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Ran Q, Li A, Tan Y, Zhang Y, Zhang Y, Chen H. Action and therapeutic targets of myosin light chain kinase, an important cardiovascular signaling mechanism. Pharmacol Res 2024; 206:107276. [PMID: 38944220 DOI: 10.1016/j.phrs.2024.107276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Accepted: 06/19/2024] [Indexed: 07/01/2024]
Abstract
The global incidence of cardiac diseases is increasing, imposing a substantial socioeconomic burden on healthcare systems. The pathogenesis of cardiovascular disease is complex and not fully understood, and the physiological function of the heart is inextricably linked to well-regulated cardiac muscle movement. Myosin light chain kinase (MLCK) is essential for myocardial contraction and diastole, cardiac electrophysiological homeostasis, vasoconstriction of vascular nerves and blood pressure regulation. In this sense, MLCK appears to be an attractive therapeutic target for cardiac diseases. MLCK participates in myocardial cell movement and migration through diverse pathways, including regulation of calcium homeostasis, activation of myosin light chain phosphorylation, and stimulation of vascular smooth muscle cell contraction or relaxation. Recently, phosphorylation of myosin light chains has been shown to be closely associated with the activation of myocardial exercise signaling, and MLCK mediates systolic and diastolic functions of the heart through the interaction of myosin thick filaments and actin thin filaments. It works by upholding the integrity of the cytoskeleton, modifying the conformation of the myosin head, and modulating innervation. MLCK governs vasoconstriction and diastolic function and is associated with the activation of adrenergic and sympathetic nervous systems, extracellular transport, endothelial permeability, and the regulation of nitric oxide and angiotensin II. Additionally, MLCK plays a crucial role in the process of cardiac aging. Multiple natural products/phytochemicals and chemical compounds, such as quercetin, cyclosporin, and ML-7 hydrochloride, have been shown to regulate cardiomyocyte MLCK. The MLCK-modifying capacity of these compounds should be considered in designing novel therapeutic agents. This review summarizes the mechanism of action of MLCK in the cardiovascular system and the therapeutic potential of reported chemical compounds in cardiac diseases by modifying MLCK processes.
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Affiliation(s)
- Qingzhi Ran
- Guang'anmen Hospital, China Academy of Traditional Chinese Medicine, Beijing 100070, China
| | - Aoshuang Li
- Dongzhimen Hospital, Beijing University of Traditional Chinese Medicine, Beijing 100053, China
| | - Yuqing Tan
- Guang'anmen Hospital, China Academy of Traditional Chinese Medicine, Beijing 100070, China
| | - Yue Zhang
- Guang'anmen Hospital, China Academy of Traditional Chinese Medicine, Beijing 100070, China.
| | - Yongkang Zhang
- Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200082, China.
| | - Hengwen Chen
- Guang'anmen Hospital, China Academy of Traditional Chinese Medicine, Beijing 100070, China.
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Grogan A, Huang W, Brong A, Kane MA, Kontrogianni-Konstantopoulos A. Alterations in cytoskeletal and Ca 2+ cycling regulators in atria lacking the obscurin Ig58/59 module. Front Cardiovasc Med 2023; 10:1085840. [PMID: 37304957 PMCID: PMC10251194 DOI: 10.3389/fcvm.2023.1085840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/26/2023] [Indexed: 06/13/2023] Open
Abstract
Introduction Obscurin (720-870 kDa) is a giant cytoskeletal and signaling protein that possesses both structural and regulatory functions in striated muscles. Immunoglobulin domains 58/59 (Ig58/59) of obscurin bind to a diverse set of proteins that are essential for the proper structure and function of the heart, including giant titin, novex-3, and phospholamban (PLN). Importantly, the pathophysiological significance of the Ig58/59 module has been further underscored by the discovery of several mutations within Ig58/59 that are linked to various forms of myopathy in humans. We previously generated a constitutive deletion mouse model, Obscn-ΔIg58/59, that expresses obscurin lacking Ig58/59, and characterized the effects of this deletion on cardiac morphology and function through aging. Our findings demonstrated that Obscn-ΔIg58/59 male animals develop severe arrhythmia, primarily manifesting as episodes of junctional escape and spontaneous loss of regular p-waves, reminiscent of human atrial fibrillation, accompanied by significant atrial enlargement that progresses in severity with aging. Methods and Results To comprehensively characterize the molecular alterations responsible for these pathologies, we performed proteomic and phospho-proteomic analyses in aging Obscn-ΔIg58/59 atria. Our studies revealed extensive and novel alterations in the expression and phosphorylation profile of major cytoskeletal proteins, Ca2+ regulators, and Z-disk associated protein complexes in the Obscn-ΔIg58/59 atria through aging. Discussion These studies implicate obscurin, particularly the Ig58/59 module, as an essential regulator of the Z-disk associated cytoskeleton and Ca2+ cycling in the atria and provide new molecular insights into the development of atrial fibrillation and remodeling.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Annie Brong
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
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Xu Parks X, Qudsi H, Braun C, Lopes CMB. The auxiliary subunit KCNE1 regulates KCNQ1 channel response to sustained calcium-dependent PKC activation. PLoS One 2020; 15:e0237591. [PMID: 32833978 PMCID: PMC7446858 DOI: 10.1371/journal.pone.0237591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 07/29/2020] [Indexed: 11/18/2022] Open
Abstract
The slow cardiac delayed rectifier current (IKs) is formed by KCNQ1 and KCNE1 subunits and is one of the major repolarizing currents in the heart. Decrease of IKs currents either due to inherited mutations or pathological remodeling is associated with increased risk for cardiac arrhythmias and sudden death. Ca2+-dependent PKC isoforms (cPKC) are chronically activated in heart disease and diabetes. Recently, we found that sustained stimulation of the calcium-dependent PKCβII isoform leads to decrease in KCNQ1 subunit membrane localization and KCNQ1/KCNE1 channel activity, although the role of KCNE1 in this regulation was not explored. Here, we show that the auxiliary KCNE1 subunit expression is necessary for channel internalization. A mutation in a KCNE1 phosphorylation site (KCNE1(S102A)) abolished channel internalization in both heterologous expression systems and cardiomyocytes. Altogether, our results suggest that KCNE1(S102) phosphorylation by PKCβII leads to KCNQ1/KCNE1 channel internalization in response to sustained PKC stimulus, while leaving KCNQ1 homomeric channels in the membrane. This preferential internalization is expected to have strong impact on cardiac repolarization. Our results suggest that KCNE1(S102) is an important anti-arrhythmic drug target to prevent IKs pathological remodeling leading to cardiac arrhythmias.
