Display Settings:

Format

Send to:

Choose Destination
Basic Res Cardiol. 2010 May;105(3):337-47. doi: 10.1007/s00395-010-0084-5. Epub 2010 Jan 27.

PDE5A suppression of acute beta-adrenergic activation requires modulation of myocyte beta-3 signaling coupled to PKG-mediated troponin I phosphorylation.

Author information

  • 1Ross 858, Division of Cardiology, Department of Medicine, Johns Hopkins University Medical Institutions, Baltimore, MD, 21205, USA.

Abstract

Phosphodiesterase type 5A (PDE5A) inhibitors acutely suppress beta-adrenergic receptor (beta-AR) stimulation in left ventricular myocytes and hearts. This modulation requires cyclic GMP synthesis via nitric oxide synthase (NOS)-NO stimulation, but upstream and downstream mechanisms remain un-defined. To determine this, adult cardiac myocytes from genetically engineered mice and controls were studied by video microscopy to assess sarcomere shortening (SS) and fura2-AM fluorescence to measure calcium transients (CaT). Enhanced SS from isoproterenol (ISO, 10 nM) was suppressed >or=50% by the PDE5A inhibitor sildenafil (SIL, 1 microM), without altering CaT. This regulation was unaltered despite co-inhibition of either the cGMP-stimulated cAMP-esterase PDE2 (Bay 60-7550), or cGMP-inhibited cAMP-esterase PDE3 (cilostamide). Thus, the SIL response could not be ascribed to cGMP interaction with alternative PDEs. However, genetic deletion (or pharmacologic blockade) of beta3-ARs, which couple to NOS signaling, fully prevented SIL modulation of ISO-stimulated SS. Importantly, both PDE5A protein expression and activity were similar in beta3-AR knockout (beta3-AR(-/-)) myocytes as in controls. Downstream, cGMP stimulates protein kinase G (PKG), and we found contractile modulation by SIL required PKG activation and enhanced TnI phosphorylation at S23, S24. Myocytes expressing the slow skeletal TnI isoform which lacks these sites displayed no modulation of ISO responses by SIL. Non-equilibrium isoelectric focusing gel electrophoresis showed SIL increased TnI phosphorylation above that from concomitant ISO in control but not beta3-AR(-/-) myocytes. These data support a cascade involving beta3-AR stimulation, and subsequent PKG-dependent TnI S23, S24 phosphorylation as primary factors underlying the capacity of acute PDE5A inhibition to blunt myocardial beta-adrenergic stimulation.

PMID:
20107996
[PubMed - indexed for MEDLINE]
PMCID:
PMC2878662
Free PMC Article

Images from this publication.See all images (6)Free text

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Publication Types, MeSH Terms, Substances, Grant Support

Publication Types

MeSH Terms

Substances

Grant Support

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Springer Icon for PubMed Central
    Loading ...
    Write to the Help Desk