Comparison of steady-state electrophysiological properties of isolated cells from bullfrog atrium and sinus venosus.
Comparison of steady-state electrophysiological properties of isolated cells from bullfrog atrium and sinus venosus.
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牛蛙心房和静脉窦分离细胞稳态电生理特性的比较。
DOI：
10.1007/bf01869709
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Giles,WR
中科院分区：
文献类型：
--
作者：
Moore,LE;Clark,RB;Shibata,EF;Giles,WR
采用单电极全细胞电压钳实验和频域分析方法，研究和比较了牛蛙心脏心房和静脉窦（起搏区）酶分散单细胞的K+电流。在“静止”或零电流电势附近进行导纳测量，可以从中获得每种电池类型的等效电路。从心房和起搏细胞的数据拟合良好的模型只包括平行的电阻电容元件，从他们的微观解剖预测。这两种两栖动物的心肌细胞都不包含横小管系统（TT），并且都具有非常少的肌浆网（SR）。这些结果补充和扩展了两个早期的研究：（i）摩尔、施密德和伊森伯格（J. Membrane Biol.81：29-40，1984）报道了在豚鼠心室细胞（其确实含有由横小管和大量SR组成的内膜系统）中SR可以电偶联到肌膜;（ii）柴田和贾尔斯（Biophys. J.45：136 a，1984）已经表明，虽然牛蛙心房细胞具有向内整流的背景K+电流，但是来自紧邻静脉窦的起搏细胞不具有。导纳测量数据也提供了证据，TTX不敏感的内向钙电流被激活的起搏器电位范围。
Single electrode whole cell voltage-clamp experiments and frequency domain analyses have been used to study and compare the K+currents in enzymatically dispersed single cells from the atrium and the sinus venosus (pacemaker region) of the bullfrog heart. Admittance measurements made near the ‘resting’ or zero-current potential yield data from which the equivalent circuit of each cell type may be obtained. Data from both atrial and pacemaker cells are well-fitted by a model consisting only of parallel resistance-capacitative elements, as predicted from their micro-anatomy. Neither of these amphibian cardiac cells contain a transverse tubule system (TT) and both have very little sarcoplasmic reticulum (SR). These results complement and extend two earlier investigations: (i) Moore, Schmid and Isenberg (J. Membrane Biol.81:29–40, 1984) have reported that in guinea pig ventricle cells (whichdocontain an internal membrane system consisting of transverse tubules and a substantial SR) the SR may be electrically coupled to the sarcolemma; (ii) Shibata and Giles (Biophys. J.45:136a, 1984) have shown that although bullfrog atrial cells have an inwardly rectifying back-ground K+current,, pacemaker cells from the immediately adjacent sinus venosus do not. Data from admittance measurements also provide evidence that a TTX-insensitive inward Ca2+current is activated in the pacemaker range of potentials.