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Affiliation(s)
- Xiaorong Xu Parks
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Haani Qudsi
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Chen Braun
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Coeli M. B. Lopes
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
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PKCβII specifically regulates KCNQ1/KCNE1 channel membrane localization. J Mol Cell Cardiol 2019; 138:283-290. [PMID: 31785237 DOI: 10.1016/j.yjmcc.2019.10.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 09/06/2019] [Accepted: 10/09/2019] [Indexed: 01/15/2023]
Abstract
The slow voltage-gated potassium channel (IKs) is composed of the KCNQ1 and KCNE1 subunits and is one of the major repolarizing currents in the heart. Activation of protein kinase C (PKC) has been linked to cardiac arrhythmias. Although PKC has been shown to be a regulator of a number of cardiac channels, including IKs, little is known about regulation of the channel by specific isoforms of PKC. Here we studied the role of different PKC isoforms on IKs channel membrane localization and function. Our studies focused on PKC isoforms that translocate to the plasma membrane in response to Gq-coupled receptor (GqPCR) stimulation: PKCα, PKCβI, PKCβII and PKCε. Prolonged stimulation of GqPCRs has been shown to decrease IKs membrane expression, but the specific role of each PKC isoform is unclear. Here we show that stimulation of calcium-dependent isoforms of PKC (cPKC) but not PKCε mimic receptor activation. In addition, we show that general PKCβ (LY-333531) and PKCβII inhibitors but not PKCα or PKCβI inhibitors blocked the effect of cPKC on the KCNQ1/KCNE1 channel. PKCβ inhibitors also blocked GqPCR-mediated decrease in channel membrane expression in cardiomyocytes. Direct activation of PKCβII using constitutively active PKCβII construct mimicked agonist-induced decrease in membrane expression and channel function, while dominant negative PKCβII showed no effect. This suggests that the KCNQ1/KCNE1 channel was not regulated by basal levels of PKCβII activity. Our results indicate that PKCβII is a specific regulator of IKs membrane localization. PKCβII expression and activation are strongly increased in many disease states, including heart disease and diabetes. Thus, our results suggest that PKCβII inhibition may protect against acquired QT prolongation associated with heart disease.
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Parks XX, Ronzier E, O-Uchi J, Lopes CM. Fluvastatin inhibits Rab5-mediated IKs internalization caused by chronic Ca 2+-dependent PKC activation. J Mol Cell Cardiol 2019; 129:314-325. [PMID: 30898664 DOI: 10.1016/j.yjmcc.2019.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 02/26/2019] [Accepted: 03/16/2019] [Indexed: 10/27/2022]
Abstract
Statins, in addition to their cholesterol lowering effects, can prevent isoprenylation of Rab GTPase proteins, a key protein family for the regulation of protein trafficking. Rab-GTPases have been shown to be involved in the control of membrane expression level of ion channels, including one of the major cardiac repolarizing channels, IKs. Decreased IKs function has been observed in a number of disease states and associated with increased propensity for arrhythmias, but the mechanism underlying IKs decrease remains elusive. Ca2+-dependent PKC isoforms (cPKC) are chronically activated in variety of human diseases and have been suggested to acutely regulate IKs function. We hypothesize that chronic cPKC stimulation leads to Rab-mediated decrease in IKs membrane expression, and that can be prevented by statins. In this study we show that chronic cPKC stimulation caused a dramatic Rab5 GTPase-dependent decrease in plasma membrane localization of the IKs pore forming subunit KCNQ1, reducing IKs function. Our data indicates fluvastatin inhibition of Rab5 restores channel localization and function after cPKC-mediated channel internalization. Our results indicate a novel statin anti-arrhythmic effect that would be expected to inhibit pathological electrical remodeling in a number of disease states associated with high cPKC activation. Because Rab-GTPases are important regulators of membrane trafficking they may underlie other statin pleiotropic effects.
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Affiliation(s)
- Xiaorong Xu Parks
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, United States of America
| | - Elsa Ronzier
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, United States of America
| | - Jin O-Uchi
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, United States of America; Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Minneapolis, MN 55455, United States of America
| | - Coeli M Lopes
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, United States of America.
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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Kloth B, Pecha S, Moritz E, Schneeberger Y, Söhren KD, Schwedhelm E, Reichenspurner H, Eschenhagen T, Böger RH, Christ T, Stehr SN. Akrinor TM, a Cafedrine/ Theodrenaline Mixture (20:1), Increases Force of Contraction of Human Atrial Myocardium But Does Not Constrict Internal Mammary Artery In Vitro. Front Pharmacol 2017; 8:272. [PMID: 28588484 PMCID: PMC5441130 DOI: 10.3389/fphar.2017.00272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 05/01/2017] [Indexed: 12/22/2022] Open
Abstract
Background: Intraoperative hypotension is a common problem and direct or indirect sympathomimetic drugs are frequently needed to stabilize blood pressure. AkrinorTM consists of the direct and the indirect sympathomimetic noradrenaline and norephedrine. Both substances are covalently bound to the phosphodiesterase (PDE) inhibitor theophylline, yielding theodrenaline and cafedrine, respectively. We investigated pharmacodynamic effects of AkrinorTM and its constituents on contractile force and tension in human atrial trabeculae and internal A. mammaria rings. Methods: Isometric contractions were measured in human atrial trabeculae at 1 Hz and 37°C. CGP 20712A and ICI 118,551 were used to elaborate β1- and β2-adrenoceptor (AR) subtypes involved and phenoxybenzamine to estimate indirect sympathomimetic action. PDE-inhibition was measured as a potentiation of force increase upon direct activation of adenylyl cyclase by forskolin. Human A. mammaria preparations were used to estimate intrinsic vasoconstriction and impact on the noradrenaline-induced vasoconstriction. Results: Clinically relevant concentrations of AkrinorTM (4.2–420 mg/l) robustly increased force in human atrial trabeculae (EC50 41 ± 3 mg/l). This direct sympathomimetic action was mediated via β1-AR and the effect size was as large as with high concentrations of calcium. Only the highest and clinically irrelevant concentration of AkrinorTM increased the potency of forskolin to a minor extent. Norephedrine has lost its indirect sympathomimetic effect when bound to theophylline. Increasing concentrations of AkrinorTM (4.2–168 mg/l) alone did not affect the tension of human A. mammaria interna rings, but shifted the noradrenaline curve rightward from -logEC50 6.18 ± 0.08 to 5.23 ± 0.05 M. Conclusion: AkrinorTM increased cardiac contractile force by direct sympathomimetic actions and PDE inhibition, did not constrict A. mammaria preparations, but shifted the concentration-response curve to the right, compatible with an α-AR antagonistic effect or PDE inhibition. The pharmacodynamic profile and potency of AkrinorTM differs from noradrenaline and norephedrine in vitro. We anticipate metabolism of theodrenaline and cafedrine resulting in a different pharmacodynamic profile of AkrinorTMin vivo.
