Rotation of actin monomers during isometric contraction of skeletal muscle
Rotation of actin monomers during isometric contraction of skeletal muscle
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DOI：
10.1117/1.2697286
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发表时间：
2007-01-01
影响因子：
3.5
通讯作者：
Burghardt, Thomas P.
中科院分区：
文献类型：
--
作者：
Borejdo, Julian;Muthu, Priya;Burghardt, Thomas P.
肌球蛋白和肌动蛋白的循环相互作用负责肌肉的收缩。然而，机械循环发生在不产生功的稳态等长收缩期间，这并不是不言而喻的。研究等长稳态收缩期间的跨桥动力学需要平衡时间分辨方法（不涉及瞬态的应用）。这项工作介绍了这样一种方法，该方法分析肌肉中一些肌动蛋白分子的各向异性波动。通过共焦全内反射 (CTIR) 显微镜从几阿托升 (10(-18) L) 的体积中收集荧光各向异性，表明肌动蛋白原聚体的方向。在此方法中，通过 TIR 照明使检测体积变浅，并通过在共轭图像平面中插入共焦孔径使检测体积变窄。信号由大约 12 个标记的肌动蛋白分子贡献。通过与 1-乙基-3-[3-二甲基氨基)-丙基]-碳二亚胺的光交联可防止收缩过程中肌原纤维的缩短。等长收缩中的均方根各向异性波动大于僵直肌原纤维中的均方根各向异性波动。结果支持这样的观点：在等长收缩期间，横桥经历机械循环。 (c) 2007 年光电仪器工程师协会。
Cyclic interactions of myosin and actin are responsible for contraction of muscle. It is not self-evident, however, that the mechanical cycle occurs during steady-state isometric contraction where no work is produced. Studying cross-bridge dynamics during isometric steady-state contraction requires an equilibrium time-resolved method (not involving application of a transient). This work introduces such a method, which analyzes fluctuations of anisotropy of a few actin molecules in muscle. Fluorescence anisotropy, indicating orientation of an actin protomer, is collected from a volume of a few attoliters (10(-18) L) by confocal total internal reflection (CTIR) microscopy. In this method, the detection volume is made shallow by TIR illumination, and narrow by confocal aperture inserted in the conjugate image plane. The signal is contributed by approximately 12 labeled actin molecules. Shortening of a myofibril during contraction is prevented by light cross-linking with 1-ethyl-3-[3-dimethylamino)-propyl]-carbodiimide. The root mean-squared anisotropy fluctuations are greater in isometrically contracting than in rigor myofibrils. The results support the view that during isometric contraction, cross-bridges undergo a mechanical cycle. (c) 2007 Society of Photo-Optical Instrumentation Engineers.