1
|
Mekies LN, Regev D, Eisen B, Fernandez‐Gracia J, Baskin P, Ben Jehuda R, Shulman R, Reiter I, Palty R, Arad M, Gottlieb E, Binah O. Depressed β-adrenergic inotropic responsiveness and intracellular calcium handling abnormalities in Duchenne Muscular Dystrophy patients' induced pluripotent stem cell-derived cardiomyocytes. J Cell Mol Med 2021; 25:3922-3934. [PMID: 33619882 PMCID: PMC8051742 DOI: 10.1111/jcmm.16341] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/05/2021] [Accepted: 01/14/2021] [Indexed: 12/20/2022] Open
Abstract
Duchenne muscular dystrophy (DMD), caused by mutations in the dystrophin gene, is an X-linked disease affecting male and rarely adult heterozygous females, resulting in death by the late 20s to early 30s. Previous studies reported depressed left ventricular function in DMD patients which may result from deranged intracellular Ca2+ -handling. To decipher the mechanism(s) underlying the depressed LV function, we tested the hypothesis that iPSC-CMs generated from DMD patients feature blunted positive inotropic response to β-adrenergic stimulation. To test the hypothesis, [Ca2+ ]i transients and contractions were recorded from healthy and DMD-CMs. While in healthy CMs (HC) isoproterenol caused a prominent positive inotropic effect, DMD-CMs displayed a blunted inotropic response. Next, we tested the functionality of the sarcoplasmic reticulum (SR) by measuring caffeine-induced Ca2+ release. In contrast to HC, DMD-CMs exhibited reduced caffeine-induced Ca2+ signal amplitude and recovery time. In support of the depleted SR Ca2+ stores hypothesis, in DMD-CMs the negative inotropic effects of ryanodine and cyclopiazonic acid were smaller than in HC. RNA-seq analyses demonstrated that in DMD CMs the RNA-expression levels of specific subunits of the L-type calcium channel, the β1-adrenergic receptor (ADRβ1) and adenylate cyclase were down-regulated by 3.5-, 2.8- and 3-fold, respectively, which collectively contribute to the depressed β-adrenergic responsiveness.
Collapse
MESH Headings
- Adrenergic Agents/pharmacology
- Adult
- Calcium/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Cell Differentiation
- Female
- Gene Expression Regulation
- Humans
- Induced Pluripotent Stem Cells/drug effects
- Induced Pluripotent Stem Cells/metabolism
- Induced Pluripotent Stem Cells/pathology
- Male
- Middle Aged
- Muscular Dystrophy, Duchenne/drug therapy
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Myocardial Contraction
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- RNA-Seq
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Sarcoplasmic Reticulum/drug effects
- Sarcoplasmic Reticulum/metabolism
- Sarcoplasmic Reticulum/pathology
Collapse
Affiliation(s)
- Lucy N. Mekies
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Danielle Regev
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Binyamin Eisen
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Jonatan Fernandez‐Gracia
- Department of Cell Biology and Cancer ScienceRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Polina Baskin
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Ronen Ben Jehuda
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
- Faculty of Biotechnology and Food EngineeringTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Rita Shulman
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Irina Reiter
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Raz Palty
- Department of BiochemistryRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Michael Arad
- Leviev Heart CenterSheba Medical CenterRamat GanIsrael
- Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Eyal Gottlieb
- Department of Cell Biology and Cancer ScienceRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Ofer Binah
- Department of PhysiologyBiophysics and Systems BiologyRappaport Faculty of MedicineTechnion – Israel Institute of TechnologyHaifaIsrael
| |
Collapse
|
2
|
Rubi L, Todt H, Kubista H, Koenig X, Hilber K. Calcium current properties in dystrophin-deficient ventricular cardiomyocytes from aged mdx mice. Physiol Rep 2018; 6. [PMID: 29333726 PMCID: PMC5789658 DOI: 10.14814/phy2.13567] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 12/11/2017] [Indexed: 11/24/2022] Open
Abstract
