CAMP-Dependent Signaling Restores AP Firing in Dormant SA Node Cells via Enhancement of Surface Membrane Currents and Calcium Coupling.

ABSTRACT: Action potential (AP) firing rate and rhythm of sinoatrial nodal cells (SANC) are controlled by synergy between intracellular rhythmic local Ca²⁺ releases (LCRs) ("Ca²⁺ clock") and sarcolemmal electrogenic mechanisms ("membrane clock"). However, some SANC do not fire APs (dormant SANC). Prior studies have shown that β-adrenoceptor stimulation can restore AP firing in these cells. Here we tested whether this relates to improvement of synchronization of clock coupling. We characterized membrane potential, ion currents, Ca²⁺ dynamics, and phospholamban (PLB) phosphorylation, regulating Ca²⁺ pump in enzymatically isolated single guinea pig SANC prior to, during, and following β-adrenoceptor stimulation (isoproterenol) or application of cell-permeant

SUBMITTER: Tsutsui K 

PROVIDER: S-EPMC8063038 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature