摘要
为从细胞水平了解房室结电生理特性以及腺苷对其作用的离子机制 ,研究急性酶分离的单个房室结细胞钾电流的特性以及腺苷对电流特性的影响。采用膜片钳技术记录单通道电流 ,此电流经膜片钳放大器 (CEZ - 2 2 0 0 )放大和低通滤波 (3KHz) ,再经Pclamp 6 .0 2软件的数据采集系统采样和最后分析。结果 :采用对称性高钾液恒温灌流 (36～ 37℃ )应用细胞贴附式膜片 ,发现房室结区有两类细胞 ,其中一种电导值为 2 3.8pS的柱状细胞和一种电导值为 6 .8pS的梭状细胞。在这两种细胞上均可记录到外向钾电流通道。此电流具有内向整流特性 ,随去极化水平的增加 ,其通道开放概率 (PO)增加 ,且能被 10mM四乙基胺完全阻断。使用腺苷后此通道的电压依赖性仍存在 ,且通道开放概率、平均开放时间、开放频率均明显高于对照组 ,且具有内向整流特性。其反转电位与钾电流相似。结论 :房室结内有两种不同电导值的细胞 ,腺苷使其电流特性的改变与腺苷使膜电位超极化和钾通道 (Ikado)
To study electrophysiological properties of cells isolated from the rabbit atrioventricular node (AVN) and effects of adenosine on their K + channel.Calciumtolerant myocytes were isolated from the region of the AV node by enzymatic and mechanical ionic currents was studied using the cell attached configurations of the patchclamp technique.We found that there are two types cells in AVN region.The single channel conductance was 6.8 pS and 23.8 pS in the ovoid shaped and rod shaped respectively.Adenosine (1～50 μmol) slowed or abolished the spontaneous activity with hyperpolarization of the membrane potential.The experiments showed that adenosine induced an inwardly rectifying time independent current.The adenosine induced current was shown to be carried by potassium ions by altered the external potassium.In a high [k +] solution,inward single channel currents were observed on membrane hyperpolarization.At potentials between -60 mV and 0 mV,the open and closed times of the single channel fitted well with single exponential and biexponential distribution,respectively.As the membrane was progressively hyperpolarized,the open time was prolonged,while the closed time was shortened and increase of open probability,frequence.These results indicate that there are two different electrophysiology characteristic cells.Adenosine suppress spontaneons activity by hyperpolarized membrane potential and induce a time independent potassium current in AV node cell.[Chinese Journal of Cardiac Pacing and Electrophysiology,2000,14(3):171～173]
出处
《中国心脏起搏与心电生理杂志》
2000年第3期171-173,共3页
Chinese Journal of Cardiac Pacing and Electrophysiology
关键词
腺苷
钾通道
膜片钳
房室结细胞
电生理特性
Adenosine Collaenase Ⅰ Potassium Channel Patch clamp Atrioventricular node cell Rabbit
