IONIC CURRENTS IN SINGLE ISOLATED BULLFROG ATRIAL CELLS
IONIC CURRENTS IN SINGLE ISOLATED BULLFROG ATRIAL CELLS
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DOI：
10.1085/jgp.81.2.153
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发表时间：
1983-01-01
影响因子：
3.8
通讯作者：
GILES, W
中科院分区：
文献类型：
--
作者：
HUME, JR;GILES, W
用酶法从牛蛙心房组织中分离出单细胞。之前的数据（Hume et Giles，1981）表明这些单个细胞处于静止状态，并具有正常的静息电位和动作电位。最小DC空间常数为. apprx。920 μ m尝试开发和完善的跨膜离子电流的定量测量技术，并确定产生不同阶段的动作电位的离子电流的各个组成部分。使用传统的2-微电极技术进行的初始电压钳实验显示了小的河豚毒素（TTX）不敏感的内向电流。该电流的小尺寸（2.5-3.0 × 10 - 4）可被认为是最小的。10-10 A）和2-微电极实验的技术难度促使了1-微电极电压钳技术的发展，该技术需要使用低电阻（0.5-2 M Ω）微量吸管电压钳实验，使用这种新技术在孤立的单个心房细胞揭示5个不同的离子电流：一个传统的瞬时Na+电流，TTX抗性的瞬时内向电流，主要由Ca 2+，持续内向电流的一个组成部分，一个缓慢发展的外向K+电流，和内向整流时间无关的背景电流。单吸微量移液管技术似乎非常适合用于在这些心脏细胞中的离子电流的定量研究，并在其他小细胞具有类似的电生理特性。
Enzymatic dispersion has been used to yield single cells from segments of bullfrog atrium. Previous data (Hume et Giles, 1981) have shown that these individual cells are quiescent and have normal resting potentials and action potentials. The minimum DC space constant is .apprx. 920 .mu.m. Attempts were made to develop and refine techniques for making quantitative measurements of the transmembrane ionic currents, and to identify the individual components of ionic current which generate different phases of the action potential. Initial voltage-clamp experiments made using a conventional 2-microelectrode technique revealed a small tetrodotoxin (TTX)-insensitive inward current. The small size of this current (2.5-3.0 .times. 10-10 A) and the technical difficulty of the 2-microelectrode experiments prompted the development of a 1-microelectrode voltage-clamp technique which requires impalements using a low-resistance (0.5-2 M.OMEGA.) micropipette. Voltage-clamp experiments using this new technique in isolated single atrial cells reveal 5 distinct ionic currents: a conventional transient Na+ current, a TTX-resistant transient inward current, carried mainly by Ca2+, a component of persistent inward current, a slowly developing outward K+ current, and an inwardly rectifying time-independent background current. The single suction micropipette technique appears well-suited for use in the quantitative study of ionic currents in these cardiac cells, and in other small cells having similar electrophysiological properties.