Hydrogen sulfide-induced enhancement of gastric fundus smooth muscle tone is mediated by voltagedependent potassium and calcium channels in mice

AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique.The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread.Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro.Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel.Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.RESULTS:We found that both CBS and CSE were expressed in the cul tured smooth muscle cel ls from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations.In addition,nicardipine and aminooxyacetic acid(AOAA),a CBS inhibitor,reduced the tension,whereas Nω-nitro-L-arginine methyl ester,a nonspecific nitric oxide synthase,increased the tension.The AOAA-induced relaxation was significantly recovered by H2S,and the Na HS-induced increase in tonic contraction was blocked by 5 mmol/L4-aminopyridine and 1μmol/L nicardipine.Na HS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents.Moreover,Na HS increased L-type Ca2+currents and caused an elevation in intracellular calcium([Ca2+]i).CONCLUSION:These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice.The excitatory effect is mediated by voltagedependent potassium and L-type calcium channels.

Effect of gingerol on colonic motility via inhibition of calcium channel currents in rats

AIM: To investigate the effect of gingerol on colonic motility and the action of L-type calcium channel currents in this process.METHODS: The distal colon was cut along the mesenteric border and cleaned with Ca^(2+)-free physiological saline solution. Muscle strips were removed and placed in Ca^(2+)-free physiological saline solution, which was oxygenated continuously. Longitudinal smooth muscle samples were prepared by cutting along the muscle strips and were then placed in a chamber. Mechanical contractile activities of isolated colonic segments in rats were recorded by a 4-channel physiograph. Colon smooth muscle cells were dissociated by enzymatic digestion. L-type calcium currents were recorded using the conventional whole-cell patch-clamp technique.RESULTS: Gingerol inhibited the spontaneous contraction of colonic longitudinal smooth muscle in a dose-dependent manner with inhibition percentages of 13.3% ± 4.1%, 43.4% ± 3.9%, 78.2% ± 3.6% and 80.5% ± 4.5% at 25 μmol/L, 50 μmol/L, 75 μmol/L and 100 μmol/L, respectively(P < 0.01). Nifedipine, an L-type calcium channel blocker, diminished the inhibition of colonic motility by gingerol. Gingerol inhibited L-type calcium channel currents in colonic longitudinal myocytes of rats. At a 75 μmol/L concentration of gingerol, the percentage of gingerolinduced inhibition was diminished by nifedipine from 77.1% ± 4.2% to 42.6% ± 3.6%(P < 0.01). Gingerol suppressed IBa in a dose-dependent manner, and the inhibition rates were 22.7% ± 2.38%, 35.77% ± 3.14%, 49.78% ± 3.48% and 53.78% ± 4.16% of control at 0 m V, respectively, at concentrations of 25 μmol/L, 50 μmol/L, 75 μmol/L and 100 μmol/L(P < 0.01). The steady-state activation curve was shifted to the right by treatment with gingerol. The value of half activation was-14.23 ± 1.12 m V in the control group and-10.56 ± 1.04 m V in the 75 μmol/L group(P < 0.05) with slope factors, Ks, of 7.16 ± 0.84 and 7.02 ± 0.93(P < 0.05) in the control and 75 μmol/L groups, respectively. However, the steady-state inactivation curve was not changed, with a half-inactivation voltage, 0.5 V, of-27.43 ± 1.26 m V in the control group and-26.56 ± 1.53 m V in the 75 μmol/L gingerol group(P > 0.05), and a slope factor, K, of 13.24 ± 1.62 in the control group and 13.45 ± 1.68(P > 0.05) in the 75 μmol/L gingerol group.CONCLUSION: Gingerol inhibits colonic motility by preventing Ca^(2+) influx through L-type calcium channels.