Duchenne muscular dystrophy (DMD), caused by mutations in the gene encoding for the cytoskeletal protein dystrophin, is linked with severe cardiac complications including cardiomyopathy development and cardiac arrhythmias. We and others recently reported that currents through L‐type calcium (Ca) channels were significantly increased, and channel inactivation was reduced in dystrophin‐deficient ventricular cardiomyocytes derived from the mdx mouse, the most commonly used animal model for human DMD. These gain‐of‐function Ca channel abnormalities may enhance the risk of Ca‐dependent arrhythmias and cellular Ca overload in the dystrophic heart. All studies, which have so far investigated L‐type Ca channel properties in dystrophic cardiomyocytes, have used hearts from either neonatal or young adult mdx mice as cell source. In consequence, the dimension of the Ca channel abnormalities present in the severely‐diseased aged dystrophic heart has remained unknown. Here, we have studied potential abnormalities in Ca currents and intracellular Ca transients in ventricular cardiomyocytes derived from aged dystrophic mdx mice. We found that both the L‐type and T‐type Ca current properties of mdx cardiomyocytes were similar to those of myocytes derived from aged wild‐type mice. Accordingly, Ca release from the sarcoplasmic reticulum was normal in cardiomyocytes from aged mdx mice. This suggests that, irrespective of the presence of a pronounced cardiomyopathy in aged mdx mice, Ca currents and Ca release in dystrophic cardiomyocytes are normal. Finally, our data imply that dystrophin‐ regulation of L‐type Ca channel function in the heart is lost during aging.
Collapse
Affiliation(s)
- Lena Rubi
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Hannes Todt
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Helmut Kubista
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Xaver Koenig
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Karlheinz Hilber
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| |
Collapse
|
3
|
Li Y, Zhang S, Zhang X, Li J, Ai X, Zhang L, Yu D, Ge S, Peng Y, Chen X. Blunted cardiac beta-adrenergic response as an early indication of cardiac dysfunction in Duchenne muscular dystrophy. Cardiovasc Res 2014; 103:60-71. [PMID: 24812281 DOI: 10.1093/cvr/cvu119] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIMS To determine whether altered beta-adrenergic responses contribute to early cardiac dysfunction in mdx (X-linked muscular dystrophy) mice, an animal model for human Duchenne muscular dystrophy. METHODS AND RESULTS Replacement fibrosis in mdx hearts gradually increased with age, suggesting a gradual loss of cardiomyocytes. Echocardiography and intra-left ventricular haemodynamic measurements detected baseline cardiac dysfunction in mdx mice at ≥8 months. However, a reduction of cardiac beta-adrenergic response to isoproterenol (ISO) was already present in mdx mice at 4 months. Ventricular myocytes (VMs) isolated from 4- and 8-month-old mdx mice had greater baseline contractile function {fractional shortening, [Ca(2+)]i, and sarcoplasmic reticulum (SR) Ca(2+) content} and ICa-L than age-matched control VMs and than myocytes isolated from 2-month-old mdx mice. ISO increased myocyte function in the VMs of 4- and 8-month-old mdx mice to the same level as in age-matched control VMs. In the VMs of 12-month-old mdx mice, ISO failed to increase myocyte function to the level in VMs of 12-month-old control mice and could not further increaseICa-L. No differences were observed in the expression of Cav1.2α1c, Cav1.2β1, Cav1.2β2, sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA), and the Na(+)/Ca(2+) exchanger. In contrast, total ryanodine receptor 2 (RyR2) and basal phosphorylation of RyR2, phospholamban, and Cav1.2α1c were found to be increased in hearts of 4-month-old mdx mice; baseline protein kinase A activity was also increased. After ISO treatment, phosphorylation levels were the same in mdx and control hearts. VMs of 4-month-old mdx mice had reduced beta1-adrenergic receptor (β1-AR) density and beta-adrenergic sensitivity. CONCLUSION In young mdx mice, the myocyte increases its contractile function to compensate for myocyte loss. However, these myocytes with enhanced baseline function have reduced potential for stimulation, decreased β1-AR density/sensitivity, leading to blunted cardiac beta-adrenergic response.
