粉防己碱对豚鼠心室肌细胞钙电流的影响

应用全细胞记录式膜片技术研究了粉防己碱（Ｔｅｔ）对豚鼠心室肌细胞Ｌ型钙电流（Ｉｃａ）的影响，Ｔｅｔ１μｍｏｌ／Ｌ使Ｉｃａ的电流－电压关系曲线之各电流值为均降低，指令电位（ＶＴ）为０ｍＶ，Ｔｅｔ０．１～３．２μｍｏｌ／Ｌ使Ｌｃａ呈浓度依赖性降低，半数抑制浓度（ＩＣ５０）为０．７μｍｏｌ／Ｌ，此外Ｔｅｔ０．３μｍｏｌ／Ｌ能阻滞异丙基肾上腺素（Ｉａｐ）０．１μｍｏｌ／Ｌ引起的Ｉｃａ的增大，证明了Ｔｅｔ可     

乙氧异黄酮二酸钠对豚鼠单个心室肌细胞钙电流的影响

应用全细胞膜片钳技术，研究乙氧异黄酮二酸钠（ｅｔｈｏｘｙ－ｉｓｏｆｌａｖｏｎｅ２－ｃａｒｂｏｘｙｌｉｃａｃｉｄ，ＥＩＣＡ）对豚鼠心室肌细胞上慢钙电流（Ｉｃａ）的影响。结果发现ＥＩＣＡ能使心室肌细胞Ｉｃａ呈剂量依赖性降低，阈浓度为１０－８ｍｏｌ／Ｌ，最大有效浓度为３×１０－５ｍｏｌ／Ｌ；１０－６ｍｏｌ／ＬＥＩＣＡ可明显阻断异丙肾上腺素（Ｉｓｏｐｒｅｎａｌｉｎｅ，Ｉｓｏ）和钙通道激动剂ＢａｙＫ８６４４所致的Ｉｃａ增加（Ｐ＜０．０１）。ＥＩＣＡ能增加外向电流（Ｌｏｕｔ），并被四乙基胺（Ｔｅｔｒａｅｔｈｙｌａｍｍｏｎｉｕｍ，ＴＥＡ，１０－６ｍｏｌ／Ｌ）所拮抗。结果提示：ＥＩＣＡ的降压、减慢心率、抗心律失常作用机制主要与阻断Ｃａ２＋通道（Ｌ型）有关。     

大黄素对大鼠腹腔巨噬细胞生物合成白三烯B4的影响

研究不同浓度大黄素对大鼠腹腔巨噬细胞（ＭΦ）生物合成白三烯Ｂ_４（ＬＴＢ_４）的影响。结果表明大黄素在５×１０￣（－７）～５×１０￣（－６）ｍｏｌ／Ｌ浓度范围内（ｎ＝４），可抑制大鼠腹腔ＭΦＬＴＢ_４的生物合成，量效关系良好（ｒ＝０．９５９１，ｎ＝４）；大黄素对大鼠腹腔ＭΦ生物合成ＬＴＢ_４的抑制率范围为２８．４±６．７％～８８．０±５．３％。大黄素５×１０￣（－６）ｍｏｌ／Ｌ，相当于氟灭酸１×１０￣（－４）ｍｏｌ／Ｌ抑制作用；ＬＴＢ_４的半数抑制率（ＩＣ_（５０））为１．２×１０￣（－６）ｍｏｌ／Ｌ。总之ＥＭＯ的抗炎机制与抑制ＭΦ生物合成ＬＴＢ_４有关。     

