模型。方法编码IKs通道α亚单位的KCNQ1基因及β亚单位的KCNE1基因共转染HEK 293细胞,潮霉素B筛选,电生理学及药理学方法鉴定。结果KCNQ1/KCNE1基因被成功转入HEK 293细胞,KCNQ1/KCNE1电流与人心肌IKs电流具有相似的电流特性;hKCNQ1/hKCNE1通道反转电位与细胞外钾离子浓度呈线性关系;选择性IKs通道阻断剂Chromanol 293B对KCNQ1/KCNE1电流具有明显而可逆的抑制作用,其IC50(+40 mV)为9.1μmol/L;无钾细胞外液可以增加KCNQ1/KCNE1电流幅度,+40 mV时电流幅度增加(28.6±2.0)%(P<0.01,n=8),但对其动力学特性无明显影响。结论已经成功构建稳定表达人心肌KCNQ1/KCNE1通道蛋白的HEK 293细胞系,其电生理学特性和药理学特性与人心肌IKs相似,可以作为研究人心肌IKs的细胞模型。

Characterization of a Chinese KCNQ1 mutation （R259H） that shortens repolarization and causes short QT syndrome 2

Objectives To evaluate the association between a KCNQ 1 mutation, R259H, and short QT syndrome （SQTS） and to explore the elec- trophysiological mechanisms underlying their association. Methods We performed genetic screening of SQTS genes in 25 probands and their family members （63 patients）. We used direct sequencing to screen the exons and intron-exon boundaries of candidate genes that en- code ion channels which contribute to the repolarization of the ventricular action potential, including KCNQI, KCNH2, KCNE1, KCNE2, KCNJ2, CACNAlc, CACNB2b and CACNA2D1. In one of the 25 SQTS probands screened, we discovered a KCNQ1 mutation, R259H. We cloned R259H and transiently expressed it in HEK-293 cells; then, currents were recorded using whole cell patch clamp techniques. Results R259H-KCNQ 1 showed significantly increased current density, which was approximately 3-fold larger than that of wild type （WT） after a depolarizing pulse at 1 s. The steady state voltage dependence of the activation and inactivation did not show significant differences between the WT and R259H mutation （P 〉 0.05）, whereas the time constant of deactivation was markedly prolonged in the mutant compared with the WT in terms of the test potentials, which indicated that the deactivation of R259H was markedly slower than that of the WT. These results suggested that the R259H mutation can effectively increase the slowly activated delayed rectifier potassium current （Irs） in phase 3 of the cardiac action potential, which may be an infrequent cause of QT interval shortening. Conclusions R259H is a gain-of-function muta- tion of the KCNQ1 channel that is responsible for SQTS2. This is the first time that the R259H mutation was detected in Chinese people.

稳定表达大电导钙激活钾通道α亚基的细胞株构建及其排钾的分子机制研究

目的·构建稳定表达大电导钙激活钾通道(large conductance Ca^2+-activated K+channel, MaxiK或BK)α亚基的HEK293细胞株,探讨BKα通道的排钾机制。方法·构建带Myc标签的BKα质粒,采用脂质体转染方法将BKα质粒转染至HEK293细胞系中,用药物G418筛选阳性单克隆细胞株,分别以Western blotting和细胞免疫荧光法检测BKα蛋白表达及定位。将稳定表达BKα蛋白的HEK293细胞系培养于玻片,形成单细胞层,分别给予5 mmol/L和100 mmol/L钾离子浓度的浴液,膜片钳单通道记录BKα的离子流。内向整流性钾通道Kir4.1的野生型和突变型(G77R、G130R、C140R和R297C)分别转染稳定转染BKα的HEK293细胞后提取膜蛋白,Western blotting检测BKα的表达情况。结果·转染后的HEK293细胞中挑选表达BKα通道的细胞株,细胞免疫荧光验证了BKα通道表达及其在细胞膜上表达。在给予100 mmol/L钾离子浓度浴液的情况下,BKα的通道开放频率(NPo)快速增加。Kir4.1的野生型和突变型分别转染稳定转染BKα的HEK293细胞后提取膜蛋白,Western blotting检测发现转染Kir4.1突变体质粒的HEK293细胞的BKα表达较野生型增加(P<0.05)。结论·成功地建立了稳定表达BKα的HEK293细胞株,BKα通道可以被高钾溶液激活;BKα通道的膜表达水平与Kir4.1通道功能状态有关,可能是由于突变的Kir4.1通道导致细胞去极化,从而激活BKα。

