Objective To study the effect of allitridum on rapidly delayed rectifier potassium current (IKr) in HEK293 cell line. Methods HEK293 cells were transiently transfected with HERG channel cDNA plasmid pcDNA3.1 via Lipofectamine. Allitridum was added to the extracellular solution by partial perfusion after giga seal at the final concentration of 30μmol/L. Whole-cell patch clamp technique was used to record the HERG currents and gating kinetics before and after allitridum exposure at room temperature. Results The amplitude and density of IHERG were both suppressed by allitridum in a voltage-dependent manner. In the presence of allitridum, the peak current of IHERG was reduced from 73.5±4.3 pA/pF to 42.1±3.6 pA/pF at the test potential of +50 mV (P<0.01). Allitridum also concentration-dependently decreased the density of the IHERG. The IC50 of allitridum was 34.74 μmol/L with a Hill coefficient of 1.01. Allitridum at 30 μmol/L caused a significant positive shift of the steady-state activation curve of IHERG and a markedly negative shift of the steady-state inactivation of IHERG, and significantly shortened the slow time constants of IHERG deactivation. Conclusion Allitridum can potently block IHERG in HEK293 cells, which might be the electrophysiological basis for its anti-arrhythmic action.%目的 研究大蒜素对HEK293细胞HERG电流的作用,探讨其抗心律失常的可能机制.方法 采用瞬时转染的方法,将HERG通道质粒转入HEK293细胞上,应用细胞外局部灌流法于膜片钳高阻抗封接形成后给予大蒜素,使其终浓度为30μmol/L.室温下,采用全细胞膜片钳技术在电压钳形模式下记录电流和门控动力学,观察大蒜素对HERG电流的作用.结果 30μmol/L大蒜素对正常大鼠心室肌细胞HERG电流有显著的阻滞效应,使其尾电流密度由73.5±4.3 pA/pF降低至42.1±3.6 pA/pF(P<0.01,n=14).其作用呈浓度依赖性.半数抑制浓度为34.74μmol/L,Hill系数为1.01.大蒜素可使HERG的电流-电压曲线降低,且随着去极化电位的增加,作用更加明显,提示其作用具有电压依赖性,门控机制研究发现大蒜素可以使通道激活曲线向更正的方向移动,进而延迟激活;使通道稳态失活更负的方向移动,导致失活加速.同时,使通道灭活的慢时间常数缩短,从而加速通道的灭活.结论 大蒜素抑制HEK293细胞上HERG电流,提示这可能是其治疗心律失常的细胞电生理基础.
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