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

Guangshuo Zhu, Dieter Groneberg, Gautam Sikka, Daijiro Hori, Mark J. Ranek, Taishi Nakamura, Eiki Takimoto, Nazareno Paolocci, Dan E. Berkowitz, Andreas Friebe, David A. Kass

Research output: Contribution to journalArticlepeer-review

Abstract

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 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.

Original languageEnglish (US)
Pages (from-to)385-392
Number of pages8
JournalHypertension
Volume65
Issue number2
DOIs
StatePublished - Feb 21 2015

Keywords

  • cardiotonic agents
  • cardiovascular physiological phenomena
  • cyclic GMP-dependent protein kinases
  • guanylate cyclase
  • nitrogen oxides
  • pharmacology
  • vasodilation

ASJC Scopus subject areas

  • Internal Medicine

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