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Energy transduction in muscle contraction : Study with single thick filaments

肌肉收缩中的能量传导：单根粗肌丝的研究

基本信息

批准号：
04640651
负责人：
ISHII Naokata
金额：
$ 1.41万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640651/
关键词：
Muscle contraction In vitro motility assay Native thick filaments Actin calbles Molluscan smooth muscle Centrifugal force Force-velocity relation Crossbridge mechanism アクチンフィラメント

项目摘要

To obtain information about the kinetics of force-generating processes in the actomyosin crossbridges which retain naturally ordered arrangement, we studied the force-velocity relations in sliding movements of native thick filaments along F-actin cables.Native thick filaments (length, up to 30 mum) were isolated from the anterior byssus retractor muscle (ABRM) of Mytilus edulis and attached to polystirene microbeads (diameter, 4mum) coated previously with poly-L-lysine. The beads were placed on F-actin cables of perfused Chara internodal cells, which was then mounted on a rotating stage of a centrifuge microscope, and the velocities of steady state, sliding movements of the beads in the presence of ATP(3mM) were measured under both positive(opposite to the direction of sliding)and negative(same as that of sliding)centrifugal loads(up to 30 pN). Under the positive load, the force-velocity relation was well described, in its most part (with the exception of a small "hump" above 0.8P0), by Hill equation and appeared markedly similar to that for frog single muscle fibers. Under the negative load, the sliding velocity initially increased with force beyond the maximal unloaded velocity (V0), then appeared to reach a steady level at 2-3V0 until the beads were eventually detached from actin cables. The results suggest that the minimal unit responsible for the classical force-velocity relations is several tens or hundreds of crossbridges, and their ordered arrangement along thick filaments plays an important role in determining the mechanical properties of muscle contraction.

为了获得保持自然有序排列的肌动蛋白桥的力生成过程动力学信息，我们研究了天然粗丝沿着f -肌动蛋白电缆滑动运动的力-速度关系。从Mytilus edulis的前足牵开肌（ABRM）中分离出天然粗丝（长度可达30微米），并将其附着在先前涂有聚l -赖氨酸的聚苯乙烯微珠（直径4微米）上。将微球放置在灌注的Chara节间细胞的F-actin电缆上，然后将其安装在离心显微镜的旋转台上，在正（与滑动方向相反）和负（与滑动方向相同）离心载荷（高达30 pN）下，测量微球在ATP存在下（3mM）的稳态滑动运动速度。在正荷载作用下，力-速度关系大部分都可以用Hill方程很好地描述（除了0.8P0以上有一个小的“驼峰”），并且与蛙单肌纤维的力-速度关系明显相似。在负载荷下，滑动速度最初随着力的增加而增加，超过最大卸载速度（V0），然后在2-3V0时达到稳定水平，直到珠粒最终与肌动蛋白索分离。结果表明，经典力-速度关系的最小单元是几十或几百个十字桥，它们沿粗细丝的有序排列对肌肉收缩的力学性能起着重要作用。