Spatial changes in transmembrane potential during extracellular electrical shocks in cultured monolayers of neonatal rat ventricular myocytes
Spatial changes in transmembrane potential during extracellular electrical shocks in cultured monolayers of neonatal rat ventricular myocytes
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DOI：
10.1161/01.res.79.4.676
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发表时间：
1996-10-01
影响因子：
20.1
通讯作者：
Kleber, AG
中科院分区：
文献类型：
--
作者：
Gillis, AM;Fast, VG;Kleber, AG
这项研究调查了组织结构中不同类型的不连续性在跨膜电位的空间分布中的作用。具体而言，我们在应用细胞外电击（EESS）期间测试了所谓的“次要来源，” IE，局部超极化和去极化。相对于动作电位振幅（Delta V-M/APA）的跨膜电势的变化在新生大鼠肌细胞的图案化培养物中测量，并通过光敏感染料（RH-237）染色，通过光学映射（96-通道阵列，6-到6-通道光dodododododode）在应用EES期间，分辨率为30 mU）（田间强度为8至22 v/cm；持续时间为6 ms）。在狭窄的细胞链中（宽度，218 +/- 59 [平均+/- sd] mu m），在相对难治期间应用EES产生了Delta V-M/APA的线性和对称曲线（-65 +/- 23％最大值）超极化与+64 +/- 15％最大去极化）。相比之下，在动作电位高原期间应用EES时，增量V-M/APA的轮廓是不对称的（-95 +/- 32％对+37 +/- 14％）。在高放大倍率下，在细胞之间的边界上未观察到次要来源。在致密的各向同性细胞单层或单层和显示细胞间裂缝的链中，经常观察到次要来源。一到几个肌细胞的大小的细胞间裂口足以产生与在密集细胞链中引起动作电位的次级来源相同的次级来源。在EES期间次级源的位置与局部传导放缓之间的位置之间存在密切的相关性。因此，密集填充的培养细胞链作为电延长行为，没有次级源在细胞边界处发生。小的细胞间裂口会产生足够大小的次要来源，以发挥刺激作用。
This study investigated the role oi different types of discontinuities in tissue architecture on the spatial distribution of the transmembrane potential. Specifically, we tested the occurrence of so-called ''secondary sources,'' ie, localized hyperpolarizations and depolarizations during the application of extracellular electrical shocks (EESs). Changes in transmembrane potential relative to action potential amplitude (Delta V-m/APA) were measured in patterned cultures of neonatal rat myocytes, stained with voltage-sensitive dye (RH-237), by optical mapping (96-channel photodiode array, 6- to 30-mu m resolution) during the application of EES (field strength, 8 to 22 V/cm; duration, 6 ms). Across narrow cell strands (width, 218 +/- 59 [mean +/- SD] mu m), EES applied during the relative refractory period produced a linear and symmetrical profile of Delta V-m/APA (-65 +/- 23% maximal hyperpolarization versus +64 +/- 15% maximal depolarization). In contrast, the profile of Delta V-m/APA was asymmetrical when EESs were applied during the action potential plateau (-95 +/- 32% versus +37 +/- 14%). At high magnification, no secondary sources were observed at the borders between cells. In dense isotropic cell monolayers or in monolayers and strands showing intercellular clefts, secondary sources were frequently observed. Intercellular clefts of the size of one to several myocytes were sufficient to produce secondary sources of the same magnitude as those that elicited action potentials in dense cell strands. There was a close correlation between the location of secondary sources during EES and localized conduction slowing during propagation. Thus, densely packed cultured cell strands behave as an electrical continuum with no secondary sources occurring at cell borders. Small intercellular clefts can create secondary sources of sufficient magnitude to exert a stimulatory effect.