51
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Delfiner MS, Nofi C, Li Y, Gerdes AM, Zhang Y. Failing Hearts Are More Vulnerable to Sympathetic, but Not Vagal Stimulation-Induced, Atrial Fibrillation-Ameliorated with Dantrolene Treatment. J Card Fail 2018; 24:460-469. [PMID: 29885493 DOI: 10.1016/j.cardfail.2018.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 05/15/2018] [Accepted: 05/21/2018] [Indexed: 10/14/2022]
Abstract
BACKGROUND Both vagal (VS) and sympathetic (SS) stimulations can increase atrial fibrillation (AF) inducibility, with VS being known as more arrhythmogenic in normal hearts. Heart failure (HF) results in autonomic dysfunction (characterized by sympathetic activation and vagal withdrawal) and is associated with an increased AF incidence. This study investigated whether failing hearts, compared with normal control hearts, respond differently to autonomic stimulation-induced AF arrhythmogenesis and the effect of dantrolene on SS-enhanced AF in HF. METHODS AND RESULTS A rat myocardial infarction (MI) HF model was used. In experiment 1, AF inducibility was compared in 9 MI-HF rats versus 10 sham-control animals at baseline, during VS, and during SS with isoproterenol infusion. In experiment 2, dantrolene treatment (n = 8) was compared with placebo-control (n = 9) on SS-induced AF inducibility in HF. Compared with the sham-control, baseline AF inducibility was higher in the MI-HF group. AF inducibility was augmented in both groups by autonomic stimulation. However, under VS the increased magnitude was less in the MI-HF group (49% ± 11% vs 80% ± 10%; P = .029), but under SS was significantly more (53% ± 8% vs 6% ± 7%; P < .001), compared with sham-control. Dantrolene significantly attenuated SS-enhanced AF in HF (69% ± 6% vs 29% ± 9%; P = .006). CONCLUSIONS Failing hearts are less sensitive to VS, but more vulnerable to SS-induced AF compared with normal-control hearts. Dantrolene can significantly attenuate SS-enhanced AF in HF, indicating that cardiac ryanodine receptor dysfunction may play a critical role in SS-enhanced AF in HF, and stabilizing leaky ryanodine receptor with the use of dantrolene may be a new treatment option in this condition.
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Affiliation(s)
- Matthew S Delfiner
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Colleen Nofi
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Ying Li
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - A Martin Gerdes
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Youhua Zhang
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York.
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52
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Fernandez-Tenorio M, Niggli E. Stabilization of Ca 2+ signaling in cardiac muscle by stimulation of SERCA. J Mol Cell Cardiol 2018; 119:87-95. [PMID: 29715473 DOI: 10.1016/j.yjmcc.2018.04.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/13/2018] [Accepted: 04/27/2018] [Indexed: 02/06/2023]
Abstract
AIMS In cardiac muscle, phosphorylation of the RyRs is proposed to increase their Ca2+ sensitivity. This mechanism could be arrhythmogenic via facilitation of spontaneous Ca2+ waves. Surprisingly, the level of Ca2+ inside the SR needed to initiate such waves has been reported to increase upon β-adrenergic stimulation, an observation which cannot be easily reconciled with elevated Ca2+ sensitivity of the RyRs. We tested the hypothesis that this change of Ca2+ wave threshold could occur indirectly, subsequent to SERCA stimulation. METHODS AND RESULTS Cytosolic and intra-SR Ca2+ waves were simultaneously recorded with confocal line-scan imaging in intact and permeabilized mouse cardiomyocytes using Rhod-2 and Fluo-5-N, respectively. We analyzed changes of several Ca2+ signaling parameters during specific SERCA stimulation by ochratoxin A (OTA), jasmonate or the Fab fragment of a phospholamban antibody. SERCA stimulation resulted in a substantial increase of the threshold for Ca2+ wave initiation. Faster Ca2+ transient decay and SR refilling confirmed SERCA acceleration. CONCLUSIONS These results suggest that isolated SERCA stimulation can elevate the intra-SR threshold for the generation of Ca2+ waves, independently of RyR phosphorylation. Simultaneously, fractional Ca2+ release and wave amplitudes are reduced. Thus, SERCA stimulation appears to exert a negative feed-back on the Ca2+-induced Ca2+ release mechanisms sustaining the waves. Thereby, it may be profoundly antiarrhythmic. This may be clinically relevant when therapies are applied to stimulate the SERCA activity (e.g. SERCA overexpression with gene therapy, future small molecule SERCA stimulators).
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Affiliation(s)
| | - Ernst Niggli
- Department of Physiology, University of Bern, 3012 Bern, Switzerland.
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53
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CRISPR/Cas9 Gene editing of RyR2 in human stem cell-derived cardiomyocytes provides a novel approach in investigating dysfunctional Ca 2+ signaling. Cell Calcium 2018; 73:104-111. [PMID: 29730419 DOI: 10.1016/j.ceca.2018.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/20/2018] [Accepted: 04/21/2018] [Indexed: 12/27/2022]
Abstract
Type-2 ryanodine receptors (RyR2s) play a pivotal role in cardiac excitation-contraction coupling by releasing Ca2+ from sarcoplasmic reticulum (SR) via a Ca2+ -induced Ca2+ release (CICR) mechanism. Two strategies have been used to study the structure-function characteristics of RyR2 and its disease associated mutations: (1) heterologous cell expression of the recombinant mutant RyR2s, and (2) knock-in mouse models harboring RyR2 point mutations. Here, we establish an alternative approach where Ca2+ signaling aberrancy caused by the RyR2 mutation is studied in human cardiomyocytes with robust CICR mechanism. Specifically, we introduce point mutations in wild-type RYR2 of human induced pluripotent stem cells (hiPSCs) by CRISPR/Cas9 gene editing, and then differentiate them into cardiomyocytes. To verify the reliability of this approach, we introduced the same disease-associated RyR2 mutation, F2483I, which was studied by us in hiPSC-derived cardiomyocytes (hiPSC-CMs) from a patient biopsy. The gene-edited F2483I hiPSC-CMs exhibited longer and wandering Ca2+ sparks, elevated diastolic Ca2+ leaks, and smaller SR Ca2+ stores, like those of patient-derived cells. Our CRISPR/Cas9 gene editing approach validated the feasibility of creating myocytes expressing the various RyR2 mutants, making comparative mechanistic analysis and pharmacotherapeutic approaches for RyR2 pathologies possible.
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54
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Gabriel-Costa D. The pathophysiology of myocardial infarction-induced heart failure. ACTA ACUST UNITED AC 2018; 25:277-284. [PMID: 29685587 DOI: 10.1016/j.pathophys.2018.04.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 03/06/2018] [Accepted: 04/14/2018] [Indexed: 12/20/2022]
Abstract
Heart failure (HF) is a multifactorial disorder and is usually the end stage of many cardiovascular diseases (CVD). HF presents one of the highest morbidity and mortality indices worldwide and high costs to public health organizations. Myocardial infarction (MI) is the most prevalent CVD in the Western world and leads to HF when its management is inadequate. It has a destructive potential for heart cells and abruptly reduces the cardiac output, a clinical condition known as heart dysfunction that might progress to HF. Many acute and chronic adaptations occur due to MI that progress to HF, e.g., neurohumoral hyperactivity, inflammatory response and cardiac remodeling. Herein, we reviewed in simplistic manner the processes involved in setting of MI until the establishment of HF.
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Affiliation(s)
- Daniele Gabriel-Costa
- Universidade da Força Aérea, Instituto de Ciências da Atividade Física, Programa de Pós-Graduação em Desempenho Humano Operacional, Rio de Janeiro, RJ, Brasil.
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55
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Power AS, Hickey AJ, Crossman DJ, Loiselle DS, Ward ML. Calcium mishandling impairs contraction in right ventricular hypertrophy prior to overt heart failure. Pflugers Arch 2018. [PMID: 29525825 DOI: 10.1007/s00424-018-2125-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Currently, there are no tailored therapies available for the treatment of right ventricular (RV) hypertrophy, and the cellular mechanisms that underlie the disease are poorly understood. We investigated the cellular changes that occur early in the progression of the disease, when RV hypertrophy is evident, but prior to the onset of heart failure. Intracellular Ca2+ ([Ca2+]i) handling was examined in a rat model of monocrotaline (MCT)-induced pulmonary hypertension and subsequent RV hypertrophy. [Ca2+]i and stress production were measured in isolated RV trabeculae under baseline conditions (1-Hz stimulation, 1.5 mM [Ca2+]o, 37 °C), and in response to inotropic interventions (5-Hz stimulation or 1-μM isoproterenol). Under baseline conditions, MCT trabeculae had impaired Ca2+ release in response to stimulation with a 45% delay in the time-to-peak Ca2+, but there was no difference in the amplitude and decay of the Ca2+ transient, or active stress relative to RV trabeculae from normotensive hearts (CON). Increasing stimulation frequency from 1 to 5 Hz increased stress in CON, but not MCT trabeculae. Similarly, β-adrenergic stimulation with isoproterenol increased Ca2+ transient amplitude and active stress in CON, but not in MCT trabeculae, despite accelerating Ca2+ transient decay in trabeculae from both groups. During isoproterenol treatment, MCT trabeculae showed increased diastolic Ca2+ leak, which may explain the blunted inotropic response to β-adrenergic stimulation. Confocal imaging of trabeculae fixed following functional measurements showed that myocytes were on average wider, and transverse-tubule organisation was disrupted in MCT which provides a mechanism to explain the observed slower release of Ca2+.
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Affiliation(s)
- Amelia S Power
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand
| | - Anthony J Hickey
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand
| | - David J Crossman
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand
| | - Denis S Loiselle
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand.,Auckland Bioengineering Institute, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand.
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56
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Suita K, Fujita T, Cai W, Hidaka Y, Jin H, Prajapati R, Umemura M, Yokoyama U, Sato M, Knollmann BC, Okumura S, Ishikawa Y. Vidarabine, an anti-herpesvirus agent, prevents catecholamine-induced arrhythmias without adverse effect on heart function in mice. Pflugers Arch 2018; 470:923-935. [PMID: 29453615 DOI: 10.1007/s00424-018-2121-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 02/04/2018] [Accepted: 02/07/2018] [Indexed: 12/11/2022]
Abstract
Sympathetic activation causes clinically important arrhythmias including atrial fibrillation (AF) and ventricular tachyarrhythmia. Although the usefulness of β-adrenergic receptor blockade therapy is widely accepted, its multiple critical side effects often prevent its initiation or continuation. The aim of this study is to determine the advantages of vidarabine, an adenylyl cyclase (AC)-targeted anti-sympathetic agent, as an alternative treatment for arrhythmia. We found that vidarabine, which we identified as a cardiac AC inhibitor, consistently shortens AF duration and reduces the incidence of sympathetic activation-induced ventricular arrhythmias. In atrial and ventricular myocytes, vidarabine inhibits adrenergic receptor stimulation-induced RyR2 phosphorylation, sarcoplasmic reticulum (SR) Ca2+ leakage, and spontaneous Ca2+ release from SR, the last of which has been considered as a potential arrhythmogenic trigger. Moreover, vidarabine also inhibits sympathetic activation-induced reactive oxygen species (ROS) production in cardiac myocytes. The pivotal role of vidarabine's inhibitory effect on ROS production with regard to its anti-arrhythmic property has also been implied in animal studies. In addition, as expected, vidarabine exerts an inhibitory effect on AC function, which is more potent in the heart than elsewhere. Indexes of cardiac function including ejection fraction and heart rate were not affected by a dosage of vidarabine sufficient to exert an anti-arrhythmic effect. These findings suggest that vidarabine inhibits catecholamine-induced AF or ventricular arrhythmia without deteriorating cardiac function in mice.
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Affiliation(s)
- Kenji Suita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.,Department of Physiology, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Takayuki Fujita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Wenqian Cai
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yuko Hidaka
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Huiling Jin
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Rajesh Prajapati
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Masanari Umemura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Motohiko Sato
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.,Department of Physiology, Aichi Medical University, Aichi, Japan
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Satoshi Okumura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.,Department of Physiology, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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57
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Abstract
For arrhythmia triggers that are secondary to dysfunctional intracellular Ca2+ cycling, there are few, if any, agents that specifically target the Ca2+ handling machinery. However, several candidates have been proposed in the literature. Here we review the idea that these agents or their derivatives will prove invaluable in clinical applications in the future.
