Characteristics and distribution of M cells in arterially perfused canine left ventricular wedge preparations
Characteristics and distribution of M cells in arterially perfused canine left ventricular wedge preparations
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DOI：
10.1161/01.cir.98.18.1921
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发表时间：
1998-11-03
期刊：
影响因子：
37.8
通讯作者：
Antzelevitch, C
中科院分区：
文献类型：
--
作者：
Yan, GX;Shimizu, W;Antzelevitch, C
背景-迄今为止，M细胞的大部分表征都是使用分离的组织和细胞完成的。本研究使用动脉灌注楔制备检查犬左心室前壁内的M细胞的特性和分布在更多的生理conditions.Methods和Results-Floating微电极被用来记录跨膜动作电位同时从心外膜，M区，和endoorths或subendoorths浦肯野网站在孤立的动脉灌注犬左心室楔制备。同时记录透壁ECG。在从左心室前壁分离的楔形标本中，动作电位最长的M细胞位于深内膜下。除心外膜和深心外膜下区域外，动作电位时程（APD）转换相当平滑。组织电阻率增加了2.8倍，在这个地区和更温和的深subendobiliary。在1000和2000 ms的基本周期长度下，跨左室壁的APD（90）离散度分别为51 ± 19和64 ± 25 ms，而跨室壁复极时间离散度较小（34+/-18和45+/-25 ms），由于心内膜到心外膜的激活顺序。结论-我们的结论是，先前在分离的组织和细胞中描述的3种心室细胞类型之间的质的差异在完整的犬左心室壁制备物中保持，其中心肌细胞电耦合良好。正如预期的那样，APD的差异在数量上较小，因为3种细胞类型之间的电紧张性相互作用。我们的数据表明，跨室壁复极离散是跨越心室壁的细胞APD的内在差异以及跨壁组织电阻率的不均匀分布的结果。
Background-Much of the characterization of the M cell to date has been accomplished using isolated tissues and cells. This study uses an arterially perfused wedge preparation to examine the characteristics and distribution of M cells within the anterior wall of the canine left ventricle under more physiological conditions.Methods and Results-Floating microelectrodes were used to record transmembrane action potentials simultaneously from epicardial, M region, and endocardial or subendocardial Purkinje sites in isolated arterially perfused canine left ventricular wedge preparations. A transmural ECG was recorded concurrently. M cells with the longest action potentials were found in the deep subendocardium in wedge preparations isolated from the anterior wall of the left ventricle. Fairly smooth transitions in action potential duration (APD) were observed except in the region between epicardium and deep subepicardium. Tissue resistivity increased 2.8-fold in this region and much more modestly in the deep subendocardium. Dispersion of APD(90) across the left ventricular wall averaged 51+/-19 and 64+/-25 ms at basic cycle lengths of 1000 and 2000 ms, respectively, whereas transmural dispersion of repolarization time was smaller (34+/-18 and 45+/-25 ms), owing to the endocardial to epicardial activation sequence.Conclusions-We conclude that the qualitative differences between the 3 ventricular cell types previously described in isolated tissues and cells are maintained in intact canine left ventricular wall preparations in which the myocardial cells are electrically well coupled. As anticipated, differences in APD are quantitatively smaller because of electrotonic interactions among the 3 cell types. Our data indicate that transmural dispersion of repolarization is the result of intrinsic differences in APD of cells spanning the ventricular wall as well as a heterogeneous distribution of tissue resistivity across the wall.