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Affiliation(s)
- Benjamin Kloth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany.,Department of Cardiovascular Surgery, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Simon Pecha
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany.,Department of Cardiovascular Surgery, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Eileen Moritz
- Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Yvonne Schneeberger
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany.,Department of Cardiovascular Surgery, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Klaus-Dieter Söhren
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Edzard Schwedhelm
- Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Hermann Reichenspurner
- Department of Cardiovascular Surgery, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Rainer H Böger
- Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Sebastian N Stehr
- Department of Anesthesia and Critical Care Medicine, Leipzig UniversityLeipzig, Germany
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Scruggs SB, Wang D, Ping P. PRKCE gene encoding protein kinase C-epsilon-Dual roles at sarcomeres and mitochondria in cardiomyocytes. Gene 2016; 590:90-6. [PMID: 27312950 DOI: 10.1016/j.gene.2016.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/23/2016] [Accepted: 06/05/2016] [Indexed: 12/26/2022]
Abstract
Protein kinase C-epsilon (PKCε) is an isoform of a large PKC family of enzymes that has a variety of functions in different cell types. Here we discuss two major roles of PKCε in cardiac muscle cells; specifically, its role in regulating cardiac muscle contraction via targeting the sarcomeric proteins, as well as modulating cardiac cell energy production and metabolism by targeting cardiac mitochondria. The importance of PKCε action is described within the context of intracellular localization, as substrate selectivity and specificity is achieved through spatiotemporal targeting of PKCε. Accordingly, the role of PKCε in regulating myocardial function in physiological and pathological states has been documented in both cardioprotection and cardiac hypertrophy.
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Affiliation(s)
- Sarah B Scruggs
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - Ding Wang
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Peipei Ping
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA.
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New Isoform of Cardiac Myosin Light Chain Kinase and the Role of Cardiac Myosin Phosphorylation in α1-Adrenoceptor Mediated Inotropic Response. PLoS One 2015; 10:e0141130. [PMID: 26512720 PMCID: PMC4626101 DOI: 10.1371/journal.pone.0141130] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/04/2015] [Indexed: 12/15/2022] Open
Abstract
Background & Aims Cardiac myosin light chain kinase (cMLCK) plays an obligatory role in maintaining the phosphorylation levels of regulatory myosin light chain (MLC2), which is thought to be crucial for regulation of cardiac function. To test this hypothesis, the role played by ventricular MLC2 (MLC2v) phosphorylation was investigated in the phenylephrine-induced increase in twitch tension using the naturally-occurring mouse strain, C57BL/6N, in which cMLCK is down regulated. Methods and Results By Western blot and nanoLC-MS/MS analysis, cMLCKs with molecular mass of 61-kDa (cMLCK-2) and/or 86-kDa were identified in mice heart. Among various mouse strains, C57BL/6N expressed cMLCK-2 alone and the closest relative strain C57BL/6J expressed both cMLCKs. The levels of MLC2v phosphorylation was significantly lower in C57BL/6N than in C57BL/6J. The papillary muscle twitch tension induced by electrical field stimulation was smaller in C57BL/6N than C57BL/6J. Phenylephrine had no effect on MLC2v phosphorylation in either strains but increased the twitch tension more potently in C57BL/6J than in C57BL/6N. Calyculin A increased papillary muscle MLC2v phosphorylation to a similar extent in both strains but increased the phenylephrine-induced inotropic response only in C57BL/6N. There was a significant positive correlation between the phenylephrine-induced inotropic response and the levels of MLC2v phosphorylation within ranges of 15–30%. Conclusions We identified a new isoform of cMLCK with a molecular mass of 61kDa(cMLCK-2) in mouse heart. In the C57BL/6N strain, only cMLCK-2 was expressed and the basal MLC2v phosphorylation levels and the phenylephrine-induced inotropic response were both smaller. We suggest that a lower phenylephrine-induced inotropic response may be caused by the lower basal MLC2v phosphorylation levels in this strain.
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Gao L, Zheng YJ, Gu SS, Tan JL, Paul C, Wang YG, Yang HT. Degradation of cardiac myosin light chain kinase by matrix metalloproteinase-2 contributes to myocardial contractile dysfunction during ischemia/reperfusion. J Mol Cell Cardiol 2014; 77:102-12. [PMID: 25451385 DOI: 10.1016/j.yjmcc.2014.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 11/25/2022]
Abstract
Although ischemia/reperfusion (I/R)-induced myocardial contractile dysfunction is associated with a prominent decrease in myofilament Ca(2+) sensitivity, the underlying mechanisms have not yet been fully clarified. Phosphorylation of ventricular myosin light chain 2 (MLC-2v) facilitates actin-myosin interactions and enhances contractility, however, its level and regulation by cardiac MLC kinase (cMLCK) and cMLC phosphatase (cMLCP) in I/R hearts are debatable. In this study, the levels and/or effects of MLC-2v phosphorylation, cMLCK, cMLCP, and proteases during I/R were determined. Global myocardial I/R-suppressed cardiac performance in isolated rat hearts was concomitant with decreases of MLC-2v phosphorylation, myofibrillar Ca(2+)-stimulated ATPase activity, and cMLCK content, but not cMLCP proteins. Consistently, simulated I/R in isolated cardiomyocytes inhibited cell shortening, Ca(2+) transients, MLC-2v phosphorylation, and myofilament sensitivity to Ca(2+). These observations were reversed by cMLCK overexpression, while the specific cMLCK knockdown by short hairpin RNA (shRNA) had the opposite effect. Moreover, the inhibition of matrix metalloproteinase-2 (MMP-2, a zinc-dependent endopeptidase) reversed IR-decreased cMLCK, MLC-2v phosphorylation, myofibrillar Ca(2+)-stimulated ATPase activity, myocardial contractile function, and myofilament sensitivity to Ca(2+), while the inhibition or knockdown of cMLCK by ML-9 or specific shRNA abolished MMP-2 inhibition-induced cardioprotection. Finally, the co-localization in cardiomyocytes and interaction in vivo of MMP-2 and cMLCK were observed. Purified recombinant rat cMLCK was concentration- and time-dependently degraded by rat MMP-2 in vitro, and this was prevented by the inhibition of MMP-2. These findings reveal that the I/R-activated MMP-2 leads to the degradation of cMLCK, resulting in a reduction of MLC-2v phosphorylation, and myofibrillar Ca(2+)-stimulated ATPase activity, which subsequently suppresses myocardial contractile function through a decrease of myofilament Ca(2+) sensitivity.
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Affiliation(s)
- Ling Gao
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Yan-Jun Zheng
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Shan-Shan Gu
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Ji-Liang Tan
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Christian Paul
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Yi-Gang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Huang-Tian Yang
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.
