This perspective attempts to shed light on an old and not yet solved controversy in cardiac physiology, i.e. the impact of increasing RyR2 open probability on myocardial function. Based on an already proved myocyte model, it is shown that increasing RyR2 open probability results in a purely short-lived increase in Ca2+ transient amplitude, and therefore it does not increase cardiac contractility. However, potentiation of RyR2 activity permanently enhances fractional Ca2+ release, shifting the intracellular Ca2+ transient vs SR Ca2+ content curve to a new state of higher efficiency. This allows the heart to maintain a given contractility despite a decrease in SR Ca2+ content, to enhance contractility if SR Ca2+ content is simultaneously preserved or to successfully counteract the effects of a negative inotropic action.
- open probability
- cardiac Contractility
- Copyright © 2017, American Journal of Physiology-Heart and Circulatory Physiology