Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
Biophys J. 2009 Nov 18;97(10):2664-73. doi: 10.1016/j.bpj.2009.08.036.
Confocal and total internal reflection fluorescence imaging was used to examine the distribution of caveolin-3, sodium-calcium exchange (NCX) and ryanodine receptors (RyRs) in rat ventricular myocytes. Transverse and longitudinal optical sectioning shows that NCX is distributed widely along the transverse and longitudinal tubular system (t-system). The NCX labeling consisted of both punctate and distributed components, which partially colocalize with RyRs (27%). Surface membrane labeling showed a similar pattern but the fraction of RyR clusters containing NCX label was decreased and no nonpunctate labeling was observed. Sixteen percent of RyRs were not colocalized with the t-system and 1.6% of RyRs were found on longitudinal elements of the t-system. The surface distribution of RyR labeling was not generally consistent with circular patches of RyRs. This suggests that previous estimates for the number of RyRs in a junction (based on circular close-packed arrays) need to be revised. The observed distribution of caveolin-3 labeling was consistent with its exclusion from RyR clusters. Distance maps for all colocalization pairs were calculated to give the distance between centroids of punctate labeling and edges for distributed components. The possible roles for punctate NCX labeling are discussed.
共聚焦和全内反射荧光成像技术被用于研究 Cav-3、钠钙交换（NCX）和兰尼碱受体（RyRs）在大鼠心室肌细胞中的分布。横向和纵向光学切片显示 NCX 广泛分布于横管和纵管系统（t 系统）。NCX 标记由点状和弥散成分组成，与 RyRs（27%）部分共定位。细胞膜标记显示出相似的模式，但包含 NCX 标记的 RyR 簇的比例减少，并且没有观察到非点状标记。16%的 RyRs 与 t 系统没有共定位，而 1.6%的 RyRs 位于 t 系统的纵轴上。RyR 标记的表面分布通常与 RyRs 的圆形斑并不一致。这表明之前对连接点（基于圆形紧密堆积阵列）的 RyR 数量的估计需要修正。观察到的 Cav-3 标记分布与它从 RyR 簇中的排除一致。为所有共定位对计算距离图，以获得点状标记的质心与弥散成分边缘之间的距离。点状 NCX 标记的可能作用被讨论。