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Apelin increases cardiac contractility via protein kinase Cε- and extracellular signal-regulated kinase-dependent mechanisms. PLoS One 2014; 9:e93473. [PMID: 24695532 PMCID: PMC3973555 DOI: 10.1371/journal.pone.0093473] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/06/2014] [Indexed: 01/05/2023] Open
Abstract
Background Apelin, the endogenous ligand for the G protein-coupled apelin receptor, is an important regulator of the cardiovascular homoeostasis. We previously demonstrated that apelin is one of the most potent endogenous stimulators of cardiac contractility; however, its underlying signaling mechanisms remain largely elusive. In this study we characterized the contribution of protein kinase C (PKC), extracellular signal-regulated kinase 1/2 (ERK1/2) and myosin light chain kinase (MLCK) to the positive inotropic effect of apelin. Methods and Results In isolated perfused rat hearts, apelin increased contractility in association with activation of prosurvival kinases PKC and ERK1/2. Apelin induced a transient increase in the translocation of PKCε, but not PKCα, from the cytosol to the particulate fraction, and a sustained increase in the phosphorylation of ERK1/2 in the left ventricle. Suppression of ERK1/2 activation diminished the apelin-induced increase in contractility. Although pharmacological inhibition of PKC attenuated the inotropic response to apelin, it had no effect on ERK1/2 phosphorylation. Moreover, the apelin-induced positive inotropic effect was significantly decreased by inhibition of MLCK, a kinase that increases myofilament Ca2+ sensitivity. Conclusions Apelin increases cardiac contractility through parallel and independent activation of PKCε and ERK1/2 signaling in the adult rat heart. Additionally MLCK activation represents a downstream mechanism in apelin signaling. Our data suggest that, in addition to their role in cytoprotection, modest activation of PKCε and ERK1/2 signaling improve contractile function, therefore these pathways represent attractive possible targets in the treatment of heart failure.
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Dirkx E, Cazorla O, Schwenk RW, Lorenzen-Schmidt I, Sadayappan S, Van Lint J, Carrier L, van Eys GJJM, Glatz JFC, Luiken JJFP. Protein kinase D increases maximal Ca2+-activated tension of cardiomyocyte contraction by phosphorylation of cMyBP-C-Ser315. Am J Physiol Heart Circ Physiol 2012; 303:H323-31. [PMID: 22636676 DOI: 10.1152/ajpheart.00749.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is involved in the regulation of cardiac myofilament contraction. Recent evidence showed that protein kinase D (PKD) is one of the kinases that phosphorylate cMyBP-C. However, the mechanism by which PKD-induced cMyBP-C phosphorylation affects cardiac contractile responses is not known. Using immunoprecipitation, we showed that, in contracting cardiomyocytes, PKD binds to cMyBP-C and phosphorylates it at Ser(315). The effect of PKD-mediated phosphorylation of cMyBP-C on cardiac myofilament function was investigated in permeabilized ventricular myocytes, isolated from wild-type (WT) and from cMyBP-C knockout (KO) mice, incubated in the presence of full-length active PKD. In WT myocytes, PKD increased both myofilament Ca(2+) sensitivity (pCa(50)) and maximal Ca(2+)-activated tension of contraction (T(max)). In cMyBP-C KO skinned myocytes, PKD increased pCa(50) but did not alter T(max). This suggests that cMyBP-C is not involved in PKD-mediated sensitization of myofilaments to Ca(2+) but is essential for PKD-induced increase in T(max). Furthermore, the phosphorylation of both PKD-Ser(916) and cMyBP-C-Ser(315) was contraction frequency-dependent, suggesting that PKD-mediated cMyBP-C phosphorylation is operational primarily during periods of increased contractile activity. Thus, during high contraction frequency, PKD facilitates contraction of cardiomyocytes by increasing Ca(2+) sensitivity and by an increased T(max) through phosphorylation of cMyBP-C.
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Affiliation(s)
- Ellen Dirkx
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht, Maastricht University, the Netherlands.
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13
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Abstract
Berbamine (BM), a natural compound derived from Berberis vulgaris L, has been reported to inhibit cardiac contractile function at higher concentrations. Here, we report that BM had concentration-dependent biphasic effects on myocardial contraction in Langendorff-perfused rat hearts, that is, at lower concentrations (30-100 nM), it displayed positive inotropic and lusitropic effects, whereas at a higher concentration of 1 μM, it caused a negative inotropic effect after an initially weak increase. These effects were further confirmed in cardiomyocytes isolated from the left ventricles of rats. Moreover, the increased cell shortening by BM at concentrations from 0.1 to 100 nM was not associated with an alteration of intracellular Ca transients. Consistently, at 30 nM, BM shifted the cell shortening--Ca transient relationship curve induced by cumulative elevation of extracellular Ca concentration to the left. Furthermore, BM significantly increased membrane-bound but not filament-bound protein kinase C epsilon (PKCε) in the isolated hearts and cardiomyocytes. Such a translocation was inhibited by PKCε-specific inhibitor PKCε V1-2 concomitant with the abolishment of the BM-induced increase in contraction. These findings reveal the positive inotropic effect of BM in the myocardium and demonstrate that BM increases myocardial contractility by increasing myofilament Ca sensitivity via a PKCε-dependent signaling pathway.
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14
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Zhu GJ, Wang F, Chen C, Xu L, Zhang WC, Fan C, Peng YJ, Chen J, He WQ, Guo SY, Zuo J, Gao X, Zhu MS. Myosin light-chain kinase is necessary for membrane homeostasis in cochlear inner hair cells. PLoS One 2012; 7:e34894. [PMID: 22485190 PMCID: PMC3317649 DOI: 10.1371/journal.pone.0034894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 03/08/2012] [Indexed: 12/04/2022] Open
Abstract
The structural homeostasis of the cochlear hair cell membrane is critical for all aspects of sensory transduction, but the regulation of its maintenance is not well understood. In this report, we analyzed the cochlear hair cells of mice with specific deletion of myosin light chain kinase (MLCK) in inner hair cells. MLCK-deficient mice showed impaired hearing, with a 5- to 14-dB rise in the auditory brainstem response (ABR) thresholds to clicks and tones of different frequencies and a significant decrease in the amplitude of the ABR waves. The mutant inner hair cells produced several ball-like structures around the hair bundles in vivo, indicating impaired membrane stability. Inner hair cells isolated from the knockout mice consistently displayed less resistance to hypoosmotic solution and less membrane F-actin. Myosin light-chain phosphorylation was also reduced in the mutated inner hair cells. Our results suggest that MLCK is necessary for maintaining the membrane stability of inner hair cells.