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Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, New York.
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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58
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Olgar Y, Celen MC, Yamasan BE, Ozturk N, Turan B, Ozdemir S. Rho-kinase inhibition reverses impaired Ca 2+ handling and associated left ventricular dysfunction in pressure overload-induced cardiac hypertrophy. Cell Calcium 2017; 67:81-90. [DOI: 10.1016/j.ceca.2017.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/24/2017] [Accepted: 09/09/2017] [Indexed: 10/18/2022]
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59
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Walker MA, Gurev V, Rice JJ, Greenstein JL, Winslow RL. Estimating the probabilities of rare arrhythmic events in multiscale computational models of cardiac cells and tissue. PLoS Comput Biol 2017; 13:e1005783. [PMID: 29145393 PMCID: PMC5689829 DOI: 10.1371/journal.pcbi.1005783] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/18/2017] [Indexed: 11/24/2022] Open
Abstract
Ectopic heartbeats can trigger reentrant arrhythmias, leading to ventricular fibrillation and sudden cardiac death. Such events have been attributed to perturbed Ca2+ handling in cardiac myocytes leading to spontaneous Ca2+ release and delayed afterdepolarizations (DADs). However, the ways in which perturbation of specific molecular mechanisms alters the probability of ectopic beats is not understood. We present a multiscale model of cardiac tissue incorporating a biophysically detailed three-dimensional model of the ventricular myocyte. This model reproduces realistic Ca2+ waves and DADs driven by stochastic Ca2+ release channel (RyR) gating and is used to study mechanisms of DAD variability. In agreement with previous experimental and modeling studies, key factors influencing the distribution of DAD amplitude and timing include cytosolic and sarcoplasmic reticulum Ca2+ concentrations, inwardly rectifying potassium current (IK1) density, and gap junction conductance. The cardiac tissue model is used to investigate how random RyR gating gives rise to probabilistic triggered activity in a one-dimensional myocyte tissue model. A novel spatial-average filtering method for estimating the probability of extreme (i.e. rare, high-amplitude) stochastic events from a limited set of spontaneous Ca2+ release profiles is presented. These events occur when randomly organized clusters of cells exhibit synchronized, high amplitude Ca2+ release flux. It is shown how reduced IK1 density and gap junction coupling, as observed in heart failure, increase the probability of extreme DADs by multiple orders of magnitude. This method enables prediction of arrhythmia likelihood and its modulation by alterations of other cellular mechanisms.
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Affiliation(s)
- Mark A. Walker
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Viatcheslav Gurev
- TJ Watson Research Center, IBM, Yorktown Heights, NY, United States of America
| | - John J. Rice
- TJ Watson Research Center, IBM, Yorktown Heights, NY, United States of America
| | - Joseph L. Greenstein
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Raimond L. Winslow
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
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60
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Dewenter M, von der Lieth A, Katus HA, Backs J. Calcium Signaling and Transcriptional Regulation in Cardiomyocytes. Circ Res 2017; 121:1000-1020. [DOI: 10.1161/circresaha.117.310355] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Calcium (Ca
2+
) is a universal regulator of various cellular functions. In cardiomyocytes, Ca
2+
is the central element of excitation–contraction coupling, but also impacts diverse signaling cascades and influences the regulation of gene expression, referred to as excitation–transcription coupling. Disturbances in cellular Ca
2+
-handling and alterations in Ca
2+
-dependent gene expression patterns are pivotal characteristics of failing cardiomyocytes, with several excitation–transcription coupling pathways shown to be critically involved in structural and functional remodeling processes. Thus, targeting Ca
2+
-dependent transcriptional pathways might offer broad therapeutic potential. In this article, we (1) review cytosolic and nuclear Ca
2+
dynamics in cardiomyocytes with respect to their impact on Ca
2+
-dependent signaling, (2) give an overview on Ca
2+
-dependent transcriptional pathways in cardiomyocytes, and (3) discuss implications of excitation–transcription coupling in the diseased heart.
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Affiliation(s)
- Matthias Dewenter
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Albert von der Lieth
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Hugo A. Katus
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Johannes Backs
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
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61
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Xiao L, Gurrola GB, Zhang J, Valdivia CR, SanMartin M, Zamudio FZ, Zhang L, Possani LD, Valdivia HH. Structure-function relationships of peptides forming the calcin family of ryanodine receptor ligands. J Gen Physiol 2017; 147:375-94. [PMID: 27114612 PMCID: PMC4845687 DOI: 10.1085/jgp.201511499] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 03/21/2016] [Indexed: 12/22/2022] Open
Abstract
Calcins are a novel family of scorpion peptides that bind with high affinity to ryanodine receptors (RyRs) and increase their activity by inducing subconductance states. Here, we provide a comprehensive analysis of the structure-function relationships of the eight calcins known to date, based on their primary sequence, three-dimensional modeling, and functional effects on skeletal RyRs (RyR1). Primary sequence alignment and evolutionary analysis show high similarity among all calcins (≥78.8% identity). Other common characteristics include an inhibitor cysteine knot (ICK) motif stabilized by three pairs of disulfide bridges and a dipole moment (DM) formed by positively charged residues clustering on one side of the molecule and neutral and negatively charged residues segregating on the opposite side. [(3)H]Ryanodine binding assays, used as an index of the open probability of RyRs, reveal that all eight calcins activate RyR1 dose-dependently with Kd values spanning approximately three orders of magnitude and in the following rank order: opicalcin1 > opicalcin2 > vejocalcin > hemicalcin > imperacalcin > hadrucalcin > maurocalcin >> urocalcin. All calcins significantly augment the bell-shaped [Ca(2+)]-[(3)H]ryanodine binding curve with variable effects on the affinity constants for Ca(2+) activation and inactivation. In single channel recordings, calcins induce the appearance of a subconductance state in RyR1 that has a unique fractional value (∼20% to ∼60% of the full conductance state) but bears no relationship to binding affinity, DM, or capacity to stimulate Ca(2+) release. Except for urocalcin, all calcins at 100 nM concentration stimulate Ca(2+) release and deplete Ca(2+) load from skeletal sarcoplasmic reticulum. The natural variation within the calcin family of peptides offers a diversified set of high-affinity ligands with the capacity to modulate RyRs with high dynamic range and potency.
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Affiliation(s)
- Liang Xiao
- Department of Marine Biotechnology, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, China Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Georgina B Gurrola
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Jing Zhang
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Carmen R Valdivia
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Mario SanMartin
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Fernando Z Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Liming Zhang
- Department of Marine Biotechnology, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, China
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México
| | - Héctor H Valdivia
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
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62
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Sankaranarayanan R, Kistamás K, Greensmith DJ, Venetucci LA, Eisner DA. Systolic [Ca 2+ ] i regulates diastolic levels in rat ventricular myocytes. J Physiol 2017; 595:5545-5555. [PMID: 28617952 PMCID: PMC5556151 DOI: 10.1113/jp274366] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/13/2017] [Indexed: 11/30/2022] Open
Abstract
KEY POINTS For the heart to function as a pump, intracellular calcium concentration ([Ca2+ ]i ) must increase during systole to activate contraction and then fall, during diastole, to allow the myofilaments to relax and the heart to refill with blood. The present study investigates the control of diastolic [Ca2+ ]i in rat ventricular myocytes. We show that diastolic [Ca2+ ]i is increased by manoeuvres that decrease sarcoplasmic reticulum function. This is accompanied by a decrease of systolic [Ca2+ ]i such that the time-averaged [Ca2+ ]i remains constant. We report that diastolic [Ca2+ ]i is controlled by the balance between Ca2+ entry and Ca2+ efflux during systole. The results of the present study identify a novel mechanism by which changes of the amplitude of the systolic Ca transient control diastolic [Ca2+ ]i . ABSTRACT The intracellular Ca concentration ([Ca2+ ]i ) must be sufficently low in diastole so that the ventricle is relaxed and can refill with blood. Interference with this will impair relaxation. The factors responsible for regulation of diastolic [Ca2+ ]i , in particular the relative roles of the sarcoplasmic reticulum (SR) and surface membrane, are unclear. We investigated the effects on diastolic [Ca2+ ]i that result from the changes of Ca cycling known to occur in heart failure. Experiments were performed using Fluo-3 in voltage clamped rat ventricular myocytes. Increasing stimulation frequency increased diastolic [Ca2+ ]i . This increase of [Ca2+ ]i was larger when SR function was impaired either by making the ryanodine receptor leaky (with caffeine or ryanodine) or by decreasing sarco/endoplasmic reticulum Ca-ATPase activity with thapsigargin. The increase of diastolic [Ca2+ ]i produced by interfering with the SR was accompanied by a decrease of the amplitude of the systolic Ca transient, such that there was no change of time-averaged [Ca2+ ]i . Time-averaged [Ca2+ ]i was increased by β-adrenergic stimulation with isoprenaline and increased in a saturating manner with increased stimulation frequency; average [Ca2+ ]i was a linear function of Ca entry per unit time. Diastolic and time-averaged [Ca2+ ]i were decreased by decreasing the L-type Ca current (with 50 μm cadmium chloride). We conclude that diastolic [Ca2+ ]i is controlled by the balance between Ca entry and efflux during systole. Furthermore, manoeuvres that decrease the amplitude of the Ca transient (without decreasing Ca influx) will therefore increase diastolic [Ca2+ ]i . This identifies a novel mechanism by which changes of the amplitude of the systolic Ca transient control diastolic [Ca2+ ]i .
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Affiliation(s)
- Rajiv Sankaranarayanan
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences CentreUniversity of ManchesterManchesterUK
| | - Kornél Kistamás
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences CentreUniversity of ManchesterManchesterUK
| | - David J. Greensmith
- Biomedical Research Centre, School of Environment and Life Sciences, Peel BuildingUniversity of SalfordSalfordUK
| | - Luigi A. Venetucci
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences CentreUniversity of ManchesterManchesterUK
| | - David A. Eisner
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences CentreUniversity of ManchesterManchesterUK
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Pereira L, Bare DJ, Galice S, Shannon TR, Bers DM. β-Adrenergic induced SR Ca 2+ leak is mediated by an Epac-NOS pathway. J Mol Cell Cardiol 2017; 108:8-16. [PMID: 28476660 DOI: 10.1016/j.yjmcc.2017.04.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 02/08/2023]
Abstract
Cardiac β-adrenergic receptors (β-AR) and Ca2+-Calmodulin dependent protein kinase (CaMKII) regulate both physiological and pathophysiological Ca2+ signaling. Elevated diastolic Ca2+ leak from the sarcoplasmic reticulum (SR) contributes to contractile dysfunction in heart failure and to arrhythmogenesis. β-AR activation is known to increase SR Ca2+ leak via CaMKII-dependent phosphorylation of the ryanodine receptor. Two independent and reportedly parallel pathways have been implicated in this β-AR-CaMKII cascade, one involving exchange protein directly activated by cAMP (Epac2) and another involving nitric oxide synthase 1 (NOS1). Here we tested whether Epac and NOS function in a single series pathway to increase β-AR induced and CaMKII-dependent SR Ca2+ leak. Leak was measured as both Ca2+ spark frequency and tetracaine-induced shifts in SR Ca2+, in mouse and rabbit ventricular myocytes. Direct Epac activation by 8-CPT (8-(4-chlorophenylthio)-2'-O-methyl-cAMP) mimicked β-AR-induced SR Ca2+ leak, and both were blocked by NOS inhibition. The same was true for myocyte CaMKII activation (assessed via a FRET-based reporter) and ryanodine receptor phosphorylation. Inhibitor and phosphorylation studies also implicated phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) downstream of Epac and above NOS activation in this pathway. We conclude that these two independently characterized parallel pathways function mainly via a single series arrangement (β-AR-cAMP-Epac-PI3K-Akt-NOS1-CaMKII) to mediate increased SR Ca2+ leak. Thus, for β-AR activation the cAMP-PKA branch effects inotropy and lusitropy (by effects on Ca2+ current and SR Ca2+-ATPase), this cAMP-Epac-NOS pathway increases pathological diastolic SR Ca2+leak. This pathway distinction may allow novel SR Ca2+ leak therapeutic targeting in treatment of arrhythmias in heart failure that spare the inotropic and lusitropic effects of the PKA branch.