Collapse
Affiliation(s)
- Ying Li
- Institute of Burn Research, Southwest Hospital, The Third Military Medical University, Chongqing, China Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Shuai Zhang
- Institute of Burn Research, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Xiaoying Zhang
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Jing Li
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA School of Medicine, Nankai University, Tianjin, China
| | - Xiaojie Ai
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA College of Biological Sciences, Shanghai Jiaotong University, Shanghai, China
| | - Li Zhang
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA Drexel University College of Medicine, Philadelphia, PA, USA
| | - Daohai Yu
- Department of Clinical Sciences, Temple University School of Medicine, Philadelphia, PA, USA
| | - Shuping Ge
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Yizhi Peng
- Institute of Burn Research, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Xiongwen Chen
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA Daping Hospital, The Third Military Medical University, Chongqing, China
| |
Collapse
|
4
|
Ascah A, Khairallah M, Daussin F, Bourcier-Lucas C, Godin R, Allen BG, Petrof BJ, Des Rosiers C, Burelle Y. Stress-induced opening of the permeability transition pore in the dystrophin-deficient heart is attenuated by acute treatment with sildenafil. Am J Physiol Heart Circ Physiol 2011; 300:H144-53. [DOI: 10.1152/ajpheart.00522.2010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Susceptibility of cardiomyocytes to stress-induced damage has been implicated in the development of cardiomyopathy in Duchenne muscular dystrophy, a disease caused by the lack of the cytoskeletal protein dystrophin in which heart failure is frequent. However, the factors underlying the disease progression are unclear and treatments are limited. Here, we tested the hypothesis of a greater susceptibility to the opening of the mitochondrial permeability transition pore (PTP) in hearts from young dystrophic ( mdx) mice (before the development of overt cardiomyopathy) when subjected to a stress protocol and determined whether the prevention of a PTP opening is involved in the cardioprotective effect of sildenafil, which we have previously reported in mdx mice. Using the 2-deoxy-[3H]glucose method to quantify the PTP opening in ex vivo perfused hearts, we demonstrate that when compared with those of controls, the hearts from young mdx mice subjected to ischemia-reperfusion (I/R) display an excessive PTP opening as well as enhanced activation of cell death signaling, mitochondrial oxidative stress, cardiomyocyte damage, and poorer recovery of contractile function. Functional analyses in permeabilized cardiac fibers from nonischemic hearts revealed that in vitro mitochondria from mdx hearts display normal respiratory function and reactive oxygen species handling, but enhanced Ca2+ uptake velocity and premature opening of the PTP, which may predispose to I/R-induced injury. The administration of a single dose of sildenafil to mdx mice before I/R prevented excessive PTP opening and its downstream consequences and reduced tissue Ca2+ levels. Furthermore, mitochondrial Ca2+ uptake velocity was reduced following sildenafil treatment. In conclusion, beyond our documentation that an increased susceptibility to the opening of the mitochondrial PTP in the mdx heart occurs well before clinical signs of overt cardiomyopathy, our results demonstrate that sildenafil, which is already administered in other pediatric populations and is reported safe and well tolerated, provides efficient protection against this deleterious event, likely by reducing cellular Ca2+ loading and mitochondrial Ca2+ uptake.
Collapse
Affiliation(s)
| | | | | | | | | | - Bruce G. Allen
- Montreal Heart Institute and
- Medicine, Université de Montréal; and
| | - Basil J. Petrof
- Meakins-Christie Laboratories and Respiratory Division, McGill University, Montreal, Quebec, Canada
| | | | | |
Collapse
|
5
|
Van Erp C, Loch D, Laws N, Trebbin A, Hoey AJ. Timeline of cardiac dystrophy in 3-18-month-old MDX mice. Muscle Nerve 2010; 42:504-13. [PMID: 20589894 DOI: 10.1002/mus.21716] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The dystrophin-deficient (mdx) mouse remains the most commonly used model for Duchenne muscular dystrophy (DMD). Mdx mice show a predominantly covert cardiomyopathy, the hallmark of which is fibrosis. We compared mdx and normal mice at six ages (3, 6, 9, 12, 15, and 18 months) using in vivo assessment of cardiac function, selective collagen staining, and measures of TGF-β mRNA, Evans blue dye infiltration, macrophage infiltration, and aortic wall thickness. Clear temporal progression was demonstrated, including early fragility of cardiomyocyte membranes, which has an unrelated impact on cardiac function but is associated with macrophage infiltration and fibrosis. Aortic wall thickness is less in older mdx mice. Mdx mice display impaired responses to inotropic challenge from a young age; this is indicative of altered adrenoreceptor function. We draw attention to the paradox of ongoing fibrosis in mdx hearts without a strong molecular signature (in the form of TGF-β mRNA expression).
