Effects of axial stretch on sarcolemmal BKCa channels in post-hatch chick ventricular myocytes
Effects of axial stretch on sarcolemmal BKCa channels in post-hatch chick ventricular myocytes
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DOI：
10.1113/expphysiol.2009.051896
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发表时间：
2010-06-01
影响因子：
2.7
通讯作者：
Naruse, Keiji
中科院分区：
文献类型：
--
作者：
Iribe, Gentaro;Jin, Honghua;Naruse, Keiji
我们之前已经报道了从培养的鸡胚胎心室肌细胞中克隆的肌上皮拉伸激活的BKCa （SAKCA）通道的电生理特性。然而，BKCa通道在更成熟的心脏电生理中的作用尚不清楚。我们研究了轴向拉伸对孵化后心室肌细胞BKCa电流的影响。使用膜片钳技术记录从2周龄小鸡分离的心室肌细胞的全细胞电流，同时将细胞保持静止长度或拉伸，使用一对碳纤维连接在细胞的两端，使肌节长度增加10%。拉伸作用后不立即影响全细胞电流。然而，持续拉伸3分钟显著增加向外电流。这种拉伸引起的变化可以通过施加10 nm的iberiotoxin，一种特定的BKCa通道阻滞剂或Na+-Ca2+无环境来逆转。这些结果在计算机模拟研究中得到了再现。本研究首次报道了孵化后心室肌细胞的肌层BKCa电流。目前的结果表明，轴向拉伸激活BKCa通道通过拉伸诱导的细胞质Na+浓度的增加，随后增加Ca2+内流。
We have previously reported the electrophysiological properties of sarcolemmal stretch-activated BKCa (SAKCA) channels cloned from cultured chick embryonic ventricular myocytes. However, the role of BKCa channels in the electrophysiology of the more mature heart is not clear. We have investigated the effects on the BKCa current of axial stretch in post-hatch ventricular myocytes. Whole-cell currents of ventricular myocytes isolated from 2-week-old chicks were recorded using the patch-clamp technique, while the cells were either held at resting length or stretched to cause a 10% increase in sarcomere length using a pair of carbon fibres attached to opposite ends of the cell. Stretch did not affect whole-cell currents immediately after the stretch was applied. However, sustained stretch for 3 min significantly increased outward currents. This stretch-induced change was reversed by applying 10 nm iberiotoxin, a specific BKCa channel blocker, or a Na+-Ca2+-free environment. These results were reproduced in a computer simulation study. The present study is the first report about the sarcolemmal BKCa current from post-hatch ventricular myocytes. The present results suggest that axial stretch activates BKCa channels via a stretch-induced increase in the cytosolic Na+ concentration followed by an increased Ca2+ influx.