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Affiliation(s)
- Laëtitia Pereira
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, United States
| | - Dan J Bare
- Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612, United States
| | - Samuel Galice
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, United States
| | - Thomas R Shannon
- Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612, United States.
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, United States.
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64
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Lascano E, Negroni J, Vila Petroff M, Mattiazzi A. Impact of RyR2 potentiation on myocardial function. Am J Physiol Heart Circ Physiol 2017; 312:H1105-H1109. [PMID: 28389603 DOI: 10.1152/ajpheart.00855.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/31/2017] [Accepted: 03/31/2017] [Indexed: 01/20/2023]
Abstract
This perspective attempts to shed light on an old and not yet solved controversy in cardiac physiology, i.e., the impact of increasing ryanodine receptor (RyR)2 open probability on myocardial function. Based on an already proven myocyte model, it was shown that increasing RyR2 open probability results in a purely short-lived increase in Ca2+ transient amplitude, and, therefore, it does not increase cardiac contractility. However, potentiation of RyR2 activity permanently enhances fractional Ca2+ release, shifting the intracellular Ca2+ transient versus sarcoplasmic reticulum (SR) Ca2+ content curve to a new state of higher efficiency. This would allow the heart to maintain a given contractility despite a decrease in SR Ca2+ content, to enhance contractility if SR Ca2+ content is simultaneously preserved or to successfully counteract the effects of a negative inotropic intervention.NEW & NOTEWORTHY Increasing ryanodine receptor (RyR)2 open probability does not increase cardiac contractility. However, RyR2 potentiation shifts the intracellular Ca2+ transient-sarcoplasmic reticulum (SR) Ca2+ content relationship toward an enhanced efficiency state, which may contribute to a positive inotropic effect, preserve contractility despite decreased SR Ca2+ content, or successfully counteract the effects of a negative inotropic action.
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Affiliation(s)
- E Lascano
- Instituto de Medicina Translacional, Transplante y Bioingeniería, Universidad Favaloro, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; and
| | - J Negroni
- Instituto de Medicina Translacional, Transplante y Bioingeniería, Universidad Favaloro, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; and
| | - M Vila Petroff
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - A Mattiazzi
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
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65
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Mechanistic and therapeutic perspectives for cardiac arrhythmias: beyond ion channels. SCIENCE CHINA-LIFE SCIENCES 2017; 60:348-355. [DOI: 10.1007/s11427-016-9005-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 12/20/2016] [Indexed: 10/19/2022]
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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67
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Sato D, Shannon TR, Bers DM. Sarcoplasmic Reticulum Structure and Functional Properties that Promote Long-Lasting Calcium Sparks. Biophys J 2016; 110:382-390. [PMID: 26789761 DOI: 10.1016/j.bpj.2015.12.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 11/18/2022] Open
Abstract
Calcium (Ca) sparks are the fundamental sarcoplasmic reticulum (SR) Ca release events in cardiac myocytes, and they have a typical duration of 20-40 ms. However, when a fraction of ryanodine receptors (RyRs) are blocked by tetracaine or ruthenium red, Ca sparks lasting hundreds of milliseconds have been observed experimentally. The fundamental mechanism underlying these extremely prolonged Ca sparks is not understood. In this study, we use a physiologically detailed mathematical model of subcellular Ca cycling to examine how Ca spark duration is influenced by the number of functional RyRs in a junctional cluster (which is reduced by tetracaine or ruthenium red) and other SR Ca handling properties. One RyR cluster contains a few to several hundred RyRs, and we use a four-state Markov RyR gating model. Each RyR opens stochastically and is regulated by cytosolic and luminal Ca. We varied the number of functional RyRs in the single cluster, diffusion within the SR network, diffusion between network and junctional SR, cytosolic Ca diffusion, SERCA uptake activity, and RyR open probability. For long-lasting Ca release events, opening events within the cluster must occur continuously because the typical open time of the RyR is only a few milliseconds. We found the following: 1) if the number of RyRs is too small, it is difficult to maintain consecutive openings and stochastic attrition terminates the release; 2) if the number of RyRs is too large, the depletion of Ca from the junctional SR terminates the release; and 3) very long release events require relatively small-sized RyR clusters (reducing flux as seen experimentally with tetracaine) and sufficiently rapid intra-SR Ca diffusion, such that local junctional intra-SR [Ca] can be maintained by intra-SR diffusion and overall SR Ca reuptake.
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Affiliation(s)
- Daisuke Sato
- Department of Pharmacology, University of California, Davis, Davis, California.
| | - Thomas R Shannon
- Molecular Biophysics and Physiology, Rush University, Chicago, Illinois
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, California
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Okatan EN, Durak AT, Turan B. Electrophysiological basis of metabolic-syndrome-induced cardiac dysfunction. Can J Physiol Pharmacol 2016; 94:1064-1073. [DOI: 10.1139/cjpp-2015-0531] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Myocardial contractility is controlled by intracellular Ca2+ cycling with the contribution of sarcoplasmic reticulum (SR). In this study, we aimed to investigate the role of altered SR function in defective regulation of intracellular Ca2+ levels in rats with metabolic syndrome (MetS) induced by a 16-week high-sucrose drinking-water diet. Electric-field stimulated transient intracellular Ca2+ changes in MetS cardiomyocytes exhibited significantly reduced amplitude (∼30%) and prolonged time courses (2-fold), as well as depressed SR Ca2+ loading (∼55%) with increased basal Ca2+ level. Consistent with these data, altered ryanodine receptor (RyR2) function and SERCA2a activity were found in MetS cardiomyocytes through Ca2+ spark measurements and caffeine application assay in a state in which sodium calcium exchanger was inhibited. Furthermore, tetracaine application assay results and hyperphosphorylated level of RyR2 also support the “leaky RyR2” hypothesis. Moreover, altered phosphorylation levels of phospholamban (PLN) support the depressed SERCA2a-activity thesis and these alterations in the phosphorylation of Ca2+-handling proteins are correlated with altered protein kinase and phosphatase activity in MetS cardiomyocytes. In conclusion, MetS-rat heart exhibits altered Ca2+ signaling largely due to altered SR function via changes in RyR2 and SERCA2a activity. These results point to RyR2 and SERCA2a as potential pharmacological targets for restoring intracellular Ca2+ homeostasis and, thereby, combatting dysfunction in MetS-rat heart.
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Affiliation(s)
- Esma N. Okatan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
| | - Aysegul Toy Durak
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
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Murakami W, Kobayashi S, Susa T, Nanno T, Ishiguchi H, Myoren T, Nishimura S, Kato T, Hino A, Oda T, Okuda S, Yamamoto T, Yano M. Recombinant Atrial Natriuretic Peptide Prevents Aberrant Ca2+ Leakage through the Ryanodine Receptor by Suppressing Mitochondrial Reactive Oxygen Species Production Induced by Isoproterenol in Failing Cardiomyocytes. PLoS One 2016; 11:e0163250. [PMID: 27657534 PMCID: PMC5033569 DOI: 10.1371/journal.pone.0163250] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 09/05/2016] [Indexed: 12/27/2022] Open
Abstract
Catecholamines induce intracellular reactive oxygen species (ROS), thus enhancing diastolic Ca2+ leakage through the ryanodine receptor during heart failure (HF). However, little is known regarding the effect of atrial natriuretic peptide (ANP) on ROS generation and Ca2+ handling in failing cardiomyocytes. The aim of the present study was to clarify the mechanism by which an exogenous ANP exerts cardioprotective effects during HF. Cardiomyocytes were isolated from the left ventricles of a canine tachycardia-induced HF model and sham-operated vehicle controls. The degree of mitochondrial oxidized DNA was evaluated by double immunohistochemical (IHC) staining using an anti-VDAC antibody for the mitochondria and an anti-8-hydroxy-2′-deoxyguanosine antibody for oxidized DNA. The effect of ANP on ROS was investigated using 2,7-dichlorofluorescin diacetate, diastolic Ca2+ sparks assessed by confocal microscopy using Fluo 4-AM, and the survival rate of myocytes after 48 h. The double IHC study revealed that isoproterenol (ISO) markedly increased oxidized DNA in the mitochondria in HF and that the ISO-induced DNA damage was markedly inhibited by the co-presence of ANP. ROS production and Ca2+ spark frequency (CaSF) were increased in HF compared to normal controls, and were further increased in the presence of ISO. Notably, ANP significantly suppressed both ISO-induced ROS and CaSF without changing sarcoplasmic reticulum Ca2+ content in HF (p<0.01, respectively). The survival rate after 48 h in HF was significantly decreased in the presence of ISO compared with baseline (p<0.01), whereas it was significantly improved by the co-presence of ANP (p<0.01). Together, our results suggest that ANP strongly suppresses ISO-induced mitochondrial ROS generation, which might correct aberrant diastolic Ca2+ sparks, eventually contributing to the improvement of cardiomyocyte survival in HF.
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Affiliation(s)
- Wakako Murakami
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Shigeki Kobayashi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
- * E-mail:
| | - Takehisa Susa
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Takuma Nanno
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Hironori Ishiguchi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Takeki Myoren
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Shigehiko Nishimura
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Takayoshi Kato
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Akihiro Hino
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Tetsuro Oda
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Shinichi Okuda
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Takeshi Yamamoto
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
| | - Masafumi Yano
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755–8505, Japan
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70
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Ho HT, Belevych AE, Liu B, Bonilla IM, Radwański PB, Kubasov IV, Valdivia HH, Schober K, Carnes CA, Györke S. Muscarinic Stimulation Facilitates Sarcoplasmic Reticulum Ca Release by Modulating Ryanodine Receptor 2 Phosphorylation Through Protein Kinase G and Ca/Calmodulin-Dependent Protein Kinase II. Hypertension 2016; 68:1171-1178. [PMID: 27647848 DOI: 10.1161/hypertensionaha.116.07666] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 08/21/2016] [Indexed: 01/01/2023]
Abstract
Although the effects and the underlying mechanism of sympathetic stimulation on cardiac Ca handling are relatively well established both in health and disease, the modes of action and mechanisms of parasympathetic modulation are poorly defined. Here, we demonstrate that parasympathetic stimulation initiates a novel mode of excitation-contraction coupling that enhances the efficiency of cardiac sarcoplasmic reticulum Ca store utilization. This efficient mode of excitation-contraction coupling involves reciprocal changes in the phosphorylation of ryanodine receptor 2 at Ser-2808 and Ser-2814. Specifically, Ser-2808 phosphorylation was mediated by muscarinic receptor subtype 2 and activation of PKG (protein kinase G), whereas dephosphorylation of Ser-2814 involved activation of muscarinic receptor subtype 3 and decreased reactive oxygen species-dependent activation of CaMKII (Ca/calmodulin-dependent protein kinase II). The overall effect of these changes in phosphorylation of ryanodine receptor 2 is an increase in systolic Ca release at the low sarcoplasmic reticulum Ca content and a paradoxical reduction in aberrant Ca leak. Accordingly, cholinergic stimulation of cardiomyocytes isolated from failing hearts improved Ca cycling efficiency by restoring altered ryanodine receptor 2 phosphorylation balance.
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Affiliation(s)
- Hsiang-Ting Ho
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Andriy E Belevych
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Bin Liu
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Ingrid M Bonilla
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Przemysław B Radwański
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Igor V Kubasov
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Héctor H Valdivia
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Karsten Schober
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Cynthia A Carnes
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Sándor Györke
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.).
