普罗帕酮对钾通道亚型Kv4.2和Kv4.3电流的影响

目的　研究普罗帕酮对钾通道亚型Kv4 2和Kv4 3电流的影响。方法　采用全细胞膜片钳技术记录稳定表达Kv4 2和Kv4 3电流的人胚胎肾细胞株 (HEK2 93细胞 )电流的变化。结果　①普罗帕酮明显抑制Kv4 2和Kv4 3电流 ,呈浓度依赖性 ,IC50 分别为 1 0 3 μmol·L- 1 和 71 μmol·L- 1 ;②普罗帕酮明显加速Kv4 2和Kv4 3电流失活 ,1 0μmol·L- 1 的普罗帕酮可使Kv4 2电流衰减时间常数τ由(38 9± 2 1 )ms变为 (9 9± 1 8)ms ,半数最大失活膜电位V1 /2 由 (- 66 6± 0 8)mV左移至 (- 70 9± 1 1 )mV ;1 0 0μmol·L- 1 的普罗帕酮可使Kv4 3电流衰减时间常数τ(1 4 4 8± 2 0 8)ms变为 (1 8 5± 2 8)ms,半数最大失活膜电位V1 /2 由 (- 4 5 6± 1 9)mV左移至 (- 52 3± 2 1 )mV ;③普罗帕酮明显左移Kv4 2和Kv4 3电流的激活曲线 ,1 0μmol·L- 1 的普罗帕酮可使Kv4 2电流半数最大激活膜电位V1 /2 由 (- 4 1± 0 5)mV左移至 (- 1 6 1± 2 4)mV ;1 0 0μmol·L- 1 的普罗帕酮可使Kv4 3半数最大激活膜电位V1 /2由 (- 6 0± 1 1 )mV左移至 (- 1 6 5± 3 0 )mV。结论　普罗帕酮明显抑制Kv4 2 ,Kv4 3电流 ,该作用可能是其治疗心律失常的机制之一。     

槲皮素通过激活Kv1.5保护糖尿病大鼠冠脉损伤

目的研究槲皮素对糖尿病大鼠CA损伤的改善作用及该作用与Kv1.5的关系。方法 30只♂SD大鼠,随机分为3组:空白对照组、糖尿病组、"糖尿病+槲皮素"组。通过大鼠冠脉流量(coronary flow,CF)测定,观察槲皮素对糖尿病所致CF变化的影响;利用冠状动脉(coronary artery,CA)张力测定,观察槲皮素对糖尿病所致CA张力变化的影响;应用膜片钳记录CA血管平滑肌细胞(vascular smooth muscle cell,VSMC)电压依赖性钾通道(voltage gated potassium channel,Kv)电流及测定CA VSMC Kv1.5 mRNA表达水平,探讨槲皮素改善糖尿病所致CA损伤的机制。结果糖尿病组CF较空白组明显下降,糖尿病大鼠饮食中补充槲皮素,可使得其CF有所增加;膳食补充槲皮素可减弱糖尿病大鼠CA对KCl的收缩反应(P<0.05);与糖尿病组相比,"糖尿病+槲皮素"组CA对Kv阻断剂4-AP的收缩幅度明显降低;糖尿病组大鼠CA VSMC Kv电流较空白组明显降低(P<0.05),膳食补充槲皮素可减小其降低幅度;RT-PCR结果表明,Kv1.5 mRNA相对表达量空白组最高,"糖尿病+槲皮素"组次之,糖尿病组最少。结论槲皮素对糖尿病CA损伤有保护作用,该作用与激活Kv1.5存在一定相关性。     

