Visualization of cardiac muscle thin filaments and measurement of their lengths by electron tomography.
Visualization of cardiac muscle thin filaments and measurement of their lengths by electron tomography.
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DOI：
10.1093/cvr/cvm117
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发表时间：
2008-03-01
影响因子：
10.8
通讯作者：
Luther PK
中科院分区：
文献类型：
--
作者：
Burgoyne T;Muhamad F;Luther PK
脊椎动物骨骼肌和心肌之间的一个有趣的区别是，前者的细丝长度是恒定的，而后者是可变的。在两种肌肉中，粗细丝的长度是恒定的。肌肉的收缩行为受到两种类型的细丝的长度的影响，因为在收缩期间产生的张力取决于细丝重叠的量。要了解心肌的行为，重要的是要知道细丝长度的分布。先前由罗宾逊和温格勒进行的详细分析使用连续的横截面来确定细丝的长度。然而，由100 nm的切片厚度设定的精度较低。在这里，我们使用电子断层扫描技术来生成大鼠和小鼠心肌的3D图像，在这些图像中，我们实际上可以看到单个细丝直到自由端，并且可以看到这些自由端具有可变的位置。为了比较，我们还测量了骨骼肌（青蛙缝匠肌）中的细丝长度。从大鼠（Sprague-Dawley）和小鼠（C57/B6）获得心脏乳头肌。从青蛙（蛙（Rana pipiens））获得skeleton肌（缝匠肌）。纵向部分（100纳米厚）用于产生倾斜系列和断层扫描图，从薄的灯丝路径进行跟踪。大鼠和小鼠的心脏乳头肌细丝范围为0.94至1.10 µm，平均长度为1.04 µm，标准差为0.03 µm。对于青蛙缝匠肌，细丝长度为0.94 µm，标准差为0.01 µm。心脏和骨骼肌的电子断层扫描可以直接可视化和高精度测量细丝的长度。
An intriguing difference between vertebrate skeletal and cardiac muscles is that the lengths of the thin filaments are constant in the former but variable in the latter. The thick filaments have constant lengths in both types of muscles. The contractile behaviour of a muscle is affected by the lengths of both types of filaments as the tension generated during contraction depends on the amount of filament overlap. To understand the behaviour of cardiac muscle, it is important to know the distribution of the thin filament lengths. The previous detailed analysis by Robinson and Winegrad used serial transverse sections to determine the lengths of the thin filaments. However, the precision, set by the 100 nm section thickness, was low. Here, we have used electron tomography to produce 3D images of rat and mouse cardiac muscles in which we can actually see individual thin filaments up to the free ends and see that these free ends have variable locations. For comparison, we also measure the thin filament lengths in skeletal muscle (frog sartorius). Cardiac papillary muscles were obtained from a rat (Sprague–Dawley) and a mouse (C57/B6). Skeletal muscle (sartorius) was obtained from a frog (Rana pipiens). Longitudinal sections (100 nm thick) were used to produce tilt series and tomograms from which the thin filament paths were traced. Cardiac papillary muscle thin filaments in rat and mouse range from 0.94 to 1.10 µm, with a mean length of 1.04 µm and standard deviation of 0.03 µm. For frog sartorius muscle, the thin filament length was 0.94 µm with standard deviation of 0.01 µm. Electron tomography of cardiac and skeletal muscles allows direct visualization and high precision measurement of the lengths of thin filaments.