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71
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Weber S, Meyer-Roxlau S, El-Armouche A. Role of protein phosphatase inhibitor-1 in cardiac beta adrenergic pathway. J Mol Cell Cardiol 2016; 101:116-126. [PMID: 27639308 DOI: 10.1016/j.yjmcc.2016.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/05/2016] [Accepted: 09/13/2016] [Indexed: 01/08/2023]
Abstract
Phosphoproteomic studies have shown that about one third of all cardiac proteins are reversibly phosphorylated, affecting virtually every cellular signaling pathway. The reversibility of this process is orchestrated by the opposing enzymatic activity of kinases and phosphatases. Conversely, imbalances in subcellular protein phosphorylation patterns are a hallmark of many cardiovascular diseases including heart failure and cardiac arrhythmias. While numerous studies have revealed excessive beta-adrenergic signaling followed by deregulated kinase expression or activity as a major driver of the latter cardiac pathologies, far less is known about the beta-adrenergic regulation of their phosphatase counterparts. In fact, most of the limited knowledge stems from the detailed analysis of the endogenous inhibitor of the protein phosphatase 1 (I-1) in cellular and animal models. I-1 acts as a nodal point between adrenergic and putatively non-adrenergic cardiac signaling pathways and is able to influence widespread cellular functions of protein phosphatase 1 which are contributing to cardiac health and disease, e.g. Ca2+ handling, sarcomere contractility and glucose metabolism. Finally, nearly all of these studies agree that I-1 is a promising drug target on the one hand but the outcome of its pharmacological regulation maybe extremely context-dependent on the other hand, thus warranting for careful interpretation of past and future experimental results. In this respect we will: 1) comprehensively review the current knowledge about structural, functional and regulatory properties of I-1 within the heart 2) highlight current working hypothesis and potential I-1 mediated disease mechanisms 3) discuss state-of-the-art knowledge and future prospects of a potential therapeutic strategy targeting I-1 by restoring the balance of cardiac protein phosphorylation.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
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Bovo E, Mazurek SR, de Tombe PP, Zima AV. Increased Energy Demand during Adrenergic Receptor Stimulation Contributes to Ca(2+) Wave Generation. Biophys J 2016; 109:1583-91. [PMID: 26488649 DOI: 10.1016/j.bpj.2015.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 08/21/2015] [Accepted: 09/01/2015] [Indexed: 02/07/2023] Open
Abstract
While β-adrenergic receptor (β-AR) stimulation ensures adequate cardiac output during stress, it can also trigger life-threatening cardiac arrhythmias. We have previously shown that proarrhythmic Ca(2+) waves during β-AR stimulation temporally coincide with augmentation of reactive oxygen species (ROS) production. In this study, we tested the hypothesis that increased energy demand during β-AR stimulation plays an important role in mitochondrial ROS production and Ca(2+)-wave generation in rabbit ventricular myocytes. We found that β-AR stimulation with isoproterenol (0.1 μM) decreased the mitochondrial redox potential and the ratio of reduced to oxidated glutathione. As a result, β-AR stimulation increased mitochondrial ROS production. These metabolic changes induced by isoproterenol were associated with increased sarcoplasmic reticulum (SR) Ca(2+) leak and frequent diastolic Ca(2+) waves. Inhibition of cell contraction with the myosin ATPase inhibitor blebbistatin attenuated oxidative stress as well as spontaneous SR Ca(2+) release events during β-AR stimulation. Furthermore, we found that oxidative stress induced by β-AR stimulation caused the formation of disulfide bonds between two ryanodine receptor (RyR) subunits, referred to as intersubunit cross-linking. Preventing RyR cross-linking with N-ethylmaleimide decreased the propensity of Ca(2+) waves induced by β-AR stimulation. These data suggest that increased energy demand during sustained β-AR stimulation weakens mitochondrial antioxidant defense, causing ROS release into the cytosol. By inducing RyR intersubunit cross-linking, ROS can increase SR Ca(2+) leak to the critical level that can trigger proarrhythmic Ca(2+) waves.
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Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Stefan R Mazurek
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois.
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73
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Dries E, Santiago DJ, Johnson DM, Gilbert G, Holemans P, Korte SM, Roderick HL, Sipido KR. Calcium/calmodulin-dependent kinase II and nitric oxide synthase 1-dependent modulation of ryanodine receptors during β-adrenergic stimulation is restricted to the dyadic cleft. J Physiol 2016; 594:5923-5939. [PMID: 27121757 PMCID: PMC5063942 DOI: 10.1113/jp271965] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 04/17/2016] [Indexed: 12/24/2022] Open
Abstract
KEY POINTS The dyadic cleft, where coupled ryanodine receptors (RyRs) reside, is thought to serve as a microdomain for local signalling, as supported by distinct modulation of coupled RyRs dependent on Ca2+ /calmodulin-dependent kinase II (CaMKII) activation during high-frequency stimulation. Sympathetic stimulation through β-adrenergic receptors activates an integrated signalling cascade, enhancing Ca2+ cycling and is at least partially mediated through CaMKII. Here we report that CaMKII activation during β-adrenergic signalling is restricted to the dyadic cleft, where it enhances activity of coupled RyRs thereby contributing to the increase in diastolic events. Nitric oxide synthase 1 equally participates in the local modulation of coupled RyRs. In contrast, the increase in the Ca2+ content of the sarcoplasmic reticulum and related increase in the amplitude of the Ca2+ transient are primarily protein kinase A-dependent. The present data extend the concept of microdomain signalling in the dyadic cleft and give perspectives for selective modulation of RyR subpopulations and diastolic events. ABSTRACT In cardiac myocytes, β-adrenergic stimulation enhances Ca2+ cycling through an integrated signalling cascade modulating L-type Ca2+ channels (LTCCs), phospholamban and ryanodine receptors (RyRs). Ca2+ /calmodulin-dependent kinase II (CaMKII) and nitric oxide synthase 1 (NOS1) are proposed as prime mediators for increasing RyR open probability. We investigate whether this pathway is confined to the high Ca2+ microdomain of the dyadic cleft and thus to coupled RyRs. Pig ventricular myocytes are studied under whole-cell voltage-clamp and confocal line-scan imaging with Fluo-4 as a [Ca2+ ]i indicator. Following conditioning depolarizing pulses, spontaneous RyR activity is recorded as Ca2+ sparks, which are assigned to coupled and non-coupled RyR clusters. Isoproterenol (ISO) (10 nm) increases Ca2+ spark frequency in both populations of RyRs. However, CaMKII inhibition reduces spark frequency in coupled RyRs only; NOS1 inhibition mimics the effect of CaMKII inhibition. Moreover, ISO induces the repetitive activation of coupled RyR clusters through CaMKII activation. Immunostaining shows high levels of CaMKII phosphorylation at the dyadic cleft. CaMKII inhibition reduces ICaL and local Ca2+ transients during depolarizing steps but has only modest effects on amplitude or relaxation of the global Ca2+ transient. In contrast, protein kinase A (PKA) inhibition reduces spark frequency in all RyRs concurrently with a reduction of sarcoplasmic reticulum Ca2+ content, Ca2+ transient amplitude and relaxation. In conclusion, CaMKII activation during β-adrenergic stimulation is restricted to the dyadic cleft microdomain, enhancing LTCC-triggered local Ca2+ release as well as spontaneous diastolic Ca2+ release whilst PKA is the major pathway increasing global Ca2+ cycling. Selective CaMKII inhibition may reduce potentially arrhythmogenic release without negative inotropy.
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Affiliation(s)
- Eef Dries
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Demetrio J Santiago
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Daniel M Johnson
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Guillaume Gilbert
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Patricia Holemans
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Sanne M Korte
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - H Llewelyn Roderick
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Karin R Sipido
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium.
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74
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CaMKII-dependent phosphorylation of RyR2 promotes targetable pathological RyR2 conformational shift. J Mol Cell Cardiol 2016; 98:62-72. [PMID: 27318036 DOI: 10.1016/j.yjmcc.2016.06.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/27/2016] [Accepted: 06/14/2016] [Indexed: 01/27/2023]
Abstract
Diastolic calcium (Ca) leak via cardiac ryanodine receptors (RyR2) can cause arrhythmias and heart failure (HF). Ca/calmodulin (CaM)-dependent kinase II (CaMKII) is upregulated and more active in HF, promoting RyR2-mediated Ca leak by RyR2-Ser2814 phosphorylation. Here, we tested a mechanistic hypothesis that RyR2 phosphorylation by CaMKII increases Ca leak by promoting a pathological RyR2 conformation with reduced CaM affinity. Acute CaMKII activation in wild-type RyR2, and phosphomimetic RyR2-S2814D (vs. non-phosphorylatable RyR2-S2814A) knock-in mouse myocytes increased SR Ca leak, reduced CaM-RyR2 affinity, and caused a pathological shift in RyR2 conformation (detected via increased access of the RyR2 structural peptide DPc10). This same trio of effects was seen in myocytes from rabbits with pressure/volume-overload induced HF. Excess CaM quieted leak and restored control conformation, consistent with negative allosteric coupling between CaM affinity and DPc10 accessible conformation. Dantrolene (DAN) also restored CaM affinity, reduced DPc10 access, and suppressed RyR2-mediated Ca leak and ventricular tachycardia in RyR2-S2814D mice. We propose that a common pathological RyR2 conformational state (low CaM affinity, high DPc10 access, and elevated leak) may be caused by CaMKII-dependent phosphorylation, oxidation, and HF. Moreover, DAN (or excess CaM) can shift this pathological gating state back to the normal physiological conformation, a potentially important therapeutic approach.
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75
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Akhlaq A, Mehmood MH, Rehman A, Ashraf Z, Syed S, Bawany SA, Gilani AH, Ilyas M, Siddiqui BS. The Prokinetic, Laxative, and Antidiarrheal Effects of Morus nigra: Possible Muscarinic, Ca(2+) Channel Blocking, and Antimuscarinic Mechanisms. Phytother Res 2016; 30:1362-76. [PMID: 27230535 DOI: 10.1002/ptr.5641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 04/15/2016] [Accepted: 04/19/2016] [Indexed: 01/14/2023]
Abstract
Morus nigra Linn. (black mulberry) is used in gastrointestinal ailments. This study demonstrates gut modulatory properties of M. nigra. The prokinetic, laxative, and antidiarrheal activities of M. nigra were assessed in mice, while isolated rabbit jejunum and guinea-pig ileum were used to explore insight into mechanism(s). At 30 and 70 mg/kg, the crude extract of M. nigra (Mn.Cr) exhibited atropine-sensitive prokinetic and laxative effects, similar to carbachol (CCh). While at higher doses (100, 300, and 500 mg/kg), Mn.Cr offered protection against castor oil-induced diarrhea. In rabbit jejunum, Mn.Cr and its chloroform fraction inhibited CCh-induced contractions more potently compared with high K(+) (80 mm). Conversely, petroleum fraction was more potent against high-K(+) -induced contractions. At 0.01 mg/mL, Mn.Cr caused a parallel shift in acetylcholine concentration-response curves (CRCs) followed by a non-parallel shift at 0.03 mg/mL, similar to dicyclomine. At further tested concentrations, Mn.Cr (0.1 and 0.3 mg/mL) and petroleum fraction suppressed Ca(2+) CRCs, similar to verapamil. In guinea-pig ileum, Mn.Cr, its aqueous and ethyl acetate fractions exhibited atropine-sensitive gut stimulant activity along with additional uncharacterized excitatory response in the aqueous fraction only. These results suggest that black mulberry possesses prokinetic, laxative, and antidiarrheal effects, putatively mediated through cholinomimetic, antimuscarinic, and Ca(2+) antagonist mechanisms, respectively. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Anam Akhlaq
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan
| | - Malik Hassan Mehmood
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan
| | - Abdul Rehman
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan.,Internal Medicine Section, Department of Medicine, Hamad Medical Corporation, PO Box 3050, Doha, Qatar
| | - Zohaib Ashraf
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan
| | - Sadia Syed
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan
| | - Samira Ahmed Bawany
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan
| | - Anwarul-Hassan Gilani
- Natural Products Research Division, Department of Biological and Biomedical Sciences, Aga Khan University, PO Box 3500, Stadium Road, Karachi, 74800, Sindh, Pakistan.,Pakistan Council for Science and Technology, G-5/2, Islamabad, Pakistan
| | - Maimoona Ilyas
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, Sindh, 75270, Pakistan
| | - Bina Shaheen Siddiqui
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, Sindh, 75270, Pakistan
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Høydal MA, Stølen TO, Kettlewell S, Maier LS, Brown JH, Sowa T, Catalucci D, Condorelli G, Kemi OJ, Smith GL, Wisløff U. Exercise training reverses myocardial dysfunction induced by CaMKIIδC overexpression by restoring Ca2+ homeostasis. J Appl Physiol (1985) 2016; 121:212-20. [PMID: 27231311 DOI: 10.1152/japplphysiol.00188.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/20/2016] [Indexed: 11/22/2022] Open
Abstract
Several conditions of heart disease, including heart failure and diabetic cardiomyopathy, are associated with upregulation of cytosolic Ca(2+)/calmodulin-dependent protein kinase II (CaMKIIδC) activity. In the heart, CaMKIIδC isoform targets several proteins involved in intracellular Ca(2+) homeostasis. We hypothesized that high-intensity endurance training activates mechanisms that enable a rescue of dysfunctional cardiomyocyte Ca(2+) handling and thereby ameliorate cardiac dysfunction despite continuous and chronic elevated levels of CaMKIIδC CaMKIIδC transgenic (TG) and wild-type (WT) mice performed aerobic interval exercise training over 6 wk. Cardiac function was measured by echocardiography in vivo, and cardiomyocyte shortening and intracellular Ca(2+) handling were measured in vitro. TG mice had reduced global cardiac function, cardiomyocyte shortening (47% reduced compared with WT, P < 0.01), and impaired Ca(2+) homeostasis. Despite no change in the chronic elevated levels of CaMKIIδC, exercise improved global cardiac function, restored cardiomyocyte shortening, and reestablished Ca(2+) homeostasis to values not different from WT. The key features to explain restored Ca(2+) homeostasis after exercise training were increased L-type Ca(2+) current density and flux by 79 and 85%, respectively (P < 0.01), increased sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a) function by 50% (P < 0.01), and reduced diastolic SR Ca(2+) leak by 73% (P < 0.01), compared with sedentary TG mice. In conclusion, exercise training improves global cardiac function as well as cardiomyocyte function in the presence of a maintained high CaMKII activity. The main mechanisms of exercise-induced improvements in TG CaMKIIδC mice are mediated via increased L-type Ca(2+) channel currents and improved SR Ca(2+) handling by restoration of SERCA2a function in addition to reduced diastolic SR Ca(2+) leak.
