Published online before print November 15, 2007, doi: 10.1161/CIRCRESAHA.107.164798
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on April 17, 2007
Revised on September 24, 2007
Accepted on November 1, 2007
Reduced Phospholamban Phosphorylation Is Associated With Impaired Relaxation in Left Ventricular Myocytes From Neuronal NO Synthase–Deficient Mice
Yin Hua Zhang ;
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.
* To whom correspondence should be addressed. 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]
|
|