Collapse
Affiliation(s)
- Christel Van Erp
- Centre for Systems Biology, Faculty of Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia
| | | | | | | | | |
Collapse
|
6
|
Kaspar RW, Allen HD, Montanaro F. Current understanding and management of dilated cardiomyopathy in Duchenne and Becker muscular dystrophy. ACTA ACUST UNITED AC 2009; 21:241-9. [PMID: 19432907 DOI: 10.1111/j.1745-7599.2009.00404.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE To review the current understanding of the pathophysiology of dilated cardiomyopathy (DCM) in patients with Duchenne and Becker muscular dystrophies, assessment of cardiac dysfunction for these patients, and the recommended pharmacological treatment options and ongoing research directions. DATA SOURCES Reviews and original research articles from scholarly journals and books. CONCLUSIONS Duchenne and Becker muscular dystrophies are debilitating neuromuscular disorders, both caused by mutations in the dystrophin gene. Most patients develop DCM as part of the disease course; in fact, DCM is the leading cause of death among these patients. Cardiac surveillance, including routine monitoring of electrocardiograms, echocardiograms, and appropriate blood biomarkers, may detect early DCM development. Although previous studies have shown that early administration of cardiac medications may delay the development of DCM, current standard of care does not emphasize cardiac surveillance and timely treatment. This, in turn, limits clinicians, including advanced practice nurses, to be optimally engaged in providing the most aggressive and proactive patient care. IMPLICATIONS FOR PRACTICE Implementing a routine cardiac assessment and timely pharmacological treatment in primary or specialty care settings is highlighted as an important step to optimize cardiac health among patients with Duchenne and Becker muscular dystrophies.
Collapse
Affiliation(s)
- Rita Wen Kaspar
- The Ohio State University College of Nursing, Columbus, Ohio, USA
| | | | | |
Collapse
|
7
|
Williams IA, Allen DG. Intracellular calcium handling in ventricular myocytes from mdx mice. Am J Physiol Heart Circ Physiol 2006; 292:H846-55. [PMID: 17012353 DOI: 10.1152/ajpheart.00688.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal degenerative disease of skeletal muscle, characterized by the absence of the cytoskeletal protein dystrophin. Some DMD patients show a dilated cardiomyopathy leading to heart failure. This study explores the possibility that dystrophin is involved in the regulation of a stretch-activated channel (SAC), which in the absence of dystrophin has increased activity and allows greater Ca(2+) into cardiomyocytes. Because cardiac failure only appears late in the progression of DMD, we examined age-related effects in the mdx mouse, an animal model of DMD. Ca(2+) measurements using a fluorescent Ca(2+)-sensitive dye fluo-4 were performed on single ventricular myocytes from mdx and wild-type mice. Immunoblotting and immunohistochemistry were performed on whole hearts to determine expression levels of key proteins involved in excitation-contraction coupling. Old mdx mice had raised resting intracellular Ca(2+) concentration ([Ca(2+)](i)). Isolated ventricular myocytes from young and old mdx mice displayed abnormal Ca(2+) transients, increased protein expression of the ryanodine receptor, and decreased protein expression of serine-16-phosphorylated phospholamban. Caffeine-induced Ca(2+) transients showed that the Na(+)/Ca(2+) exchanger function was increased in old mdx mice. Two SAC inhibitors streptomycin and GsMTx-4 both reduced resting [Ca(2+)](i) in old mdx mice, suggesting that SACs may be involved in the Ca(2+)-handling abnormalities in these animals. This finding was supported by immunoblotting data, which demonstrated that old mdx mice had increased protein expression of canonical transient receptor potential channel 1, a likely candidate protein for SACs. SACs may play a role in the pathogenesis of the heart failure associated with DMD. Early in the disease process and before the onset of clinical symptoms increased, SAC activity may underlie the abnormal Ca(2+) handling in young mdx mice.
