Leach J K, Brady A J, Skipper B J, Millis D L
Am J Physiol. 1980 Jan;238(1):H8-13. doi: 10.1152/ajpheart.1980.238.1.H8.
Duration and intensity of force development have been shown to be less during active muscle shortening than during isometric contraction. The purpose of this study was to compare force developed during controlled shortening with that predicted by the Frank-Starling relation. Paillary muscles from the right ventricles of rabbits were arranged for isometric tension recording, and isometric contractions were recorded at several lengths. The muscles were then permitted to shorten at velocities of 0.2--6 mm/s, shortening beginning 150--200 ms after the stimulus. Length-tension-time curves constructed from the isometric contractions were used to determine predicted shortening tension (Pp), which was compared with actual tension during shortening (Ps) at corresponding times and lengths. Ps was significantly less than Pp and the ratio Ps/Pp decreased with increasing velocity of shortening. The decrease in Ps/Pp was directly related to the duration of shortening (P less than 0.001), suggesting that the fall of shortening tension reflected both the Hill force-velocity relation and shortening deactivation.
已表明，在肌肉主动缩短过程中，力量发展的持续时间和强度比等长收缩时要小。本研究的目的是比较在受控缩短过程中产生的力量与根据弗兰克 - 斯塔林关系预测的力量。将来自兔右心室的乳头肌安排用于等长张力记录，并在几个长度下记录等长收缩。然后让肌肉以0.2 - 6毫米/秒的速度缩短，缩短在刺激后150 - 200毫秒开始。由等长收缩构建的长度 - 张力 - 时间曲线用于确定预测的缩短张力（Pp），并将其与相应时间和长度下缩短过程中的实际张力（Ps）进行比较。Ps显著小于Pp，且Ps/Pp比值随缩短速度的增加而降低。Ps/Pp的降低与缩短持续时间直接相关（P小于0.001），这表明缩短张力的下降既反映了希尔力 - 速度关系，也反映了缩短失活。