两面针碱对钙调蛋白依赖环核苷酸磷酸二酯酶的抑制作用

以钙调蛋白依赖环核苷酸磷酸二酯酶（ＣａＭ－ＰＤＥ）为分子模型，应用正文试验证实两面针碱（Ｎｉ－ｔｉｄｉｎｅ，Ｎｉｔ）是一种新的ＣａＭ拮抗剂。实验结果表明：①：Ｎｉｔ抑制ＣａＭ－ＰＤＥ活性ＩＣ５０为８６μｍｏｌ／Ｌ。②７５μｍｏｌ／ＬＮｉｔ对０～８０ｎｇ／ｍｌＣａＭ存在下，ＣａＭ－ＰＤＥＶｍａｘ基本不变，半激活浓度（ＡＣ５０）增大，抑制常数（Ｋｉ）为６６μｍｏｌ／Ｌ。提示Ｎｉｔ以竞争方式拮抗ＣａＭ对其靶酶（ＰＤＥ）的活化。③７５μｍｏｌ／ＬＮｉｔ对ＣａＭ－ＰＤＥ抑制动力学研究：改变底物（ｃＡＭＦ）浓度，ＣａＭ－ＰＤＥ的Ｖｍａｘ减少，米氏常数（Ｋｍ）值增大，Ｋｉ为６４μｍｏｌ／Ｌ，α＞１。提示Ｎｉｔ对ＣａＭ－ＰＤＥ的抑制作用是非竞争一竞争性混合型抑制。由此推测Ｎｉｔ可能通过与ＣａＭ竞争酶分子上的ＣａＭ结合位点从而抑制ＣａＭ－ＰＤＥ的激活活性。     

粉防己碱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粉防己碱（Ｔｅｔ）对豚鼠心室肌细胞Ｌ型钙电流（Ｉ（Ｃａ））的影响。Ｔｅｔ１μｍｏｌ／Ｌ使Ｉ（Ｃａ））的电流－电压关系曲线之各电流值均降低。指令电位（ＶＴ）为０ｍＶ，Ｔｅｔ０．１～３．２μｍｏｌ／Ｌ　使Ｉ（Ｃａ）呈浓度依赖性降低，半数抑制浓度（Ｌ（５０））为０．７μｍｏｌ／Ｌ。此外，Ｔｅｔ０．３μｍｏｌ／Ｌ能阻滞异丙基肾上腺素（Ｉ（ｓｐ））０．１μｍｏｌ／Ｌ引起的Ｉ（Ｃａ）的增大。证明Ｔｅｔ可阻滞豚鼠心室肌细胞Ｌ型钙电流，并提示有增大延迟整流钾电流（Ｉ（ｏｕｔ））的作用。     

α1受体激动对浦肯野纤维延迟后除极的双相效应

用乙酰毒毛旋花子甙元（ＡＳ）２×１０－７ｍｏｌ／Ｌ中毒诱发绵羊心室浦肯野纤维产生延迟后除极（ＤＡＤ）作为模型，在心得安５×１０－７ｍｏｌ／Ｌ作用下观察苯肾上腺素（ＰＥ）１０－７ｍｏｌ／Ｌ、３×１０－７ｍｏｌ／Ｌ和１０－６ｍｏｌ／Ｌ等不同浓度对ＤＡＤ幅值的影响。６０ｍｉｎ持续灌流中，前２０ｍｉｎＤＡＤ幅值分别增加８％、９％和１０％（每一浓度ｎ＝８，Ｐ＜０．０５）；随后４０ｍｉｎ内，ＤＡＤ幅值呈剂量依赖性减小，ＰＥ１０－７ｍｏｌ／Ｌ减值６．９±０．２％（ｎ＝８，Ｐ＜０．０５），ＰＥ３×１０－７ｍｏｌ／Ｌ减值１３．９±０．１％（ｎ＝８，Ｐ＜０．０１），ＰＥ１０－６ｍｏｌ／Ｌ减值１８．６±０．２％（ｎ＝８，Ｐ＜０．０１）。ＰＥ的作用可被哌唑嗪５×１０－７ｍｏｌ／Ｌ所阻断，提示ＰＥ作用经α１受体兴奋引起。     

