SPONTANEOUS FORMS OF CALCIUM RELEASE THAT STAY LOCAL

摘要

"The Cardiac Contraction Cycle: Is Ca~(2+) Going Local?" is a valuable "summation" of cellular mechanisms that contribute to spatio-temporal Ca~(2+) regulation within cardiac cells. While the opening scene highlights spontaneous stochastic Ca~(2+) releases via ryanodine receptors of the sarcolemmic reticulum, most of the subsequent focus shifts to action potential-triggered RyR Ca~(2+) release, i.e., synchronized form of RyR Ca~(2+) release. It is a pity that, within the context of "Ca~(2+) Going Local," the functional importance, in health and disease, of spontaneous RyR Ca~(2+) release, i.e., a localized, unsynchronized form of RyR Ca~(2+) release, is not addressed. For example, in cardiac pacemaker cells, local submembrane RyR Ca~(2+) releases are a crucial mechanism for normal automaticity (5).