Drouin E, Charpentier F, Gauthier C, Laurent K, Le Marec H
Laboratory of Experimental Cardiology, National Center for Scientific Research, Nantes, France.
J Am Coll Cardiol. 1995 Jul;26(1):185-92. doi: 10.1016/0735-1097(95)00167-x.
The present work was designed to provide an initial characterization of M cells in the normal human heart.
Recent studies have uncovered a unique population of cells in the midmyocardial region of the canine ventricle. These cells, named M cells, were found to possess electrophysiologic features and a pharmacologic responsiveness different from those of other myocardial cells. Although well characterized in the dog, their presence or absence in the human heart is unknown.
Standard microelectrode techniques were used to map slices of ventricular free wall obtained from normal human hearts (n = 4). Preparations were paced at cycle lengths ranging from 1 to 10 s.
We identified three cell subtypes: endocardial, subepicardial (M cells) and epicardial cells. The principal features differentiating M cells from the other cell subtypes were their longer action potential duration, more accentuated action potential duration rate relations and greater maximal rate of increase in action potential upstroke (Vmax). Our findings suggest that M cells represent approximately 30% of the cellular mass of the left ventricular wall. Concordance between changes in their repolarization and changes in QTU interval provide support for the role of M cells in the generation of the electrocardiographic (ECG) U wave.
This study provides evidence for the existence of M cells in the human heart that contribute to heterogeneity of repolarization within the ventricular wall. Our findings provide strong support for the hypothesis that M cells contribute importantly to the manifestation of the U wave on the ECG.
本研究旨在对正常人体心脏中的M细胞进行初步特征描述。
最近的研究在犬类心室的心肌中层区域发现了一群独特的细胞。这些细胞被命名为M细胞，具有与其他心肌细胞不同的电生理特征和药理反应性。尽管在犬类中已得到充分表征，但它们在人体心脏中是否存在尚不清楚。
使用标准微电极技术对取自正常人体心脏（n = 4）的心室游离壁切片进行标测。以1至10秒的周期长度对标本进行起搏。
我们识别出三种细胞亚型：心内膜细胞、心外膜下（M细胞）和心外膜细胞。将M细胞与其他细胞亚型区分开来的主要特征是其较长的动作电位时程、更明显的动作电位时程速率关系以及更大的动作电位上升最大速率（Vmax）。我们的研究结果表明，M细胞约占左心室壁细胞质量的30%。它们复极化变化与QTU间期变化之间的一致性为M细胞在心电图（ECG）U波产生中的作用提供了支持。
本研究为人体心脏中存在M细胞提供了证据，这些细胞导致心室壁复极化的异质性。我们的研究结果为M细胞对心电图上U波表现有重要贡献这一假说提供了有力支持。