黄芩苷通过硫氧还原蛋白介导对SH-SY5Y细胞保护作用

目的 研究黄芩苷对过氧化氢(H₂O₂)损伤后的成人神经细胞瘤细胞母细胞SH-SY5Y细胞的影响,进一步探讨黄芩苷保护SH-SY5Y细胞的作用机制. 方法 不同浓度黄芩苷预先处理正常培养的SH-SY5Y细胞24 h,200 μmol.L^-1 H₂O₂损伤上述SH-SY5Y细胞24 h,采用实时荧光定量聚合酶链反应(PCR)技术检测各实验组细胞的硫氧还原蛋白(Trx)mRNA的表达;采用酶联免疫吸附测定(ELISA)技术检测各实验组细胞的Trx 蛋白的表达. 结果 黄芩苷在50～300 μmol.L^-1浓度范围内对SH-SY5Y细胞无细胞毒作用,0,50,100和200 μmol.L^-1黄芩苷组SH-SY5Y细胞存活率分别为(0.410±0.096),(1.304±0.101),(0.899±0.089)和(0.609±0.023),50,100和200 μmol.L^-1均明显高于H₂O₂ 损伤组(0.339±0.073)的存活率,正常组,H2O2损伤组,50 ,100和200 μmol.L^-1黄芩苷组Trx mRNA的表达水平分别为(1.023±0.014),(0.021±0.004),(0.054±0.005),(0.071±0.013)和(0.042±0.004);正常组Trx蛋白表达水平为(26.230±0.857),H₂O₂损伤组为(19.230±0.982),50,100和200 μmol.L^-1黄芩苷组Trx蛋白表达水平分别为(22.440±0.888),(23.020±1.070),(22.330±1.067). 结论 黄芩苷对H₂O₂损伤后的SH-SY5Y细胞有保护作用,其作用机制可能与黄芩苷抑制H2O2诱导的Trx表达下调作用有关,起到抗氧化应激及抗细胞凋亡的作用.     

蝙蝠葛苏林碱对HEK293细胞中L-型钙通道CaV1.2的作用

摘 要 目的：探讨蝙蝠葛苏林碱（DS）对人胚肾细胞（HEK293）上表达的L 型钙通道Cav1.2的作用。方法: 采用脂质体转染法,将L 型钙通道Cav1.2蛋白基因转染到HEK293细胞上,全细胞膜片钳技术记录L 型钙电流ICav1.2,观察DS对L 型钙通道电生理特性的影响。结果:DS在1, 3, 10 μmol·L-1浓度范围内呈浓度依赖性抑制ICav1.2 电流,其抑制率分别为（14.68±4.02）%、（32.37±6.63）% 和（59.63±5.23）%;3 μmol·L-1 的DS对ICav1.2的抑制率与相同浓度的伊拉地平比较,其抑制强度约为伊拉地平的40%。结论:DS可浓度依赖性抑制HEK293细胞上表达的Cav1.2,其作用强度比特异性L 型钙通道阻断药伊拉地平要弱。     

雌激素对Kv2.1钾电流及大鼠海马神经元延迟整流钾电流的影响

目的研究17β-雌二醇对Kv2.1钾电流和原代培养大鼠海马神经元延迟整流钾电流的作用。方法采用HEK293-Kv2.1细胞培养、大鼠海马神经元原代培养和膜片钳全细胞记录技术。结果17β-雌二醇浓度依赖地抑制Kv2.1钾电流和原代培养大鼠海马神经元延迟整流钾电流(I_K)。17β-雌二醇抑制Kv2.1钾电流和原代培养大鼠海马神经元延迟整流钾电流的IC₅₀分别为2.4和4.0 μmol·L^-1。通道动力学研究发现，17β-雌二醇(3 μmol·L^-1)显著左移Kv2.1钾电流的稳态激活和失活曲线，但只显著左移海马神经元延迟整流钾电流稳态激活曲线，而不影响该电流的稳态失活曲线。结论17β-雌二醇抑制Kv2.1钾电流与抑制I_K的程度相近，17β-雌二醇抑制I_K的作用可能部分通过阻断Kv2.1钾电流而实现。     

抗心律失常药E-4031对豚鼠心室肌细胞Na+/Ca2+交换电流的影响

应用全细胞电压钳的斜坡脉冲程序测定离体豚鼠心肌细胞准稳态电流电压关系曲线,研究Ⅲ类抗心律失常药E-4031对Na⁺/Ca²⁺交换电流的影响,结果表明E-4031 0.1, 1.0, 10, 50 μmol·L^-1使Ni²⁺敏感电流浓度依赖性增加,膜电位+50 mV时分别增加(70±38)%,(91±53)%,(118±63)%,(122±51)%;膜电位-100 mV时增加(25±20)%,(51±32)%,(113±84)%,(93±73)%。提示E-4031对心室肌细胞Na⁺/Ca²⁺交换电流的增强作用可能是其正性变力作用的重要机理。     

