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Abu-Khousa M, Fiegle DJ, Sommer ST, Minabari G, Milting H, Heim C, Weyand M, Tomasi R, Dendorfer A, Volk T, Seidel T. The Degree of t-System Remodeling Predicts Negative Force-Frequency Relationship and Prolonged Relaxation Time in Failing Human Myocardium. Front Physiol 2020; 11:182. [PMID: 32231589 PMCID: PMC7083140 DOI: 10.3389/fphys.2020.00182] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/17/2020] [Indexed: 01/28/2023] Open
Abstract
The normally positive cardiac force-frequency relationship (FFR) becomes flat or negative in chronic heart failure (HF). Here we explored if remodeling of the cardiomyocyte transverse tubular system (t-system) is associated with alterations in FFR and contractile kinetics in failing human myocardium. Left-ventricular myocardial slices from 13 failing human hearts were mounted into a biomimetic culture setup. Maximum twitch force (F), 90% contraction duration (CD90), time to peak force (TTP) and time to relaxation (TTR) were determined at 37°C and 0.2–2 Hz pacing frequency. F1Hz/F0.5Hz and F2Hz/F0.5Hz served as measures of FFR, intracellular cardiomyocyte t-tubule distance (ΔTT) as measure of t-system remodeling. Protein levels of SERCA2, NCX1, and PLB were quantified by immunoblotting. F1Hz/F0.5Hz (R2 = 0.82) and F2Hz/F0.5Hz (R2 = 0.5) correlated negatively with ΔTT, i.e., samples with severe t-system loss exhibited a negative FFR and reduced myocardial wall tension at high pacing rates. PLB levels also predicted F1Hz/F0.5Hz, but to a lesser degree (R2 = 0.49), whereas NCX1 was not correlated (R2 = 0.02). CD90 correlated positively with ΔTT (R2 = 0.39) and negatively with SERCA2/PLB (R2 = 0.42), indicating that both the t-system and SERCA activity are important for contraction kinetics. Surprisingly, ΔTT was not associated with TTP (R2 = 0) but rather with TTR (R2 = 0.5). This became even more pronounced when interaction with NCX1 expression was added to the model (R2 = 0.79), suggesting that t-system loss impairs myocardial relaxation especially when NCX1 expression is low. The degree of t-system remodeling predicts FFR inversion and contraction slowing in failing human myocardium. Moreover, together with NCX, the t-system may be important for myocardial relaxation.
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Affiliation(s)
- Maha Abu-Khousa
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dominik J Fiegle
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sophie T Sommer
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Ghazali Minabari
- Department of Cardiac Surgery, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, Bad Oeynhausen, Germany
| | - Christian Heim
- Department of Cardiac Surgery, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Michael Weyand
- Department of Cardiac Surgery, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Roland Tomasi
- Walter Brendel Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany.,Department of Anaesthesiology, University Hospital, LMU Munich, Munich, Germany
| | - Andreas Dendorfer
- Walter Brendel Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Munich Heart Alliance, Munich, Germany
| | - Tilmann Volk
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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2
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Morissette MP, Susser SE, Stammers AN, Moffatt TL, Wigle JT, Wigle TJ, Netticadan T, Premecz S, Jassal DS, O’Hara KA, Duhamel TA. Exercise-induced increases in the expression and activity of cardiac sarcoplasmic reticulum calcium ATPase 2 is attenuated in AMPKα2kinase-dead mice. Can J Physiol Pharmacol 2019; 97:786-795. [DOI: 10.1139/cjpp-2018-0737] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Exercise enhances cardiac sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) function through unknown mechanisms. The present study tested the hypothesis that the positive effects of exercise on SERCA2a expression and function in the left ventricle is dependent on adenosine-monophosphate-activated protein kinase (AMPK) α2 function. AMPKα2kinase-dead (KD) transgenic mice, which overexpress inactivated AMPKα2subunit, and wild-type C57Bl/6 (WT) mice were randomized into sedentary groups or groups with access to running wheels. After 5 months, exercised KD mice exhibited shortened deceleration time compared with sedentary KD mice. In left ventricular tissue, the ratio of phosphorylated AMPKαThr172:total AMPKα was 65% lower (P < 0.05) in KD mice compared with WT mice. The left ventricle of KD mice had 37% lower levels of SERCA2a compared with WT mice. Although exercise increased SERCA2a protein levels in WT mice by 53%, this response of exercise was abolished in exercised KD mice. Exercise training reduced total phospholamban protein content by 23% in both the WT and KD mice but remained 20% higher overall in KD mice. Collectively, these data suggest that AMPKα influences SERCA2a and phospholamban protein content in the sedentary and exercised heart, and that exercise-induced changes in SERCA2a protein are dependent on AMPKα function.
