Crosstalk between Mitochondrial and Sarcoplasmic Reticulum Ca2+ Cycling Modulates Cardiac Pacemaker Cell Automaticity
Open Access
- 29 May 2012
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 7 (5), e37582
- https://doi.org/10.1371/journal.pone.0037582
Abstract
Mitochondria dynamically buffer cytosolic Ca2+ in cardiac ventricular cells and this affects the Ca2+ load of the sarcoplasmic reticulum (SR). In sinoatrial-node cells (SANC) the SR generates periodic local, subsarcolemmal Ca2+ releases (LCRs) that depend upon the SR load and are involved in SANC automaticity: LCRs activate an inward Na+-Ca2+ exchange current to accelerate the diastolic depolarization, prompting the ensemble of surface membrane ion channels to generate the next action potential (AP). To determine if mitochondrial Ca2+ (Ca2+m), cytosolic Ca2+ (Ca2+c)-SR-Ca2+ crosstalk occurs in single rabbit SANC, and how this may relate to SANC normal automaticity. Inhibition of mitochondrial Ca2+ influx into (Ru360) or Ca2+ efflux from (CGP-37157) decreased [Ca2+]m to 80±8% control or increased [Ca2+]m to 119±7% control, respectively. Concurrent with inhibition of mitochondrial Ca2+ influx or efflux, the SR Ca2+ load, and LCR size, duration, amplitude and period (imaged via confocal linescan) significantly increased or decreased, respectively. Changes in total ensemble LCR Ca2+ signal were highly correlated with the change in the SR Ca2+ load (r2 = 0.97). Changes in the spontaneous AP cycle length (Ru360, 111±1% control; CGP-37157, 89±2% control) in response to changes in [Ca2+]m were predicted by concurrent changes in LCR period (r2 = 0.84). A change in SANC Ca2+m flux translates into a change in the AP firing rate by effecting changes in Ca2+c and SR Ca2+ loading, which affects the characteristics of spontaneous SR Ca2+ release.Keywords
This publication has 33 references indexed in Scilit:
- Ca2+-regulated-cAMP/PKA signaling in cardiac pacemaker cells links ATP supply to demandJournal of Molecular and Cellular Cardiology, 2011
- Letter to the editor: “Validating the requirement for beat-to-beat coupling of the Ca2+ clock and M clock in pacemaker cell normal automaticity”American Journal of Physiology-Heart and Circulatory Physiology, 2011
- CGP-37157 Inhibits the Sarcoplasmic Reticulum Ca2+ATPase and Activates Ryanodine Receptor Channels in Striated MuscleMolecular Pharmacology, 2010
- Role of perinuclear mitochondria in the spatiotemporal dynamics of spontaneous Ca2+ waves in interstitial cells of Cajal‐like cells of the rabbit urethraBritish Journal of Pharmacology, 2010
- If and SR Ca2+ release both contribute to pacemaker activity in canine sinoatrial node cellsJournal of Molecular and Cellular Cardiology, 2010
- Role of mitochondrial dysfunction in cardiac glycoside toxicityJournal of Molecular and Cellular Cardiology, 2010
- A novel quantitative explanation for the autonomic modulation of cardiac pacemaker cell automaticity via a dynamic system of sarcolemmal and intracellular proteinsAmerican Journal of Physiology-Heart and Circulatory Physiology, 2010
- NCLX is an essential component of mitochondrial Na + /Ca 2+ exchangeProceedings of the National Academy of Sciences of the United States of America, 2009
- Mitochondrial free calcium regulation during sarcoplasmic reticulum calcium release in rat cardiac myocytesJournal of Molecular and Cellular Cardiology, 2009
- Sequential Opening of Mitochondrial Ion Channels as a Function of Glutathione Redox Thiol StatusPublished by Elsevier BV ,2007