胺碘酮对大鼠心肌梗死后重构心肌细胞钾电流的作用

目的观察胺碘酮对大鼠心肌梗死后重构心肌钾通道的作用,探讨胺碘酮对心肌梗死后电重构的影响。方法采用脂肪乳灌胃方法建立大鼠高脂血症模型后结扎冠状动脉左前降支建立急性心肌梗死动物模型,应用全细胞膜片钳技术记录急性心肌梗死模型大鼠胺碘酮灌胃1wk后重构区心室肌细胞内向整流钾电流(Ik1)、瞬时外向钾电流(Ito)的变化。结果在实验电压-120mV时,模型组大鼠心室肌细胞Ik1为(-15.66±1.40)PA/PF,较正常组(-21.02±1.95)PA/PF降低(n=4,P<0.01),胺碘酮组(-11.07±1.11)PA/PF,较模型组明显降低(n=4,P<0.05)。在实验电压+50mV时,模型组大鼠心室肌细胞内Ito为(7.29±1.02)PA/PF,较正常组(13.24±1.16)PA/PF降低(n=4,P<0.01),胺碘酮组(4.12±1.01)PA/PF,较模型组降低(n=4,P<0.05)。结论胺碘酮抑制心梗后重构心肌细胞的Ik1、Ito,影响动作电位的复极过程。     

黄豆苷元磷脂复合物的制备及大鼠体内生物利用度的研究

目的 制备黄豆苷元磷脂复合物并测定其在大鼠体内的生物利用度。方法 以黄豆苷元与大豆磷脂的复合率为评价指标,采用单因素试验和正交设计优化制备工艺;分别测定黄豆苷元、黄豆苷元-磷脂的物理混合物及黄豆苷元磷脂复合物在水中和正辛醇中的表观溶解度;3组大鼠分别灌胃给予黄豆苷元原料药、黄豆苷元-磷脂的物理混合物及黄豆苷元磷脂复合物后,采用LC-MS/MS测定不同时间血浆中药物浓度,比较相对生物利用度。结果 黄豆苷元磷脂复合物优化的制备条件为：反应溶剂为无水乙醇,投料比为1.5∶1(磷脂/药物的摩尔比),1 g·L^-1反应物浓度条件下60 ℃搅拌2 h,结果显示：磷脂复合物在水和正辛醇中表观溶解度比原料药分别提高3.1倍和5.4倍;大鼠灌胃给予黄豆苷元和黄豆苷元磷脂复合物后,Cmax分别为(667±65),(7 509±688)ng·mL^-1,Tmax分别为(3.00±0.82),(0.42±0.17)h,AUC0–∞分别为(8 302 ±590),(28 870±2 411)ng·h·mL^-1。黄豆苷元磷脂复合物口服生物利用度是黄豆苷元原料药的3.48倍。结论 将黄豆苷元制成磷脂复合物后在水中的溶解度有所提高,在正辛醇中的溶解度有显著提高,增加了黄豆苷元在胃肠道中的吸收,明显提高黄豆苷元口服生物利用度。     

黄芩苷对SH-SY5Y细胞损伤的Bcl-2和Bcl-xL mRNA基因表达的影响

目的 探讨黄芩苷对过氧化氢(H₂O₂)诱导的SH-SY5Y细胞损伤的Bcl-2和Bcl-xL mRNA表达的影响. 方法 建立人神经母细胞瘤SH-SY5Y细胞的体外H₂O₂损伤模型,采用噻唑蓝(MTT)法检测不同浓度黄芩苷对SH-SY5Y细胞存活率的影响,采用Real-time PCR法检测各组细胞的Bcl-2和Bcl-xL表达水平的变化. 结果 50,100,200 μmol.L^-1黄芩苷组细胞存活率分别为130.4%,89.9%和60.9%,H₂O₂损伤组细胞存活率为33.9%,50,100 μmol.L^-1黄芩苷组与H₂O₂损伤组比较,差异有统计学意义(P<0.01). 50,100,200 μmol.L^-1黄芩苷组Bcl-2 mRNA表达量分别为(11.48±0.48),(7.37±1.57),(7.39±2.01),H₂O₂损伤组为(5.84±0.58);50,100,200 μmol.L-1黄芩苷组Bcl-xL mRNA表达量分别为(19.96±2.22),(11.36±3.94),(13.07±2.37),H₂O₂损伤组为(7.95±0.58),50 μmol.L^-1组Bcl-2 和Bcl-xL mRNA与H^₂O^₂损伤组比较,差异均有统计学意义(均P<0.05). 结论 黄芩苷对H₂O₂诱导的SH-SY5Y细胞损伤的保护作用,可能与黄芩苷上调Bcl-2和Bcl-xL的表达而起到抗凋亡的作用有关.     