大鼠肺动脉平滑肌细胞的外向钾电流及四乙基铵对此电流作用的量效关系

以全细胞膜片钳制技术观察大鼠肺动脉平滑肌细胞外向钾电流的基本特性及四乙基铵（ＴＥＡ）对其作用的量效关系。结果表明：１．将细胞膜电位钳制在－５０ｍＶ，当指令电位大于－５０ｍＶ时，可以记录到电压依赖性的外向钾电流；２．当指令电位为＋７０ｍＶ时，在１０－３ｍｏｌ／Ｌ、１０－４ｍｏｌ／Ｌ、１０－５ｍｏｌ／Ｌ和１０－６ｍｏｌ／Ｌ各浓度的四乙基铵可使外向钾电流分别降低４８．３７％、４１．２１％、２２．１５％和１０．４７％。四乙基铵对外向钾电流的作用具有浓度依赖关系     

绒毛膜促性腺激素对人胃腺癌细胞胞浆cAMP水平的影响

为探讨绒毛膜促性腺激素（ｈＣＧ）作用于胃腺癌细胞后的信号传递机制,我们对ｈＣＧ对胃腺癌ＳＧＣ－７９０１细胞胞浆内ｃＡＭＰ含量的影响进行了观察。结果显示：当ｈＣＧ的浓度由１０＾－１１ｍｏｌ／Ｌ增加到１０＾－６ｍｏｌ／Ｌ时,胞内ｃＡＭＰ的水平从２．１ｐｍｏｌ／ｍｇ蛋白增至约１０ｐｍｏｌ／ｍｇ蛋白（Ｐ〈０．０１）,与对照组相比有显著性差别（Ｐ〈０．０１）。同时,此效应还具有时间依赖性,即随着ｈＣＧ作用时     

谷氨酸的神经毒性作用及其作用机制

目的研究谷氨酸对神经细胞的毒性作用及其作用机制。方法取体外培养的胎鼠大脑皮层神经，分组加入不同浓度的谷氨酸、Ｎ－甲基－Ｄ－天冬氨酸（ＮＭＤＡ）或海藻酸（ＫＡ），ＤＬ－２－ａｍｉｎｏ－５－ｐｈｏｓｐｈｏｎｏｖａｌｅｒｉｃａｃｉｄ（ＡＰＶ）、４－Ｈｙｄｒｏｘｙｑｕｉｎｏｌｉｎｅ－２－ｃａｒｂｏｘｙｌｉｃａｃｉｄｈｙｄｒａｔｅ（ＨＱＣＡ），作用３０ｍｉｎ，２４ｈ后测定培养液内乳酸脱氢酶（ＬＤＨ）含量，并用苔盼蓝鉴定神经细胞活性。结果与空白对照组比较，加入谷氨酸组细胞培养内ＬＨＤ以及神经细胞蓝染率均显著增加（Ｐ＜０．０１），且其程度与加入的药物剂量成正相关。谷氨酸ＬＤ５０为５１．１０±４．２９μｍｏｌ／Ｌ，与ＮＭＤＡ（６６．１７±６．２０μｍｏｌ／Ｌ）相似，但显著低于ＫＡ（１７２．８０±１６．４０μｍｏｌ／Ｌ）。ＡＰＶ或ＨＱＣＡ能显著抑制谷氨酸所致的ＬＤＨ增加。结论谷氨酸的确具有神经毒性作用，这种作用可能主要是通过ＮＭＤＡ受体介导的     

钙指示剂Fura－2／AM对血小板功能及细胞内游离钙测定结果的影响

本实验结果表明，以Ｆｕｒａ－２／ＡＭ负载家兔洗脱血小板，当Ｆｕｒａ－２／ＡＭ的浓度低于２μｍｏｌ／Ｌ时，３μｍｏｌ／Ｌ和１０μｍｏｌ／Ｌ花生四稀酸（ＡＡ）诱导的血小板聚集（透光度增加：７２．５±７．８４％）及释放反应（ＡＴＰ释放：１．１２±０．２１μｍｏｌ／４×１０５血小板）不受影响，但随Ｆｕｒａ－２／ＡＭ浓度增加，ＡＡ的聚集和释放反应明显减弱（Ｐ＜０．０５或Ｐ＜０．０１）。Ｆｕｒａ－２／ＡＭ浓度对单一血小板内钙（［Ｃａ２＋］ｉ）的静息水平无影响，但Ｆｕｒａ－２／ＡＭ为２μｍｏｌ／Ｌ时，ＡＡ诱导的［Ｃａ２＋］ｉ动员最明显。另外，标本中血小板的数量也明显影响［Ｃａ２＋］ｉ的测定结果（Ｐ＜０．０５或Ｐ＜０．０１）。提示，Ｆｕｒａ－２／ＡＭ浓度过高，很可能导致过多的钙离子被螯合，降低了血小板的功能，同时，细胞内游离钙与Ｆｕｒａ－２／ＡＭ的结合过程存在着饱和性。     

