Arora Rishi, Aistrup Gary L, Supple Stephen, Frank Caleb, Singh Jasleen, Tai Shannon, Zhao Anne, Chicos Laura, Marszalec William, Guo Ang, Song Long-Sheng, Wasserstrom J Andrew
Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois,.
Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
Heart Rhythm. 2017 Feb;14(2):273-281. doi: 10.1016/j.hrthm.2016.09.022. Epub 2016 Sep 23.
The peculiarities of transverse tubule (T-tubule) morphology and distribution in the atrium-and how they contribute to excitation-contraction coupling-are just beginning to be understood.
The objectives of this study were to determine T-tubule density in the intact, live right and left atria in a large animal and to determine intraregional differences in T-tubule organization within each atrium.
Using confocal microscopy, T-tubules were imaged in both atria in intact, Langendorf-perfused normal dog hearts loaded with di-4-ANEPPS. T-tubules were imaged in large populations of myocytes from the endocardial surface of each atrium. Computerized data analysis was performed using a new MatLab (Mathworks, Natick, MA) routine, AutoTT.
There was a large percentage of myocytes that had no T-tubules in both atria with a higher percentage in the right atrium (25.1%) than in the left atrium (12.5%) (P < .02). The density of transverse and longitudinal T-tubule elements was low in cells that did contain T-tubules, but there were no significant differences in density between the left atrial appendage, the pulmonary vein-posterior left atrium, the right atrial appendage, and the right atrial free wall. In contrast, there were significant differences in sarcomere spacing and cell width between different regions of the atria.
There is a sparse T-tubule network in atrial myocytes throughout both dog atria, with significant numbers of myocytes in both atria-the right atrium more so than the left atrium-having no T-tubules at all. These regional differences in T-tubule distribution, along with differences in cell width and sarcomere spacing, may have implications for the emergence of substrate for atrial fibrillation.
横小管（T小管）在心房中的形态和分布特点，以及它们如何促进兴奋-收缩偶联，目前才刚刚开始被了解。
本研究的目的是确定大型动物完整、活体的右心房和左心房中的T小管密度，并确定每个心房内T小管组织的区域差异。
使用共聚焦显微镜，对用di-4-ANEPPS装载的、经Langendorff灌注的完整正常犬心脏的两个心房中的T小管进行成像。从每个心房的心内膜表面的大量心肌细胞中对T小管进行成像。使用新的MatLab（Mathworks，纳蒂克，马萨诸塞州）程序AutoTT进行计算机数据分析。
两个心房中都有很大比例的心肌细胞没有T小管，右心房（25.1%）的比例高于左心房（12.5%）（P <.02）。在含有T小管的细胞中，横向和纵向T小管元件的密度较低，但左心耳、肺静脉-左心房后部、右心耳和右心房游离壁之间的密度没有显著差异。相比之下，心房不同区域之间的肌节间距和细胞宽度存在显著差异。
整个犬心房的心房肌细胞中存在稀疏的T小管网络，两个心房中都有大量心肌细胞——右心房比左心房更多——完全没有T小管。T小管分布的这些区域差异，以及细胞宽度和肌节间距的差异，可能对房颤底物的出现有影响。