Calcium channels and iron uptake into the heart

Iron overload can lead to iron deposits in many tissues,particularly in the heart.It has also been shown to be associated with elevated oxidative stress in tissues.Elevated cardiac iron deposits can lead to iron overload cardiomyopathy,a condition which provokes mortality due to heart failure in iron-overloaded patients.Currently,the mechanism of iron uptake into cardiomyocytes is still not clearly understood.Growing evidence suggests L-type Ca2+channels(LTCCs)as a possible pathway for ferrous iron(Fe2+)uptake into cardiomyocytes under iron overload conditions.Nevertheless,controversy still exists since some findings on pharmacological interventions and those using different cell types do not support LTCC’s role as a portal for iron uptake in cardiac cells.Recently,T-type Ca2+channels (TTCC)have been shown to play an important role in the diseased heart.Although TTCC and iron uptake in cardiomyocytes has not been investigated greatly,a recent finding indicated that TTCC could be an important portal in thalassemic hearts.In this review,comprehensive findings collected from previous studies as well as a discussion of the controversy regarding iron uptake mechanisms into cardiomyocytes via calcium channels are presented with the hope that understanding the cellular iron uptake mechanism in cardiomyocytes will lead to improved treatment and prevention strategies,particularly in iron-overloaded patients.

Effects of Tiaomaiyin and Its Disassembled Prescription on Expression of L-type Calcium Channel β2 Subunit in Rat Model of Tachyarrhythmia

[Objectives] To study the effects of Tiaomaiyin and its disassembled prescription on expression of L-type calcium channel β2 subunit in rat model of tachyarrhythmia. [Methods] Sixty Wistar rats were randomly divided into model group,Tiaomaiyin prescription group( whole prescription group),main efficacy group of removing heat to cool blood( blood cooling group),and auxiliary drug efficacy group of benefiting qi and nourishing heart( qi benefiting group),auxiliary efficacy group of promoting flow of qi and blood circulation( qi flow promoting group),and amiodarone group( western medicine group). Aconitine was given 7 d after the intragastric administration of the corresponding drugs,and the time of occurrence of arrhythmia in each group was observed. The left ventricular myocardium was subjected to reverse transcription-polymerase chain reaction and Western blotting. [Results] The ventricular premature beats( VPB) time in the whole prescription group and western medicine group was significantly longer than that in the model group. Ventricular tachycardia( VT),ventricular fibrillation( VF),and cardiac arrest( CA) were longer in the whole prescription group,blood cooling group,and western medicine group. The mRNA and protein expression of L-type calcium channel β2 subunit in the whole prescription group,blood cooling group and western medicine group were significantly decreased. [Conclusions] Tiaomaiyin whole prescription group and blood cooling group can reduce the occurrence time of tachyarrhythmia and reduce the expression of LTCC β2 in myocardium.

Antiepileptic Drug-Induced Apoptosis Was Prevented by L-Type Calcium Channel Activator in Cultured Rat Cortical Cells

Experimental data have shown that antiepileptic drugs cause neurodegeneration in developing rats. Valproate (VPA) is the drug of choice in primary generalized epilepsies, and carbamazepine (CBZ) is one of the most prescribed drugs in partial seizures. These drugs block sodium channels, thereby reducing sustained repetitive neuronal firing. The intracellular mechanisms whereby AEDs induce neuronal cell death are unclear. We examined whether AEDs induce apoptotic cell death in cultured cortical cells and whether calcium ions are involved in the AED-induced cell death. VPA and CBZ increased apoptotic cell death and induced morphological changes that were characterized by cell shrinkage and nuclear condensation or fragmentation. Incubation of cortical cultures with VPA or CBZ decreased phospho-Akt levels. CBZ decreased the intracellular calcium levels. On the other hand, FPL64176, an L-type calcium channel activator, increased the intracellular calcium levels and prevented the AED-induced apoptosis. Glycogen synthase kinase-3 inhibitors, such as alsterpaullone and azakenpaullone, prevented the AED-induced apoptosis. These results suggest that intracellular calcium level changes are associated with AEDs and apoptosis and that the activation of glycogen synthase kinase-3 is involved in the death of rat cortical neurons.