Effects of calmodulin-dependent protein kinase II inhibitor, KN-93, on electrophysiological features of rabbit hypertrophic cardiac myocytes

Cardiac hypertrophy is an independent risk factor for sudden cardiac death in clinical settings and the incidence of sudden cardiac death and ventricular arrhythmias are closely related.The aim of this study was to determine the effects of the calmodulin-dependent protein kinase(CaMK) Ⅱ inhibitor,KN-93,on L-type calcium current(I Ca,L) and early after-depolarizations(EADs) in hypertrophic cardiomyocytes.A rabbit model of myocardial hypertrophy was constructed through abdominal aortic coarctation(LVH group).The control group(sham group) received a sham operation,in which the abdominal aortic was dissected but not coarcted.Eight weeks later,the degree of left ventricular hypertrophy(LVH) was evaluated using echocardiography.Individual cardiomyocyte was isolated through collagenase digestion.Action potentials(APs) and I Ca,L were recorded using the perforated patch clamp technique.APs were recorded under current clamp conditions and I Ca,L was recorded under voltage clamp conditions.The incidence of EADs and I ca,L in the hypertrophic cardiomyocytes were observed under the conditions of low potassium(2 mmol/L),low magnesium(0.25 mmol/L) Tyrode’s solution perfusion,and slow frequency(0.25-0.5 Hz) electrical stimulation.The incidence of EADs and I ca,L in the hypertrophic cardiomyocytes were also evaluated after treatment with different concentrations of KN-92(KN-92 group) and KN-93(KN-93 group).Eight weeks later,the model was successfully established.Under the conditions of low potassium,low magnesium Tyrode’s solution perfusion,and slow frequency electrical stimulation,the incidence of EADs was 0/12,11/12,10/12,and 5/12 in sham group,LVH group,KN-92 group(0.5 μmol/L),and KN-93 group(0.5 μmol/L),respectively.When the drug concentration was increased to 1 μmol/L in KN-92 group and KN-93 group,the incidence of EADs was 10/12 and 2/12,respectively.At 0 mV,the current density was 6.7±1.0 and 6.3±0.7 PA·PF-1 in LVH group and sham group,respectively(P>0.05,n=12).When the drug concentration was 0.5 μmol/L i     

