Wohlfart B
Acta Physiol Scand. 1979 Aug;106(4):395-409. doi: 10.1111/j.1748-1716.1979.tb06419.x.
Isometric force and membrane action potential were recorded simultaneously in rabbit papillary muscles (36.5 degrees--37.5 degrees C). One to three test stimuli were given at various intervals (0.20--10.0 s) after a series of control contractions at constant stimulation intervals (1.0--1.5 s). Optimum peak force always occurred when the preceding test interval was 0.80 s. When this interval was greater than 0.80 s, time to peak force was a linear function of the action potential duration. Furthermore, under these conditions the action potential duration (AP1) and peak force (F1) of the test contraction could be used to predict peak force (F2) of the subsequent contraction elicited after a fixed interval (0.80--1.50 s) according to the equation (regression plane): F2 = BAPAP1 + BFF1 + A. Constants BAP and BF are interpreted to provide information about calcium influx during the action potential and of the recirculation of calcium between contractions, respectively. F2 deviated towards higher values than predicted from the equation when the preceding test contraction was triggered to occur at an interval less than 0.80 s. This may be due to an intensified calcium transport into the cell during the action potential after these short intervals. The action potential duration was inversely related to both the inotropic state of the muscle (representing a feed-back mechanism) and the preceding stimulation interval.
在兔乳头肌（36.5摄氏度至37.5摄氏度）中同时记录等长力和膜动作电位。在以恒定刺激间隔（1.0至1.5秒）进行一系列对照收缩后，以不同间隔（0.20至10.0秒）施加一至三个测试刺激。当先前的测试间隔为0.80秒时，总是会出现最佳峰值力。当该间隔大于0.80秒时，达到峰值力的时间是动作电位持续时间的线性函数。此外，在这些条件下，测试收缩的动作电位持续时间（AP1）和峰值力（F1）可用于根据方程（回归平面）预测在固定间隔（0.80至1.50秒）后引发的后续收缩的峰值力（F2）：F2 = BAPAP1 + BFF1 + A。常数BAP和BF分别被解释为提供有关动作电位期间钙内流以及收缩之间钙再循环的信息。当先前的测试收缩以小于0.80秒的间隔触发时，F2偏离方程预测的值而向更高值偏移。这可能是由于在这些短间隔后的动作电位期间钙向细胞内的转运增强。动作电位持续时间与肌肉的变力状态（代表一种反馈机制）和先前的刺激间隔均呈负相关。
