Poggesi C, Bottinelli R, Vitale M, Testa S
Pflugers Arch. 1984 Nov;402(3):321-4. doi: 10.1007/BF00585517.
The degree and decay of postextrasystolic potentiation were studied in isolated rat papillary muscle at Lmax, the length at which developed force was maximum, and at shorter lengths. Potentiation curves were constructed relating the degree of potentiation with the time interval between any given extrasystole and the last steady-state beat. At all stimulation rates tested (ranging from 3 to 60/min), potentiation curves were found to be dependent on muscle length: at any interval the degree of potentiation increased progressively with decreasing initial muscle length. At all lengths and stimulation frequencies tested, the decay of potentiation was a function of the number of beats following the extrasystole. This relationship could be fitted by a single exponential equation. The exponential constant of the decay was significantly smaller at Lmax than at shorter lengths. These results suggest that muscle length affects more than one step of the E-C coupling processes.
在离体大鼠乳头肌中，于Lmax（即产生最大力量时的长度）和较短长度下，研究了期外收缩后增强的程度和衰减情况。构建了增强程度与任意给定期外收缩和最后一个稳态搏动之间的时间间隔相关的增强曲线。在所有测试的刺激频率（范围为3至60次/分钟）下，发现增强曲线取决于肌肉长度：在任何间隔下，增强程度随着初始肌肉长度的减小而逐渐增加。在所有测试的长度和刺激频率下，增强的衰减是期外收缩后搏动次数的函数。这种关系可以用单个指数方程拟合。衰减的指数常数在Lmax时明显小于在较短长度时。这些结果表明，肌肉长度对兴奋 - 收缩偶联过程的多个步骤都有影响。
