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Dewan S, Witayavanitkul N, Kumar M, Mayer BJ, Betancourt L, Cazorla O, de Tombe PP. Depressed myocardial cross-bridge cycling kinetics in a female guinea pig model of diastolic heart failure. J Gen Physiol 2023; 155:e202213288. [PMID: 37102986 PMCID: PMC10140646 DOI: 10.1085/jgp.202213288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/10/2023] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Cardiac hypertrophy is associated with diastolic heart failure (DHF), a syndrome in which systolic function is preserved but cardiac filling dynamics are depressed. The molecular mechanisms underlying DHF and the potential role of altered cross-bridge cycling are poorly understood. Accordingly, chronic pressure overload was induced by surgically banding the thoracic ascending aorta (AOB) in ∼400 g female Dunkin Hartley guinea pigs (AOB); Sham-operated age-matched animals served as controls. Guinea pigs were chosen to avoid the confounding impacts of altered myosin heavy chain (MHC) isoform expression seen in other small rodent models. In vivo cardiac function was assessed by echocardiography; cardiac hypertrophy was confirmed by morphometric analysis. AOB resulted in left ventricle (LV) hypertrophy and compromised diastolic function with normal systolic function. Biochemical analysis revealed exclusive expression of β-MHC isoform in both sham control and AOB LVs. Myofilament function was assessed in skinned multicellular preparations, skinned single myocyte fragments, and single myofibrils prepared from frozen (liquid N2) LVs. The rates of force-dependent ATP consumption (tension-cost) and force redevelopment (Ktr), as well as myofibril relaxation time (Timelin) were significantly blunted in AOB, indicating reduced cross-bridge cycling kinetics. Maximum Ca2+ activated force development was significantly reduced in AOB myocytes, while no change in myofilament Ca2+ sensitivity was observed. Our results indicate blunted cross-bridge cycle in a β-MHC small animal DHF model. Reduced cross-bridge cycling kinetics may contribute, at least in part, to the development of DHF in larger mammals, including humans.
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Affiliation(s)
- Sukriti Dewan
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Namthip Witayavanitkul
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Beth J Mayer
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Lauren Betancourt
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
| | - Olivier Cazorla
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
| | - Pieter P de Tombe
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
- Phymedexp INSERM, CNRS, University of Montpellier , Montpellier, France
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Parry TL, Hayward R. Exercise Protects against Cancer-induced Cardiac Cachexia. Med Sci Sports Exerc 2019; 50:1169-1176. [PMID: 29315166 DOI: 10.1249/mss.0000000000001544] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cancer has been shown to negatively stimulate autophagy, leading to a decline in cardiac function. Although exercise is cardioprotective, its influence over autophagy-mediated tumor growth and cardiac function are not well defined. PURPOSE This study aimed to determine the effect of exercise on tumor morphology and cardiac function. METHODS Fisher 344 rats (n = 28) were assigned to one of four groups: 1) sedentary non-tumor bearing (SED), 2) sedentary tumor bearing (SED + T), 3) wheel run non-tumor bearing (WR), or 4) wheel run tumor bearing (WR + T). Rats remained sedentary or exercised for 6 wk. At week 4, rats in tumor groups were inoculated with MatBIII tumor cells. At week 6, cardiac function was measured. RESULTS SED + T animals exhibited significantly lower left ventricular developed pressure when compared with SED, WR, and WR + T (P < 0.05). This coincided with a significant increase in cardiac autophagy (increased LC3-II) in SED + T animals when compared with SED, WR, and WR + T (P < 0.05). Furthermore, SED + T hearts showed a significant increase in β-myosin heavy chain expression versus nontumor groups (P < 0.05). Tumor mass was significantly larger (P < 0.001) in SED + T animals when compared with WR + T animals, which was accompanied by a significant increase in tumor LC3-II protein expression (P < 0.05). CONCLUSION Nonexercised tumor-bearing rats showed severe cardiac dysfunction and excessive, maladaptive autophagy in the heart and tumors. Voluntary exercise preserved cardiac function and attenuated the autophagic response in heart and tumor tissues. This preservation may be related to the reduced tumor growth in aerobically exercised rats, to the improved regulation of autophagy by exercise, or both.