Abnormal Calcium “Sparks” in Cardiomyocytes of Post-myocardial Infarction Heart

In ischemic hypertrophic myocardium, contractile dysfunction can be attributed to the decreased calcium induced calcium release （CICR） in cytoplasm. This study aimed to investigate the electrophysiological properties and the expression of L calcium channel subunits in post-MI myocardium. The ischemic heart remodeling model was established in SD rats. The expressions of calcium channel subunits were determined by realtime RT-PCR. Whole cell patch clamp was used to record the electrophysiological properties of L calcium channel. The results showed that the L calcium channel agonist Bayk 8644 induced the significantly decreased CICR in the rat cardiomyocyte 6 weeks after myocardial infarction （MI）. In the post-MI cardiomyocytes, the amplitude of ICaL decreased dramatically and the inactivation curve of the current shifted to more negative potential. At mRNA level, the expression of the calcium channel alpha1c, beta2c subunits decreased dramatically in the ventricle of post-MI rats. The expression of alpha2/delta subunit, however, remained constant. It is concluded that the abnormal expression of the L calcium channel subunits in post-MI cardiomyocytes contributes to the ICaL decrease at early stage of the ischemic remodeling in cardiomyocytes, which leads to the decreased CICR in the cell and contractile dysfunction of myocardium.

微小RNA-26b-5p对缺血性心律失常大鼠心房肌细胞L型钙通道的影响

目的探讨微小RNA(miR)-26b-5p对磷脂酰肌醇3-激酶(PI3K)/磷脂酰肌醇3,4,5-三磷酸(PIP3)信号通路的调控作用以及对缺血性心律失常大鼠心房肌细胞L型钙通道的影响。方法选择SD大鼠72只,按照随机数表法分为假手术组、模型组、LY294002组、阴性对照组、过表达组、联合组,每组12只。各组给予相应干预24h,除假手术组外的其余各组大鼠建立缺血性心律失常模型,假手术组大鼠仅开胸不结扎。建模过程中检测各组大鼠心律失常指标,采用Curtis-Walker评分法进行心律失常评分;荧光定量PCR法检测心房肌细胞中miR-26b-5p表达;全细胞膜片钳技术记录心房肌细胞L型钙通道电流(ICa-L);蛋白印迹法检测L型钙通道α1C亚基(CACNA1C)、钙调蛋白及PI3K/PIP3通路相关蛋白表达。结果与模型组比较,LY294002组大鼠左心室室性期前收缩次数、室性心动过速持续时间、心室颤动持续时间、心律失常评分、心房肌细胞ICa-L峰值密度绝对值、CACNA1C、钙调蛋白表达显著升高,磷酸化PI3K、PIP3、磷酸化蛋白激酶B(Akt)表达显著降低,过表达组大鼠左心室室性期前收缩次数、室性心动过速持续时间、心室颤动持续时间、心律失常评分、心房肌细胞ICa-L峰值密度绝对值、CACNA1C、钙调蛋白表达显著降低,miR-26b-5p、磷酸化PI3K、PIP3、磷酸化Akt表达显著升高(P<0.05)。与过表达组比较,联合组大鼠左心室室性期前收缩次数、室性心动过速持续时间、心室颤动持续时间、心律失常评分、心房肌细胞ICa-L峰值密度绝对值、CACNA1C、钙调蛋白表达显著升高,磷酸化PI3K、PIP3、磷酸化Akt表达显著降低(0.82±0.08vs1.09±0.11,0.91±0.09vs1.17±0.11,0.94±0.09vs1.20±0.12,P<0.05)。结论miR-26b-5p过表达可能通过激活PI3K/PIP3相关信号通路,阻滞缺血性心律失常大鼠心房肌细胞L型钙通道,改善心律失常表现。

Comparative identification of Ca～(2+) channel expression in INS-1 and rat pancreatic β cells

