This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 102/2/242    most recent CIRCRESAHA.107.164798v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhang, Y. H. Articles by Casadei, B. Search for Related Content PubMed PubMed Citation Articles by Zhang, Y. H. Articles by Casadei, B. Pubmed/NCBI databases Gene GEO Profiles HomoloGene UniGene Compound via MeSH Substance via MeSH Related Collections Contractile function Calcium cycling/excitation-contraction coupling Cell signalling/signal transduction Genetically altered mice Related Article

(Circulation Research. 2008;102:242.)
© 2008 American Heart Association, Inc.

Cellular Biology

Reduced Phospholamban Phosphorylation Is Associated With Impaired Relaxation in Left Ventricular Myocytes From Neuronal NO Synthase–Deficient Mice

Yin Hua Zhang^*, Mei Hua Zhang^*, Claire E. Sears, Krzysztof Emanuel, Charles Redwood, Ali El-Armouche, Evangelia G. Kranias, Barbara Casadei

From the Department of Cardiovascular Medicine (Y.H.Z., M.H.Z., C.E.S., K.E., C.R., B.C.), University of Oxford, John Radcliffe Hospital, United Kingdom; Institute of Experimental and Clinical Pharmacology (A.E.-A.), University Hospital Eppendorf, Hamburg, Germany; and Department of Pharmacology and Cell Biophysics (E.G.K.), University of Cincinnati College of Medicine, Ohio.

Correspondence to Barbara Casadei, MD, PhD, University Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom. E-mail barbara.casadei{at}cardiov.ox.ac.uk

Stimulation of nitric oxide (NO) release from the coronary endothelium facilitates myocardial relaxation via a cGMP-dependent reduction in myofilament Ca²⁺ sensitivity. Recent evidence suggests that NO released by a neuronal NO synthase (nNOS) in the myocardium can also hasten left ventricular relaxation; however, the mechanism underlying these findings is uncertain. Here we show that both relaxation (TR₅₀) and the rate of [Ca²⁺]_i transient decay (tau) are significantly prolonged in field-stimulated or voltage-clamped left ventricular myocytes from nNOS^–/– mice and in wild-type myocytes (nNOS^+/+) after acute nNOS inhibition. Disabling the sarcoplasmic reticulum abolished the differences in TR₅₀ and tau, suggesting that impaired sarcoplasmic reticulum Ca²⁺ reuptake may account for the slower relaxation in nNOS^–/– mice. In line with these findings, disruption of nNOS (but not of endothelial NOS) decreased phospholamban phosphorylation (P-Ser¹⁶ PLN), whereas nNOS inhibition had no effect on TR₅₀ or tau in PLN^–/– myocytes. Inhibition of cGMP signaling had no effect on relaxation in either group whereas protein kinase A inhibition abolished the difference in relaxation and PLN phosphorylation by decreasing P-Ser¹⁶ PLN and prolonging TR₅₀ in nNOS^+/+ myocytes. Conversely, inhibition of type 1 or 2A protein phosphatases shortened TR₅₀ and increased P-Ser¹⁶ PLN in nNOS^–/– but not in nNOS^+/+ myocytes, in agreement with data showing increased protein phosphatase activity in nNOS^–/– hearts. Taken together, our findings identify a novel mechanism by which myocardial nNOS promotes left ventricular relaxation by regulating the protein kinase A–mediated phosphorylation of PLN and the rate of sarcoplasmic reticulum Ca²⁺ reuptake via a cGMP-independent effect on protein phosphatase activity.

Key Words: neuronal NOS • nitric oxide • relaxation • phospholamban • phosphatases

Related Article:

Neuronal NO Synthase–Derived NO: A Novel Relaxing Factor in Myocardium?

Norio Fukuda, Jin O-Uchi, and Satoshi Kurihara
Circ. Res. 2008 102: 148-150. [Extract] [Full Text] [PDF]

This article has been cited by other articles:

				F. Garofalo, M. L. Parisella, D. Amelio, B. Tota, and S. Imbrogno Phospholamban S-nitrosylation modulates Starling response in fish heart Proc R Soc B, November 22, 2009; 276(1675): 4043 - 4052. [Abstract] [Full Text] [PDF]

				D. E. Burger, X. Lu, M. Lei, F.-L. Xiang, L. Hammoud, M. Jiang, H. Wang, D. L. Jones, S. M. Sims, and Q. Feng Neuronal Nitric Oxide Synthase Protects Against Myocardial Infarction-Induced Ventricular Arrhythmia and Mortality in Mice Circulation, October 6, 2009; 120(14): 1345 - 1354. [Abstract] [Full Text] [PDF]

				P. J. Schaeffer, J. DeSantiago, J. Yang, T. P. Flagg, A. Kovacs, C. J. Weinheimer, M. Courtois, T. C. Leone, C. G. Nichols, D. M. Bers, et al. Impaired contractile function and calcium handling in hearts of cardiac-specific calcineurin b1-deficient mice Am J Physiol Heart Circ Physiol, October 1, 2009; 297(4): H1263 - H1273. [Abstract] [Full Text] [PDF]

				T. M. A. Mohamed, D. Oceandy, S. Prehar, N. Alatwi, Z. Hegab, F. M. Baudoin, A. Pickard, A. O. Zaki, R. Nadif, E. J. Cartwright, et al. Specific Role of Neuronal Nitric-oxide Synthase when Tethered to the Plasma Membrane Calcium Pump in Regulating the {beta}-Adrenergic Signal in the Myocardium J. Biol. Chem., May 1, 2009; 284(18): 12091 - 12098. [Abstract] [Full Text] [PDF]

				J. G.F. Bronzwaer and W. J. Paulus Nitric oxide: the missing lusitrope in failing myocardium Eur. Heart J., October 2, 2008; 29(20): 2453 - 2455. [Full Text] [PDF]

				S. K. Powers and M. J. Jackson Exercise-Induced Oxidative Stress: Cellular Mechanisms and Impact on Muscle Force Production Physiol Rev, October 1, 2008; 88(4): 1243 - 1276. [Abstract] [Full Text] [PDF]

				X. Loyer, A. M. Gomez, P. Milliez, M. Fernandez-Velasco, P. Vangheluwe, L. Vinet, D. Charue, E. Vaudin, W. Zhang, Y. Sainte-Marie, et al. Cardiomyocyte Overexpression of Neuronal Nitric Oxide Synthase Delays Transition Toward Heart Failure in Response to Pressure Overload by Preserving Calcium Cycling Circulation, June 24, 2008; 117(25): 3187 - 3198. [Abstract] [Full Text] [PDF]

				H. Wang, M. J. Kohr, C. J. Traynham, D. G. Wheeler, P. M. L. Janssen, and M. T. Ziolo Neuronal nitric oxide synthase signaling within cardiac myocytes targets phospholamban Am J Physiol Cell Physiol, June 1, 2008; 294(6): C1566 - C1575. [Abstract] [Full Text] [PDF]

				N. Fukuda, J. O-Uchi, and S. Kurihara Neuronal NO Synthase-Derived NO: A Novel Relaxing Factor in Myocardium? Circ. Res., February 1, 2008; 102(2): 148 - 150. [Full Text] [PDF]