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MESH Headings
- Actin Cytoskeleton/metabolism
- Actins/metabolism
- Animals
- Cell Membrane/enzymology
- Cell Membrane/metabolism
- Epithelium/enzymology
- Epithelium/metabolism
- Evoked Potentials, Auditory, Brain Stem
- Gene Expression
- Hair Cells, Auditory, Inner/enzymology
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/ultrastructure
- Homeostasis
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Myosin Light Chains/metabolism
- Myosin VIIa
- Myosin-Light-Chain Kinase/deficiency
- Myosin-Light-Chain Kinase/genetics
- Myosin-Light-Chain Kinase/physiology
- Myosins/metabolism
- Organ of Corti/cytology
- Osmotic Pressure
- Phosphorylation
- Protein Processing, Post-Translational
- Sequence Deletion
- Sodium-Potassium-Exchanging ATPase/genetics
- Sodium-Potassium-Exchanging ATPase/metabolism
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Affiliation(s)
- Guang-Jie Zhu
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Fang Wang
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Chen Chen
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Lin Xu
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Wen-Cheng Zhang
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
- Zhejiang Provincial Key Lab for Technology & Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, University Park, Wenzhou, China
| | - Chi Fan
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Ya-Jing Peng
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Jie Chen
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Wei-Qi He
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Shi-Ying Guo
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Xia Gao
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
- * E-mail: (XG); (M-SZ)
| | - Min-Sheng Zhu
- MOE Key Laboratory for Model Animal and Diseases Studies, Nanjing Drum Tower Hospital and Model Animal Research Center of Nanjing University, Nanjing, China
- Zhejiang Provincial Key Lab for Technology & Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, University Park, Wenzhou, China
- * E-mail: (XG); (M-SZ)
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15
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Wakili R, Yeh YH, Yan Qi X, Greiser M, Chartier D, Nishida K, Maguy A, Villeneuve LR, Boknik P, Voigt N, Krysiak J, Kääb S, Ravens U, Linke WA, Stienen GJM, Shi Y, Tardif JC, Schotten U, Dobrev D, Nattel S. Multiple potential molecular contributors to atrial hypocontractility caused by atrial tachycardia remodeling in dogs. Circ Arrhythm Electrophysiol 2010; 3:530-41. [PMID: 20660541 DOI: 10.1161/circep.109.933036] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Atrial fibrillation impairs atrial contractility, inducing atrial stunning that promotes thromboembolic stroke. Action potential (AP)-prolonging drugs are reported to normalize atrial hypocontractility caused by atrial tachycardia remodeling (ATR). Here, we addressed the role of AP duration (APD) changes in ATR-induced hypocontractility. METHODS AND RESULTS ATR (7-day tachypacing) decreased APD (perforated patch recording) by ≈50%, atrial contractility (echocardiography, cardiomyocyte video edge detection), and [Ca(2+)](i) transients. ATR AP waveforms suppressed [Ca(2+)](i) transients and cell shortening of control cardiomyocytes; whereas control AP waveforms improved [Ca(2+)](i) transients and cell shortening in ATR cells. However, ATR cardiomyocytes clamped with the same control AP waveform had ≈60% smaller [Ca(2+)](i) transients and cell shortening than control cells. We therefore sought additional mechanisms of contractile impairment. Whole-cell voltage clamp revealed reduced I(CaL); I(CaL) inhibition superimposed on ATR APs further suppressed [Ca(2+)](i) transients in control cells. Confocal microscopy indicated ATR-impaired propagation of the Ca(2+) release signal to the cell center in association with loss of t-tubular structures. Myofilament function studies in skinned permeabilized cardiomyocytes showed altered Ca(2+) sensitivity and force redevelopment in ATR, possibly due to hypophosphorylation of myosin-binding protein C and myosin light-chain protein 2a (immunoblot). Hypophosphorylation was related to multiple phosphorylation system abnormalities where protein kinase A regulatory subunits were downregulated, whereas autophosphorylation and expression of Ca(2+)-calmodulin-dependent protein kinase IIδ and protein phosphatase 1 activity were enhanced. Recovery of [Ca(2+)](i) transients and cell shortening occurred in parallel after ATR cessation. CONCLUSIONS Shortening of APD contributes to hypocontractility induced by 1-week ATR but accounts for it only partially. Additional contractility-suppressing mechanisms include I(CaL) current reduction, impaired subcellular Ca(2+) signal transmission, and altered myofilament function associated with abnormal myosin and myosin-associated protein phosphorylation. The complex mechanistic basis of the atrial hypocontractility associated with AF argues for upstream therapeutic targeting rather than interventions directed toward specific downstream pathophysiological derangements.
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Affiliation(s)
- Reza Wakili
- Department of Medicine and Research Center, Université de Montréal, Montreal, Quebec, Canada
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16
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Wang GY, Yeh CC, Jensen BC, Mann MJ, Simpson PC, Baker AJ. Heart failure switches the RV alpha1-adrenergic inotropic response from negative to positive. Am J Physiol Heart Circ Physiol 2009; 298:H913-20. [PMID: 20035030 DOI: 10.1152/ajpheart.00259.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Right ventricular (RV) failure is a serious common clinical problem that is poorly understood. Therefore, for failing and nonfailing hearts, we examined the distinctive inotropic responses induced in the RV myocardium after the stimulation of alpha(1)-adrenergic receptors (ARs). In RV trabeculae from nonfailing mouse hearts, alpha(1)-ARs induced a negative inotropic response, consistent with our previous study. In marked contrast, in RV trabeculae from failing hearts, 12 wk after coronary artery ligation, alpha(1)-ARs induced a positive inotropic response. Mechanistically, experiments with skinned trabeculae showed that alpha(1)-ARs decreased myofilament Ca(2+) sensitivity in the nonfailing RV myocardium, whereas alpha(1)-ARs increased Ca(2+) sensitivity in heart failure. This suggests that a switch in the Ca(2+) sensitivity response to alpha(1)-AR stimulation explained the switch in the RV alpha(1)-AR inotropic response in heart failure. Myosin light chain kinase (MLCK) can increase myofilament Ca(2+) sensitivity, and the smooth muscle isoform (smMLCK), which is also present in cardiomyocytes, was more abundant in the RV myocardium from failing versus nonfailing hearts. Moreover, the MLCK inhibitor ML-9 prevented the switch of the RV myocardium to a positive alpha(1)-AR inotropic response in heart failure. In the left ventricular myocardium, in contrast, alpha(1)-AR inotropic responses were not different in failing versus nonfailing hearts, and smMLCK abundance was not increased in heart failure. In relation to human disease, we found that smMLCK mRNA and protein levels were increased in RVs from failing human hearts. We conclude that the RV inotropic response to alpha(1)-ARs is switched from negative to positive in heart failure, through a pathway involving increased myofilament Ca(2+) sensitivity. Since alpha(1)-AR agonist catecholamines are elevated in heart failure, increased alpha(1)-AR inotropic responses in the RV myocardium may be adaptive in heart failure by helping the failing RV respond to increased pulmonary pressures.
