In human fetal myocardium, muscle length and contraction frequency independently modulate the active state and action potential, providing insights into excitation-contraction coupling.
Abstract Active state and action potential measurements were performed on papillary muscles from human foetuses.Changes in these two parameters induced by alterations in muscle length and contraction frequency were studied.Shortening of the muscle not only reduced the intensity of the active state, but also shortened its time course without any concomitant alteration in action potential duration.A decrease in stimulation frequency caused a reduction in the intensity of the active state and an increase in the durations of the active state and the action potential.The change in the action potential duration was considerably greater than that of the active state.The results are discussed in the relation to the activator hypothesis for excitation‐contraction coupling in the myocardium.
Gennser et al. (Wed,) studied this question.
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