Collapse
MESH Headings
- Age Factors
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium-Binding Proteins/metabolism
- Cardiac Output, Low/etiology
- Cardiac Output, Low/metabolism
- Cardiac Output, Low/pathology
- Cardiac Output, Low/physiopathology
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Dilated/physiopathology
- Disease Models, Animal
- Electric Stimulation
- Fibrosis
- Heart Ventricles/metabolism
- Heart Ventricles/physiopathology
- Intercellular Signaling Peptides and Proteins
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Muscular Dystrophy, Animal/complications
- Muscular Dystrophy, Duchenne/complications
- Myocardial Contraction
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Peptides/pharmacology
- Phosphorylation
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Sodium-Calcium Exchanger/drug effects
- Sodium-Calcium Exchanger/metabolism
- Spider Venoms/pharmacology
- Streptomycin/pharmacology
- TRPC Cation Channels/drug effects
- TRPC Cation Channels/metabolism
- Time Factors
Collapse
Affiliation(s)
- Iwan A Williams
- Bosch Institute, School of Medical Sciences, University of Sydney F13, NSW 2006 Australia
| | | |
Collapse
|
8
|
Du XJ, Fang L, Kiriazis H. Sex dimorphism in cardiac pathophysiology: experimental findings, hormonal mechanisms, and molecular mechanisms. Pharmacol Ther 2006; 111:434-75. [PMID: 16439025 DOI: 10.1016/j.pharmthera.2005.10.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 10/25/2005] [Indexed: 11/30/2022]
Abstract
The higher cardiovascular risk in men and post-menopausal women implies a protective action of estrogen. A large number of experimental studies have provided strong support to this concept. However, the recent clinical trials with negative outcomes regarding hormone replacement therapy call for "post hoc" reassessment of existing information, models, and research strategies as well as a summary of recent findings. Sex steroid hormones, in particular estrogen, regulate numerous processes that are related to the development and progression of cardiovascular disease through a variety of signaling pathways. Use of genetically modified models has resulted in interesting information on diverse actions mediated by steroid receptors. By focusing on experimental findings, we have reviewed hormonal, cellular, and signaling mechanisms responsible for sex dimorphism and actions of hormone replacement therapy and addressed current limitations and future directions of experimental research.
Collapse
Affiliation(s)
- Xiao-Jun Du
- Experimental Cardiology Laboratory, Baker Heart Research Institute, 75 Commercial Road, Melbourne, Victoria 3004, Australia.
| | | | | |
Collapse
|
9
|
Woolf PJ, Lu S, Cornford-Nairn R, Watson M, Xiao XH, Holroyd SM, Brown L, Hoey AJ. Alterations in dihydropyridine receptors in dystrophin-deficient cardiac muscle. Am J Physiol Heart Circ Physiol 2006; 290:H2439-45. [PMID: 16415078 DOI: 10.1152/ajpheart.00844.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The deficiency of dystrophin, a critical membrane stabilizing protein, in the mdx mouse causes an elevation in intracellular calcium in myocytes. One mechanism that could elicit increases in intracellular calcium is enhanced influx via the L-type calcium channels. This study investigated the effects of the dihydropyridines BAY K 8644 and nifedipine and alterations in dihydropyridine receptors in dystrophin-deficient mdx hearts. A lower force of contraction and a reduced potency of extracellular calcium (P < 0.05) were evident in mdx left atria. The dihydropyridine agonist BAY K 8644 and antagonist nifedipine had 2.7- and 1.9-fold lower potencies in contracting left atria (P < 0.05). This corresponded with a 2.0-fold reduction in dihydropyridine receptor affinity evident from radioligand binding studies of mdx ventricular homogenates (P < 0.05). Increased ventricular dihydropyridine receptor protein was evident from both radioligand binding studies and Western blot analysis and was accompanied by increased mRNA levels (P < 0.05). Patch-clamp studies in isolated ventricular myocytes showed no change in L-type calcium current density but revealed delayed channel inactivation (P < 0.05). This study indicates that a deficiency of dystrophin leads to changes in dihydropyridine receptors and L-type calcium channel properties that may contribute to enhanced calcium influx. Increased influx is a potential mechanism for the calcium overload observed in dystrophin-deficient cardiac muscle.