丙泊酚对人子宫平滑肌细胞Ca2+跨膜内流和肌浆网钙释放功能的影响

目的观察丙泊酚对足月产妇子宫平滑肌细胞Ca2+跨膜内流和肌浆网Ca2+释放功能的影响,探讨其抑制子宫平滑肌收缩功能的可能机制。方法取正常孕足月待产的子宫平滑肌组织,胶原酶消化法培养子宫平滑肌细胞。①40个孔板中活性良好的子宫平滑肌细胞随机等分为4组(n=10):对照组(C组)、低浓度丙泊酚组(P1组)、中浓度丙泊酚组(P2组)、高浓度丙泊酚组(P3组),用Fluo-3AM钙荧光指示剂染色后,分别给予Hank液、10μmol/L丙泊酚(终浓度)、50μmol/L丙泊酚、250μmol/L丙泊酚处理20 min,然后加入40 mmol/L氯化钾,每个孔板在激光共聚焦显微镜下随机选定10个子宫平滑肌细胞,利用图形分析软件分析细胞内钙荧光强度,取钙荧光强度峰值的平均值反映子宫平滑肌细胞游离Ca2+浓度([Ca2+]i)。②再以20 mmol/L咖啡因代替氯化钾,其余处理及分组同前。结果①与基础值比较,各组加入丙泊酚后子宫平滑肌细胞[Ca2+]i差异无统计学意义(P>0.05),加入氯化钾后[Ca2+]i均升高(P<0.01);与C组相比,加入氯化钾后P1组子宫平滑肌细胞[Ca2+]i差异无统计学意义(P>0.05),P2组和P3组加入氯化钾后[Ca2+]i明显低于C组(均P<0.01),且P3组[Ca2+]i低于P2组(P<0.05)。②与基础值比较,各组加入丙泊酚后子宫平滑肌细胞[Ca2+]i差异无统计学意义(均P>0.05),加入咖啡因后[Ca2+]i升高(P<0.01);加入咖啡因后各组子宫平滑肌细胞[Ca2+]i差异无统计学意义(P>0.05)。结论丙泊酚可浓度依赖性地抑制足月产妇子宫平滑肌细胞电压依赖型钙通道开放而减少Ca2+跨膜内流,而对肌浆网Ryanodine型Ca2+释放功能无明显影响。     

二十二碳六烯酸对大鼠心肌细胞通道的影响

目的:探讨二十二碳六烯酸(DHA)对大鼠心室肌细胞动作电位(AP)及钠通道电流(INa)的影响。阐述DHA抗心律失常的机制。方法:采用酶消化法获得大鼠心室肌细胞,用膜片钳技术分别记录0、20、40、60、80、100和120μmol/L DHA对大鼠心室肌细胞AP复极25%、50%和90%时程(APD25、APD50和APD90),对AP最大上升速率(Vmax)、幅值(APA)、超射值(OS)及INa的影响。结果:①不同浓度DHA对APD25、APD50和APD90呈浓度依赖性延长(P<0.05,n=20),对Vmax、APA和OS的影响无显著性差异(P>0.05,n=20)。②不同浓度DHA对INa呈浓度依赖性阻滞、I-V曲线上移、稳态失活曲线左移、失活后恢复时间延长,对稳态激活曲线无影响。在指令电压-30 mV时,上述浓度DHA对INa阻滞分别为(1.51±1.32)%、(21.13±4.62)%、(51.61±5.73)%、(67.62±6.52)%、(73.49±7.59)%和(79.95±7.62)%(P<0.05,n=20),DHA对INa的半效作用浓度(EC50)为(47.91±1.57)mol/L。结论:DHA对APD的延长及对钠通道的抑制作用可能是其抗心律失常机制之一。     

Effects of Chinese herbs on multiple ion channels in isolated ventricular myocytes

Background Shensong Yangxin (SSYX) is one of the compound recipe of Chinese materia medica. This study was conducted to investigate the effects of SSYX on sodium current (I(Na)), L-type calcium current (I(Ca,L)), transient outward potassium current (I(to)), delayed rectifier current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated ventricular myocytes. Methods Whole cell patch-clamp technique was used to study ion channel currents in enzymatically isolated guinea pig or rat ventricular myocytes. Results SSYX decreased peak I(Na) by (44.84±7.65)% from 27.21±5.35 to 14.88±2.75 pA/pF (n=5, P&lt;0.05). The medicine significantly inhibited the I(Ca,L). At concentrations of 0.25, 0.50, and 1.00 g/100 ml, the peak I(Ca,L) was reduced by (19.22±1.10)%, (44.82±6.50)% and (50.69±5.64)%, respectively (n=5, all P&lt;0.05). SSYX lifted the I-V curve of both I(Na) and I(Ca,L) without changing the threshold, peak and reversal potentials. At the concentration of 0.5%, the drug blocked the transient component of I(to) by 50.60% at membrane voltage of 60 mV and negatively shifted the inactive curve and delayed the recovery from channel inactivation. The tail current density of I(K) was decreased by (30.77±1.11)% (n=5, P&lt;0.05) at membrane voltage of 50 mV after exposure to the medicine and the time-dependent activity of I(K) was also inhibited. Similar to the effect on I(K), the SSYX inhibited I(K1) by 33.10% at the test potential of –100 mV with little effect on reversal potential and the rectification property. Conclusions The experiments revealed that SSYX could block multiple ion channels such as I(Na) I(Ca,L), I(k), I(to) and I(K1), which may change the action potential duration and contribute to some of its antiarrhythmic effects.     

