Soluble guanylate cyclase is required for systemic vasodilation but not positive inotropy induced by nitroxyl in the mouse

Hypertension. 2015 Feb;65(2):385-92. doi: 10.1161/HYPERTENSIONAHA.114.04285. Epub 2014 Dec 1.


Nitroxyl (HNO), the reduced and protonated form of nitric oxide (NO·), confers unique physiological effects including vasorelaxation and enhanced cardiac contractility. These features have spawned current pharmaceutical development of HNO donors as heart failure therapeutics. HNO interacts with selective redox sensitive cysteines to effect signaling but is also proposed to activate soluble guanylate cyclase (sGC) in vitro to induce vasodilation and potentially enhance contractility. Here, we tested whether sGC stimulation is required for these HNO effects in vivo and if HNO also modifies a redox-sensitive cysteine (C42) in protein kinase G-1α to control vasorelaxation. Intact mice and isolated arteries lacking the sGC-β subunit (sGCKO, results in full sGC deficiency) or expressing solely a redox-dead C42S mutant protein kinase G-1α were exposed to the pure HNO donor, CXL-1020. CXL-1020 induced dose-dependent systemic vasodilation while increasing contractility in controls; however, vasodilator effects were absent in sGCKO mice whereas contractility response remained. The CXL-1020 dose reversing 50% of preconstricted force in aortic rings was ≈400-fold greater in sGCKO than controls. Cyclic-GMP and cAMP levels were unaltered in myocardium exposed to CXL-1020, despite its inotropic-vasodilator activity. In protein kinase G-1α(C42S) mice, CXL-1020 induced identical vasorelaxation in vivo and in isolated aortic and mesenteric vessels as in littermate controls. In both groups, dilation was near fully blocked by pharmacologically inhibiting sGC. Thus, sGC and cGMP-dependent signaling are necessary and sufficient for HNO-induced vasodilation in vivo but are not required for positive inotropic action. Redox modulation of protein kinase G-1α is not a mechanism for HNO-mediated vasodilation.

Keywords: cardiotonic agents; cardiovascular physiological phenomena; cyclic GMP-dependent protein kinases; guanylate cyclase; nitrogen oxides; pharmacology; vasodilation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / drug effects
  • Cardiotonic Agents / pharmacology*
  • Cyclic GMP / physiology
  • Cyclic GMP-Dependent Protein Kinase Type I / chemistry
  • Cyclic GMP-Dependent Protein Kinase Type I / deficiency
  • Cyclic GMP-Dependent Protein Kinase Type I / genetics
  • Cysteine / chemistry
  • Guanylate Cyclase / deficiency
  • Guanylate Cyclase / genetics
  • Guanylate Cyclase / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Muscle, Smooth, Vascular / physiopathology
  • Myocardial Contraction / drug effects
  • Myocardial Contraction / physiology
  • Myocardium / metabolism
  • Nitric Oxide / physiology
  • Nitric Oxide Donors / pharmacology
  • Nitrogen Oxides / pharmacology*
  • Oxidation-Reduction
  • Receptors, Cytoplasmic and Nuclear / deficiency
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / physiology*
  • Second Messenger Systems / physiology
  • Soluble Guanylyl Cyclase
  • Sulfonamides / pharmacology
  • Vasodilation / drug effects
  • Vasodilation / physiology*


  • Cardiotonic Agents
  • Nitric Oxide Donors
  • Nitrogen Oxides
  • Receptors, Cytoplasmic and Nuclear
  • Sulfonamides
  • Nitric Oxide
  • Cyclic GMP-Dependent Protein Kinase Type I
  • Guanylate Cyclase
  • Soluble Guanylyl Cyclase
  • nitroxyl
  • Cyclic GMP
  • Cysteine