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Affiliation(s)
- Marc P. Morissette
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Shanel E. Susser
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Andrew N. Stammers
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Teri L. Moffatt
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Jeffrey T. Wigle
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R2E 3N4, Canada
| | - Theodore J. Wigle
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Thomas Netticadan
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Albrechtsen Research Centre, Winnipeg, MB R2H 2A6, Canada
- Agriculture and Agri-Food Canada, Winnipeg, MB R3C 3G7, Canada
| | - Sheena Premecz
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
| | - Davinder S. Jassal
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Albrechtsen Research Centre, Winnipeg, MB R2H 2A6, Canada
- Section of Cardiology, Department of Internal Medicine, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R3A 1R9, Canada
| | - Kimberley A. O’Hara
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Todd A. Duhamel
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
- Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
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3
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Høydal MA, Kirkeby-Garstad I, Karevold A, Wiseth R, Haaverstad R, Wahba A, Stølen TL, Contu R, Condorelli G, Ellingsen Ø, Smith GL, Kemi OJ, Wisløff U. Human cardiomyocyte calcium handling and transverse tubules in mid-stage of post-myocardial-infarction heart failure. ESC Heart Fail 2018; 5:332-342. [PMID: 29431258 PMCID: PMC5933953 DOI: 10.1002/ehf2.12271] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/06/2017] [Accepted: 01/09/2018] [Indexed: 11/08/2022] Open
Abstract
AIMS Cellular processes in the heart rely mainly on studies from experimental animal models or explanted hearts from patients with terminal end-stage heart failure (HF). To address this limitation, we provide data on excitation contraction coupling, cardiomyocyte contraction and relaxation, and Ca2+ handling in post-myocardial-infarction (MI) patients at mid-stage of HF. METHODS AND RESULTS Nine MI patients and eight control patients without MI (non-MI) were included. Biopsies were taken from the left ventricular myocardium and processed for further measurements with epifluorescence and confocal microscopy. Cardiomyocyte function was progressively impaired in MI cardiomyocytes compared with non-MI cardiomyocytes when increasing electrical stimulation towards frequencies that simulate heart rates during physical activity (2 Hz); at 3 Hz, we observed almost total breakdown of function in MI. Concurrently, we observed impaired Ca2+ handling with more spontaneous Ca2+ release events, increased diastolic Ca2+ , lower Ca2+ amplitude, and prolonged time to diastolic Ca2+ removal in MI (P < 0.01). Significantly reduced transverse-tubule density (-35%, P < 0.01) and sarcoplasmic reticulum Ca2+ adenosine triphosphatase 2a (SERCA2a) function (-26%, P < 0.01) in MI cardiomyocytes may explain the findings. Reduced protein phosphorylation of phospholamban (PLB) serine-16 and threonine-17 in MI provides further mechanisms to the reduced function. CONCLUSIONS Depressed cardiomyocyte contraction and relaxation were associated with impaired intracellular Ca2+ handling due to impaired SERCA2a activity caused by a combination of alteration in the PLB/SERCA2a ratio and chronic dephosphorylation of PLB as well as loss of transverse tubules, which disrupts normal intracellular Ca2+ homeostasis and handling. This is the first study that presents these mechanisms from viable and intact cardiomyocytes isolated from the left ventricle of human hearts at mid-stage of post-MI HF.
