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Circ Res. 2012 Sep 28;111(8):1002-11. Epub 2012 Jul 31.

Nitroxyl-mediated disulfide bond formation between cardiac myofilament cysteines enhances contractile function.

Author information

1
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. wgao3@jhmi.edu

Abstract

RATIONALE:

In the myocardium, redox/cysteine modification of proteins regulating Ca(2+) cycling can affect contraction and may have therapeutic value. Nitroxyl (HNO), the one-electron-reduced form of nitric oxide, enhances cardiac function in a manner that suggests reversible cysteine modifications of the contractile machinery.

OBJECTIVE:

To determine the effects of HNO modification in cardiac myofilament proteins.

METHODS AND RESULTS:

The HNO-donor, 1-nitrosocyclohexyl acetate, was found to act directly on the myofilament proteins, increasing maximum force (F(max)) and reducing the concentration of Ca(2+) for 50% activation (Ca(50)) in intact and skinned cardiac muscles. The effects of 1-nitrosocyclohexyl acetate are reversible by reducing agents and distinct from those of another HNO donor, Angeli salt, which was previously reported to increase F(max) without affecting Ca50. Using a new mass spectrometry capture technique based on the biotin switch assay, we identified and characterized the formation by HNO of a disulfide-linked actin-tropomyosin and myosin heavy chain-myosin light chain 1. Comparison of the 1-nitrosocyclohexyl acetate and Angeli salt effects with the modifications induced by each donor indicated the actin-tropomyosin and myosin heavy chain-myosin light chain 1 interactions independently correlated with increased Ca(2+) sensitivity and force generation, respectively.

CONCLUSIONS:

HNO exerts a direct effect on cardiac myofilament proteins increasing myofilament Ca(2+) responsiveness by promoting disulfide bond formation between critical cysteine residues. These findings indicate a novel, redox-based modulation of the contractile apparatus, which positively impacts myocardial function, providing further mechanistic insight for HNO as a therapeutic agent.

PMID:
22851540
PMCID:
PMC3470471
DOI:
10.1161/CIRCRESAHA.112.270827
[Indexed for MEDLINE]
Free PMC Article

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