左心室肥厚兔缓慢型延迟整流钾电流通道KCNQ1和KCNE1 mRNA表达的变化

目的:观察左心室肥厚兔左心室内外膜心肌细胞中缓慢型延迟整流钾电流(IKs)通道KCNQ1和KCNE1 mRNA表达水平的差异,探讨IKs通道在兔肥厚心肌复极离散度增大中的作用。方法:55只雄性日本大耳白兔随机分为实验组30只和对照组25只。实验组行肾上腹主动脉次全结扎,使腹主动脉缩窄50%~60%;对照组除不做丝线结扎外,其余处理同实验组。术后8周处死动物,应用荧光定量PCR技术检测IKs通道KCNQ1和KCNE1 mRNA的表达。结果:对照组左心室内膜IKs通道mRNA表达水平低于心外膜(P<0.001);实验组左心室内外膜IKs通道mRNA表达水平均低于对照组(P<0.001)。结论:IKs通道减少使复极时限延长,其不均一性减小可能是肥厚心肌复极离散度增大的原因。

兔肥厚心肌细胞内膜和外膜慢反应延迟整流钾电流和动作电位时程的变化

目的探讨肥厚心肌的电生理重构机制,观察肥厚心肌细胞内膜和外膜慢反应延迟整流钾电流(IKs)和动作电位时程(APD)的变化。方法家兔16只随机分为假手术组和心肌肥厚组。心肌肥厚组通过部分结扎腹主动脉的方法造成兔压力负荷性心肌肥厚模型,假手术组只暴露腹主动脉而不行缩窄术。实验以胶原酶分离兔心肌细胞,采用全细胞膜片钳记录IKs和APD。结果①假手术组和心肌肥厚组心内膜的IKs均显著小于心外膜。②与假手术组相比,心肌肥厚组心内膜和心外膜的IKs显著减小。③假手术组和心肌肥厚组心内膜的APD均显著长于心外膜。④与假手术组相比,心肌肥厚组心内膜和心外膜的APD显著延长。结论肥厚心肌IKs存在跨室壁异质性,同时伴有心外膜和心内膜不均一的IKs减小,造成复极时程延长和跨室壁复极不均一性的增加。

Yotiao蛋白在心律失常中的生物学功能研究进展

Yotiao蛋白是A型激酶锚定蛋白(AKAP) 9基因的表达产物,属于AKAP家族成员,是调控缓慢激活延迟整流钾通道(IKs)亚基磷酸化功能的重要蛋白之一。随着基因分子生物学和全外显子测序技术的发展,越来越多的心律失常被证实与基因和遗传因素有关。许多严重的心律失常(心房颤动、长QT综合征、Brugada综合征等)均与编码心脏钾离子通道的基因突变相关。Yotiao蛋白直接与心脏组织的IKs通道KCNQ1亚基结合,并通过招募蛋白激酶A、磷脂酶1、腺苷酸环化酶等重要蛋白激酶形成大分子传导复合体,特异性地调节细胞底物磷酸化过程中的各种信号转导通路。

Effect of Interleukin-1β on I_A and I_K Currents in Cultured Murine Trigeminal Ganglion Neurons

To investigate the effect of intedeukin-1β （IL-1β） on IA and IK currents in cultured murine trigeminal ganglion （TG） neurons, whole-cell patch clamp technique was used to record the IA and IK currents before and after 20 ng/mL IL-1β perfusion. Our results showed that 20 ng/mL IL-1β inhibited IA currents （18.3±10.7）% （n=6, P〈0.05）. IL-1β at 20 ng/mL had no effect on G-V curve of IA but moved the H-infinity curve V0.5 from -36.6±6. 1 mV to-42.4±5.2 mV （n=5, P〈0.01）. However, 20 ng/mL IL-1β had effect on neither the amplitude nor the G-V curve of IK. IL-1β was found to selectively inhibit IA current in TG neurons and the effect may contribute to hyperalgesia under various inflammatory conditions.

