Nitric oxide regulates cardiac intracellular Na+ and Ca2+ by modulating Na/K ATPase via PKCε and phospholemman-dependent mechanism

Davor Pavlovic, Andrew R. Hall, Erika J. Kennington, Karen Aughton, Andrii Boguslavskyi, William Fuller, Sanda Despa, Donald M Bers, Michael J. Shattock

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

In the heart, Na/K-ATPase regulates intracellular Na+ and Ca2+ (via NCX), thereby preventing Na+ and Ca2+ overload and arrhythmias. Here, we test the hypothesis that nitric oxide (NO) regulates cardiac intracellular Na+ and Ca2+ and investigate mechanisms and physiological consequences involved. Effects of both exogenous NO (via NO-donors) and endogenously synthesized NO (via field-stimulation of ventricular myocytes) were assessed in this study. Field stimulation of rat ventricular myocytes significantly increased endogenous NO (18±2μM), PKCε activation (82±12%), phospholemman phosphorylation (at Ser-63 and Ser-68) and Na/K-ATPase activity (measured by DAF-FM dye, western-blotting and biochemical assay, respectively; p<0.05, n=6) and all were abolished by Ca2+-chelation (EGTA 10mM) or NOS inhibition l-NAME (1mM). Exogenously added NO (spermine-NONO-ate) stimulated Na/K-ATPase (EC50=3.8μM; n=6/grp), via decrease in Km, in PLMWT but not PLMKO or PLM3SA myocytes (where phospholemman cannot be phosphorylated) as measured by whole-cell perforated-patch clamp. Field-stimulation with l-NAME or PKC-inhibitor (2μM Bis) resulted in elevated intracellular Na+ (22±1.5 and 24±2 respectively, vs. 14±0.6mM in controls) in SBFI-AM-loaded rat myocytes. Arrhythmia incidence was significantly increased in rat hearts paced in the presence of l-NAME (and this was reversed by l-arginine), as well as in PLM3SA mouse hearts but not PLMWT and PLMKO. We provide physiological and biochemical evidence for a novel regulatory pathway whereby NO activates Na/K-ATPase via phospholemman phosphorylation and thereby limits Na+ and Ca2+ overload and arrhythmias. This article is part of a Special Issue entitled "Na+ Regulation in Cardiac Myocytes".

Original languageEnglish (US)
Pages (from-to)164-171
Number of pages8
JournalJournal of Molecular and Cellular Cardiology
Volume61
DOIs
StatePublished - Aug 2013

Keywords

  • Arrhythmia
  • FXYD-1
  • Nitric oxide
  • Phospholemman
  • Protein kinase C
  • Sodium pump

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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