AIM:To identify and compare the profile of Ca2+ channel subunit expression in INS-1 and rat pancreatic β cells. METHODS:The rat insulin-secreting INS-1 cell line was cultured in RPMI-1640 with Wistar rats employed as islet donors.Ca2+ channel subunit expression in INS-1 and isolated rat β cells were examined by reverse transcription polymerase chain reaction (RT-PCR).Absolute real-time quantitative PCR was performed in a Bio-Rad iQ5 Gradient Real Time PCR system and the data analyzed using an iQ5 system to identify the expression level of the Ca 2+ channel subunits. RESULTS:In INS-1 cells,the L-type Ca 2+ channel 1C subunit had the highest expression level and the TPRM2 subunit had the second highest expression. In rat β cells,the TPRC4 β subunit expression was dominant and the expression of the L-type 1C subunit exceeded the 1D subunit expression about two-fold. This result agreed with other studies,confirming the important role of the L-type 1C subunit in insulinsecreting cells,and suggested that non-voltageoperated Ca 2+ channels may have an important role in biphasic insulin secretion. CONCLUSION:Twelve major Ca 2+ channel subunit types were identified in INS-1 and rat β cells and significant differences were observed in the expression of certain subunits between these cells.

lncRNA KCNQ1OT1调控miR-384/CACNA1C轴对心肌细胞增殖、凋亡的影响

目的探讨长链非编码RNA钾电压门控通道亚家族Q成员1反向转录物1(lncRNA KCNQ1OT1)调控miR-384/L型钙离子通道α1C亚基基因(CACNA1C)轴对心肌细胞增殖、凋亡的影响。方法实时荧光定量PCR(qRT-PCR)、Western blot分别检测正常培养的大鼠心肌H9c2、CP-R073细胞及缺氧/复氧(H/R)诱导的H9c2、CP-R073细胞中的KCNQ1OT1、miR-384、CACNA1C蛋白表达。将H9c2细胞分为Ct组、Model组、si-NC组、si-KCNQ1OT1组、mimic NC组、miR-384 mimic组、si-KCNQ1OT1+inhibitor NC组、si-KCNQ1OT1+miR-384 inhibitor组。除Ct组外,其他组H9c2细胞均需转染对应物质后构建H/R损伤模型。qRT-PCR检测细胞中KCNQ1OT1、miR-384表达;CCK-8法、EdU染色检测细胞增殖;流式细胞术检测细胞凋亡;ELISA法检测细胞中肌红蛋白(Mb)、肌钙蛋白-Ⅰ(cTnⅠ)水平;Western blot检测CACNA1C、增殖细胞核抗原(PCNA)、半胱氨酰天冬氨酸特异性蛋白酶-3(Caspase-3)、Bcl-2相关X蛋白(Bax)蛋白表达;双荧光素酶报告基因实验验证KCNQ1OT1与miR-384、miR-384与CACNA1C的关系。结果H/R诱导的H9c2、CP-R073细胞中KCNQ1OT1、CACNA1C蛋白表达升高,miR-384表达降低,且H/R诱导的H9c2细胞中KCNQ1OT1、CACNA1C蛋白表达最高,miR-384表达最低,因此,后续选择H9c2细胞为研究对象。与Ct组比较,Model组细胞中KCNQ1OT1、细胞凋亡率、Mb、cTnⅠ水平、CACNA1C、Caspase-3、Bax蛋白表达升高,miR-384表达、D 450值、EdU阳性率、PCNA蛋白表达降低(P<0.05);沉默KCNQ1OT1或过表达miR-384可促进H/R诱导的H9c2细胞增殖,抑制细胞凋亡;miR-384 inhibitor减弱了沉默KCNQ1OT1对H/R诱导的H9c2细胞增殖的促进作用,以及对细胞凋亡的抑制作用;KCNQ1OT1靶向调控miR-384/CACNA1C轴。结论沉默KCNQ1OT1可能通过上调miR-384来抑制CACNA1C表达,进而促进H/R诱导的H9c2细胞增殖,抑制细胞凋亡。

黄芪对感染病毒大鼠心肌细胞L型钙通道的效应

目的:了解黄芪对感染柯萨奇病毒心肌细胞 L 型钙通道的影响,以探讨黄芪用于心肌炎治疗的作用机制。方法:以柯萨奇 B_3病毒感染急性分离的成年大鼠心肌细胞,利用膜片钳技术记录 L 型钙通道电流。结果:黄芪不影响正常心肌细胞 L 型钙通道电流的幅度,但可减缓 L 型钙通道电流的衰减。病毒感染增加心肌细胞 L 型钙通道电流的幅度,并改变其电压依赖性而使电流电压曲线向左下偏移。黄芪可抑制病毒感染细胞 L 型钙通道电流的增加。结论:黄芪通过抑制感染细胞经 L 型钙通道的跨膜钙内流和稳定 L 型钙通道的作用,可防止病毒感染可能导致的细胞内钙超载和异常电活动。