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Affiliation(s)
- Morten A Høydal
- Norwegian University of Science and Technology, K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway;
| | - Tomas O Stølen
- Norwegian University of Science and Technology, K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway
| | - Sarah Kettlewell
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Lars S Maier
- Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | | | - Tomas Sowa
- Heart Center of the University of Göttingen, Göttingen, Germany; and
| | - Daniele Catalucci
- National Research Council, Institute of Genetic and Biomedical Research-UOS Milan and Humanitas Research Hospital, Milan, Italy
| | - Gianluigi Condorelli
- National Research Council, Institute of Genetic and Biomedical Research-UOS Milan and Humanitas Research Hospital, Milan, Italy
| | - Ole J Kemi
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Ulrik Wisløff
- Norwegian University of Science and Technology, K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway
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Kao YH, Hsu JC, Chen YC, Lin YK, Lkhagva B, Chen SA, Chen YJ. ZFHX3 knockdown increases arrhythmogenesis and dysregulates calcium homeostasis in HL-1 atrial myocytes. Int J Cardiol 2016; 210:85-92. [DOI: 10.1016/j.ijcard.2016.02.091] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 02/09/2016] [Accepted: 02/14/2016] [Indexed: 11/25/2022]
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78
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Bobin P, Varin A, Lefebvre F, Fischmeister R, Vandecasteele G, Leroy J. Calmodulin kinase II inhibition limits the pro-arrhythmic Ca2+ waves induced by cAMP-phosphodiesterase inhibitors. Cardiovasc Res 2016; 110:151-61. [PMID: 26851245 DOI: 10.1093/cvr/cvw027] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 01/22/2016] [Indexed: 01/29/2023] Open
Abstract
AIMS A major concern of using phosphodiesterase (PDE) inhibitors in heart failure is their potential to increase mortality by inducing arrhythmias. By diminishing cyclic adenosine monophosphate (cAMP) hydrolysis, they promote protein kinase A (PKA) activity under β-adrenergic receptor (β-AR) stimulation, hence enhancing Ca(2+) cycling and contraction. Yet, cAMP also activates CaMKII via PKA or the exchange protein Epac, but it remains unknown whether these pathways are involved in the pro-arrhythmic effect of PDE inhibitors. METHODS AND RESULTS Excitation-contraction coupling was investigated in isolated adult rat ventricular myocytes loaded with Fura-2 and paced at 1 Hz allowing coincident measurement of intracellular Ca(2+) and sarcomere shortening. The PDE4 inhibitor Ro 20-1724 (Ro) promoted the inotropic effects of the non-selective β-AR agonist isoprenaline (Iso) and also spontaneous diastolic Ca(2+) waves (SCWs). PDE4 inhibition potentiated RyR2 and PLB phosphorylation at specific PKA and CaMKII sites increasing sarcoplasmic reticulum (SR) Ca(2+) load and SR Ca(2+) leak measured in a 0Na(+)/0Ca(2+) solution ± tetracaine. PKA inhibition suppressed all the effects of Iso ± Ro, whereas CaMKII inhibition prevented SR Ca(2+) leak and diminished SCW incidence without affecting the inotropic effects of Ro. Inhibition of Epac2 but not Epac1 diminished the occurrence of SCWs. PDE3 inhibition with cilostamide induced an SR Ca(2+) leak, which was also blocked by CaMKII inhibition. CONCLUSION Our results show that PDE inhibitors exert inotropic effects via PKA but lead to SCWs via both PKA and CaMKII activation partly via Epac2, suggesting the potential use of CaMKII inhibitors as adjuncts to PDE inhibition to limit their pro-arrhythmic effects.
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Affiliation(s)
- Pierre Bobin
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
| | - Audrey Varin
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
| | - Florence Lefebvre
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
| | - Rodolphe Fischmeister
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
| | - Grégoire Vandecasteele
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
| | - Jérôme Leroy
- Inserm, UMR-S 1180, Univ. Paris-Sud, Université Paris-Saclay, F-92296, Châtenay-Malabry, France
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79
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Mazzocchi G, Sommese L, Palomeque J, Felice JI, Di Carlo MN, Fainstein D, Gonzalez P, Contreras P, Skapura D, McCauley MD, Lascano EC, Negroni JA, Kranias EG, Wehrens XHT, Valverde CA, Mattiazzi A. Phospholamban ablation rescues the enhanced propensity to arrhythmias of mice with CaMKII-constitutive phosphorylation of RyR2 at site S2814. J Physiol 2016; 594:3005-30. [PMID: 26695843 DOI: 10.1113/jp271622] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/14/2015] [Indexed: 01/27/2023] Open
Abstract
KEY POINTS Mice with Ca(2+) -calmodulin-dependent protein kinase (CaMKII) constitutive pseudo-phosphorylation of the ryanodine receptor RyR2 at Ser2814 (S2814D(+/+) mice) exhibit a higher open probability of RyR2, higher sarcoplasmic reticulum (SR) Ca(2+) leak in diastole and increased propensity to arrhythmias under stress conditions. We generated phospholamban (PLN)-deficient S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice, to test the hypothesis that PLN ablation can prevent the propensity to arrhythmias of S2814D(+/+) mice. PLN ablation partially rescues the altered intracellular Ca(2+) dynamics of S2814D(+/+) hearts and myocytes, but enhances SR Ca(2+) sparks and leak on confocal microscopy. PLN ablation diminishes ventricular arrhythmias promoted by CaMKII phosphorylation of S2814 on RyR2. PLN ablation aborts the arrhythmogenic SR Ca(2+) waves of S2814D(+/+) and transforms them into non-propagating events. A mathematical human myocyte model replicates these results and predicts the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a CaMKII-dependent leaky RyR2. ABSTRACT Mice with constitutive pseudo-phosphorylation at Ser2814-RyR2 (S2814D(+/+) ) have increased propensity to arrhythmias under β-adrenergic stress conditions. Although abnormal Ca(2+) release from the sarcoplasmic reticulum (SR) has been linked to arrhythmogenesis, the role played by SR Ca(2+) uptake remains controversial. We tested the hypothesis that an increase in SR Ca(2+) uptake is able to rescue the increased arrhythmia propensity of S2814D(+/+) mice. We generated phospholamban (PLN)-deficient/S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice (SD(+/+) /KO). SD(+/+) /KO myocytes exhibited both increased SR Ca(2+) uptake seen in PLN knock-out (PLNKO) myocytes and diminished SR Ca(2+) load (relative to PLNKO), a characteristic of S2814D(+/+) myocytes. Ventricular arrhythmias evoked by catecholaminergic challenge (caffeine/adrenaline) in S2814D(+/+) mice in vivo or programmed electric stimulation and high extracellular Ca(2+) in S2814D(+) /(-) hearts ex vivo were significantly diminished by PLN ablation. At the myocyte level, PLN ablation converted the arrhythmogenic Ca(2+) waves evoked by high extracellular Ca(2+) provocation in S2814D(+/+) mice into non-propagated Ca(2+) mini-waves on confocal microscopy. Myocyte Ca(2+) waves, typical of S2814D(+/+) mice, could be evoked in SD(+/+) /KO cells by partially inhibiting SERCA2a. A mathematical human myocyte model replicated these results and allowed for predicting the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a Ca(2+) -calmodulin-dependent protein kinase (CaMKII)-dependent leaky RyR2. Our results demonstrate that increasing SR Ca(2+) uptake by PLN ablation can prevent the arrhythmic events triggered by SR Ca(2+) leak due to CaMKII-dependent phosphorylation of the RyR2-S2814 site and underscore the benefits of increasing SERCA2a activity on SR Ca(2+) -triggered arrhythmias.
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Affiliation(s)
- G Mazzocchi
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - L Sommese
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - J Palomeque
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - J I Felice
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - M N Di Carlo
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - D Fainstein
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - P Gonzalez
- Cátedra de Patología, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - P Contreras
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - D Skapura
- Departments of Molecular Physiology and Biophysics, Medicine (in Cardiology), and Pediatrics, Baylor College of Medicine, Cardiovascular Research Institute, Houston, TX, 77030, USA
| | - M D McCauley
- Departments of Molecular Physiology and Biophysics, Medicine (in Cardiology), and Pediatrics, Baylor College of Medicine, Cardiovascular Research Institute, Houston, TX, 77030, USA
| | - E C Lascano
- Departamento de Biología Comparada, Celular y Molecular, Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Argentina
| | - J A Negroni
- Departamento de Biología Comparada, Celular y Molecular, Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Argentina
| | - E G Kranias
- Department of Pharmacology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267
| | - X H T Wehrens
- Departments of Molecular Physiology and Biophysics, Medicine (in Cardiology), and Pediatrics, Baylor College of Medicine, Cardiovascular Research Institute, Houston, TX, 77030, USA
| | - C A Valverde
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
| | - A Mattiazzi
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Cs Médicas, UNLP, La Plata, Argentina
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Fischer TH, Kleinwächter A, Herting J, Eiringhaus J, Hartmann N, Renner A, Gummert J, Haverich A, Schmitto JD, Sossalla S. Inhibition of CaMKII Attenuates Progressing Disruption of Ca2+Homeostasis Upon Left Ventricular Assist Device Implantation in Human Heart Failure. Artif Organs 2016; 40:719-26. [DOI: 10.1111/aor.12677] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Thomas H. Fischer
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
- German Center for Cardiovascular Research (DZHK); Göttingen Germany
| | - Astrid Kleinwächter
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
| | - Jonas Herting
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
- German Center for Cardiovascular Research (DZHK); Göttingen Germany
| | - Jörg Eiringhaus
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
| | - Nico Hartmann
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
- German Center for Cardiovascular Research (DZHK); Göttingen Germany
| | - André Renner
- Department for Heart and Transplantation Surgery; Heart Center; Bad Oeynhausen Germany
| | - Jan Gummert
- Department for Heart and Transplantation Surgery; Heart Center; Bad Oeynhausen Germany
| | - Axel Haverich
- Department for Thoracic and Heart Surgery; Medical University of Hannover; Hannover Germany
| | - Jan D. Schmitto
- Department for Thoracic and Heart Surgery; Medical University of Hannover; Hannover Germany
| | - Samuel Sossalla
- Department for Cardiology and Pulmonology; Georg-August University; Göttingen Germany
- German Center for Cardiovascular Research (DZHK); Göttingen Germany
- Department for Internal Medicine III, Cardiology, Angiology, and Intensive Care Medicine; University Medical Center; Kiel Germany
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Mesubi OO, Anderson ME. Atrial remodelling in atrial fibrillation: CaMKII as a nodal proarrhythmic signal. Cardiovasc Res 2016; 109:542-57. [PMID: 26762270 DOI: 10.1093/cvr/cvw002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/05/2016] [Indexed: 01/10/2023] Open
Abstract
CaMKII is a serine-threonine protein kinase that is abundant in myocardium. Emergent evidence suggests that CaMKII may play an important role in promoting atrial fibrillation (AF) by targeting a diverse array of proteins involved in membrane excitability, cell survival, calcium homeostasis, matrix remodelling, inflammation, and metabolism. Furthermore, CaMKII inhibition appears to protect against AF in animal models and correct proarrhythmic, defective intracellular Ca(2+) homeostasis in fibrillating human atrial cells. This review considers current concepts and evidence from animal and human studies on the role of CaMKII in AF.