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Affiliation(s)
- Morten Andre Høydal
- Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Idar Kirkeby-Garstad
- K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Asbjørn Karevold
- K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Rune Wiseth
- K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | | | - Alexander Wahba
- Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Tomas L Stølen
- Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Riccardo Contu
- Department of Cardiovascular Medicine, Humanitas Research Hospital CNR (National Research Council of Italy), Humanitas University, Milan, Italy
| | - Gianluigi Condorelli
- Department of Cardiovascular Medicine, Humanitas Research Hospital CNR (National Research Council of Italy), Humanitas University, Milan, Italy
| | - Øyvind Ellingsen
- Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,St. Olavs University Hospital, Trondheim, Norway
| | - Godfrey L Smith
- K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Institute of Cardiovascular and Medical Sciences and School of Life Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK
| | - Ole J Kemi
- Institute of Cardiovascular and Medical Sciences and School of Life Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK
| | - Ulrik Wisløff
- Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,K.G. Jebsen Center of Exercise in Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia
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4
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Lancel S, Qin F, Lennon SL, Zhang J, Tong X, Mazzini MJ, Kang YJ, Siwik DA, Cohen RA, Colucci WS. Oxidative posttranslational modifications mediate decreased SERCA activity and myocyte dysfunction in Galphaq-overexpressing mice. Circ Res 2010; 107:228-32. [PMID: 20508180 DOI: 10.1161/circresaha.110.217570] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Myocyte contractile dysfunction occurs in pathological remodeling in association with abnormalities in calcium regulation. Mice with cardiac myocyte-specific overexpression of Galphaq develop progressive left ventricular failure associated with myocyte contractile dysfunction and calcium dysregulation. OBJECTIVE We tested the hypothesis that myocyte contractile dysfunction in the Galphaq mouse heart is mediated by reactive oxygen species, and in particular, oxidative posttranslational modifications, which impair the function of sarcoplasmic reticulum Ca2+-ATPase (SERCA). METHODS AND RESULTS Freshly isolated ventricular myocytes from Galphaq mice had marked abnormalities of myocyte contractile function and calcium transients. In Galphaq myocardium, SERCA protein was not altered in quantity but displayed evidence of oxidative cysteine modifications reflected by decreased biotinylated iodoacetamide labeling and evidence of specific irreversible oxidative modifications consisting of sulfonylation at cysteine 674 and nitration at tyrosines 294/295. Maximal calcium-stimulated SERCA activity was decreased 47% in Galphaq myocardium. Cross-breeding Galphaq mice with transgenic mice that have cardiac myocyte-specific overexpression of catalase (a) decreased SERCA oxidative cysteine modifications, (b) decreased SERCA cysteine 674 sulfonylation and tyrosine 294/295 nitration, (c) restored SERCA activity, and (d) improved myocyte calcium transients and contractile function. CONCLUSIONS In Galphaq-induced cardiomyopathy, myocyte contractile dysfunction is mediated, at least in part, by 1 or more oxidative posttranslational modifications of SERCA. Protein oxidative posttranslational modifications contribute to the pathophysiology of myocardial dysfunction and thus may provide a target for therapeutic intervention.
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Affiliation(s)
- Steve Lancel
- Cardiovascular Medicine Section, Department of Medicine, Boston University Medical Center, 88 E Newton St, Boston, MA 02118, USA
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5
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Unno K, Isobe S, Izawa H, Cheng XW, Kobayashi M, Hirashiki A, Yamada T, Harada K, Ohshima S, Noda A, Nagata K, Kato K, Yokota M, Murohara T. Relation of functional and morphological changes in mitochondria to myocardial contractile and relaxation reserves in asymptomatic to mildly symptomatic patients with hypertrophic cardiomyopathy. Eur Heart J 2009; 30:1853-62. [DOI: 10.1093/eurheartj/ehp184] [Citation(s) in RCA: 39] [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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6
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Gupta RC, Mishra S, Rastogi S, Sharov VG, Sabbah HN. Improvement of cardiac sarcoplasmic reticulum calcium cycling in dogs with heart failure following long-term therapy with the Acorn Cardiac Support Device. Heart Fail Rev 2006; 10:149-55. [PMID: 16258722 DOI: 10.1007/s10741-005-4642-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Abnormal Ca(2+)-homeostasis is a hall-marked characteristic of the failing heart. In the normal myocardium, the sarcoplasmic reticulum (SR) is a principal organelle that controls intracellular Ca(2+) concentration during the cardiac cycle. The SR consists of longitudinal and terminal cisternea regions. The former contains the Ca(2+)-ATPase pump or SERCA-2a whose function is to transport cytosolic Ca(2+) into the lumen of the SR during diastole and whose activity is regulated by reversible phosphorylation of the endogenously SR-bound phospholamban (PLB). The SR's terminal cisternea region contains ryanodine-sensitive Ca(2+)-release channels (RR), the activity of which is regulated by direct