葛根素对大鼠心肌细胞L型钙离子通道的影响

目的 :观察葛根素对大鼠L型钙离子通道的作用。方法 :恒流Langendorff灌流 ,I型胶原酶解分离 ,全细胞膜片钳技术记录离子电流。结果 :2 .4mmol·L- 1葛根素可以抑制单个大鼠心室肌细胞L型钙离子通道电流 ,且成时间依赖性 ;葛根素可以促进L型钙通道电流 电压 (I V)曲线的上移。结论 :葛根素可以抑制大鼠心室肌细胞的L型钙离子通道电流 。

甲基莲心碱对心肌细胞I_(Na)、I_(Ca-L)及稳态外向K^+电流的影响

目的 为证明甲基莲心碱（ Ｎｅｆｅｒｉｎｅ， Ｎｅｆ） 对单个心肌细胞离子通道电流的影响及抗心律失常作用的离子通道机制。方法 采用全细胞记录膜片钳技术，记录了 Ｎｅｆ 对培养大鼠心室肌细胞钠电流（ Ｉ Ｎａ） 及豚鼠心室肌细胞动作电位、 Ｉ Ｎａ 、 Ｌ 型钙电流（ Ｉ Ｃａ Ｌ） 及稳态外向 Ｋ＋ 电流的影响。结果 Ｎｅｆ ３０ ，１００ μｍｏｌ· Ｌ－ １ 明显抑制培养大鼠心室肌细胞 Ｉ Ｎａ ，分别从对照水平的（３４ ±０７） ｎ Ａ 降至（２１ ±０５） 和（０４ ±０２） ｎ Ａ。 Ｎｅｆ １０ μｍｏｌ· Ｌ－ １ 可降低豚鼠心室肌细胞动作电位振幅、静息电位，延长动作电位时程。 Ｎｅｆ １０ ，３０ μｍｏｌ· Ｌ－ １ 分别使豚鼠心室肌细胞 Ｉ Ｎａ 及 Ｉ Ｃａ Ｌ从给药前的（７９ ±２１） ｎ Ａ 和（６８９ ±２４３） ｐ Ａ 降至（４０ ±１４） 、（１３ ±０６） ｎ Ａ和（３７４ ±１７２） 、（１０９ ±６７） ｐ Ａ。 Ｎｅｆ １０ μｍｏｌ· Ｌ－ １ 还抑制 Ｉ Ｎａ 、稳态外向 Ｋ＋ 电流和 Ｉ Ｃａ Ｌ的 Ｉ Ｖ 曲线并使后者的峰值电流电位略右移。结论 Ｎｅｆ 有钠、 Ｌ 型钙通道阻滞作用并抑制稳态外向 Ｋ＋ 电流。

大鼠全脑缺血后海马CA1区锥体神经元L型钙通道电流的改变(英文)

已有研究表明在脑缺血期间及再灌流后早期,海马CA1锥体神经元细胞内钙浓度明显升高,这一钙超载被认为是缺血性脑损伤的重要机制之一.电压依赖性钙通道是介导正常CA1神经元钙内流的主要途径.实验观察了脑缺血再灌流后早期海马CA1锥体神经元电压依赖性L型钙通道的变化.以改良的四血管闭塞法制作大鼠 15min前脑缺血模型,在急性分离的海马CA1神经元上,采用膜片钳细胞贴附式记录L型电压依赖性钙通道电流.脑缺血后CA1神经元L型钙通道的总体平均电流明显增大,这是由于通道的开放概率增加所致.进一步分析单通道动力学显示,脑缺血后通道的开放时间变长,通道的开放频率增大.