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Affiliation(s)
- Guan-Ying Wang
- Veterans Affairs Medical Center and Department of Medicine, University of California, San Francisco, 94121, USA
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17
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Weiss M, Hassna R, Sermsappasuk P, Bednarek T. Pharmacokinetic–pharmacodynamic modeling of the effect of propofol on α1-adrenoceptor-mediated positive inotropy in rat heart. Eur J Pharm Sci 2009; 38:389-94. [DOI: 10.1016/j.ejps.2009.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 09/03/2009] [Accepted: 09/06/2009] [Indexed: 10/20/2022]
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18
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Age-dependent differential crosstalk between alpha(1)-adrenergic and angiotensin receptors. Can J Cardiol 2009; 25:481-5. [PMID: 19668783 DOI: 10.1016/s0828-282x(09)70123-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Previous reports of crosstalk between alpha(1)- adrenergic receptors (alpha(1)-AR) and angiotensin receptors (ATR) have pointed to the existence of physiological regulation between the sympathetic nervous system and the renin-angiotensin system at the receptor level. This regulation may have an important role in the control of blood pressure and may be modified in different cardiovascular pathologies. Aging is considered to be an independent cardiovascular risk factor. Nevertheless, neither the variation in physiological action or interaction of signal transduction between these two receptors as a result of aging has been established. To clarify these aspects, the interaction between alpha(1)-AR and ATR was evaluated. METHODS The inotropic response of alpha(1)-AR to agonists was assessed in the presence and absence of angiotensin II using the left atria of 3.5-, 12-, 18- and 24-month-old (young adult, middle aged, elderly and aged, respectively) male Wistar rats. In the four age groups of rat hearts, the activities of tyrosine kinase were measured when just the AT(1)R subtype was activated, or when both alpha(1)-AR and AT(1)R were activated. The activities of cytosolic phospholipase A(2) and the levels of cyclic GMP were investigated when just the AT(2)R subtype was activated, or when both alpha(1)-AR and AT(2)R were activated. RESULTS No effect was found on the cumulative concentration-response curve for phenylephrine when AT(1)R was activated in 3.5- or 12-month-old rats. However, in 18- and 24-month-old rats, the maximum positive inotropic response and the negative logarithm of the effective 50% concentration increased markedly. No effect was found on the cumulative concentration response curve induced by phenylephrine when AT(2)R was activated. The activities of tyrosine kinase increased significantly in 3.5- and 12-month-old rats, but there was no difference in 18- and 24-month-old rats when alpha(1)-AR and AT(1)R were both activated compared with when just AT(1)R was activated. Cytosolic phospholipase A(2) activity and cyclic GMP levels decreased significantly when both alpha(1)-AR and AT(2)R were activated compared with when just AT(2)R was activated. CONCLUSIONS In the isolated left atria of elderly and aged rats, the activation of AT(1)R enhanced the positive inotropic response induced by the activation of alpha(1)-AR. The activation of AT(2)R had no effect on the positive inotropic response induced by the activation of alpha(1)-AR. The action of alpha(1)-AR increased the signal transduction of AT(1)R in young-adult and middle-aged rat hearts but had no effect in elderly and aged hearts. The action of alpha(1)-AR had no effect on AT(2)R signal transduction.
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19
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Schwoerer AP, Neuber C, Schmechel A, Melnychenko I, Mearini G, Boknik P, Kirchhefer U, Schmitz W, Ehmke H, Eschenhagen T, El-Armouche A. Mechanical unloading of the rat heart involves marked changes in the protein kinase–phosphatase balance. J Mol Cell Cardiol 2008; 45:846-52. [DOI: 10.1016/j.yjmcc.2008.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 09/08/2008] [Accepted: 09/08/2008] [Indexed: 02/06/2023]
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20
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Riise J, Nguyen CHT, Qvigstad E, Sandnes DL, Osnes JB, Skomedal T, Levy FO, Krobert KA. Prostanoid F receptors elicit an inotropic effect in rat left ventricle by enhancing myosin light chain phosphorylation. Cardiovasc Res 2008; 80:407-15. [PMID: 18703533 DOI: 10.1093/cvr/cvn216] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIMS The aims of this study were to determine if the prostanoid F receptor (FPR)-mediated inotropic effect in rat ventricle is mediated by increased phosphorylation of myosin light chain-2 (MLC-2) and to elucidate the signalling pathway(s) activated by FPRs to regulate MLC-2 phosphorylation. METHODS AND RESULTS Contractility was measured in left ventricular strips from adult male rats. Strips were also snap-frozen, and changes in the phosphorylation level of both MLC-2 and myosin phosphatase targeting subunit-2 (MYPT-2) were quantified. FPR stimulation with fluprostenol increased contractility by approximately 100% above basal and increased phosphorylation of both MLC-2 (by approximately 30%) and MYPT-2 (by approximately 50%). The FPR-mediated inotropic effect and MLC-2 phosphorylation were reduced by a similar magnitude in the presence of the myosin light chain kinase (MLCK) inhibitor ML-7 (approximately 60-70%) and an inhibitor of Ca(2+)/calmodulin, W-7 (approximately 35%). Inhibition of Rho-associated kinase by Y-27632 reduced the FPR-mediated inotropic effect and MLC-2 phosphorylation by approximately 40-45% and MYPT-2 phosphorylation by approximately 70%. ML-7 and Y-27632 together reduced contractility and MLC-2 phosphorylation by approximately 70-80%. The FPR-mediated inotropic effect was only modestly affected by high concentrations of the inositol tris-phosphate (IP(3)) receptor blocker 2-APB, but not by the protein kinase C (PKC) inhibitor bisindolylmaleimide. CONCLUSION The FPR-evoked inotropic effect is mediated by increasing the phosphorylation of MLC-2 through regulation of both MLCK and myosin light chain phosphatase activities. The second messenger IP(3) and PKC are unlikely to be involved in the signalling cascade of the FPR-mediated positive inotropic effect. Therefore, FPR signalling mechanism(s) regulating MLC-2 phosphorylation likely extend beyond those classically established for G(q/11)-coupled receptors.