Effect of etomidate on voltage-dependent potassium currents in rat isolated hippocampal pyramidal neurons

Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current （IK（DR）） and transient outward potassium current （I_K（A）） in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student＇s paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited IK（DR） by 49.2% at ＋40 mV when depolarized from -110 mV （P 〈0.01, n=8）, while did not affect IK（A） （/1=8, P 〉0.05）. The IC50value of etomidate for blocking IK（DR）was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V1/2 of activation curve was shifted from （17.3±1.5） mV to （10.7±9.9） mV （n=8, P 〈0.05）, the V1/2 of inactivation curve was shifted from （-18.3±2.2） mV to （-45.3±9.4） mV （n=8, P 〈0.05）. Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of IK（DR））to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited IK（DR） but not IK（A） in rat hippocampal pyramidal neurons. IK（DR） was inhibited by etomidate in a concentration-dependent manner, while IK（A） remained unaffected.     

四氢小檗碱衍生物86035对豚鼠心室肌L型钙通道的抑制作用

目的　研究氯苄基四氢小檗碱 (CPU) 86 0 35对豚鼠单个心室肌细胞L型钙通道的抑制作用 ,分析对L型钙通道相互作用的状态依赖性。方法　采用膜片钳全细胞技术 ,记录不同浓度(5 0～ 2 5 0 μmol/L)CPU86 0 35作用前后的L型钙电流 (ICa L)。结果　 (1)CPU86 0 35呈剂量依赖性地抑制L型钙电流 ,半数抑制浓度 (IC50 )为 75 μmol/L。(2 )CPU86 0 35对L型钙电流的抑制依赖于保持电位(HP)。HP =- 4 0mV时 ,75 μmol/LCPU86 0 35的抑制率为 4 9%± 2 % ,HP =- 80mv时 ,抑制率为6 4 %± 4 %。 (3)CPU86 0 35作用后 ,稳态激活曲线右移 ,V1/ 2 由对照的 6 7mV± 1 6mV变为 15 4mV±0 8mV。 (4)CPU 86 0 35作用后 ,稳态失活曲线右移 ,V1/ 2 由对照的 - 19 1mV± 2 5mV变为 - 12 6mV± 2 7mV。 (5 )用药后L型钙通道从失活状态恢复的时间变长。结论　CPU86 0 35对L型钙通道有较强的抑制作用 ,药物可能主要与通道的静息状态结合     

齐墩果酸诱导Jurkat细胞凋亡及对ROS和细胞内Ca2+含量的影响

目的 探讨齐墩果酸对白血病Jurkat细胞株增殖抑制和诱导凋亡作用,分析凋亡发生与细胞内活性氧(ROS)及钙离子浓度([Ca2+]i)变化的关系.方法 应用MTT法检测细胞增殖抑制;流式细胞仪检测细胞凋亡率和细胞周期;DCFH-DA荧光定量法检测ROS含量;Fluo-3AM荧光负载方法测定[Ca2+]i的变化.结果 齐墩果酸对Jurkat细胞的增殖具有浓度依赖性和时间依赖性抑制作用,0,40,80,160 μmol/L齐墩果酸作用24 h细胞凋亡率分别为(7.36±0.40)％、(19.80±1.59)％、(29.39±0.64)％、(34.72±0.94)％,G0/G1期细胞比例分别为(54.26±1.43)％、(85.83±0.91)％、(91.18±1.32)％、(92.90±1.19)％.80 μmol/L和160μmol/L齐墩果酸处理24 h,细胞中ROS和[Ca2+]i水平均明显高于对照组(P＜0.05),ROS和[Ca2+]i水平均与细胞凋亡率呈正相关(r分别为0.95、0.97).结论 细胞中ROS和Ca2+可能参与了齐墩果酸对Jurkat细胞的抑制增殖和诱导凋亡作用.     