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Affiliation(s)
- Traci L Parry
- McAllister Heart Institute and Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC
| | - Reid Hayward
- School of Sport and Exercise Science, and the University of Northern Colorado Cancer Rehabilitation Institute, University of Northern Colorado, Greeley, CO
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Zhang X, Liu ZQ, Singh D, Wehner GJ, Powell DK, Campbell KS, Fornwalt BK, Wenk JF. Regional quantification of myocardial mechanics in rat using 3D cine DENSE cardiovascular magnetic resonance. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3733. [PMID: 28481037 PMCID: PMC10539034 DOI: 10.1002/nbm.3733] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 06/07/2023]
Abstract
Rat models have assumed an increasingly important role in cardiac research. However, a detailed profile of regional cardiac mechanics, such as strains and torsion, is lacking for rats. We hypothesized that healthy rat left ventricles (LVs) exhibit regional differences in cardiac mechanics, which are part of normal function. In this study, images of the LV were obtained with 3D cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance in 10 healthy rats. To evaluate regional cardiac mechanics, the LV was divided into basal, mid-ventricular, and apical regions. The myocardium at the mid-LV was further partitioned into four wall segments (i.e. septal, inferior, lateral, and anterior) and three transmural layers (i.e. sub-endocardium, mid-myocardium, and sub-epicardium). The six Lagrangian strain components (i.e. Err , Ecc , Ell , Ecl , Erl , and Ecr ) were computed from the 3D displacement field and averaged within each region of interest. Torsion was quantified using the circumferential-longitudinal shear angle. While peak systolic Ecl differed between the mid-ventricle and apex, the other five components of peak systolic strain were similar across the base, mid-ventricle, and apex. In the mid-LV myocardium, Ecc decreased gradually from the sub-endocardial to the sub-epicardial layer. Ell demonstrated significant differences between the four wall segments, with the largest magnitude in the inferior segment. Err was uniform among the four wall segments. Ecl varied along the transmural direction and among wall segments, whereas Erl differed only among the wall segments. Erc was not associated with significant variations. Torsion also varied along the transmural direction and among wall segments. These results provide fundamental insights into the regional contractile function of healthy rat hearts, and form the foundation for future studies on regional changes induced by disease or treatments.
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Affiliation(s)
- Xiaoyan Zhang
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Zhan-Qiu Liu
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Dara Singh
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Gregory J. Wehner
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - David K. Powell
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY, USA
| | | | - Brandon K. Fornwalt
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- Institute for Advanced Application, Geisinger Health System, Danville, PA
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
- Department of Surgery, University of Kentucky, Lexington, KY, USA
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Blackmore HL, Niu Y, Fernandez-Twinn DS, Tarry-Adkins JL, Giussani DA, Ozanne SE. Maternal diet-induced obesity programs cardiovascular dysfunction in adult male mouse offspring independent of current body weight. Endocrinology 2014; 155:3970-80. [PMID: 25051449 PMCID: PMC4255219 DOI: 10.1210/en.2014-1383] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Obese pregnancies are not only associated with adverse consequences for the mother but also the long-term health of her child. Human studies have shown that individuals from obese mothers are at increased risk of premature death from cardiovascular disease (CVD), but are unable to define causality. This study aimed to determine causality using a mouse model of maternal diet-induced obesity. Obesity was induced in female C57BL/6 mice by feeding a diet rich in simple sugars and saturated fat 6 weeks prior to pregnancy and throughout pregnancy and lactation. Control females were fed laboratory chow. Male offspring from both groups were weaned onto chow and studied at 3, 5, 8, and 12 weeks of age for gross cardiac morphometry using stereology, cardiomyocyte cell area by histology, and cardiac fetal gene expression using qRT-PCR. Cardiac function was assessed by isolated Langendorff technology at 12 weeks of age and hearts were analyzed at the protein level for the expression of the β1 adrenergic receptor, muscarinic type-2 acetylcholine receptor, and proteins involved in cardiac contraction. Offspring from obese mothers develop pathologic cardiac hypertrophy associated with re-expression of cardiac fetal genes. By young adulthood these offspring developed severe systolic and diastolic dysfunction and cardiac sympathetic dominance. Importantly, cardiac dysfunction occurred in the absence of any change in corresponding body weight and despite the offspring eating a healthy low-fat diet. These findings provide a causal link to explain human observations relating maternal obesity with premature death from CVD in her offspring.
