Double‐hyperbolic force‐velocity relation in frog muscle fibres.
Double‐hyperbolic force‐velocity relation in frog muscle fibres.
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青蛙肌纤维的双双曲力-速度关系。
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发表时间：
1988
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通讯作者：
K. Edman
中科院分区：
文献类型：
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作者：
K. Edman
1. 在从林蛙胫骨前肌中分离出的单纤维中，在融合破伤风（1-3 摄氏度）期间，研究了 2.10 微米肌节长度下的力和缩短速度之间的关系。缩短速度是从整个纤维记录的，在一些实验中，同时从短段（约 0.6 毫米）记录，同时释放制剂以在选定的力水平下等渗缩短（“负载夹”记录）。该片段由放置在纤维表面上的不透明毛发标记来定义。标记之间的距离通过光电探测器系统记录。 2.力-速度关系有两个不同的区域，每个区域都呈现向上凹的形状，分别位于测量的等长力（P0）的0-78％和78-100％范围内。力-速度关系的两个部分可以通过双曲函数或单指数函数很好地拟合。高力区域的曲率比中低负载的曲率更明显。力-速度关系的两个部分（力-速度曲线的“断点”）之间的转变发生在 P0 的 78.4 +/- 0.4%（平均值 +/- S.E. 平均值，n = 12）处，对应于最大缩短速度 (Vmax) 的 10.9 +/- 0.4%。当对整个纤维和沿同一纤维的一小段进行测量时，力-速度曲线的总体形状以及 P0 78% 附近断点的出现是相同的。 3. 在五个实验中，针对 P0 至 1.6-1.8 P0 范围内的载荷，描述了力-速度关系的“负”分支。负分支形成了 0.78 P0 和 P0 之间记录的力-速度关系的平滑延续。力-速度关系在 0.90 P0 和 1.20 P0 之间几乎持平，在此范围内缩短或伸长的速度差异为 Vmax 的 1.8 +/- 0.3%（平均值 +/- S.E.，n = 5）。 4. 肌节长度从 1.85 微米增加到 2.60 微米不会影响 Vmax，但会导致力-速度关系的曲率稳定减小，无论是在中低载荷还是在高力范围内。通过添加 98 mM 蔗糖制成高渗林格溶液，通过纤维的渗透压缩产生力-速度关系形状的类似变化。（摘要截断为 400 字）
1. The relationship between force and velocity of shortening was studied at 2.10 micron sarcomere length during fused tetani (1‐3 degrees C) in single fibres isolated from the anterior tibialis muscle of Rana temporaria. The speed of shortening was recorded from the whole fibre and, in some experiments, simultaneously from a short (ca. 0.6 mm) segment, while the preparation was released to shorten isotonically at selected force levels (‘load‐clamp’ recording). The segment was defined by opaque markers of hair that were placed on the fibre surface. The distance between the markers was recorded by means of a photo‐electric detector system. 2. The force‐velocity relation had two distinct regions, each one exhibiting an upwards concave shape, that were located within the ranges 0‐78 and 78‐100% of the measured isometric force (P0), respectively. The two portions of the force‐velocity relation could be fitted well by hyperbolic functions or by single‐exponential functions. The curvature was more pronounced in the high‐force region than at low‐intermediate loads. The transition between the two portions of the force‐velocity relation (the ‘break point’ of the force‐velocity curve) occurred at 78.4 +/‐ 0.4% of P0 (mean +/‐ S.E. of mean, n = 12) corresponding to 10.9 +/‐ 0.4% of maximum velocity of shortening (Vmax). The general shape of the force‐velocity curve, and the appearance of a break point near 78% of P0, was the same when measurements were made from the whole fibre and from a short segment along the same fibre. 3. The ‘negative’ branch of the force‐velocity relation was delineated for loads ranging from P0 to 1.6‐1.8 P0 in five experiments. The negative branch formed a smooth continuation of the force‐velocity relation recorded between 0.78 P0 and P0. The force‐velocity relation was nearly flat between 0.90 P0 and 1.20 P0, the difference in speed of shortening or elongation being 1.8 +/‐ 0.3% (mean +/‐ S.E. of mean, n = 5) of Vmax over this range. 4. An increase in sarcomere length from 1.85 to 2.60 micron did not affect Vmax but caused a steady decrease in curvature of the force‐velocity relation, both at low‐intermediate loads and in the high‐force range. Similar changes in shape of the force‐velocity relation were produced by osmotic compression of the fibre in a Ringer solution made hypertonic by addition of 98 mM‐sucrose.(ABSTRACT TRUNCATED AT 400 WORDS)