Walcott B, Dewey M M
J Cell Biol. 1980 Oct;87(1):204-8. doi: 10.1083/jcb.87.1.204.
Laser diffraction techniques coupled with simultaneous tension measurements were used to determine the length-tension relation in intact, small (0.5-mm thick, 10-mm wide, 20-25-mm long) bundles of a Limulus (horseshoe crab) striated muscle, the telson levator muscle. This muscle differs from the model vertebrate systems in that the thick filaments are not of a constant length, but shorten from 4.9 to approximately 2.0 micrometers as the sarcomeres shorten from 7 to 3 micrometers. In the Limulus muscle, the length-tension relation plateaued to an average maximum tension of 0.34 N/mm2 at a sarcomere length of 6.5 micrometers (Lo) to 8.0 micrometers. In the sarcomere length range from 3.8 to 12.5 micrometers, the muscle developed 50% or more of the maximum tension. When the sarcomere lengths are normalized (expressed as L/Lo) and the Limulus data are compared to those from frog muscle, it is apparent that Limulus muscle develops tension over a relatively greater range of sarcomere lengths.
结合同步张力测量的激光衍射技术被用于确定完整的、小型（0.5毫米厚、10毫米宽、20 - 25毫米长）鲎（马蹄蟹）横纹肌束——尾节提肌的长度-张力关系。该肌肉与典型的脊椎动物肌肉系统不同，其粗肌丝长度并非恒定不变，而是随着肌节从7微米缩短至3微米，粗肌丝长度从4.9微米缩短至约2.0微米。在鲎肌肉中，肌节长度在6.5微米（Lo）至8.0微米时，长度-张力关系趋于平稳，平均最大张力为0.34 N/mm2。在肌节长度范围为3.8至12.5微米时，肌肉产生的张力达到最大张力的50%或更多。当肌节长度进行归一化处理（表示为L/Lo）并将鲎的数据与青蛙肌肉的数据进行比较时，很明显鲎肌肉在相对更大的肌节长度范围内产生张力。
