Depolarization of cardiac membrane potential synchronizes calcium sparks and waves in tissue.

摘要: The diastolic membrane potential (Vm) can be hyperpolarized or depolarized by various factors such as hyperkalemia hypokalemia in the long term, delayed afterdepolarizations short term. In this study, we investigate how Vm affects Ca sparks and waves. We use a physiologically detailed mathematical model to individual that affect spark generation wave propagation. focus on voltage range of −90 ∼ −70 mV, which is just below for sodium channel activation. find depolarization promotes propagation hyperpolarization prevents it. This finding directly validated clamp experiments with waves using isolated rat ventricular myocytes. transport sodium-calcium exchanger (NCX) determined well Na concentrations. Depolarized reduces NCX-mediated efflux, elevating [Ca]i, thus promoting Moreover, spontaneous releases cause initiation multiple indicates during afterdepolarizations, release units (CRUs) interact not immediately adjacent CRUs via diffusion, but also further fast (∼0.1 ms) changes mediated Ca-sensitive NCX. may contribute significantly synchronization among cells tissue.