Microelectrode study of the genesis of the monophasic action potential by contact electrode technique
Microelectrode study of the genesis of the monophasic action potential by contact electrode technique
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DOI：
10.1046/j.1540-8167.2002.01246.x
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发表时间：
2002-12-01
影响因子：
2.7
通讯作者：
Franz, MR
中科院分区：
文献类型：
--
作者：
Knollmann, BC;Tranquillo, J;Franz, MR
单相动作电位的产生
引言：尽管在临床和实验研究中广泛使用接触电极记录单相动作电位（MAPs），但接触式MAP产生的机制仍未得到证实。“弗朗茨假说”假定MAP是由一个电流源驱动的，该电流源源于被MAP电极压力去极化的细胞与紧邻其的正常细胞之间的边界。到目前为止，没有直接的实验数据支持这一假说。
方法与结果：在10个Langendorff灌注的小鼠心脏中，将一个微型MAP探头插入右心室（RV），并轻轻压在朝上的RV游离壁的心内膜上。在稳定接触和稳定记录MAP期间，从RV上方降下装有KCl的玻璃微电极，以记录在MAP电极接触部位中心以及其周边外0.05和0.2 mm处的跨膜动作电位（TAPs）。中心处的TAPs在心外膜层具有正常的静息电位（RP）（-78±4 mV），但向更深层逐渐降低，在MAP电极表面正上方达到最小RP为-23±0.8 mV。在MAP周边外0.05 mm处的RPs在心外膜表面正常，并且随着跨壁深度增加，其降低程度明显小于中心记录（最小RP -41±0.8 mV，n = 11，P < 0.00001）。在距MAP电极周边0.2 mm处的TAPs在整个RV壁上具有正常的RPs。
结论：这些直接数据首次支持了以下假说：MAP是通过局部一定体积细胞的压力去极化产生的，这些细胞（1）与正常细胞之间有明显的电压梯度，（2）提供了一个强大的局部电流源，（3）当用电路模型模拟时，产生了接触式MAP电极所记录的场电位。
Monophasic Action Potential Genesis. Introduction: Despite widespread use of the contact electrode for recording monophasic action potentials (MAPs) in both clinical and experimental research, the mechanism underlying the genesis of the contact MAP remains unproven. The "Franz hypothesis" assumes that the MAP is driven by a current source originating at the boundary between cells depolarized by the MAP electrode pressure and normal cells immediately adjacent to it. To date, no direct experimental data exist to support this hypothesis.Methods and Results: In 10 Langendorff-perfused mouse hearts, a miniaturized MAP probe was inserted into the right ventricle (RV) and gently pressed against the endocardium of the upward-facing RV free wall. During stable contact and stable MAP recording, KCl-filled glass microelectrodes were lowered from above the RV to record transmembrane action potentials (TAPs) at the center of and 0.05 and 0.2 mm outside the perimeter of the MAP electrode contact site. TAPs at the center had normal resting potentials (RP) in epicardial layers (-78 +/- 4mV) but showed gradual decrease toward deeper layers, reaching a minimum RP of -23 +/- 0.8 mV directly above the MAP electrode surface. RPs at 0.05 mm outside the MAP perimeter were normal at the epicardial surface and with increasing transmural depth showed significantly less decrease than central recordings (min RP -41 +/- 0.8 mV, n = 11, P < 0.00001). TAPs at 0.2 mm from the MAP electrode perimeter had normal RPs across the entire RV wall.Conclusion: These direct data are the first to support the hypothesis that the MAP is generated locally through pressure depolarization of a circumscript volume of cells that (1) has sharp voltage gradients toward normal cells, (2) provides a strong local current source, and (3) when simulated with a circuit model creates the field potential recorded by the contact MAP electrode.