Format

Send to

Choose Destination
J Mol Cell Cardiol. 2015 Sep;86:168-78. doi: 10.1016/j.yjmcc.2015.07.024. Epub 2015 Aug 1.

Real-time relationship between PKA biochemical signal network dynamics and increased action potential firing rate in heart pacemaker cells: Kinetics of PKA activation in heart pacemaker cells.

Author information

1
Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel. Electronic address: yaely@bm.technion.ac.il.
2
Department of Biomedical Engineering, The Johns Hopkins University of Medicine, Baltimore, MD, USA.
3
Laboratory of Cardiovascular Science, Biomedical Research Center Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, USA.
4
System Biology Institute, Yale University, New Haven, CT, USA.
5
Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
6
Laboratory of Cardiovascular Science, Biomedical Research Center Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, USA. Electronic address: lakattae@grc.nia.nih.gov.

Abstract

cAMP-PKA protein kinase is a key nodal signaling pathway that regulates a wide range of heart pacemaker cell functions. These functions are predicted to be involved in regulation of spontaneous action potential (AP) generation of these cells. Here we investigate if the kinetics and stoichiometry of increase in PKA activity match the increase in AP firing rate in response to β-adrenergic receptor (β-AR) stimulation or phosphodiesterase (PDE) inhibition, that alters the AP firing rate of heart sinoatrial pacemaker cells. In cultured adult rabbit pacemaker cells infected with an adenovirus expressing the FRET sensor AKAR3, the EC50 in response to graded increases in the intensity of β-AR stimulation (by Isoproterenol) the magnitude of the increases in PKA activity and the spontaneous AP firing rate were similar (0.4±0.1nM vs. 0.6±0.15nM, respectively). Moreover, the kinetics (t1/2) of the increases in PKA activity and spontaneous AP firing rate in response to β-AR stimulation or PDE inhibition were tightly linked. We characterized the system rate-limiting biochemical reactions by integrating these experimentally derived data into a mechanistic-computational model. Model simulations predicted that phospholamban phosphorylation is a potent target of the increase in PKA activity that links to increase in spontaneous AP firing rate. In summary, the kinetics and stoichiometry of increases in PKA activity in response to a physiological (β-AR stimulation) or pharmacological (PDE inhibitor) stimuli match those of changes in the AP firing rate. Thus Ca(2+)-cAMP/PKA-dependent phosphorylation limits the rate and magnitude of increase in spontaneous AP firing rate.

KEYWORDS:

Computational modeling; Coupled-clock system; Pacemaker; Phosphorylation

PMID:
26241846
PMCID:
PMC4558217
DOI:
10.1016/j.yjmcc.2015.07.024
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center