Three-dimensional distribution of ryanodine receptor clusters in cardiac myocytes
Three-dimensional distribution of ryanodine receptor clusters in cardiac myocytes
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DOI：
10.1529/biophysj.105.077180
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发表时间：
2006-07-01
影响因子：
3.4
通讯作者：
Izu, Leighton T.
中科院分区：
文献类型：
--
作者：
Chen-Izu, Ye;McCulle, Stacey L.;Izu, Leighton T.
ryanodine受体（RyR2）聚集成功能性Ca2+释放单元是心脏兴奋-收缩（E-C）耦合的当前模型的核心。利用免疫标记和共聚焦显微镜，我们分析了RyR2簇在大鼠和心室心房肌细胞中的分布。采用一种新颖的横切面方法和数字反褶积技术，提高了三维结构的分辨率。与先前的报道相反，在心室肌细胞中测量到的RyR2簇横向间距平均为1.05 μ m，在心房肌细胞中估计为0.97 μ m。嵌入的RyR2簇分布在细胞外围的z -盘之间，但在细胞内部没有，在表面局部z -盘的两侧形成双行。测量z盘上RyR2簇相邻行之间的纵向间距，心室肌细胞平均值为1.87 μ m，心房肌细胞平均值为1.69 μ m。测量的RyR2簇分布与Ca2+波产生的模型是兼容的。典型的RyR2簇的大小接近250 nm，这表明在一个簇中可能存在大约100个RyR2s。讨论了簇大小和三维间距对当前E-C耦合模型的重要性。
The clustering of ryanodine receptors (RyR2) into functional Ca2+ release units is central to current models for cardiac excitation-contraction (E-C) coupling. Using immunolabeling and confocal microscopy, we have analyzed the distribution of RyR2 clusters in rat and ventricular atrial myocytes. The resolution of the three-dimensional structure was improved by a novel transverse sectioning method as well as digital deconvolution. In contrast to earlier reports, the mean RyR2 cluster transverse spacing was measured 1.05 mu m in ventricular myocytes and estimated 0.97 mu m in atrial myocytes. Intercalated RyR2 clusters were found interspersed between the Z-disks on the cell periphery but absent in the interior, forming double rows flanking the local Z-disks on the surface. The longitudinal spacing between the adjacent rows of RyR2 clusters on the Z-disks was measured to have a mean value of 1.87 mu m in ventricular and 1.69 mu m in atrial myocytes. The measured RyR2 cluster distribution is compatible with models of Ca2+ wave generation. The size of the typical RyR2 cluster was close to 250 nm, and this suggests that similar to 100 RyR2s might be present in a cluster. The importance of cluster size and three-dimensional spacing for current E-C coupling models is discussed.