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Affiliation(s)
- Heather L Blackmore
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science (H.L.B., D.S.F.-T., J.L.T.-A., S.E.O.), Addenbrookes Hospital, Cambridge CB2 0QQ, United Kingdom; and Department of Physiology, Development, and Neuroscience (Y.N., D.A.G.), University of Cambridge, Cambridge CB2 3EG, United Kingdom
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Gresham KS, Mamidi R, Stelzer JE. The contribution of cardiac myosin binding protein-c Ser282 phosphorylation to the rate of force generation and in vivo cardiac contractility. J Physiol 2014; 592:3747-65. [PMID: 24951619 DOI: 10.1113/jphysiol.2014.276022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cardiac myosin binding protein-C phosphorylation plays an important role in modulating cardiac muscle function and accelerating contraction. It has been proposed that Ser282 phosphorylation may serve as a critical molecular switch that regulates the phosphorylation of neighbouring Ser273 and Ser302 residues, and thereby govern myofilament contractile acceleration in response to protein kinase A (PKA). Therefore, to determine the regulatory roles of Ser282 we generated a transgenic (TG) mouse model expressing cardiac myosin binding protein-C with a non-phosphorylatable Ser282 (i.e. serine to alanine substitution, TG(S282A)). Myofibrils isolated from TG(S282A) hearts displayed robust PKA-mediated phosphorylation of Ser273 and Ser302, and the increase in phosphorylation was identical to TG wild-type (TG(WT)) controls. No signs of pathological cardiac hypertrophy were detected in TG(S282A) hearts by either histological examination of cardiac sections or echocardiography. Baseline fractional shortening, ejection fraction, isovolumic relaxation time, rate of pressure development and rate of relaxation (τ) were unaltered in TG(S282A) mice. However, the increase in cardiac contractility as well as the acceleration of pressure development observed in response to β-adrenergic stimulation was attenuated in TG(S282A) mice. In agreement with our in vivo data, in vitro force measurements revealed that PKA-mediated acceleration of cross-bridge kinetics in TG(S282A) myocardium was significantly attenuated compared to TG(WT) myocardium. Taken together, our data suggest that while Ser282 phosphorylation does not regulate the phosphorylation of neighbouring Ser residues and basal cardiac function, full acceleration of cross-bridge kinetics and left ventricular pressure development cannot be achieved in its absence.
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Affiliation(s)
- Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
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Parry TL, Hydock DS, Jensen BT, Lien CY, Schneider CM, Hayward R. Endurance exercise attenuates cardiotoxicity induced by androgen deprivation and doxorubicin. Can J Physiol Pharmacol 2014; 92:356-62. [PMID: 24784469 DOI: 10.1139/cjpp-2013-0294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Doxorubicin (DOX) is associated with cardiac dysfunction and irreversible testicular damage. Androgen deprivation therapy (ADT) is administered prior to DOX treatment to preserve testicular function. However, ADT may exacerbate DOX-induced cardiac dysfunction. Exercise is cardioprotective, but the effects of exercise on cardiac function during combined ADT and DOX treatment are currently unknown. In this study, male Sprague-Dawley rats were randomly assigned to experimental groups: control (CON), ADT, DOX, or ADT+DOX. Animals received ADT or control implants on days 1 and 29 of the 56-day protocol. Animals remained sedentary (SED) or engaged in treadmill endurance exercise (TM) beginning on day 1. On day 15, the animals received DOX at 1 mg·(kg body mass)(-1)·d(-1) by intraperitoneal injection for 10 consecutive days, or an equivalent volume of saline. On day 57, cardiac function was assessed in vivo and ex vivo. Animals treated with DOX alone, or with combined ADT+DOX, showed significant (P < 0.05) reductions in left ventricular developed pressure (-21% and -27%), maximal rate of pressure development (-29% and -32%), and maximal rate of pressure decline (25% and 31%), respectively when compared with the sedentary control animals. Endurance exercise training attenuated (P > 0.05) cardiac dysfunction associated with combined ADT+DOX treatment, indicating that exercise during simultaneous ADT+DOX treatment is cardioprotective.
