Plateau and descending limb of the sarcomere length‐tension relation in short length‐clamped segments of frog muscle fibres.
Plateau and descending limb of the sarcomere length‐tension relation in short length‐clamped segments of frog muscle fibres.
复制标题
青蛙肌纤维短长度夹紧段中肌节长度张力关系的平台和降肢。
DOI：
10.1113/jphysiol.1988.sp017181
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
C. Tesi
中科院分区：
文献类型：
--
作者：
M. Bagni;G. Cecchi;F. Colomo;C. Tesi
1.肌节长度和强直张力之间的关系是在10 - 12摄氏度下对从青蛙的胫骨前肌和半腱肌分离的70 - 80微米长的单纤维段进行测定的。在固定端或长度钳收缩期间，通过激光衍射仪测量节段条纹间距。2.在肌节长度约为2.10微米时，强直张力迅速上升到稳定的平台，与记录条件无关。在固定端条件下，肌节长度较大时，张力升高发生在两个不同的阶段：最初的快速升高，随后是慢得多的蠕变。在长度钳收缩中，张力蠕变完全消失。3.胫骨前肌纤维长度夹持段的肌节长度-张力图显示，在约1.96 - 2.16 μ m之间存在一个明确的平坦区域，张力变化小于1.5%。高度线性的下降分支在约3.53微米处达到零张力。相对于半腱肌纤维的长度夹紧段的长度张力图，向左移动约0.10微米，可以通过假设细丝长度在不同的肌肉中变化来初步解释。4.这些结果与Gordon，Huxley & Julian（1966）先前的工作一致，并支持Huxley，1957，1980的假说，即肌肉张力是由独立的力发生器同时作用产生的，与肌动蛋白丝重叠的肌球蛋白桥的数量成比例。
1. The relation between sarcomere length and tetanic tension was determined at 10‐12 degrees C for 70‐80 microns long segments of single fibres isolated from the tibialis anterior and semitendinosus muscles of the frog. Measurements of segment striation spacings were performed during fixed‐end or length‐clamp contractions by means of a laser light diffractometer. 2. At sarcomere lengths of around 2.10 microns tetanic tension rose promptly to a steady plateau, independent of the recording conditions. At greater sarcomere lengths under fixed‐end conditions the tension rise occurred in two distinct stages: an initial rapid rise followed by a much slower creep. The tension creep was entirely abolished in length‐clamp contractions. 3. The sarcomere length‐tension diagram of length‐clamped segments of tibialis anterior fibres exhibited a definite flat region between about 1.96 and 2.16 microns where tension varied by less than 1.5%. The highly linear descending limb reached zero tension at about 3.53 microns. The shift to the left by about 0.10 microns, with respect to the length‐tension diagram of length‐clamped segments of semitendinosus fibres, may be tentatively explained by assuming that thin filament lengths vary in different muscles. 4. The results are in agreement with those of a previous work by Gordon, Huxley & Julian (1966) and support the hypothesis (Huxley, 1957, 1980) that muscle tension is produced by simultaneous action of independent force generators, in proportion to the number of myosin bridges overlapped by actin filaments.