芍药苷对大鼠心肌细胞L钙通道的阻断作用

目的 在单个大鼠心肌细胞上 ,研究芍药苷对L型钙通道的阻断作用。方法 采用全细胞膜片钳技术。结果 芍药苷浓度依赖性阻断ICa ,L,其IC50 为 387μmol·L- 1 。应用 40 0 μmol·L- 1 芍药苷后 ,ICa,L最大电流幅度下降 51 % ,但I U曲线的形态和反转电位没有变化 ,激活曲线也没有明显的改变 ;失活曲线向较负电压的方向偏移约 8 3mV ,通道从失活中恢复的时间明显延长 ,由给药前的 (96± 1 7)ms增至 (1 85± 2 8)ms ;芍药苷的阻断作用没有显示出频率依赖性。结论 芍药苷对心肌细胞ICa 。

中药甘松挥发油对大鼠心室肌细胞膜L型钙通道的影响

目的研究甘松挥发油对大鼠心室肌细胞膜L型钙通道的影响,探讨甘松挥发油在离子通道水平抗心律失常的作用机制。方法用急性酶解法分离大鼠心室肌细胞,采用全细胞膜片钳记录技术,观察不同浓度的甘松挥发油对L型钙通道的影响。结果浓度为3,5,10,20,50μg/g甘松挥发油可浓度依赖性地抑制L型钙电流,在浓度为10μg/g时,给药后电流密度抑制约为(45.7±3.5)%(n=5,P<0.01),可使心肌细胞L型钙电流-电压曲线上移,但激活电位、峰电位及反转电位无改变;使激活曲线向正电位方向变化,V1/2从(-5.47±0.50)mV右移至(-2.77±0.49)mV(n=5,P<0.05);使失活曲线向负电位方向变化,V1/2从(-20.82±0.48)mV左移至(-29.44±1.03)mV(n=5,P<0.05)。结论甘松挥发油可通过浓度依赖性地抑制大鼠心肌细胞膜L型钙通道电流,使I-V曲线上移;使激活曲线右移,使失活曲线左移。

枸杞糖肽对缺氧及KCl诱导的心肌细胞钙超载的影响

目的:研究枸杞糖肽(LbGp)对低氧心肌细胞内钙浓度([Ca2+]i)的影响,以及对KCl诱导的心肌细胞钙超载的影响。方法:采用SD大鼠乳鼠进行心肌细胞培养,建立心肌缺氧模型,实验分3组:正常对照组;缺氧模型组:细胞缺氧6h;枸杞糖肽预处理组:加入枸杞糖肽,再行缺氧6h。MTT法检测细胞活力。以Fluo/AM荧光指示剂负载,通过激光扫描共聚焦显微系统和Flou3/AM荧光指示剂标记技术,观察枸杞糖肽对缺氧心肌细胞游离钙含量的影响。加入终浓度60mmol·L-1KCl溶液,动态观察KCl刺激后心肌细胞[Ca2+]i的动态变化及LbGp预处理后对KCl诱导的钙超载的影响。结果:心肌细胞缺氧时间延长,损伤随之加剧,缺氧枸杞糖肽组心肌细胞荧光密度均较模型组显著降低(P<0.01),50μg·mL-1LbGp最为明显,[Ca2+]i明显减少。枸杞糖肽组加入KCl溶液后[Ca2+]i荧光强度曲线升高,但与模型组比较,幅度明显减小,25,50,100μg·mL-1LbGp且呈现量效关系。结论:低氧导致心肌细胞钙超载,而枸杞糖肽能减轻钙超载。亦能对抗KCl诱导的心肌细胞钙超载。机制之一是枸杞糖肽作用于L型钙通道。