Collapse
Affiliation(s)
- Peter J Woolf
- Centre for Biomedical Research, Faculty of Sciences, University of Southern Queensland, Toowoomba, 4350 Queensland, Australia
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Quinlan JG, Hahn HS, Wong BL, Lorenz JN, Wenisch AS, Levin LS. Evolution of the mdx mouse cardiomyopathy: physiological and morphological findings. Neuromuscul Disord 2004; 14:491-6. [PMID: 15336690 DOI: 10.1016/j.nmd.2004.04.007] [Citation(s) in RCA: 218] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 02/27/2004] [Accepted: 04/19/2004] [Indexed: 11/19/2022]
Abstract
Heart failure is a major cause of death in boys with Duchenne muscular dystrophy. In order to determine if the cardiac function of the mdx mouse is similarly disturbed, we performed murine echocardiograms and left heart catheterization studies, along with morphometric analysis of cardiac fibrosis. Serial echocardiograms in mdx mice revealed the evolution from normal cardiac function in young mice to a dilated cardiomyopathy in adult mice. Very old mdx mice exhibited a widespread but patchy increase in ventricular wall fibrosis. These results show that the mdx cardiac function is more impaired than was previously thought and shares important clinical features with the cardiomyopathy of Duchenne muscular dystrophy.
Collapse
Affiliation(s)
- John G Quinlan
- Departments of Neurology, University of Cincinnati, 4011 Medical Science Building, 231 Cincinnati, OH 45267-0525, USA
| | | | | | | | | | | |
Collapse
|
11
|
McNally EM, Towbin JA. Cardiomyopathy in Muscular Dystrophy Workshop 28–30 September 2003, Tucson, Arizona. Neuromuscul Disord 2004; 14:442-8. [PMID: 15266661 DOI: 10.1016/j.nmd.2004.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
12
|
Rohman MS, Emoto N, Takeshima Y, Yokoyama M, Matsuo M. Decreased mAKAP, ryanodine receptor, and SERCA2a gene expression in mdx hearts. Biochem Biophys Res Commun 2003; 310:228-35. [PMID: 14511675 DOI: 10.1016/j.bbrc.2003.09.005] [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] [Indexed: 02/03/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a common genetic disease resulting from mutations in the dystrophin gene. The lack of dystrophin function as a cytoskeletal protein leads to abnormal intracellular Ca(2+) homeostasis, the actual source and functional consequences of which remain obscure. The mdx mouse, a mouse model of DMD, revealed alterations in contractile properties that are likely due to defective Ca(2+) handling. However, the exact mechanisms of the Ca(2+) handling defect are unclear. We performed suppressive subtractive hybridization to isolate differentially expressed genes between 5-month-old mdx and control mice. We observed a decrease in muscle A-kinase anchoring protein (mAKAP) in the mdx hearts. We noticed not only down-regulation of mAKAP mRNA but also decreased mRNA level of the molecules involved in Ca(2+) handling and excitation-contraction (E-C) coupling in the sarcoplasmic reticulum (SR), the cardiac ryanodine receptor, and the sarcoplasmic reticulum Ca(2+) ATPase. Therefore, dystrophin deficiency may cause an impairment of SR Ca(2+) homeostasis and E-C coupling in mdx hearts, in part, by decreased gene expression of molecules involved in SR Ca(2+) handling.
Collapse
Affiliation(s)
- Mohammad Saifur Rohman
- Department of Internal Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Chuo, Kobe 6500017, Japan.
| | | | | | | | | |
Collapse
|