溶血磷脂酰胆碱刺激脑微血管平滑肌细胞增殖的细胞内信号转导途径

通过测定［³H］胸腺嘧啶核苷(［³H］TdR)参入和结晶紫染色法测定平滑肌细胞增殖,研究了溶血磷脂酰胆碱(LPC)刺激牛脑微血管平滑肌细胞(BCMSMC)增殖的细胞内信号转导途径. 结果显示,LPC能浓度依赖性(1 nmol·L^-1-10 μmol·L^-1)诱导BCMSMC摄取［³H］TdR,在LPC的浓度为10 μmol·L^-1时作用达最大,cpm由366±142升至1761±296(P<0.01);LPC亦能浓度依赖性(1 nmol·L^-1-10 μmol·L^-1)诱导BCMSMC增殖,在LPC浓度为1 μmol·L^-1时促增殖作用达坪值,A_{595 nm}由0.060±0.009增至0.100±0.015(P<0.01). 丝裂原激活蛋白激酶(MAPK)特异性抑制剂PD 98059(2-50 μmol·L^-1),血小板衍生生长因子受体抑制剂酪氨酸磷酸化抑制剂AG 1296(2-50 μmol·L^-1)以及蛋白质酪氨酸激酶抑制剂除莠霉素A(2-10 μmol· L^-1)能浓度依赖性地抑制LPC的上述作用. 表明LPC能促进BCMSMC增殖,其细胞内信号转导与MAPK途径有关.     

人心律失常相关基因Kv1.5和Kv4.2在蟾蜍卵母细胞上的表达(英文)

本文采用基因克隆、膜片钳和微注射技术,分别将人的心律失常相关基因Ｋｖ１.５和Ｋｖ４．２ｃＤＮＡ转录入ｃＲＮＡ,将Ｋｖ１．５ｃＲＮＡ和Ｋｖ４．２ｃＲＮＡ分别注射蟾蜍卵母细胞（Ｘｅｎｏｐｕｓｏｏｃｙｔｅｓ）,分别在蟾蜍孵母细胞上获得纯净、单一的超速延迟性整流钾电流（I(Ｋｕｒ),ｕｌｔｒａｒａｐｉｄｄｅｌａｙｅｄｒｅｃｔｉｆｉｅｒＫ＋　ｃｕｒｒｓｅｎｔ）和瞬时外向钾电流（Ｉ(ｔｏ),ｔｒａｎｓｉｅｎｔ　ｏｕｔｗａｒｄＫ＋　ｃｕｒｒｅｎｔ）表达,克服以往在筛选评价抗心律失常药物时,人新鲜心肌细胞取材困难,以及多种电流在细胞膜上共同表达等缺点,从而建立筛选评价Ⅲ类抗心律失常药物的先进药理模型。     

人心律失常相关基因Kv1.5和Kv4.2在蟾卵母细胞上的表达

本文采用基因克隆、膜片钳和微注射技术，分别将人的心律失常相关基因Kv1.5和Kv4.2 cDNA转录入cRNA,将Kv1.5 cRNA和Kv4.2 cRNA分别注射蟾蜍卵母细胞（Xenopus oocytes)，分别在蟾蜍卵母细胞上获得纯净，单一的超速延迟性整流钾电流（Ikur,ultrarapid delayed rectifier K^ current)和瞬时外向钾电流（Ito,transient outward K^ current)表达，克服以往在筛选评价抗心律失常药物时，人新鲜心肌细胞取材困难，以及多种电流在细胞膜上共同表达等缺点，从而建立筛选评价Ⅲ类抗心律失常药物的先进药理模型。     

JZTX-XIII, a Kv channel gating modifier toxin from Chinese tarantula Chilobrachys jingzhao

Jingzhaotoxin-XIII (JZTX-XIII), a 35 residue polypeptide, with the ability to inhibit voltage-dependent potassium channels in the shab (Kv2) and shal (Kv4) subfamilies, was purified from the venom of the Chinese tarantula Chilobrachys jingzhao. Electrophysiological recordings carried out in Xenopus laevis oocytes showed that JZTX-XIII acted as gating modifier of voltage-dependent K⁺ channels which inhibited the Kv2.1 channel and Kv4.1 channel, with the IC₅₀ value of 0.47 μM and 1.17 μM, respectively. JZTX-XIII shares high sequence similarity with gating modifier toxins inhibiting a wide variety of ion channels including Nav1.5 subtype, but it showed no Nav1.5 channel activity. Structure-function analysis indicates that the acidic residues of Glu10 and Glu17 in JZTX-XIII might be responsible for the loss of the Nav1.5 channel inhibitory potency for JZTX-XIII.     