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Affiliation(s)
- Jon Riise
- Department of Pharmacology, University of Oslo, Sognsvannsvn. 20, Building A2/A3, PO Box 1057 Blindern, N-0316 Oslo, Norway
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21
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Mou YA, Reboul C, Andre L, Lacampagne A, Cazorla O. Late exercise training improves non-uniformity of transmural myocardial function in rats with ischaemic heart failure. Cardiovasc Res 2008; 81:555-64. [DOI: 10.1093/cvr/cvn229] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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22
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El-Armouche A, Wittköpper K, Degenhardt F, Weinberger F, Didié M, Melnychenko I, Grimm M, Peeck M, Zimmermann WH, Unsöld B, Hasenfuss G, Dobrev D, Eschenhagen T. Phosphatase inhibitor-1-deficient mice are protected from catecholamine-induced arrhythmias and myocardial hypertrophy. Cardiovasc Res 2008; 80:396-406. [PMID: 18689792 DOI: 10.1093/cvr/cvn208] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Phosphatase inhibitor-1 (I-1) is a conditional amplifier of beta-adrenergic signalling downstream of protein kinase A by inhibiting type-1 phosphatases only in its PKA-phosphorylated form. I-1 is downregulated in failing hearts and thus contributes to beta-adrenergic desensitization. It is unclear whether this should be viewed as a predominantly adverse or protective response. METHODS AND RESULTS We generated transgenic mice with cardiac-specific I-1 overexpression (I-1-TG) and evaluated cardiac function and responses to catecholamines in mice with targeted disruption of the I-1 gene (I-1-KO). Both groups were compared with their wild-type (WT) littermates. I-1-TG developed cardiac hypertrophy and mild dysfunction which was accompanied by a substantial compensatory increase in PP1 abundance and activity, confounding cause-effect relationships. I-1-KO had normal heart structure with mildly reduced sensitivity, but unchanged maximal contractile responses to beta-adrenergic stimulation, both in vitro and in vivo. Notably, I-1-KO were partially protected from lethal catecholamine-induced arrhythmias and from hypertrophy and dilation induced by a 7 day infusion with the beta-adrenergic agonist isoprenaline. Moreover, I-1-KO exhibited a partially preserved acute beta-adrenergic response after chronic isoprenaline, which was completely absent in similarly treated WT. At the molecular level, I-1-KO showed lower steady-state phosphorylation of the cardiac ryanodine receptor/Ca(2+) release channel and the sarcoplasmic reticulum (SR) Ca(2+)-ATPase-regulating protein phospholamban. These alterations may lower the propensity for diastolic Ca(2+) release and Ca(2+) uptake and thus stabilize the SR and account for the protection. CONCLUSION Taken together, loss of I-1 attenuates detrimental effects of catecholamines on the heart, suggesting I-1 downregulation in heart failure as a beneficial desensitization mechanism and I-1 inhibition as a potential novel strategy for heart failure treatment.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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23
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Kockskämper J, Khafaga M, Grimm M, Elgner A, Walther S, Kockskämper A, von Lewinski D, Post H, Grossmann M, Dörge H, Gottlieb PA, Sachs F, Eschenhagen T, Schöndube FA, Pieske B. Angiotensin II and myosin light-chain phosphorylation contribute to the stretch-induced slow force response in human atrial myocardium. Cardiovasc Res 2008; 79:642-51. [PMID: 18503051 DOI: 10.1093/cvr/cvn126] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Stretch is an important regulator of atrial function. The functional effects of stretch on human atrium, however, are poorly understood. Thus, we characterized the stretch-induced force response in human atrium and evaluated the underlying cellular mechanisms. METHODS AND RESULTS Isometric twitch force of human atrial trabeculae (n = 252) was recorded (37 degrees C, 1 Hz stimulation) following stretch from 88 (L88) to 98% (L98) of optimal length. [Na(+)](i) and pH(i) were measured using SBFI and BCECF epifluorescence, respectively. Stretch induced a biphasic force increase: an immediate increase [first-phase, Frank-Starling mechanism (FSM)] to approximately 190% of force at L88 followed by an additional slower increase [5-10 min; slow force response (SFR)] to approximately 120% of the FSM. FSM and SFR were unaffected by gender, age, ejection fraction, and pre-medication with major cardiovascular drugs. There was a positive correlation between the amplitude of the FSM and the SFR. [Na(+)](i) rose by approximately 1 mmol/L and pH(i) remained unchanged during the SFR. Inhibition of Na(+)/H(+)-exchange (3 microM HOE642), Na(+)/Ca(2+)-exchange (5 microM KB-R7943), or stretch-activated channels (0.5 microM GsMtx-4 and 80 microM streptomycin) did not reduce the SFR. Inhibition of angiotensin-II (AngII) receptors (5 microM saralasin and 0.5 microM PD123319) or pre-application of 0.5 microM AngII, however, reduced the SFR by approximately 40-60%. Moreover, stretch increased phosphorylation of myosin light chain 2 (MLC2a) and inhibition of MLC kinase (10 microM ML-7 and 5 microM wortmannin) decreased the SFR by approximately 40-85%. CONCLUSION Stretch elicits a SFR in human atrium. The atrial SFR is mediated by stretch-induced release and autocrine/paracrine actions of AngII and increased myofilament Ca(2+) responsiveness via phosphorylation of MLC2a by MLC kinase.
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Affiliation(s)
- Jens Kockskämper
- Division of Cardiology, Medical University of Graz, Auenbruggerplatz 15, A-8036 Graz, Austria
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Ait Mou Y, le Guennec JY, Mosca E, de Tombe PP, Cazorla O. Differential contribution of cardiac sarcomeric proteins in the myofibrillar force response to stretch. Pflugers Arch 2008; 457:25-36. [PMID: 18449562 DOI: 10.1007/s00424-008-0501-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 03/18/2008] [Accepted: 03/18/2008] [Indexed: 11/24/2022]
Abstract
The present study examined the contribution of myofilament contractile proteins to regional function in guinea pig myocardium. We investigated the effect of stretch on myofilament contractile proteins, Ca(2+) sensitivity, and cross-bridge cycling kinetics (K (tr)) of force in single skinned cardiomyocytes isolated from the sub-endocardial (ENDO) or sub-epicardial (EPI) layer. As observed in other species, ENDO cells were stiffer, and Ca(2+) sensitivity of force at long sarcomere length was higher compared with EPI cells. Maximal K (tr) was unchanged by stretch, but was higher in EPI cells possibly due to a higher alpha-MHC content. Submaximal Ca(2+)-activated K (tr) increased only in ENDO cells with stretch. Stretch of skinned ENDO muscle strips induced increased phosphorylation in both myosin-binding protein C and myosin light chain 2. We concluded that transmural MHC isoform expression and differential regulatory protein phosphorylation by stretch contributes to regional differences in stretch modulation of activation in guinea pig left ventricle.
