Housmans P R, Lee N K, Blinks J R
Science. 1983 Jul 8;221(4606):159-61. doi: 10.1126/science.6857274.
When active shortening of the cat papillary muscle was allowed at any time during a contraction, the intracellular concentration of free calcium ions, detected with the calcium-sensitive bioluminescent protein aequorin, was higher than at comparable times in isometric twitches. The difference was not attributable to the differences of length involved or to motion artifacts, and must have been related to the act of shortening or the difference in force development in the two types of contractions. This observation and the phenomenon of shortening deactivation are both consistent with the hypothesis that attachment of cross bridges increases the affinity of the myofilaments for calcium ions.
当在猫乳头肌收缩过程中的任何时刻允许其主动缩短时，用钙敏感生物发光蛋白水母发光蛋白检测到的细胞内游离钙离子浓度，高于等长收缩时相应时刻的浓度。这种差异并非归因于所涉及的长度差异或运动伪影，而必定与缩短行为或两种收缩类型中力的发展差异有关。这一观察结果和缩短失活现象均与横桥附着增加肌丝对钙离子亲和力的假说一致。
