Ultrastructure of the resting and contracted striated muscle fiber at different degrees of stretch.
Ultrastructure of the resting and contracted striated muscle fiber at different degrees of stretch.
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DOI：
10.1083/jcb.11.1.95
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发表时间：
1961-10
期刊：
影响因子：
--
通讯作者：
BUCHTHAL F
中科院分区：
文献类型：
--
作者：
CARLSEN F;KNAPPEIS GG;BUCHTHAL F
被动拉伸，等长收缩，缩短条纹，非甘油化的青蛙肌纤维的电子显微镜照片进行了研究。通过比较固定前、固定中、固定后和切片后的肌节长度和纤维直径，评价不同制备步骤所致的伪影。在固定前和固定过程中记录静息和收缩纤维的张力和长度。可以追踪I丝进入I带两侧A丝之间的A带，产生重叠区，其随着拉伸线性减小，随着缩短而增加。这与滑动细丝模型一致。在等长收缩过程中，A肌丝和I肌丝长度的减少，以及肌节长度为3.7 μ m的纤维仍能产生最大强直张力的30%的发现，都不能用滑动肌丝模型来解释。在仍然有重叠的肌腱连接处附近的肌节缩短只能解释这种张力的六分之一，这表明即使那些肌节拉伸到A和I丝之间存在间隙的程度，在等长收缩期间也会被激活（刚度增加）。缩短也与纤维长度的变化有关。A丝的直径保持不变的拉伸和等长收缩。缩短50%与A丝直径增加13%有关。原纤维和原纤维间空间所占的面积随着缩短而增加，表明当缩短达到40%时，原纤维的体积减少20%。
Passive stretch, isometric contraction, and shortening were studied in electron micrographs of striated, non-glycerinated frog muscle fibers. The artifacts due to the different steps of preparation were evaluated by comparing sarcomere length and fiber diameter before, during, and after fixation and after sectioning. Tension and length were recorded in the resting and contracted fiber before and during fixation. The I filaments could be traced to enter the A band between the A filaments on both sides of the I band, creating a zone of overlap which decreased linearly with stretch and increased with shortening. This is consistent with a sliding filament model. The decrease in the length of the A and I filaments during isometric contraction and the finding that fibers stretched to a sarcomere length of 3.7 µ still developed 30 per cent of the maximum tetanic tension could not be explained in terms of the sliding filament model. Shortening of the sarcomeres near the myotendinous junctions which still have overlap could account for only one-sixth of this tension, indicating that even those sarcomeres stretched to such a degree that there is a gap between A and I filaments are activated during isometric contraction (increase in stiffness). Shortening, too, was associated with changes in filament length. The diameter of A filaments remained unaltered with stretch and with isometric contraction. Shortening of 50 per cent was associated with a 13 per cent increase in A filament diameter. The area occupied by the fibrils and by the interfibrillar space increased with shortening, indicating a 20 per cent reduction in the volume of the fibrils when shortening amounted to 40 per cent.
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DOI：
10.1083/jcb.3.5.631
发表时间：
1957-09-25
期刊：
The Journal of biophysical and biochemical cytology
影响因子：
--
作者：
HUXLEY HE
通讯作者：
HUXLEY HE
影响因子：
64.8
作者：
HUXLEY, AF;NIEDERGERKE, R
通讯作者：
NIEDERGERKE, R
影响因子：
--
作者：
Ramsey, RW;Street, SF
通讯作者：
Street, SF
影响因子：
5.5
作者：
HUXLEY, AF;PEACHEY, LD
通讯作者：
PEACHEY, LD
DOI：
10.1083/jcb.2.4.3
发表时间：
1956-01-01
期刊：
JOUR BIOPHYS AND BIOCHEM CYTOL
影响因子：
--
作者：
BORYSKO, EMIL
通讯作者：
BORYSKO, EMIL