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A novel sustained inward current activated at the diastolic pacemaker potential

一种在舒张起搏器电位下激活的新型持续内向电流

基本信息

批准号：
08557004
负责人：
NOMA Akinori
金额：
$ 1.79万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08557004/
关键词：
Cardiae Myocyte Cell volume Jonic channel K^+ channel Cl^- channel cell thickness クロールチャネル

项目摘要

To clarify the relationship between the ionic current flow and the cell volume change, the cell width was measured using an optic device during patch clamp experiments in guinea-pig ventricular myocytes. On switching the isotonic bath solution to 50,70,150 and 200% osmotic solutions, the cell width changed to 121.1(]SY.+-。[)3.3% (n=4), 110.8(]SY.+-。[)2.2% (n=27), 87.1(]SY.+-。[)1.8% (n=6), 82.6(]SY.+-。[)1.1% (n=6) of control, respectively. The applicaation of 300 nM isoprenaline (Iso) in the 70% hypotonic solution induced a decrease of the cell width from 111.2(]SY.+-。[)1.4% to 106.2(]SY.+-。[)1.8%, (n=13). Following the Iso-induced volume decrease, returning to the isotonic solution induced a decrease of the cell width below the control level (94.8(]SY.+-。[)1.6%). The application of Iso in the isotonic solution also decreased the cell width to 96.5(]SY.+-。[)1.3% (n=8) control, accompanied by a membrane depolarization of 2-4 mV.In other 5 cells neither Iso-induced volume decrease nor membrane depolarization was observed. Under the ruptured whole-cell voltage clamp condition, Iso activated the inward Cl<@D1-@>D1 current and decreased the cell width. If a large outward or inward K<@D1+@>D1 current was induced by shifting the holding potential and by applying 200 muM pinacidil, the cell width decreased or increased, respectively. Under the gramicidin-perforated whole-cell clamp condition, the cell width did not change even when a large inward K<@D1+@>D1 current was induced. When the application of test solution was limited to a half of the elongated myocyte by using a micro-pipette, the cell width increased or decreased in the part exposed to the hypotonic or hypertonic test solutions, respectively. While the rest part of the myocyte responded in the opposite direction. It is concluded that a continuous ionic flux through ion channels is capable of inducing cell volume change.

为了阐明离子电流与细胞体积变化之间的关系，在豚鼠心室肌细胞膜片钳实验中，用光学装置测量了细胞宽度。当将等渗浴溶液切换到50、70、150和200%渗透溶液时，细胞宽度变为121.1(]sy.+-。[)3.3%(n=4)，110.8(SY+-)。[)2.2%(n=27)，87.1([Sy.+-])。[)1.8%(n=6)，82.6(SY+-)。[]分别为对照1.1%(n=6)。在70%低渗液中加入300nM异丙肾上腺素(Iso)，细胞宽度由111.2(Sy.+-)减小。[)1.4%至106.2(对+-)。[]1.8%，(n=13)。在Iso诱导的体积减小之后，返回等张溶液导致细胞宽度减少到低于对照水平(94.8(]sy.+)。[)1.6%)。在等渗溶液中应用Iso，细胞宽度也减小到96.5(]sy.+-)。[]1.3%(n=8)对照组，伴有2-4 mV的膜去极化，其余5个细胞均未观察到Iso引起的体积减小或膜去极化。在破裂的全细胞电压钳条件下，Iso激活了内向电流d1-d1，减小了细胞宽度。如果通过改变保持电位和施加200微米的吡那地尔引起较大的向外或向内K&lt；@d1+@&gt；d1电流，细胞宽度分别减小或增加。在革兰西丁穿孔的全细胞钳制条件下，即使在诱导大的内向K&lt；@d1+@&gt；d1电流的情况下，细胞宽度也没有改变。当使用微量吸管将测试液的应用限制在延长的心肌细胞的一半时，暴露于低渗或高渗测试液的部分细胞宽度分别增加或减小。而心肌细胞的其余部分则以相反的方向反应。结果表明，通过离子通道的连续离子通量能够引起细胞体积的变化。