Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions
Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions
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DOI：
10.1152/ajpheart.00948.2003
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发表时间：
2004-07-01
影响因子：
4.8
通讯作者：
Sugiura, S
中科院分区：
文献类型：
--
作者：
Nishimura, S;Yasuda, S;Sugiura, S
心脏最显著的特征之一是它能够根据外部负荷调整功输出。为了检查是否一个单一的心肌细胞制剂保留这种属性，我们测量了一个单一的大鼠心肌细胞的收缩功能，在广泛的负荷条件下，使用力长度测量系统实现自适应控制。一对碳纤维被用来夹住心肌细胞，在显微镜下连接到每一端。一根纤维是刚性的，用作机械锚，同时监测顺应性纤维的弯曲运动以进行力-长度测量。此外，通过使用基于自适应控制的压电平移器来控制柔性纤维的位置，我们可以在收缩期间动态地改变负载。在无负荷条件下，最大缩短速度为106 +/- 8.9 mum/s（n = 13个细胞），在等长条件下，峰值发展力达到5，720 nN（41.6 +/- 5.6 mN/mm（2）; n = 17个细胞）。当我们模拟生理工作条件，包括等长收缩，然后是缩短和放松，平均功输出为828 +/- 123 J/m（3）（n = 20个细胞）。在所有这些条件下获得的张力-长度环的左上角近似于一条线，类似于心室的收缩末期压力-容积关系。所描述的所有功能特征与使用乳头肌或小梁制备物的研究所建立的功能特征类似。总之，本研究结果证实了这样一个事实，即每个心肌细胞形成心室功能的功能基础，单细胞力学可以是亚细胞事件和心室力学之间的联系。
One of the most salient characteristics of the heart is its ability to adjust work output to external load. To examine whether a single cardiomyocyte preparation retains this property, we measured the contractile function of a single rat cardiomyocyte under a wide range of loading conditions using a force-length measurement system implemented with adaptive control. A pair of carbon fibers was used to clamp the cardiomyocyte, attached to each end under a microscope. One fiber was stiff, serving as a mechanical anchor, while the bending motion of the compliant fiber was monitored for force-length measurement. Furthermore, by controlling the position of the compliant fiber using a piezoelectric translator based on adaptive control, we could change load dynamically during contractions. Under unloaded conditions, maximal shortening velocity was 106 +/- 8.9 mum/s (n = 13 cells), and, under isometric conditions, peak developed force reached 5,720 nN (41.6 +/- 5.6 mN/mm(2); n = 17 cells). When we simulated physiological working conditions consisting of an isometric contraction, followed by shortening and relaxation, the average work output was 828 +/- 123 J/m(3) (n = 20 cells). The top left corners of tension-length loops obtained under all of these conditions approximate a line, analogous to the end-systolic pressure-volume relation of the ventricle. All of the functional characteristics described were analogous to those established by studies using papillary muscle or trabeculae preparations. In conclusion, the present results confirmed the fact that each myocyte forms the functional basis for ventricular function and that single cell mechanics can be a link between subcellular events and ventricular mechanics.