Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.

Calcium (Ca2+) and 3',5'-cyclic adenosine monophosphate (cAMP) play a critical role for cardiac excitation-contraction-coupling. Both second messengers are known to interact with each other, for example via Ca2+-dependent modulation of phosphodiesterase 1 (PDE1) and adenylyl cyclase 5/6 (A...

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Main Authors: Julia U Sprenger, Nadja I Bork, Jonas Herting, Thomas H Fischer, Viacheslav O Nikolaev
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2016-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC5145230?pdf=render
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spelling doaj-e96e2f12833245c5aafa5a5ebf6ef4cc2020-11-25T00:42:28ZengPublic Library of Science (PLoS)PLoS ONE1932-62032016-01-011112e016797410.1371/journal.pone.0167974Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.Julia U SprengerNadja I BorkJonas HertingThomas H FischerViacheslav O NikolaevCalcium (Ca2+) and 3',5'-cyclic adenosine monophosphate (cAMP) play a critical role for cardiac excitation-contraction-coupling. Both second messengers are known to interact with each other, for example via Ca2+-dependent modulation of phosphodiesterase 1 (PDE1) and adenylyl cyclase 5/6 (AC 5/6) activities, which is supposed to occur especially at the local level in distinct subcellular microdomains. Currently, many studies analyze global and local cAMP signaling and its regulation in resting cardiomyocytes devoid of electrical stimulation. For example, Förster resonance energy transfer (FRET) microscopy is a popular approach for visualization of real time cAMP dynamics performed in resting cardiomyocytes to avoid potential contractility-related movement artifacts. However, it is unknown whether such data are comparable with the cell behavior under more physiologically relevant conditions during contraction. Here, we directly compare the cAMP-FRET responses to AC stimulation and PDE inhibition in resting vs. paced adult mouse ventricular cardiomyocytes for both cytosolic and subsarcolemmal microdomains. Interestingly, no significant differences in cAMP dynamics could be detected after β-adrenergic (isoproterenol) stimulation, suggesting low impact of rapidly changing contractile Ca2+ concentrations on cytosolic cAMP levels associated with AC activation. However, the contribution of the calcium-dependent PDE1, but not of the Ca2+-insensitive PDE4, to the regulation of cAMP levels after forskolin stimulation was significantly increased. This increase could be mimicked by pretreatment of resting cells with Ca2+ elevating agents. Ca2+ imaging demonstrated significantly higher amplitudes of Ca2+ transients in forskolin than in isoproterenol stimulated cells, suggesting that forskolin stimulation might lead to stronger activation of PDE1. In conclusion, changes in intracellular Ca2+ during cardiomyocyte contraction dynamically interact with cAMP levels, especially after strong AC stimulation. The use of resting cells for FRET-based measurements of cAMP can be justified under β-adrenergic stimulation, while the reliable analysis of PDE1 effects may require electric field stimulation.http://europepmc.org/articles/PMC5145230?pdf=render
collection DOAJ
language English
format Article
sources DOAJ
author Julia U Sprenger
Nadja I Bork
Jonas Herting
Thomas H Fischer
Viacheslav O Nikolaev
spellingShingle Julia U Sprenger
Nadja I Bork
Jonas Herting
Thomas H Fischer
Viacheslav O Nikolaev
Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
PLoS ONE
author_facet Julia U Sprenger
Nadja I Bork
Jonas Herting
Thomas H Fischer
Viacheslav O Nikolaev
author_sort Julia U Sprenger
title Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
title_short Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
title_full Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
title_fullStr Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
title_full_unstemmed Interactions of Calcium Fluctuations during Cardiomyocyte Contraction with Real-Time cAMP Dynamics Detected by FRET.
title_sort interactions of calcium fluctuations during cardiomyocyte contraction with real-time camp dynamics detected by fret.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2016-01-01
description Calcium (Ca2+) and 3',5'-cyclic adenosine monophosphate (cAMP) play a critical role for cardiac excitation-contraction-coupling. Both second messengers are known to interact with each other, for example via Ca2+-dependent modulation of phosphodiesterase 1 (PDE1) and adenylyl cyclase 5/6 (AC 5/6) activities, which is supposed to occur especially at the local level in distinct subcellular microdomains. Currently, many studies analyze global and local cAMP signaling and its regulation in resting cardiomyocytes devoid of electrical stimulation. For example, Förster resonance energy transfer (FRET) microscopy is a popular approach for visualization of real time cAMP dynamics performed in resting cardiomyocytes to avoid potential contractility-related movement artifacts. However, it is unknown whether such data are comparable with the cell behavior under more physiologically relevant conditions during contraction. Here, we directly compare the cAMP-FRET responses to AC stimulation and PDE inhibition in resting vs. paced adult mouse ventricular cardiomyocytes for both cytosolic and subsarcolemmal microdomains. Interestingly, no significant differences in cAMP dynamics could be detected after β-adrenergic (isoproterenol) stimulation, suggesting low impact of rapidly changing contractile Ca2+ concentrations on cytosolic cAMP levels associated with AC activation. However, the contribution of the calcium-dependent PDE1, but not of the Ca2+-insensitive PDE4, to the regulation of cAMP levels after forskolin stimulation was significantly increased. This increase could be mimicked by pretreatment of resting cells with Ca2+ elevating agents. Ca2+ imaging demonstrated significantly higher amplitudes of Ca2+ transients in forskolin than in isoproterenol stimulated cells, suggesting that forskolin stimulation might lead to stronger activation of PDE1. In conclusion, changes in intracellular Ca2+ during cardiomyocyte contraction dynamically interact with cAMP levels, especially after strong AC stimulation. The use of resting cells for FRET-based measurements of cAMP can be justified under β-adrenergic stimulation, while the reliable analysis of PDE1 effects may require electric field stimulation.
url http://europepmc.org/articles/PMC5145230?pdf=render
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