Blockade of the human cardiac K+ channel Kv1.5 by the antibiotic erythromycin

Erythromycin administration has been associated with a prolongation of cardiac repolarization in certain clinical settings. This could be due to blockade of voltage-dependent K⁺ channels in the human heart. For this reason we examined the effects of erythromycin on a rapidly activating delayed rectifier K⁺ channel (Kv1.5) cloned from human heart and stably expressed in human embryonic kidney cells. When examined using the whole-cell patch clamp technique, erythromycin (100 μM) blocked Kv1.5 current in a time-dependent manner but required prolonged exposure to do so. However, when we examined Kv1.5 current using inside-out macropatches, erythromycin applied to the cytoplasmic surface rapidly (within 1-2 min) inhibited Kv1.5 current with an IC₅₀ value of 2.6 x 10^-5M (1.7 - 3.9 x 10^-5M, 95% C.L.). The main effect of erythromycin was to accelerate the rate of Kv1.5 current decay thereby reducing the current at the end of a prolonged voltage-clamp pulse. Erythromycin also blocked Kv1.5 current in both a voltage- and frequency-dependent manner but had little effect on the activation kinetics, deactivation kinetics, or the steady-state inactivation properties of Kv1.5. These data suggest that erythromycin acts as a blocker of an activated state of the Kv1.5 channel and that it may access its binding site from the intracellular face of the channel. This study is the first to examine the effects of erythromycin on a cloned human cardiac K⁺ channel. It is concluded that erythromycin blocks Kv1.5 at clinically relevant concentrations. Blockade of voltage-dependent K⁺ channels in the heart could contribute to the alterations in cardiac repolarization that have been observed with erythromycin. Received: 22 November 1996 / Accepted: 26 February 1997     

Hydrogen peroxide modulates the Kv1.5 channel expressed in a mammalian cell line

Reactive oxygen species have been implicated in different types of cardiac arrhythmias including human atrial fibrillation. Kv1.5, the presumed molecular correlate of I_Kur, is an important determinant of human atrial repolarization. The aim of this study was to assess the effects of H₂O₂, at pathophysiologically relevant concentrations (20–1,000 M), on Kv1.5 expressed in Chinese hamster ovary cell line. Kv1.5 cDNA in pcDNA3 expression vector and CD8, a surface marker protein, were cotransfected in cells by calcium phosphate precipitation. Kv1.5 activation kinetics were significantly accelerated while the activation curve was negatively shifted by 10 mV (V_1/2 changed from –9.3 to –19.0 mV) in the presence of 100 M H₂O₂. The shift in Kv1.5 peak current I-V curve was voltage-dependent, the current amplitude being increased for voltages <+20 mV but decreased for high depolarizing voltages. The rapid activation time constant obtained from a bi-exponential fitting was decreased from 16.1±3.4 ms to 8.8±1.5 ms for a –20 mV depolarization (n=9; P=0.01) and from 4.3±2.1 ms to 2.3±0.4 ms when cells were depolarized to +20 mV (P<0.05). Kv1.5 steady-state inactivation was not modified by H₂O₂. Intracellular application of SOD or catalase reduced the H₂O₂ induced shift of activation I-V curve and SOD significantly decreased Kv1.5 amplitude at +40 mV (n=9; P<0.05). In conclusion, H₂O₂ increased Kv1.5 current amplitude at voltages corresponding to the action potential repolarization phase and accelerated Kv1.5 channel opening. These changes can reduce the action potential duration, leading to a shortening of the atrial effective refractory period. H₂O₂-induced changes in Kv1.5 properties could thus be involved in initiation or perpetuation of AF.David Caouette and Christiane Dongmo contributed equally to this article     

Blockers of the Kv1.5 channel for the treatment of atrial arrhythmias

Atrial arrhythmias are a common problem in cardiological practice. Despite the availability of several antiarrhythmic drugs there is a medical need for safer and more efficient treatments. The voltage-gated potassium channel Kv1.5 is regarded as a promising target for the development of new atrial selective drugs with fewer side effects. This review summarises patents claiming such compounds. The chemistry and biological data disclosed in these patents are discussed in light of recent work demonstrating the antiarrhythmic effects of Kv1.5 blockers in vivo.     

