Oxidant stress from nitric oxide synthase–3 uncoupling stimulates cardiac pathologic remodeling from chronic pressure load
Eiki Takimoto, … , Yibin Wang, David A. Kass
Eiki Takimoto, … , Yibin Wang, David A. Kass
Published May 2, 2005
Citation Information: J Clin Invest. 2005;115(5):1221-1231. https://doi.org/10.1172/JCI21968.
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Article Cardiology

Oxidant stress from nitric oxide synthase–3 uncoupling stimulates cardiac pathologic remodeling from chronic pressure load

Abstract

Cardiac pressure load stimulates hypertrophy, often leading to chamber dilation and dysfunction. ROS contribute to this process. Here we show that uncoupling of nitric oxide synthase–3 (NOS3) plays a major role in pressure load–induced myocardial ROS and consequent chamber remodeling/hypertrophy. Chronic transverse aortic constriction (TAC; for 3 and 9 weeks) in control mice induced marked cardiac hypertrophy, dilation, and dysfunction. Mice lacking NOS3 displayed modest and concentric hypertrophy to TAC with preserved function. NOS3–/– TAC hearts developed less fibrosis, myocyte hypertrophy, and fetal gene re-expression (B-natriuretic peptide and α–skeletal actin). ROS, nitrotyrosine, and gelatinase (MMP-2 and MMP-9) zymogen activity markedly increased in control TAC, but not in NOS3–/– TAC, hearts. TAC induced NOS3 uncoupling in the heart, reflected by reduced NOS3 dimer and tetrahydrobiopterin (BH4), increased NOS3-dependent generation of ROS, and lowered Ca2+-dependent NOS activity. Cotreatment with BH4 prevented NOS3 uncoupling and inhibited ROS, resulting in concentric nondilated hypertrophy. Mice given the antioxidant tetrahydroneopterin as a control did not display changes in TAC response. Thus, pressure overload triggers NOS3 uncoupling as a prominent source of myocardial ROS that contribute to dilatory remodeling and cardiac dysfunction. Reversal of this process by BH4 suggests a potential treatment to ameliorate the pathophysiology of chronic pressure-induced hypertrophy.

Authors

Eiki Takimoto, Hunter C. Champion, Manxiang Li, Shuxun Ren, E. Rene Rodriguez, Barbara Tavazzi, Giuseppe Lazzarino, Nazareno Paolocci, Kathleen L. Gabrielson, Yibin Wang, David A. Kass

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Figure 6

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Evidence of NOS3 uncoupling in WT TAC hearts. (A) In the WT sham heart, ...
Evidence of NOS3 uncoupling in WT TAC hearts. (A) In the WT sham heart, NOS3 appeared as both a dimer (NOS3-d) and a monomer (NOS3-m), with the largest fraction as a dimer. In boiled samples (control), the dimer was replaced by the monomeric form. The 3-week WT TAC heart exhibited largely the monomeric form, although total NOS3 expression assessed by Western blot (B) was not altered. (C) NOS Ca2+-dependent and -independent activity based on L-citrulline formation. Ca2+-dependent activity declined in WT TAC hearts (*P < 0.05). Low levels were also seen in NOS3–/– mutants, reflecting NOS1 activity. Ca2+-independent NOS2 activity showed little change. (D) Impact of pharmacological NOS3 inhibition on luminol chemiluminescence assay. Coincubation with 1 mM L-NAME inhibited 50% of luminol chemiluminescence in 3-week and 9-week WT TAC heart lysates and inhibited less than 15% at base line, supporting an increased role of NOS in O2– generation with TAC. Corresponding data for NOS3–/– myocardium are shown at right. *P < 0.05 versus WT sham at 3 weeks.