Sustained soluble guanylate cyclase stimulation offsets nitric-oxide synthase inhibition to restore acute cardiac modulation by sildenafil

Takahiro Nagayama, Manling Zhang, Steven Hsu, Eiki Takimoto, David A Kass

Research output: Contribution to journalArticle

Abstract

Phosphodiesterase type 5 (PDE5) inhibitors are used to treat erectile dysfunction, and growing evidence supports potential cardiovascular utility. Their efficacy declines with reduced nitric-oxide synthase (NOS) activity common to various diseases. We tested whether direct soluble guanylate cyclase (sGC) stimulation restores in vivo cardiovascular modulation by PDE5 inhibition despite acute or chronically suppressed NOS activity. Mice (C57/Bl6; n = 62) were studied by in vivo pressure-volume analysis to assess acute modulation by the PDE5 inhibitor sildenafil (SIL; 100 μg/kg/min) of the cardiac response to isoproterenol (ISO) with or without NOS inhibition [Nω-nitro- L-arginine methyl ester (L-NAME)] and cotreatment by the sGC stimulator 2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5- (4-morpholinyl) pyrimidine-4,6-diamine (BAY 41-8543). SIL induced mild vasodilation but no basal cardiac effects and markedly blunted ISO-stimulated contractility. Acute BAY 41-8543 at a dose lacking cardiovascular effects did not alter ISO responses. However, after acute L-NAME, SIL ceased to influence cardiovascular function, but adding BAY 41-8543 fully restored SIL effects. After 1 week of L-NAME, neither SIL nor SIL + BAY 41-8543 acutely induced vasodilation or blunted ISO responses. However, sustained BAY 41-8543 despite concurrent NOS inhibition restored the cardiovascular efficacy of SIL. The disparity between acute and chronic NOS inhibition related to diffusion of PDE5 away from myocyte z-bands coupled with reduced protein kinase G activation. Both were restored by sustained sGC costimulation. Thus, PDE5 regulation of adrenergic reserve and systemic vasodilation depends upon NOS-induced cGMP/protein kinase G and can be enhanced by sustained low-level stimulation of sGC. This may prove beneficial for enhancing the efficacy of PDE5 inhibitors in conditions with chronically reduced NOS activity.

Original languageEnglish (US)
Pages (from-to)380-387
Number of pages8
JournalJournal of Pharmacology and Experimental Therapeutics
Volume326
Issue number2
DOIs
StatePublished - Aug 2008

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Nitric Oxide Synthase
Type 5 Cyclic Nucleotide Phosphodiesterases
Isoproterenol
Phosphodiesterase 5 Inhibitors
NG-Nitroarginine Methyl Ester
Vasodilation
Cyclic GMP-Dependent Protein Kinases
Diamines
Erectile Dysfunction
Sildenafil Citrate
Inhibition (Psychology)
Soluble Guanylyl Cyclase
Adrenergic Agents
Muscle Cells
BAY 41-8543
Pressure

ASJC Scopus subject areas

  • Pharmacology

Cite this

Sustained soluble guanylate cyclase stimulation offsets nitric-oxide synthase inhibition to restore acute cardiac modulation by sildenafil. / Nagayama, Takahiro; Zhang, Manling; Hsu, Steven; Takimoto, Eiki; Kass, David A.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 326, No. 2, 08.2008, p. 380-387.

Research output: Contribution to journalArticle

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