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Affiliation(s)
- Olurotimi O Mesubi
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Medicine, The Johns Hopkins University School of Medicine, 1830 E. Monument Street, Suite 9026, Baltimore, MD 21287, USA
| | - Mark E Anderson
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Medicine, The Johns Hopkins University School of Medicine, 1830 E. Monument Street, Suite 9026, Baltimore, MD 21287, USA Department of Physiology and the Program in Cellular and Molecular Medicine, The Johns Hopkins School of Medicine, Baltimore, MD, USA
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82
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Haghighi K, Pritchard TJ, Liu GS, Singh VP, Bidwell P, Lam CK, Vafiadaki E, Das P, Ma J, Kunduri S, Sanoudou D, Florea S, Vanderbilt E, Wang HS, Rubinstein J, Hajjar RJ, Kranias EG. Human G109E-inhibitor-1 impairs cardiac function and promotes arrhythmias. J Mol Cell Cardiol 2015; 89:349-59. [PMID: 26455482 PMCID: PMC4689614 DOI: 10.1016/j.yjmcc.2015.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/18/2015] [Accepted: 10/04/2015] [Indexed: 01/09/2023]
Abstract
A hallmark of human and experimental heart failure is deficient sarcoplasmic reticulum (SR) Ca-uptake reflecting impaired contractile function. This is at least partially attributed to dephosphorylation of phospholamban by increased protein phosphatase 1 (PP1) activity. Indeed inhibition of PP1 by transgenic overexpression or gene-transfer of constitutively active inhibitor-1 improved Ca-cycling, preserved function and decreased fibrosis in small and large animal models of heart failure, suggesting that inhibitor-1 may represent a potential therapeutic target. We recently identified a novel human polymorphism (G109E) in the inhibitor-1 gene with a frequency of 7% in either normal or heart failure patients. Transgenic mice, harboring cardiac-specific expression of G109E inhibitor-1, exhibited decreases in contractility, Ca-kinetics and SR Ca-load. These depressive effects were relieved by isoproterenol stimulation. Furthermore, stress conditions (2Hz +/- Iso) induced increases in Ca-sparks, Ca-waves (60% of G109E versus 20% in wild types) and after-contractions (76% of G109E versus 23% of wild types) in mutant cardiomyocytes. Similar findings were obtained by acute expression of the G109E variant in adult cardiomyocytes in the absence or presence of endogenous inhibitor-1. The underlying mechanisms included reduced binding of mutant inhibitor-1 to PP1, increased PP1 activity, and dephosphorylation of phospholamban at Ser16 and Thr17. However, phosphorylation of the ryanodine receptor at Ser2808 was not altered while phosphorylation at Ser2814 was increased, consistent with increased activation of Ca/calmodulin-dependent protein kinase II (CaMKII), promoting aberrant SR Ca-release. Parallel in vivo studies revealed that mutant mice developed ventricular ectopy and complex ventricular arrhythmias (including bigeminy, trigeminy and ventricular tachycardia), when challenged with isoproterenol. Inhibition of CaMKII activity by KN-93 prevented the increased propensity to arrhythmias. These findings suggest that the human G109E inhibitor-1 variant impairs SR Ca-cycling and promotes arrhythmogenesis under stress conditions, which may present an additional insult in the compromised function of heart failure carriers.
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Affiliation(s)
- Kobra Haghighi
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Tracy J Pritchard
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Guan-Sheng Liu
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Vivek P Singh
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Philip Bidwell
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Chi Keung Lam
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece
| | - Parthib Das
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Jianyong Ma
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Swati Kunduri
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Despina Sanoudou
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece; 4th Department of Internal Medicine, Medical School, University of Athens and Attikon Hospital, Greece
| | - Stela Florea
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Erica Vanderbilt
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Hong-Shang Wang
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States
| | - Jack Rubinstein
- Division of Cardiology, Internal Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, United States
| | - Roger J Hajjar
- Cardiovascular Research Center, Ichan School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, United States
| | - Evangelia G Kranias
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, United States; Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece.
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83
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Abstract
Despite improvements in the therapy of underlying heart disease, sudden cardiac death is a major cause of death worldwide. Disturbed Na and Ca handling is known to be a major predisposing factor for life-threatening tachyarrhythmias. In cardiomyocytes, many ion channels and transporters, including voltage-gated Na and Ca channels, cardiac ryanodine receptors, Na/Ca-exchanger, and SR Ca-ATPase are involved in this regulation. We have learned a lot about the pathophysiological relevance of disturbed ion channel function from monogenetic disorders. Changes in the gating of a single ion channel and the activity of an ion pump suffice to dramatically increase the propensity for arrhythmias even in structurally normal hearts. Nevertheless, patients with heart failure with acquired dysfunction in many ion channels and transporters exhibit profound dysregulation of Na and Ca handling and Ca/calmodulin-dependent protein kinase and are especially prone to arrhythmias. A deeper understanding of the underlying arrhythmic principles is mandatory if we are to improve their outcome. This review addresses basic tachyarrhythmic mechanisms, the underlying ionic mechanisms and the consequences for ion homeostasis, and the situation in complex diseases like heart failure.
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Affiliation(s)
- Stefan Wagner
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.)
| | - Lars S Maier
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.).
| | - Donald M Bers
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.)
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84
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Guilbert A, Lim HJ, Cheng J, Wang Y. CaMKII-dependent myofilament Ca2+ desensitization contributes to the frequency-dependent acceleration of relaxation. Cell Calcium 2015; 58:489-99. [PMID: 26297240 DOI: 10.1016/j.ceca.2015.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 11/15/2022]
Abstract
BACKGROUND Previous studies suggest that CaMKII activity is required for frequency-dependent acceleration of relaxation (FDAR) in ventricular myocytes. We propose that the underlying mechanism involves CaMKII-dependent regulation of myofilament Ca(2+) sensitivity. METHODS AND RESULTS Cardiac function was measured in mice using murine echo machine. [Ca(2+)]i and sarcomere length were measured by IonOptix Ca(2+) image system. Increasing pacing rate from 0.5 to 4 Hz in left ventricular myocytes induced frequency-dependent myofilament Ca(2+) desensitization (FDMCD) and FDAR. Acute inhibition of PKA or PKC had no effect, whereas CaMKII inhibition abolished both FDMCD and FDAR. Co-immunoprecipitation of CaMKII and troponin I (TnI) has been detected and CaMKII inhibition significantly reduced serine residue phosphorylation of TnI. Finally, chronic inhibition of CaMKII in vivo reduced TnI phosphorylation and abolished both FDAR and FDMCD, leading to impaired diastolic function. CONCLUSIONS Our results suggest that CaMKII-dependent TnI phosphorylation is involved in FDMCD and the consequent FDAR and that CaMKII inhibition removes this mechanism and thus induces diastolic dysfunction.
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Affiliation(s)
| | - Hyun Joung Lim
- Department of Pediatrics, Emory University, Atlanta, USA
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA.
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85
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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86
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Luongo TS, Lambert JP, Yuan A, Zhang X, Gross P, Song J, Shanmughapriya S, Gao E, Jain M, Houser SR, Koch WJ, Cheung JY, Madesh M, Elrod JW. The Mitochondrial Calcium Uniporter Matches Energetic Supply with Cardiac Workload during Stress and Modulates Permeability Transition. Cell Rep 2015; 12:23-34. [PMID: 26119731 DOI: 10.1016/j.celrep.2015.06.017] [Citation(s) in RCA: 279] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/08/2015] [Accepted: 06/04/2015] [Indexed: 12/13/2022] Open
Abstract
Cardiac contractility is mediated by a variable flux in intracellular calcium (Ca(2+)), thought to be integrated into mitochondria via the mitochondrial calcium uniporter (MCU) channel to match energetic demand. Here, we examine a conditional, cardiomyocyte-specific, mutant mouse lacking Mcu, the pore-forming subunit of the MCU channel, in adulthood. Mcu(-/-) mice display no overt baseline phenotype and are protected against mCa(2+) overload in an in vivo myocardial ischemia-reperfusion injury model by preventing the activation of the mitochondrial permeability transition pore, decreasing infarct size, and preserving cardiac function. In addition, we find that Mcu(-/-) mice lack contractile responsiveness to acute β-adrenergic receptor stimulation and in parallel are unable to activate mitochondrial dehydrogenases and display reduced bioenergetic reserve capacity. These results support the hypothesis that MCU may be dispensable for homeostatic cardiac function but required to modulate Ca(2+)-dependent metabolism during acute stress.
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Affiliation(s)
- Timothy S Luongo
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jonathan P Lambert
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Ancai Yuan
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Xueqian Zhang
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Polina Gross
- Center for Cardiovascular Research, Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jianliang Song
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Santhanam Shanmughapriya
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Erhe Gao
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Mohit Jain
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - Steven R Houser
- Center for Cardiovascular Research, Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Walter J Koch
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Joseph Y Cheung
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Muniswamy Madesh
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - John W Elrod
- Center for Translational Medicine, Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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87
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Grimm M, Ling H, Willeford A, Pereira L, Gray CBB, Erickson JR, Sarma S, Respress JL, Wehrens XHT, Bers DM, Brown JH. CaMKIIδ mediates β-adrenergic effects on RyR2 phosphorylation and SR Ca(2+) leak and the pathophysiological response to chronic β-adrenergic stimulation. J Mol Cell Cardiol 2015; 85:282-91. [PMID: 26080362 DOI: 10.1016/j.yjmcc.2015.06.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 06/06/2015] [Accepted: 06/09/2015] [Indexed: 12/21/2022]
Abstract
Chronic activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) has been implicated in the deleterious effects of β-adrenergic receptor (β-AR) signaling on the heart, in part, by enhancing RyR2-mediated sarcoplasmic reticulum (SR) Ca(2+) leak. We used CaMKIIδ knockout (CaMKIIδ-KO) mice and knock-in mice with an inactivated CaMKII site S2814 on the ryanodine receptor type 2 (S2814A) to investigate the involvement of these processes in β-AR signaling and cardiac remodeling. Langendorff-perfused hearts from CaMKIIδ-KO mice showed inotropic and chronotropic responses to isoproterenol (ISO) that were similar to those of wild type (WT) mice; however, in CaMKIIδ-KO mice, CaMKII phosphorylation of phospholamban and RyR2 was decreased and isolated myocytes from CaMKIIδ-KO mice had reduced SR Ca(2+) leak in response to isoproterenol (ISO). Chronic catecholamine stress with ISO induced comparable increases in relative heart weight and other measures of hypertrophy from day 9 through week 4 in WT and CaMKIIδ-KO mice, but the development of cardiac fibrosis was prevented in CaMKIIδ-KO animals. A 4-week challenge with ISO resulted in reduced cardiac function and pulmonary congestion in WT, but not in CaMKIIδ-KO or S2814A mice, implicating CaMKIIδ-dependent phosphorylation of RyR2-S2814 in the cardiomyopathy, independent of hypertrophy, induced by prolonged β-AR stimulation.
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Affiliation(s)
- Michael Grimm
- Department of Pharmacology, University of California, San Diego, CA, USA
| | - Haiyun Ling
- Department of Pharmacology, University of California, San Diego, CA, USA
| | - Andrew Willeford
- Department of Pharmacology, University of California, San Diego, CA, USA
| | - Laetitia Pereira
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Charles B B Gray
- Department of Pharmacology, University of California, San Diego, CA, USA
| | | | - Satyam Sarma
- Department of Molecular Physiology & Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Jonathan L Respress
- Department of Molecular Physiology & Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander H T Wehrens
- Department of Molecular Physiology & Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Joan Heller Brown
- Department of Pharmacology, University of California, San Diego, CA, USA.
