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

Pavlovic, D., Hall, A. R., Kennington, E. J., Aughton, K., Boguslavskyi, A., Fuller, W. , Despa, S., Bers, D. M. and Shattock, M. J. (2013) Nitric oxide regulates cardiac intracellular Na+ and Ca2+ by modulating Na/K ATPase via PKCε and phospholemman-dependent mechanism. Journal of Molecular and Cellular Cardiology, 61, pp. 164-171. (doi:10.1016/j.yjmcc.2013.04.013) (PMID:23612119) (PMCID:PMC3981027)

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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 ± 2 μM), 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 10 mM) or NOS inhibition l-NAME (1 mM). Exogenously added NO (spermine-NONO-ate) stimulated Na/K-ATPase (EC50 = 3.8 μM; 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 (2 μM Bis) resulted in elevated intracellular Na+ (22 ± 1.5 and 24 ± 2 respectively, vs. 14 ± 0.6 mM 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”.

Item Type:Articles
Additional Information:This work was supported by grants from the British Heart Foundation and the Medical Research Council and National Institute of Health R01-HL81562.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Fuller, Dr Will
Authors: Pavlovic, D., Hall, A. R., Kennington, E. J., Aughton, K., Boguslavskyi, A., Fuller, W., Despa, S., Bers, D. M., and Shattock, M. J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Journal of Molecular and Cellular Cardiology
Publisher:Elsevier
ISSN:0022-2828
ISSN (Online):1095-8584
Published Online:20 April 2013
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in Journal of Molecular and Cellular Cardiology 61:164-171
Publisher Policy:Reproduced under a Creative Commons License

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