Effects of BmkTXKβ on electrophysiological properties of rabbit atrial myocytes

Objective To investigate the effects of BmkTXKβ, a newly purified ‘long chain’ peptide inhibitor of K+ channels from the Chinese scorpion Buthus martensi Karsch (BmK), on the electrophysiological properties of isolated rabbit atrial myocytes. Methods The standard whole-cell patch-clamp technique was used to study the effects of multiple concentrations of BmkTXKβ on potassium currents and action potentials. Results BmkTXKβ produced concentration-dependent prolongation of action potential duration at 20%, 50%, and 90% repolarization (APD20,50,90) without any use-dependence. Meanwhile, it had no significant effect on RMP, APA, or Vmax （n=9）. At a dose of 1 μmol/L, BmkTXKβ decreased Ito by 41.4% (n=10, P&lt;0.01) at a membrane potential of +50 mV ［from （13.63±0.87） pA/pF to （7.98±0.78） pA/pF］. Ito was reduced significantly with an IC50 value of 1.82 μmol/L (95% confidence interval: 1.47-2.17 μmol/L), in a clear concentration-dependent manner. BmkTXKβ blocked IKs and IKs,tail with an IC50 of 20.15 μmol/L and a 95% confidence interval of 16.93-23.37 μmol/L. At a concentration of 10 μmol/L, BmkTXKβ blocked both IKs (mean reduction 37.3％±4.2%, P&lt;0.01, n=7) and IKs,tail (mean reduction 35.8％±4.1%, P&lt;0.01, n=7). At 0 mV, 10 μmol/L BmkTXKβ inhibited both IKr (mean reduction 40.5％±2.6%, P&lt;0.01, n=6) and IKr,tail (mean reduction 42.3％±2.9%, P&lt;0.01, n=6). Blocking of IKr by BmkTXKβ occurred in a concentration-dependent manner, with an IC50 of 17.21 μmol/L (95% confidence interval: 14.76-19.66 μmol/L). An absence of effects on IK1 was observed for BmkTXKβ, with no change in reversal-potential (n=6, P&gt;0.05). Conclusions BmkTXKβ exerts direct blocking effects on several potassium channels involved in cardiac repolarization, and has a strong effect on prolonging the repolarization of rabbit cardiomyocytes without reverse frequency dependence. This finding suggests that BmkTXKβ could be a promising class Ⅲ drug for anti-arrhythmic therapy without the risk of proarrhythmia.     

SKF96365和氯化镍对环匹阿尼酸诱导的大鼠PASMC［Ca2＋］i升高的影响

目的：研究SKF96365和氯化镍（NiCl2）对环匹阿尼酸（CPA）诱导的大鼠远端肺动脉平滑肌细胞（PASMC）内游离钙离子浓度（[Ca2＋]i）变化的影响。方法培养大鼠PASMC,运用荧光显微镜和InCyte细胞内钙浓度检测系统观测CPA、SKF96365和NiCl2对PASMC[Ca2＋]i的影响。结果含5μmol／L硝苯地平的无钙Krebs溶液孵育PASMC,10μmol／LCPA使PASMC[Ca2＋]i短暂小幅升高,恢复细胞外Ca2＋至2．5mmol／L后,10μmol／LCPA使PASMC[Ca2＋]i迅速显著升高;50μmol／LSKF96365和500μmol／LNiCl2均能明显抑制10μmol／LCPA引起的PASMC[Ca2＋]i升高,但对高钾（60mmol／LKCl）溶液引起的PASMC[Ca2＋]i升高无影响。结论CPA可致大鼠PASMC[Ca2＋]i升高,且能被SKF96365和NiCl2阻断,提示CPA可能诱发细胞外Ca2＋经钙池操纵性钙通道（SOCC）内流,SKF96365和NiCl2能选择性抑制SOCC活性使经SOCC的Ca2＋内流减少。