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88
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Abstract
The loss of contractile function is a hallmark of heart failure. Although increasing intracellular Ca(2+) is a possible strategy for improving contraction, current inotropic agents that achieve this by raising intracellular cAMP levels, such as β-agonists and phosphodiesterase inhibitors, are generally deleterious when administered as long-term therapy due to arrhythmia and myocardial damage. Nitroxyl donors have been shown to improve cardiac function in normal and failing dogs, and in isolated cardiomyocytes they increase fractional shortening and Ca(2+) transients, independently from cAMP/PKA or cGMP/PKG signaling. Instead, nitroxyl targets cysteines in the EC-coupling machinery and myofilament proteins, reversibly modifying them to enhance Ca(2+) handling and myofilament Ca(2+) sensitivity. Phase I-IIa trials with CXL-1020, a novel pure HNO donor, reported declines in left and right heart filling pressures and systemic vascular resistance, and increased cardiac output and stroke volume index. These findings support the concept of nitroxyl donors as attractive agents for the treatment of acute decompensated heart failure.
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89
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Negroni JA, Morotti S, Lascano EC, Gomes AV, Grandi E, Puglisi JL, Bers DM. β-adrenergic effects on cardiac myofilaments and contraction in an integrated rabbit ventricular myocyte model. J Mol Cell Cardiol 2015; 81:162-75. [PMID: 25724724 DOI: 10.1016/j.yjmcc.2015.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/10/2015] [Accepted: 02/17/2015] [Indexed: 12/21/2022]
Abstract
A five-state model of myofilament contraction was integrated into a well-established rabbit ventricular myocyte model of ion channels, Ca(2+) transporters and kinase signaling to analyze the relative contribution of different phosphorylation targets to the overall mechanical response driven by β-adrenergic stimulation (β-AS). β-AS effect on sarcoplasmic reticulum Ca(2+) handling, Ca(2+), K(+) and Cl(-) currents, and Na(+)/K(+)-ATPase properties was included based on experimental data. The inotropic effect on the myofilaments was represented as reduced myofilament Ca(2+) sensitivity (XBCa) and titin stiffness, and increased cross-bridge (XB) cycling rate (XBcy). Assuming independent roles of XBCa and XBcy, the model reproduced experimental β-AS responses on action potentials and Ca(2+) transient amplitude and kinetics. It also replicated the behavior of force-Ca(2+), release-restretch, length-step, stiffness-frequency and force-velocity relationships, and increased force and shortening in isometric and isotonic twitch contractions. The β-AS effect was then switched off from individual targets to analyze their relative impact on contractility. Preventing β-AS effects on L-type Ca(2+) channels or phospholamban limited Ca(2+) transients and contractile responses in parallel, while blocking phospholemman and K(+) channel (IKs) effects enhanced Ca(2+) and inotropy. Removal of β-AS effects from XBCa enhanced contractile force while decreasing peak Ca(2+) (due to greater Ca(2+) buffering), but had less effect on shortening. Conversely, preventing β-AS effects on XBcy preserved Ca(2+) transient effects, but blunted inotropy (both isometric force and especially shortening). Removal of titin effects had little impact on contraction. Finally, exclusion of β-AS from XBCa and XBcy while preserving effects on other targets resulted in preserved peak isometric force response (with slower kinetics) but nearly abolished enhanced shortening. β-AS effects on XBCa and XBcy have greater impact on isometric and isotonic contraction, respectively.
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Affiliation(s)
- Jorge A Negroni
- Department of Comparative, Cellular and Molecular Biology, Universidad Favaloro, Buenos Aires, Argentina.
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, CA, USA
| | - Elena C Lascano
- Department of Comparative, Cellular and Molecular Biology, Universidad Favaloro, Buenos Aires, Argentina
| | - Aldrin V Gomes
- Department of Neurobiology, Physiology and Behavior, University of California Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, CA, USA
| | - José L Puglisi
- Department of Pharmacology, University of California Davis, CA, USA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, CA, USA.
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90
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Curran J, Mohler PJ. Alternative Paradigms for Ion Channelopathies: Disorders of Ion Channel Membrane Trafficking and Posttranslational Modification. Annu Rev Physiol 2015; 77:505-24. [DOI: 10.1146/annurev-physiol-021014-071838] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jerry Curran
- The Dorothy M. Davis Heart & Lung Research Institute,
- Department of Physiology and Cell Biology, and
| | - Peter J. Mohler
- The Dorothy M. Davis Heart & Lung Research Institute,
- Department of Physiology and Cell Biology, and
- Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio 43210;
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91
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Bell JR, Raaijmakers AJ, Curl CL, Reichelt ME, Harding TW, Bei A, Ng DC, Erickson JR, Vila Petroff M, Harrap SB, Delbridge LM. Cardiac CaMKIIδ splice variants exhibit target signaling specificity and confer sex-selective arrhythmogenic actions in the ischemic-reperfused heart. Int J Cardiol 2015; 181:288-96. [DOI: 10.1016/j.ijcard.2014.11.159] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/24/2014] [Accepted: 11/23/2014] [Indexed: 01/16/2023]
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92
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Dulce RA, Mayo V, Rangel EB, Balkan W, Hare JM. Interaction between neuronal nitric oxide synthase signaling and temperature influences sarcoplasmic reticulum calcium leak: role of nitroso-redox balance. Circ Res 2015; 116:46-55. [PMID: 25326127 PMCID: PMC4282621 DOI: 10.1161/circresaha.116.305172] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/16/2014] [Indexed: 11/16/2022]
Abstract
RATIONALE Although nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results because of inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here, we show that temperature significantly modulates NO effects. OBJECTIVE To test the hypothesis that temperature profoundly affects nitroso-redox equilibrium, thereby affecting sarcoplasmic reticulum (SR) calcium (Ca(2+)) leak. METHODS AND RESULTS We measured SR Ca(2+) leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (neuronal nitric oxide synthase-deficient mice-1 [NOS1(-/-)]), and hyper S-nitrosoglutathione reductase-deficient (GSNOR(-/-)) mice. In WT cardiomyocytes, SR Ca(2+) leak increased because temperature decreased from 37°C to 23°C, whereas in NOS1(-/-) cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR(-/-) cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1(-/-) cardiomyocytes; reducing leak at 37°C but increasing it at subphysiological temperatures. Oxypurinol and Tempol diminished the leak in NOS1(-/-) cardiomyocytes. Cooling from 37°C to 23°C increased reactive oxygen species generation in WT but decreased it in NOS1(-/-) cardiomyocytes. Oxypurinol further reduced reactive oxygen species generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca(2+) content in NOS1(-/-) cells but had no effect in WT or GSNOR(-/-). CONCLUSIONS Ca(2+) leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating reactive oxygen species production because temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and reactive oxygen species which in turn has a major effect on SR Ca(2+).
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Affiliation(s)
- Raul A Dulce
- From the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, FL
| | - Vera Mayo
- From the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, FL
| | - Erika B Rangel
- From the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, FL
| | - Wayne Balkan
- From the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, FL
| | - Joshua M Hare
- From the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, FL.
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93
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Willis BC, Salazar-Cantú A, Silva-Platas C, Fernández-Sada E, Villegas CA, Rios-Argaiz E, González-Serrano P, Sánchez LA, Guerrero-Beltrán CE, García N, Torre-Amione G, García-Rivas GJ, Altamirano J. Impaired oxidative metabolism and calcium mishandling underlie cardiac dysfunction in a rat model of post-acute isoproterenol-induced cardiomyopathy. Am J Physiol Heart Circ Physiol 2014; 308:H467-77. [PMID: 25527782 DOI: 10.1152/ajpheart.00734.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stress-induced cardiomyopathy, triggered by acute catecholamine discharge, is a syndrome characterized by transient, apical ballooning linked to acute heart failure and ventricular arrhythmias. Rats receiving an acute isoproterenol (ISO) overdose (OV) suffer cardiac apex ischemia-reperfusion damage and arrhythmia, and then undergo cardiac remodeling and dysfunction. Nevertheless, the subcellular mechanisms underlying cardiac dysfunction after acute damage subsides are not thoroughly understood. To address this question, Wistar rats received a single ISO injection (67 mg/kg). We found in vivo moderate systolic and diastolic dysfunction at 2 wk post-ISO-OV; however, systolic dysfunction recovered after 4 wk, while diastolic dysfunction worsened. At 2 wk post-ISO-OV, cardiac function was assessed ex vivo, while mitochondrial oxidative metabolism and stress were assessed in vitro, and Ca(2+) handling in ventricular myocytes. These were complemented with sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), phospholamban (PLB), and RyR2 expression studies. Ex vivo, basal mechanical performance index (MPI) and oxygen consumption rate (MVO2) were unchanged. Nevertheless, upon increase of metabolic demand, by β-adrenergic stimulation (1-100 nM ISO), the MPI versus MVO2 relation decreased and shifted to the right, suggesting MPI and mitochondrial energy production uncoupling. Mitochondria showed decreased oxidative metabolism, membrane fragility, and enhanced oxidative stress. Myocytes presented systolic and diastolic Ca(2+) mishandling, and blunted response to ISO (100 nM), and all these without apparent changes in SERCA, PLB, or RyR2 expression. We suggest that post-ISO-OV mitochondrial dysfunction may underlie decreased cardiac contractility, mainly by depletion of ATP needed for myofilaments and Ca(2+) transport by SERCA, while exacerbated oxidative stress may enhance diastolic RyR2 activity.
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Affiliation(s)
- B Cicero Willis
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Ayleen Salazar-Cantú
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Christian Silva-Platas
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and
| | - Evaristo Fernández-Sada
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - César A Villegas
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Eduardo Rios-Argaiz
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Pilar González-Serrano
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Luis A Sánchez
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México
| | - Carlos E Guerrero-Beltrán
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and
| | - Noemí García
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and
| | - Guillermo Torre-Amione
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and Methodist DeBakey Heart and Vascular Center, The Methodist Hospital, Houston, Texas
| | - Gerardo J García-Rivas
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and
| | - Julio Altamirano
- Endowed Chair in Cardiology and Vascular Medicine, School of Medicine, Tecnológico de Monterrey, Monterrey México; Basic and Translational Research Center, Hospital Zambrano-Hellion, TEC Salud, San Pedro, Garza-García, México; and
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94
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Briston SJ, Dibb KM, Solaro RJ, Eisner DA, Trafford AW. Balanced changes in Ca buffering by SERCA and troponin contribute to Ca handling during β-adrenergic stimulation in cardiac myocytes. Cardiovasc Res 2014; 104:347-54. [PMID: 25183792 PMCID: PMC4240166 DOI: 10.1093/cvr/cvu201] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 07/24/2014] [Accepted: 08/25/2014] [Indexed: 01/01/2023] Open
Abstract
AIMS During activation of cardiac myocytes, less than 1% of cytosolic Ca is free; the rest is bound to buffers, largely SERCA, and troponin C. Signalling by phosphorylation, as occurs during β-adrenergic stimulation, changes the Ca-binding affinity of these proteins and may affect the systolic Ca transient. Our aim was to determine the effects of β-adrenergic stimulation on Ca buffering and to differentiate between the roles of SERCA and troponin. METHODS AND RESULTS Ca buffering was studied in cardiac myocytes from mice: wild-type (WT), phospholamban-knockout (PLN-KO), and mice expressing slow skeletal troponin I (ssTnI) that is not protein kinase A phosphorylatable. WT cells showed no change in Ca buffering in response to the β-adrenoceptor agonist isoproterenol (ISO). However, ISO decreased Ca buffering in PLN-KO myocytes, presumably unmasking the role of troponin. This effect was confirmed in WT cells in which SERCA activity was blocked with the application of thapsigargin. In contrast, ISO increased Ca buffering in ssTnI cells, presumably revealing the effect of an increase in Ca binding to SERCA. CONCLUSIONS These data indicate the individual roles played by SERCA and troponin in Ca buffering during β-adrenergic stimulation and that these two buffers effectively counterbalance each other so that Ca buffering remains constant during β-adrenergic stimulation, a factor which may be physiologically important. This study also emphasizes the importance of taking into account Ca buffering, particularly in disease states where Ca binding to myofilaments or SERCA may be altered.