and indirect reversible phosphorylation. These channels release the SR-stored Ca(2+) during contraction. We have shown that in left ventricular (LV) myocardium from dogs with coronary microembolization-induced heart failure, ability of the SR to sequester and release Ca(2+) during the cardiac cycles is impaired. This abnormality was associated with reduced expression (protein and mRNA) levels of Ca(2+)-ATPase, PLB, and reduced PLB phosphorylation. Long-term therapy with the Acorn Cardiac Support Device (CSD) is associated with restoration of the ability of the SR to sequester Ca(2+). This improvement in SR function following chronic CSD therapy was due primarily to increased affinity of the SERCA-2a for calcium. The later was associated with (1) increased phosphorylation of PLB at serine 16 and threonine 17, (2) unchanged protein expression of PLB and (3) unchanged protein expression of SERCA-2a in LV myocardium of CSD-treated dogs compared to controls. This review summarizes our current understanding of the role of the CSD in modulating SR calcium cycling in an experimental canine model of chronic heart failure produced by multiple sequential intracoronary microembolizations.
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Affiliation(s)
- Ramesh C Gupta
- Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Heart and Vascular Institute, Henry Ford Health System, Detroit, Michigan, USA
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7
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Heerdt PM, Klotz S, Burkhoff D. Cardiomyopathic etiology and SERCA2a reverse remodeling during mechanical support of the failing human heart. Anesth Analg 2006; 102:32-7. [PMID: 16368801 DOI: 10.1213/01.ane.0000183642.09435.ad] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Many hearts in end-stage, chronic failure (CHF) retain the capacity to reverse abnormal expression of genes regulating myocyte calcium cycling when supported with a left ventricular assist device (LVAD). In the present study, we determined whether LVAD-induced upregulation of the gene encoding for the key calcium cycling protein sarcoplasmic endoreticular calcium adenosine triphosphatase subtype 2a (SERCA2a) is influenced by the nature of underlying disease broadly characterized as ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy. Data from Northern blot analysis of SERCA2a messenger (m)RNA within 84 heart samples (50 CHF [23 DCM and 27 ICM] and 34 CHF+LVAD [18 DCM and 16 ICM]) were used for characterizing gene expression. In addition, measurements of the force-frequency relationship (FFR), a reflection of in vivo SERCA2a function, were obtained in myocardial trabeculae isolated from 75 hearts (51 CHF [29 DCM and 22 ICM] and 24 CHF+LVAD [10 DCM and 14 ICM]). SERCA2a mRNA demonstrated upregulation after LVAD that was not influenced by ICM or DCM. However, only in DCM hearts was the proportion of trabeculae exhibiting a normal FFR increased after LVAD. Thus, although upregulated SERCA2a gene expression after LVAD support is independent of myopathic origin, normalization of myocardial FFR, an index of SERCA2a function, is not. These data provide new insight into the process of cardiac "reverse molecular remodeling," and underscore potential differences in the impact of disease processes on posttranscriptional events.
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Affiliation(s)
- Paul M Heerdt
- Department of Anesthesiology, Weill Medical College of Cornell University and Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
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8
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Tong CW, Gaffin RD, Zawieja DC, Muthuchamy M. Roles of phosphorylation of myosin binding protein-C and troponin I in mouse cardiac muscle twitch dynamics. J Physiol 2004; 558:927-41. [PMID: 15194741 PMCID: PMC1665013 DOI: 10.1113/jphysiol.2004.062539] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A normal heart increases its contractile force with increasing heart rate. Although calcium handling and myofibrillar proteins have been implicated in maintaining this positive force-frequency relationship (FFR), the exact mechanisms by which it occurs have not been addressed. In this study, we have developed an analytical method to define the calcium-force loop data, which characterizes the function of the contractile proteins in response to calcium that is independent of the calcium handling proteins. Results demonstrate that increasing the stimulation frequency causes increased force production per unit calcium concentration and decreased frequency-dependent calcium sensitivity during the relaxation phase. We hypothesize that phosphorylation of myosin binding protein-C (MyBP-C) and troponin I (TnI) acts coordinately to change the rates of force generation and relaxation, respectively. To test this hypothesis, we performed simultaneous calcium and force measurements on stimulated intact mouse papillary bundles before and after inhibition of MyBP-C and TnI phosphorylation using the calcium/calmodulin kinase II (CaMK2) inhibitor autocamtide-2 related inhibitory peptide, or the protein kinase A (PKA) inhibitor 14-22 amide. CaMK2 inhibition reduced both MyBP-C and TnI phosphorylation and decreased active force without changing the magnitude of the [Ca(2+)](i) transient. This reduced the normalized change in force per change in calcium by 19-39%. Data analyses demonstrated that CaMK2 inhibition changed the myofilament characteristics via a crossbridge feedback mechanism. These results strongly suggest that the phosphorylation of MyBP-C and TnI contributes significantly to the rates of force development and relaxation.
