Lakatta E G
Gerontology Research Center, National Institute on Aging, Baltimore, Maryland 21224.
J Am Coll Cardiol. 1987 Nov;10(5):1157-64. doi: 10.1016/s0735-1097(87)80361-3.
The results of several different types of investigations over the last decade clearly indicate that muscle length modulates the extent of myofilament calcium ion (Ca2+) activation. Similarly, the fiber length during a contraction, which is determined in part by the load encountered during shortening, also determines the extent of myofilament Ca2+ activation. Thus, "contractile" or "inotropic" state as it refers to the extent of myofilament activation can, in theory, no longer be considered independent of the muscle length, as was formerly thought to be the case. Accordingly, terms such as preload, afterload and myocardial contractile state as they pertain to cardiac muscle properties lose part of their significance in light of current knowledge.
过去十年中几项不同类型的研究结果清楚地表明，肌肉长度调节肌丝钙离子（Ca2+）激活的程度。同样，收缩过程中的纤维长度部分取决于缩短过程中遇到的负荷，它也决定了肌丝Ca2+激活的程度。因此，理论上，“收缩性”或“变力性”状态（指肌丝激活的程度）不再能像以前认为的那样被视为与肌肉长度无关。相应地，鉴于目前的知识，诸如前负荷、后负荷和心肌收缩状态等与心肌特性相关的术语失去了部分意义。