人类eag相关基因编码的钾通道Ikr与长QT综合征

人类eag相关基因(HERG)编码快速激活的延迟整流钾通道(Ikr)的α亚基、Ikr电流主要参与心肌动作电位的复极过程。HERG发生突变或药物作用于Ikr都可诱发长QT综合征。后者的发病机制及治疗方法和措施是目前临床研究的热点。

The ionic mechanisms of long QT interval in diabetic rabbits

Objective Abnormal QT prolongation associated with arrhythmias is considered the major cardiac electrical disorder and a significant predictor of mortality in diabetic patients. The precise ionic mechanisms for diabetic QT prolongation remained unclear. The present study was designed to analyze the changes of ventricular repolarization and the underlying ionic mechanisms in diabetic rabbit hearts. Methods Diabetes was induced by a single injection ofalloxan （145mg/kg, Lv. ）. After the development of diabetes （10 weeks）, ECG was measured. Whole-cell patch-clamp technique was applied to record the action potential duration （APD50, APD90）, slowly activating outward rectifying potassium current （IKs）, L-type calcium current （ICa-L） and inward rectifying potassium current （IK1）. Results The action potential duration （APD50 and APD90） of ventricular myocytes was obviously prolonged from 271.5＋32.3 ms and 347.8＋36.3 ms to 556.6~72.5 ms and 647.9~72.2 ms respectively （P〈 0.05）. Meanwhile the normalized peak current densities of IKs in ventricular myocytes investigated by whole-cell patch clamp was smaller in diabetic rabbits than that in control group at test potential of＋50mV （1.27~0.20 pA/pF vs 3.08~0.67 pA/pF, P〈0.05）. And the density of the ICa-L was increased apparently at the test potential of 10 mV （-2.67~0.41 pA/pF vs -5.404-1.08 pA/pF, P〈0.05）. Conclusion Ventricular repolarization was prolonged in diabetic rabbits, it may be partly due to the increased L-type calcium current and reduced slow delayed rectifier K＋ current （IKs） （J Geriatr Cardio12010; 7：25-29）.

1-磷酸鞘氨醇对心肌细胞延迟整流钾电流2种成分的作用

目的:研究1-磷酸鞘氨醇(S1P)对豚鼠心室肌细胞延迟整流钾电流的2种成分快速激活整流钾电流(IKr)和缓慢激活整流钾电流(IKs)的作用。方法:用胶原酶酶解法急性分离豚鼠心室肌细胞,随机分为正常对照组、S1P(1.1μmol/L)组、S1P(1.1μmol/L)加苏拉明(Suramin)(200μmol/L)组。利用全细胞膜片钳的方法记录心室肌细胞IKr和IKs及其尾电流。结果:①对照组IKr和IKr的尾电流分别为(0.85±0.53)nA和(0.65±0.40)nA。加入S1P后,IKr和IKr的尾电流受到明显抑制,下降到(0.63±0.37)nA和(0.56±0.29)nA(P<0.05,n=6)。而加入S1P加Suramin后,抑制作用消失,IKr和IKr的尾电流为(0.85±0.41)nA和(0.71±0.43)nA,与对照组相比差异无统计学意义(P>0.05,n=6)。②对照组IKs和IKs的尾电流分别为(1.53±0.61)nA和(0.82±0.34)nA。加入S1P后,下降到(1.47±0.46)nA和(0.79±0.41)nA,但差异无统计学意义(P>0.05,n=6)。结论:S1P可降低豚鼠心室肌细胞IKr的幅值,并且是通过其特异性的G蛋白耦联S1P受体介导而产生这些作用。S1P对豚鼠心室肌细胞IKs没有作用。

兔肥厚心肌慢反应延迟整流钾通道表达的变化

目的:慢反应延迟整流钾通道(IKs)是心肌细胞复极的重要组成部分,本实验观察左心室肥厚对心外膜下心肌(Epi)和心内膜下心肌(Endo)IKs的mRNA表达水平变化。方法:家兔16只随机分为假手术组和心肌肥厚组。心肌肥厚组通过部分结扎腹主动脉的方法造成兔压力负荷性心肌肥厚模型,假手术组只暴露腹主动脉而不行缩窄术。应用RT-PCR技术检测IKs通道基因KvLQT1(α亚单位)和minK(β亚单位)的mRNA表达。结果:假手术组EpiIKs通道α亚单位基因KvLQT1为Endo的2.5倍,EpiIKs通道β亚单位基因minK为Endo的3.3倍。与假手术组相比,心肌肥厚组Epi和EndoIKs通道α亚单位基因KvLQT1表达分别降低40%和25%,心肌肥厚组Epi和EndoIKs通道β亚单位基因minK表达分别降低50%和33%。结论:IKs通道基因KvLQT1和minK的mRNA表达存在跨室壁的差异。心肌肥厚可造成Epi和EndoIKs的mRNA表达不均一的下降。