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Affiliation(s)
- Carl W Tong
- 336 Reynolds Medical Building, Cardiovascular Research Institute and Department of Medical Physiology, College of Medicine, Texas A & M University System Health Science Center, College Station, TX 77843-1114, USA
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9
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Takimoto E, Soergel DG, Janssen PML, Stull LB, Kass DA, Murphy AM. Frequency- and Afterload-Dependent Cardiac Modulation In Vivo by Troponin I With Constitutively Active Protein Kinase A Phosphorylation Sites. Circ Res 2004; 94:496-504. [PMID: 14726477 DOI: 10.1161/01.res.0000117307.57798.f5] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute beta-adrenergic stimulation enhances cardiac contractility, accelerates muscle relaxation, and amplifies the inotropic and lusitropic response to increased stimulation frequency. These effects are modulated by phosphorylation of calcium handling and myofilament proteins such as troponin I (TnI) by protein kinase A (PKA). To more directly delineate the role of TnI PKA phosphorylation, transgenic mice were generated that overexpress cardiac TnI in which the serine residues normally targeted by PKA are mutated to aspartic acid to mimic constitutive phosphorylation (TnIDD22,23). Native cardiac TnI was near completely replaced in one transgenic line as assessed by in vitro phosphorylation, and this led to reduced calcium sensitivity of myofibrillar MgATPase, as expected. TnIDD22,23 mice had mildly enhanced basal systolic and diastolic function, and displayed marked augmentation of frequency-dependent inotropy and relaxation, with a peak frequency response 2-fold greater in mutants than controls (P<0.005). Increasing afterload prolonged relaxation more in nontransgenic than TnIDD22,23 (P<0.02), whereas contractile responses to afterload were similar between these strains. Isoproterenol treatment eliminated the differential force-frequency and afterload response between TnIDD22,23 and controls. In contrast to in vivo studies, isolated isometric trabeculae from nontransgenic and TnIDD22,23 mice had similar basal, isoproterenol-, and frequency-stimulated function, suggesting that muscle shortening may be important to TnI PKA effects. These results support a novel role for cardiac TnI PKA phosphorylation in the rate-dependent enhancement of systolic and diastolic function in vivo and afterload sensitivity of relaxation. These results have implications for cardiac failure in which force-frequency modulation is blunted and afterload relaxation sensitivity increased in association with diminished PKA TnI phosphorylation.