苯甲酰胺类Kv1.5钾离子通道阻滞剂的研究(英文)

文献报道Kv1.5钾离子通道为治疗心房颤动的一个安全有效的靶点。在前期研究中我们证明化合物CPUY11018有中等的抑制Kv1.5钾离子通道的作用, 但其稳定性较差。为了改善其稳定性同时为了探讨构效关系, 本文利用骨架迁越原理, 合成了4个系列共17个苯甲酰胺类衍生物并测定其Kv1.5阻滞活性。其中, 化合物8c显示出良好的Kv1.5阻滞活性。     

Chemical and Biological Study of Novel Aplysiatoxin Derivatives from the Marine Cyanobacterium Lyngbya sp.

Since 1970s, aplysiatoxins (ATXs), a class of biologically active dermatoxins, were identified from the marine mollusk Stylocheilus longicauda, whilst further research indicated that ATXs were originally metabolized by cyanobacteria. So far, there have been 45 aplysiatoxin derivatives discovered from marine cyanobacteria with various geographies. Recently, we isolated two neo-debromoaplysiatoxins, neo-debromoaplysiatoxin G (1) and neo-debromoaplysiatoxin H (2) from the cyanobacterium Lyngbya sp. collected from the South China Sea. The freeze-dried cyanobacterium was extracted with liquid–liquid extraction of organic solvents, and then was subjected to multiple chromatographies to yield neo-debromoaplysiatoxin G (1) (3.6 mg) and neo-debromoaplysiatoxin H (2) (4.3 mg). They were elucidated with spectroscopic methods. Moreover, the brine shrimp toxicity of the aplysiatoxin derivatives representing differential structural classifications indicated that the debromoaplysiatoxin was the most toxic compound (half inhibitory concentration (IC₅₀) value = 0.34 ± 0.036 µM). While neo-aplysiatoxins (neo-ATXs) did not exhibit apparent brine shrimp toxicity, but showed potent blocking action against potassium channel Kv1.5, likewise, compounds 1 and 2 with IC₅₀ values of 1.79 ± 0.22 µM and 1.46 ± 0.14 µM, respectively. Therefore, much of the current knowledge suggests the ATXs with different structure modifications may modulate multiple cellular signaling processes in animal systems leading to the harmful effects on public health.     

Symmetric Kv1.5 Blockers Discovered by Focused Screening

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Effects of the atrial antiarrhythmic drug AVE0118 on cardiac ion channels

Previous studies in pigs and goats have demonstrated that AVE0118 prolongs atrial refractoriness without any effect on the QT-interval. The purpose of the present study was to investigate the effect of the compound on various cardiac ion channels. AVE0118 blocked the pig Kv1.5 and the human Kv1.5 expressed in Xenopus oocytes with IC₅₀ values of 5.4±0.7 M and 6.2±0.4 M respectively. In Chinese hamster ovary (CHO) cells, AVE0118 decreased the steady-state hKv1.5 current with an IC₅₀ of 1.1±0.2 M. The hKv4.3/KChIP2.2 current in CHO cells was blocked by AVE0118 by accelerating the apparent time-constant of inactivation (_inact), and the integral current was inhibited with an IC₅₀ of 3.4±0.5 M. At 10 M AVE0118 _inact decreased from 9.3±0.6 ms (n=8, control) to 3.0±0.3 ms (n=8). The K_ACh current was investigated in isolated pig atrial myocytes by application of 10 M carbachol. At a clamp potential of –100 mV the I_KACh was half-maximally blocked by 4.5±1.6 M AVE0118. In the absence of carbachol, AVE0118 had no effect on the inward current recorded at –100 mV. Effects on the I_Kr current were investigated on HERG channels expressed in CHO cells. AVE0118 blocked this current half-maximally at approximately 10 M. Comparable results were obtained in isolated guinea pig ventricular myocytes, where half-maximal inhibition of the I_Kr tail current occurred at a similar concentration of AVE0118. Other ionic currents, like the I_Ks, I_KATP (recorded in guinea pig ventricular myocytes), and L-type Ca²⁺ (recorded in pig atrial myocytes) were blocked by 10 M AVE0118 by 10±3% (n=6), 28±7% (n=4), and 22±13% (n=5) respectively. In summary, AVE0118 preferentially inhibits the atrial K⁺ channels I_Kur, I_to and I_KACH. This profile may explain the selective prolongation of atrial refractoriness described previously in pigs and goats.