盐酸关附甲素对大鼠心室肌细胞膜L型钙通道(J_(Ca-L))的影响

目的:研究盐酸关附甲素对正常大鼠心室肌细胞L型钙离子通道(I_(Ca-L))的影响。方法:应用膜片钳全细胞记录法,记录关附甲素对I_(Ca-L)的作用并对通道动力学进行初步评价。结果:关附甲素呈浓度依赖性阻滞I_(Ca-L),在25,125,250和1000μmol·L^(-1)时I_(Ca-L)峰值电流密度(去极化至0mV时)分别减少为用药前的81．76%, 77．54%,76．46%和64．77%(P＜0．05)。关附甲素使I_(Ca-L)的I-V曲线上移,但不改变其激活电位、峰值电位。关附甲素呈轻度使用依赖性阻滞I_(Ca-L),对I_(Ca-L)静息态有阻滞作用。关附甲素对I_(Ca-L)激活曲线无明显影响,但使I_(Ca-L)失活后再激活的恢复时间常数(τ)延长,有作用于I_(Ca-L)的失活态的可能。结论:因为关附甲素产生明显I_(Ca-L)阻滞的浓度远大于临床浓度,其对I_(Ca-L)的阻滞作用可能不是抗心律失常的主要作用机制。关附甲素呈浓度依赖性阻滞I_(Ca-L),其作用于L型钙通道的静息态,也有可能作用于失活态。

L型钙离子通道α_1亚基D亚型在发育小鼠磨牙牙胚成牙本质细胞中的表达

目的 :研究成牙本质细胞分化不同阶段L型钙离子通道α1亚基D亚型的分布情况。方法 :采用兔抗小鼠L型钙离子通道α1D亚基多克隆抗体进行牙胚免疫组织化学染色。结果 :在前成牙本质细胞胞体、功能性成牙本质细胞的近矿化端以及成熟成牙本质细胞的胞体和突起上均发现有L型钙离子通道α1亚基D亚型分布。结论

MicroRNA-1在心肌肥大中对L-型钙通道β_2亚基的负性调控作用

目的:研究微小RNA-1(microRNA-1,miR-1)在心肌细胞肥大中对L-型钙通道β2亚基(Cavβ2)的负性调控作用及机制。方法:应用异丙肾上腺素(ISO)诱导心肌细胞肥大;采用HJ2000通用图像分析系统测定心肌细胞表面积;应用数据库microCosm预测miR-1的靶基因;构建含Cavβ23’UTR报告基因质粒和miR-1瞬时共转染HEK293细胞,验证Cavβ2为miR-1靶基因;应用qRT-PCR或Western blot方法检测心房钠尿肽(ANP)、β-肌球蛋白重链(β-MHC)、miR-1和Cavβ2mRNA和蛋白表达水平;转染miR-1模拟物上调miR-1或应用Cavβ2RNAi干扰Cavβ2蛋白的表达,观察对心肌细胞肥大的影响。结果:①在ISO诱导的心肌细胞肥大中,miR-1表达显著下降;应用miR-1 mimic转染心肌细胞使miR-1表达上调,心肌细胞表面积、ANP和β-MHC mRNA表达均显著低于ISO组(P<0.05)。②网络数据库预测显示Cavβ2为miR-1的潜在靶点;将miR-1和含Cavβ23’UTR报告基因质粒共转染HEK293细胞,其萤光值显著降低(P<0.01)。转染miR-1 mimic使心肌细胞miR-1表达上调,可以明显抑制Cavβ2蛋白的表达。③在ISO诱导心肌细胞肥大中Cavβ2表达较对照组显著增加;应用RNAi技术下调Cavβ2表达可明显抑制心肌细胞表面积、ANP和β-MHC mRNA表达的增加。结论:预测并验证L-型钙通道β2亚基为miR-1的靶基因。miR-1可能通过抑制其靶基因Cavβ2蛋白的表达,降低细胞内钙离子浓度,抑制心肌细胞肥大。

灯盏花素对大鼠全脑缺血再灌注后海马神经元L型钙通道的影响

目的观察灯盏花素对大鼠全脑缺血再灌注后海马神经元L型钙通道平均开放概率和开放时间的影响。方法制作全脑缺血大鼠模型,再灌注1．5 h、3．0 h、4．5 h和6．0 h,急性分离海马CA1区神经元,采用膜片钳技术细胞贴附式方法记录神经细胞膜上单通道Ca^(2+)电流,分析L型钙通道平均开放概率和开放时间,在此基础上观察灯盏花素对其影响。结果不同浓度的灯盏花素能降低海马神经元L型钙通道的平均开放概率和开放时间,且在缺血再灌注3．0 h内作用明显。结论灯盏花素对脑缺血再灌注脑损伤有一定的保护作用。