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Affiliation(s)
- Eiki Takimoto
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md 21205, USA
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10
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Brixius K, Wollmer A, Bölck B, Mehlhorn U, Schwinger RHG. Ser16-, but not Thr17-phosphorylation of phospholamban influences frequency-dependent force generation in human myocardium. Pflugers Arch 2003; 447:150-7. [PMID: 14530977 DOI: 10.1007/s00424-003-1163-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 07/29/2003] [Indexed: 10/26/2022]
Abstract
Beta-adrenoceptor/cAMP-dependent Ser16-phosphorylation as well as Ca(2+)-dependent Thr17-phosphorylation of phospholamban (PLB) influences SERCA 2a activity and thus myocardial contractility. To determine the cross-signaling between Ca2+ and cAMP pathways, the phosphorylation of Ser16-PLB and Thr17-PLB was studied at increasing stimulation frequencies as well as in the presence of beta-adrenergic stimulation in isolated ventricular trabeculae from failing (dilative cardiomyopathy, DCM, heart transplants, n=9) and non-failing human myocardium (donor hearts, NF, n=9). In addition, we measured the intracellular Ca(2+)-transient (fura-2) at increasing stimulation frequencies (0.5-3.0 Hz). Protein expression of SERCA 2a and phospholamban was similar in DCM and NF. In DCM, diastolic [Ca2+]i was increased and systolic [Ca2+]i as well as Ser16 PLB-phosphorylation were decreased as compared to NF at 0.5 Hz. The positive force-frequency relationship in human non-failing myocardium was accompanied by a frequency-dependent increase in Ser16-PLB, but not Thr17-PLB phosphorylation. In DCM, Ser16-PLB as well as Thr17-PLB phosphorylation were not altered at higher stimulation frequencies. After application of isoprenaline (1 microM), a profound increase in Ser16-PLB phosphorylation was accompanied by a small increase in Thr17-PLB phosphorylation, only in NF. The frequency-dependent phosphorylation of Ser16-PLB may favor an increase in Ca2+ transient and force generation in humans. Cross talk signaling of Ser16/Thr17-PLB phosphorylation after beta-adrenergic stimulation exists in non-failing, but not in failing human myocardium. The Ca(2+)-dependent CaM-kinase activity may be altered in human heart failure.
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Affiliation(s)
- Klara Brixius
- Laboratory of Muscle Research and Molecular Cardiology, Department of Internal Medicine III, University of Cologne, Joseph-Stelzmann-Str. 9, 50924 Cologne, Germany
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Communal C, Sumandea M, de Tombe P, Narula J, Solaro RJ, Hajjar RJ. Functional consequences of caspase activation in cardiac myocytes. Proc Natl Acad Sci U S A 2002; 99:6252-6. [PMID: 11972044 PMCID: PMC122935 DOI: 10.1073/pnas.092022999] [Citation(s) in RCA: 275] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cardiomyocyte apoptosis is present in many cardiac disease states, including heart failure and ischemic heart disease. Apoptosis is associated with the activation of caspases that mediate the cleavage of vital and structural proteins. However, the functional contribution of apoptosis to these conditions is not known. Furthermore, in cardiac myocytes, apoptosis may not be complete, allowing the cells to persist for a prolonged period within the myocardium. Therefore, we examined whether caspase-3 cleaved cardiac myofibrillar proteins and, if so, whether it affects contractile function. The effects of caspase-3 were studied in vitro on individual components of the cardiac myofilament including alpha-actin, alpha-actinin, myosin heavy chain, myosin light chain 1/2, tropomyosin, cardiac troponins (T, I, C), and the trimeric troponin complex. Exposure of the myofibrillar protein (listed above) to caspase-3 for 4 h resulted in the cleavage of alpha-actin and alpha-actinin, but not myosin heavy chain, myosin light chain 1/2, and tropomyosin, into three fragments (30, 20, and 15 kDa) and one major fragment (45 kDa), respectively. When cTnT, cTnI, and cTnC were incubated individually with caspase-3, there was no detectable cleavage. However, when the recombinant troponin complex was exposed to caspase-3, cTnT was cleaved, resulting in fragments of 25 kDa. Furthermore, rat cardiac myofilaments exposed to caspase-3 exhibited similar patterns of myofibrillar protein cleavage. Treatment with the caspase inhibitor DEVD-CHO or z-VAD-fmk abolished the cleavage. Myofilaments, isolated from adult rat ventricular myocytes after induction of apoptotic pathway by using beta-adrenergic stimulation, displayed a similar pattern of actin and TnT cleavage. Exposure of skinned fiber to caspase-3 decreased maximal Ca(2+)-activated force and myofibrillar ATPase activity. Our results indicate that caspase-3 cleaved myofibrillar proteins, resulting in an impaired force/Ca(2+) relationship and myofibrillar ATPase activity. Induction of apoptosis in cardiac cells was associated with similar cleavage of myofilaments. Therefore, activation of apoptotic pathways may lead to contractile dysfunction before cell death.