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Affiliation(s)
- Sarah J Briston
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Core Technology Facility, 46 Grafton St, Manchester M13 9NT, UK
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Core Technology Facility, 46 Grafton St, Manchester M13 9NT, UK
| | - R John Solaro
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - David A Eisner
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Core Technology Facility, 46 Grafton St, Manchester M13 9NT, UK
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Core Technology Facility, 46 Grafton St, Manchester M13 9NT, UK
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95
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Poláková E, Illaste A, Niggli E, Sobie EA. Maximal acceleration of Ca2+ release refractoriness by β-adrenergic stimulation requires dual activation of kinases PKA and CaMKII in mouse ventricular myocytes. J Physiol 2014; 593:1495-507. [PMID: 25772298 DOI: 10.1113/jphysiol.2014.278051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 08/30/2014] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Refractoriness of calcium release in heart cells is altered in several disease states, but the physiological mechanisms that regulate this process are incompletely understood. We examined refractoriness of calcium release in mouse ventricular myocytes and investigated how activation of different intracellular signalling pathways influenced this process. We found that refractoriness of calcium release is abbreviated by stimulation of the 'fight-or-flight' response, and that simultaneous activation of multiple intracellular signalling pathways contributes to this response. Data obtained under several conditions at the subcellular, microscopic level were consistent with results obtained at the cellular level. The results provide insight into regulation of cardiac calcium release and how alterations to this process may increase arrhythmia risk under different conditions. ABSTRACT Time-dependent refractoriness of calcium (Ca(2+)) release in cardiac myocytes is an important factor in determining whether pro-arrhythmic release patterns develop. At the subcellular level of the Ca(2+) spark, recent studies have suggested that recovery of spark amplitude is controlled by local sarcoplasmic reticulum (SR) refilling whereas refractoriness of spark triggering depends on both refilling and the sensitivity of the ryanodine receptor (RyR) release channels that produce sparks. Here we studied regulation of Ca(2+) spark refractoriness in mouse ventricular myocytes by examining how β-adrenergic stimulation influenced sequences of Ca(2+) sparks originating from individual RyR clusters. Our protocol allowed us to separately measure recovery of spark amplitude and delays between successive sparks, and data were interpreted quantitatively through simulations with a stochastic mathematical model. We found that, compared with spark sequences measured under control conditions: (1) β-adrenergic stimulation with isoproterenol (isoprenaline) accelerated spark amplitude recovery and decreased spark-to-spark delays; (2) activating protein kinase A (PKA) with forskolin accelerated amplitude recovery but did not affect spark-to-spark delays; (3) inhibiting PKA with H89 retarded amplitude recovery and increased spark-to-spark delays; (4) preventing phosphorylation of the RyR at serine 2808 with a knock-in mouse prevented the decrease in spark-to-spark delays seen with β-adrenergic stimulation; (5) inhibiting either PKA or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) during β-adrenergic stimulation prevented the decrease in spark-to-spark delays seen without inhibition. The results suggest that activation of either PKA or CaMKII is sufficient to speed SR refilling, but activation of both kinases appears necessary to observe increased RyR sensitivity. The data provide novel insight into β-adrenergic regulation of Ca(2+) release refractoriness in mouse myocytes.
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Affiliation(s)
- Eva Poláková
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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96
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Xiong F, Yin Y, Dubé B, Pagé P, Vinet A. Electrophysiological changes preceding the onset of atrial fibrillation after coronary bypass grafting surgery. PLoS One 2014; 9:e107919. [PMID: 25247814 PMCID: PMC4172567 DOI: 10.1371/journal.pone.0107919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 08/24/2014] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The incidence of Post-CABG atrial fibrillation (AF) lies between 25% and 40%. It worsens morbidity and raises post-operative costs. Detection of incoming AF soon enough for prophylactic intervention would be helpful. The study is to investigate the electrophysiological changes preceding the onset of AF and their relationship to the preoperative risk. METHODS AND RESULTS Patients were recorded continuously for the first four days after coronary artery bypass grafting surgery (CABG) with three unipolar electrodes sutured to the atria (AEG). The patients experiencing an AF lasting more than 10 minutes were selected and the two hours before the onset were analyzed. Four variables were found to show significant changes in the two hours prior to the first prolonged AF: increasing rate of premature atrial activation, increasing incidence of short transient arrhythmias, acceleration of heart rate, and rise of low frequency content of heart rate. The main contrast was between the first and last hour before AF onset. Preoperative risk was not predictive of the onset time of AF and did not correlate with the amplitude of changes prior to AF. CONCLUSIONS Post-CABG AF were preceded by electrophysiological changes occurring in the last hour before the onset of the arrhythmia, whereas none of these changes was found to occur in all AF patients. The risk was a weighted sum of factors related to the density of premature activations and the state of atrial substrate reflected by the sinus rhythm and its frequency content prior to AF. Preoperative risk score seems unhelpful in setting a detection threshold for the AF onset.
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Affiliation(s)
- Feng Xiong
- Research Center, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Canada
- Montréal Heart Institute, Université de Montréal, Montréal, Canada
| | - Yalin Yin
- Research Center, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Canada
| | - Bruno Dubé
- Research Center, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Canada
- Biomedical Engineering Institute, Université de Montréal, Montréal, Canada
| | - Pierre Pagé
- Research Center, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Canada
- Montréal Heart Institute, Université de Montréal, Montréal, Canada
- Department of Surgery, Université de Montréal, Montréal, Canada
| | - Alain Vinet
- Research Center, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Canada
- Biomedical Engineering Institute, Université de Montréal, Montréal, Canada
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97
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Park H, Park H, Lee D, Oh S, Lim J, Hwang HJ, Park S, Pak HN, Lee MH, Joung B. Increased phosphorylation of Ca(2+) handling proteins as a proarrhythmic mechanism in myocarditis. Circ J 2014; 78:2292-301. [PMID: 25056499 DOI: 10.1253/circj.cj-14-0277] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Because fatal arrhythmia is an important cause of death in patients with myocarditis, we investigated the proarrhythmic mechanisms of experimental autoimmune myocarditis. METHODS AND RESULTS: Myocarditis was induced by injection of 2 mg porcine cardiac myosin into the footpads of adult Lewis rats on days 1 and 8 (Myo, n=15) and the results compared with Control rats (Control, n=15). In an additional 15 rats, 6 mg/kg prednisolone was injected into the gluteus muscle before the injection of porcine cardiac myosin on days 1 and 8 (MyoS, n=15). Hearts with myocarditis had longer action potential duration (APD), slower conduction velocity (CV; P<0.01 vs. Control), higher CV heterogeneity, greater fibrosis, higher levels of immunoblotting of high-mobility group protein B1, interleukin 6 and tumor necrosis factor-α proteins. Steroid treatment partially reversed the translations for myocarditis, CV heterogeneity, reduced APD at 90% recovery to baseline, increased CV (P<0.01), and reversed fibrosis (P<0.05). Programmed stimulation triggered sustained ventricular tachycardia in Myo rats (n=4/5), but not in controls (n=0/5) or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitor (KN93) treated Myo rats (n=0/5, P=0.01). CaMKII autophosphorylation at Thr287 (201%), and RyR2 phosphorylation at Ser2808 (protein kinase A/CaMKII site, 126%) and Ser2814 (CaMKII site, 21%) were increased in rats with myocarditis and reversed by steroid. CONCLUSIONS The myocarditis group had an increased incidence of arrhythmia caused by increased phosphorylation of Ca(2+)handling proteins. These changes were partially reversed by an antiinflammatory treatment and CaMKII inhibition.
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Affiliation(s)
- Hyelim Park
- Cardiology Division, Yonsei University College of Medicine
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98
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Arrhythmias, elicited by catecholamines and serotonin, vanish in human chronic atrial fibrillation. Proc Natl Acad Sci U S A 2014; 111:11193-8. [PMID: 25024212 DOI: 10.1073/pnas.1324132111] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atrial fibrillation (AF) is the most common heart rhythm disorder. Transient postoperative AF can be elicited by high sympathetic nervous system activity. Catecholamines and serotonin cause arrhythmias in atrial trabeculae from patients with sinus rhythm (SR), but whether these arrhythmias occur in patients with chronic AF is unknown. We compared the incidence of arrhythmic contractions caused by norepinephrine, epinephrine, serotonin, and forskolin in atrial trabeculae from patients with SR and patients with AF. In the patients with AF, arrhythmias were markedly reduced for the agonists and abolished for forskolin, whereas maximum inotropic responses were markedly blunted only for serotonin. Serotonin and forskolin produced spontaneous diastolic Ca(2+) releases in atrial myocytes from the patients with SR that were abolished or reduced in myocytes from the patients with AF. For matching L-type Ca(2+)-current (ICa,L) responses, serotonin required and produced ∼ 100-fold less cAMP/PKA at the Ca(2+) channel domain compared with the catecholamines and forskolin. Norepinephrine-evoked ICa,L responses were decreased by inhibition of Ca(2+)/calmodulin-dependent kinase II (CaMKII) in myocytes from patients with SR, but not in those from patients with AF. Agonist-evoked phosphorylation by CaMKII at phospholamban (Thr-17), but not of ryanodine2 (Ser-2814), was reduced in trabeculae from patients with AF. The decreased CaMKII activity may contribute to the blunting of agonist-evoked arrhythmias in the atrial myocardium of patients with AF.
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99
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Camors E, Valdivia HH. CaMKII regulation of cardiac ryanodine receptors and inositol triphosphate receptors. Front Pharmacol 2014; 5:101. [PMID: 24847270 PMCID: PMC4021131 DOI: 10.3389/fphar.2014.00101] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 04/17/2014] [Indexed: 01/08/2023] Open
Abstract
Ryanodine receptors (RyRs) and inositol triphosphate receptors (InsP3Rs) are structurally related intracellular calcium release channels that participate in multiple primary or secondary amplified Ca(2+) signals, triggering muscle contraction and oscillatory Ca(2+) waves, or activating transcription factors. In the heart, RyRs play an indisputable role in the process of excitation-contraction coupling as the main pathway for Ca(2+) release from sarcoplasmic reticulum (SR), and a less prominent role in the process of excitation-transcription coupling. Conversely, InsP3Rs are believed to contribute in subtle ways, only, to contraction of the heart, and in more important ways to regulation of transcription factors. Because uncontrolled activity of either RyRs or InsP3Rs may elicit life-threatening arrhythmogenic and/or remodeling Ca(2+) signals, regulation of their activity is of paramount importance for normal cardiac function. Due to their structural similarity, many regulatory factors, accessory proteins, and post-translational processes are equivalent for RyRs and InsP3Rs. Here we discuss regulation of RyRs and InsP3Rs by CaMKII phosphorylation, but touch on other kinases whenever appropriate. CaMKII is emerging as a powerful modulator of RyR and InsP3R activity but interestingly, some of the complexities and controversies surrounding phosphorylation of RyRs also apply to InsP3Rs, and a clear-cut effect of CaMKII on either channel eludes investigators for now. Nevertheless, some effects of CaMKII on global cellular activity, such as SR Ca(2+) leak or force-frequency potentiation, appear clear now, and this constrains the limits of the controversies and permits a more tractable approach to elucidate the effects of phosphorylation at the single channel level.
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Affiliation(s)
- Emmanuel Camors
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor MI, USA
| | - Héctor H Valdivia
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor MI, USA
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100
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Joiner MLA, Koval OM. CaMKII and stress mix it up in mitochondria. Front Pharmacol 2014; 5:67. [PMID: 24822046 PMCID: PMC4013469 DOI: 10.3389/fphar.2014.00067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/24/2014] [Indexed: 11/25/2022] Open
Abstract
CaMKII is a newly discovered resident of mitochondria in the heart. Mitochondrial CaMKII promotes poor outcomes after heart injury from a number of pathological conditions, including myocardial infarction (MI), ischemia reperfusion (IR), and stress from catecholamine stimulation. A study using the inhibitor of CaMKII, CaMKIIN, with expression delimited to myocardial mitochondria, indicates that an underlying cause of heart disease results from the opening of the mitochondrial permeability transition pore (mPTP). Evidence from electrophysiological and other experiments show that CaMKII inhibition likely suppresses mPTP opening by reducing Ca2+ entry into mitochondria. However, we expect other proteins involved in Ca2+ signaling in the mitochondria are affected with CaMKII inhibition. Several outstanding questions remain for CaMKII signaling in heart mitochondria. Most importantly, how does CaMKII, without the recognized N-terminal mitochondrial targeting sequence transfer to mitochondria?
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Affiliation(s)
| | - Olha M Koval
- Internal Medicine/Cardiology, University of Iowa Iowa City, IA, USA
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