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Affiliation(s)
- Younss Ait Mou
- INSERM, U 637, Université MONTPELLIER I, UFR de Médecine, F-34295, Montpellier, France
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25
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Kockskämper J, von Lewinski D, Khafaga M, Elgner A, Grimm M, Eschenhagen T, Gottlieb PA, Sachs F, Pieske B. The slow force response to stretch in atrial and ventricular myocardium from human heart: functional relevance and subcellular mechanisms. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 97:250-67. [PMID: 18466959 DOI: 10.1016/j.pbiomolbio.2008.02.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mechanical load is an important regulator of cardiac force. Stretching human atrial and ventricular trabeculae elicited a biphasic force increase: an immediate increase (Frank-Starling mechanism) followed by a further slow increase (slow force response, SFR). In ventricle, the SFR was unaffected by AT- and ET-receptor antagonism, by inhibition of protein-kinase-C, PI-3-kinase, and NO-synthase, but attenuated by inhibition of Na+/H+- (NHE) and Na+/Ca2+ exchange (NCX). In atrium, however, neither NHE- nor NCX-inhibition affected the SFR. Stretch elicited a large NHE-dependent [Na+]i increase in ventricle but only a small, NHE-independent [Na+]i increase in atrium. Stretch-activated non-selective cation channels contributed to basal force development in atrium but not ventricle and were not involved in the SFR in either tissue. Interestingly, inhibition of AT receptors or pre-application of angiotensin II or endothelin-1 reduced the atrial SFR. Furthermore, stretch increased phosphorylation of atrial myosin light chain 2 (MLC2) and inhibition of myosin light chain kinase (MLCK) attenuated the SFR in atrium and ventricle. Thus, in human heart both atrial and ventricular myocardium exhibit a stretch-dependent SFR that might serve to adjust cardiac output to increased workload. In ventricle, there is a robust NHE-dependent (but angiotensin II- and endothelin-1-independent) [Na+]i increase that is translated into a [Ca2+]i and force increase via NCX. In atrium, on the other hand, there is an angiotensin II- and endothelin-dependent (but NHE- and NCX-independent) force increase. Increased myofilament Ca2+ sensitivity through MLCK-induced phosphorylation of MLC2 is a novel mechanism contributing to the SFR in both atrium and ventricle.
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Affiliation(s)
- Jens Kockskämper
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, Graz, Austria
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Zhang H, Zhang L. Role of protein kinase C isozymes in the regulation of alpha1-adrenergic receptor-mediated contractions in ovine uterine arteries. Biol Reprod 2007; 78:35-42. [PMID: 17901075 PMCID: PMC2391137 DOI: 10.1095/biolreprod.107.063479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Previously, we demonstrated that activation of protein kinase C (PRKC) enhanced alpha(1)-adrenergic receptor-induced contractions in nonpregnant ovine uterine arteries but inhibited the contractions in pregnant ovine uterine arteries. The present study tested the hypothesis that differential regulation of PRKC isozyme activities contributes to the different effects of phorbol 12, 13-dibutyrate (PDBu) on alpha(1)-adrenergic receptor-mediated contractions between the pregnant and nonpregnant ovine uterine arteries. Phenylephrine-induced contractions of ovine nonpregnant and pregnant uterine arteries were determined in the absence or presence of the PRKC activator PDBu and/or in combination with conventional and novel PRKC isozyme inhibitor GF109203X, PRKC isozyme-selective inhibitory peptides for conventional PRKC, PRKCB1, PRKCB2, and PRKCE. GF109203X produced a concentration-dependent inhibition of phenylephrine-induced contractions in both nonpregnant and pregnant uterine arteries, and it reversed the PDBu-mediated potentiation and inhibition of phenylephrine-induced contractions in nonpregnant and pregnant uterine artieries, respectively. In addition, PRKCB1, PRKCB2, and PRKCE inhibitory peptides blocked the PDBu-mediated responses in both nonpregnant and pregnant uterine arteries. Western blot analysis showed that PDBu induced a membrane translocation of PRKCA, PRKCB1, PRKCB2, and PRKCE in pregnant uterine arteries, and PRKCB1, PRKCB2, and PRKCE in nonpregnant uterine arteries. The results disprove the hypothesis that the dichotomy of PRKC mechanisms in the regulation of alpha(1)-adrenergic receptor-induced contractions in nonpregnant and pregnant uterine arteries is caused by the activation of different PRKC isozymes, and suggest downstream mechanisms of differential subcellular distributions for the distinct functional effects of PRKC isozymes in the adaptation of uterine arteries to pregnancy.
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Affiliation(s)
| | - Lubo Zhang
- Correspondence: Lubo Zhang, Center for Perinatal Biology, Department of Physiology & Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA 92350. FAX: 909 558 4029; e-mail:
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Grimm M, El-Armouche A, Zhang R, Anderson ME, Eschenhagen T. Reduced contractile response to α1-adrenergic stimulation in atria from mice with chronic cardiac calmodulin kinase II inhibition. J Mol Cell Cardiol 2007; 42:643-52. [PMID: 17292391 DOI: 10.1016/j.yjmcc.2006.12.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 12/15/2006] [Accepted: 12/20/2006] [Indexed: 10/01/2022]
Abstract
The sustained positive inotropic effect of alpha-adrenoceptor agonists in the heart is associated with a small increase in intracellular Ca(2+) transients together with a larger sensitization of myofilaments to Ca(2+). The multifunctional Ca(2+) and calmodulin-dependent protein kinase II (CaMKII) could contribute to this effect, either by affecting the Ca(2+) release (ryanodine receptor) or by an uptake mechanism (via phospholamban [PLB] and SR Ca(2+) ATPase). Here we examined the role of CaMKII in the positive inotropic effect of the alpha-adrenoceptor agonist phenylephrine in left atria isolated from a genetic mouse model of cardiac CaMKII inhibition (AC3-I). Compared to atria from wild-type (WT) or AC3-C (scrambled peptide), AC3-I atria showed the following abnormalities. PLB phosphorylation at Thr17, a known CaMKII target, was significantly lower ( approximately 20%). Post-rest (30 s, 1 Hz, 37 degrees C) potentiation of force was absent (AC3-C, 190% of pre-rest amplitude). Basal force was approximately 20% lower at 1.8 mM Ca(2+), but normal at high Ca(2+) concentration (>4.5 mM). The maximal positive inotropic effect of phenylephrine, which was more pronounced at low frequencies in WT and AC3-C atria, lost its frequency dependence (1 Hz to 8 Hz). Thus, the effect of phenylephrine was reduced by approximately 50% at 1 Hz, but was normal at 8 Hz. All three groups showed a negative force-frequency relation, and did not differ in the frequency-dependent acceleration of relaxation. Our data indicate a role of CaMKII in post-rest potentiation and the positive inotropic effect of alpha-adrenergic stimulation at low frequencies.
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Affiliation(s)
- Michael Grimm
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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