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Affiliation(s)
- Catherine Communal
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA 02129, USA
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Somura F, Izawa H, Iwase M, Takeichi Y, Ishiki R, Nishizawa T, Noda A, Nagata K, Yamada Y, Yokota M. Reduced myocardial sarcoplasmic reticulum Ca(2+)-ATPase mRNA expression and biphasic force-frequency relations in patients with hypertrophic cardiomyopathy. Circulation 2001; 104:658-63. [PMID: 11489771 DOI: 10.1161/hc3101.093869] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The relationship between left ventricular (LV) contractile functional reserve and gene expression of Ca(2+)-handling proteins in patients with hypertrophic cardiomyopathy (HCM) remains to be clarified. METHODS AND RESULTS We calculated the maximum first derivative of LV pressure (LV dP/dt(max)) and the LV pressure half-time (T(1/2)) during pacing in 14 patients with nonobstructive HCM (LV ejection fraction >55%) and 7 control subjects. Endomyocardial tissue was obtained, and mRNA levels of sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2), ryanodine receptor-2, phospholamban, calsequestrin, and Na(+)/Ca(2+) exchanger were quantified by use of a real-time quantitative reverse transcription-polymerase chain reaction method. Group A consisted of 7 HCM patients who showed a progressive rise in the LV dP/dt(max) with increased heart rate. Group B consisted of 7 HCM patients in whom the heart rate-LV dP/dt(max) relation was biphasic at physiological pacing rates. Both the mean maximal wall thickness and the LV hypertrophy score in group B were greater than in group A (20+/-5 versus 15+/-3 mm and 7+/-1 versus 5+/-2 points, respectively). SERCA2 mRNA levels were significantly lower in group B (SERCA2/GAPDH ratio 0.34+/-0.15) compared with group A (0.72+/-0.27) and control subjects (0.85+/-0.47), whereas the mRNA expression of ryanodine receptor-2, phospholamban, calsequestrin, and Na(+)/Ca(2+) exchanger were similar in all groups. CONCLUSIONS These results suggest that downregulation of SERCA2 mRNA, resulting in altered Ca(2+) handling, may contribute to impaired LV contractile reserve in HCM patients with severe hypertrophy, even in the absence of detectable baseline systolic dysfunction.
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Affiliation(s)
- F Somura
- Cardiovascular Division, Department of Clinical Pathophysiology, the First Department of Internal Medicine, Nagoya University, Japan
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Dash R, Frank KF, Carr AN, Moravec CS, Kranias EG. Gender influences on sarcoplasmic reticulum Ca2+-handling in failing human myocardium. J Mol Cell Cardiol 2001; 33:1345-53. [PMID: 11437540 DOI: 10.1006/jmcc.2001.1394] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gender has recently been implicated as an important modulator of cardiovascular disease. However, it is not known how gender may specifically influence the Ca2+-handling deficits that characterize the depressed cardiac contractility of human heart failure. To elucidate the contributory role of gender to sarcoplasmic reticulum (SR) Ca2+ cycling alterations, the protein levels of SR Ca2+-ATPase (SERCA), phospholamban, and calsequestrin, as well as the site-specific phospholamban phosphorylation status, were quantified in a mixed gender population of failing (n=14) and donor (n=15) myocardia. The apparent affinity (EC50) and the maximal velocity (Vmax) of SR Ca2+-uptake were also determined to lend functional significance to any observed protein alterations. Phospholamban and calsequestrin levels were not altered; however, SERCA protein levels were significantly reduced in failing hearts. Additionally, phospholamban phosphorylation (serine-16 and threonine-17 sites) and myocardial cAMP content were both attenuated. The alterations in SR protein levels were also accompanied by a decreased V(max)and an increased EC50 (diminished apparent affinity) of SR Ca2+-uptake for Ca2+ in failing myocardia. Myocardial protein levels and Ca2+ uptake parameters were then analyzed with respect to gender, which revealed that the decreases in phosphorylated serine-16 were specific to male failing hearts, reflecting increases in the EC50 values of SR Ca2+-uptake for Ca2+, compared to donor males. These findings suggest that although decreased SERCA protein and phospholamban phosphorylation levels contribute to depressed SR Ca2+-uptake and left ventricular function in heart failure, the specific subcellular alterations which underlie these effects may not be uniform with respect to gender.
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Affiliation(s)
- R Dash
- Department of Pharmacology & Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575, USA
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