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Affiliation(s)
- Traci L Parry
- a School of Sport and Exercise Science, University of Northern Colorado, Greeley, CO 80639, USA
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Chen Y, Ye L, Zhong J, Li X, Yan C, Chandler MP, Calvin S, Xiao F, Negia M, Low WC, Zhang J, Yu X. The Structural Basis of Functional Improvement in Response to Human Umbilical Cord Blood Stem Cell Transplantation in Hearts With Postinfarct LV Remodeling. Cell Transplant 2013; 24:971-83. [PMID: 24332083 DOI: 10.3727/096368913x675746] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Cellular therapy for myocardial repair has been one of the most intensely investigated interventional strategies for acute myocardial infarction. Although the therapeutic potential of stem cells has been demonstrated in various studies, the underlying mechanisms for such improvements are poorly understood. In the present study, we investigated the long-term effects of stem cell therapy on both myocardial fiber organization and regional contractile function using a rat model of postinfarct remodeling. Human nonhematopoietic umbilical cord blood stem cells (nh-UCBSCs) were administered via tail vein to rats 2 days after infarct surgery. Animals were maintained without immunosuppressive therapy. In vivo and ex vivo MR imaging was performed on infarct hearts 10 months after cell transplantation. Compared to the age-matched rats exposed to the identical surgery, both global and regional cardiac functions of the nh-UCBSC-treated hearts, such as ejection fraction, ventricular strain, and torsion, were significantly improved. More importantly, the treated hearts exhibited preserved fiber orientation and water diffusivities that were similar to those in sham-operated control hearts. These data provide the first evidence that nh-UCBSC treatment may prevent/delay untoward structural remodeling in postinfarct hearts, which supports the improved LV function observed in vivo in the absence of immunosuppression, suggesting a beneficial paracrine effect occurred with the cellular therapy.
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Affiliation(s)
- Yong Chen
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
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Cheng Y, Wan X, McElfresh TA, Chen X, Gresham KS, Rosenbaum DS, Chandler MP, Stelzer JE. Impaired contractile function due to decreased cardiac myosin binding protein C content in the sarcomere. Am J Physiol Heart Circ Physiol 2013; 305:H52-65. [PMID: 23666674 DOI: 10.1152/ajpheart.00929.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations in cardiac myosin binding protein C (MyBP-C) are a common cause of familial hypertrophic cardiomyopathy (FHC). The majority of MyBP-C mutations are expected to reduce MyBP-C expression; however, the consequences of MyBP-C deficiency on the regulation of myofilament function, Ca²⁺ homeostasis, and in vivo cardiac function are unknown. To elucidate the effects of decreased MyBP-C expression on cardiac function, we employed MyBP-C heterozygous null (MyBP-C+/-) mice presenting decreases in MyBP-C expression (32%) similar to those of FHC patients carrying MyBP-C mutations. The levels of MyBP-C phosphorylation were reduced 53% in MyBP-C+/- hearts compared with wild-type hearts. Skinned myocardium isolated from MyBP-C+/- hearts displayed decreased cross-bridge stiffness at half-maximal Ca²⁺ activations, increased steady-state force generation, and accelerated rates of cross-bridge recruitment at low Ca²⁺ activations (<15% and <25% of maximum, respectively). Protein kinase A treatment abolished basal differences in rates of cross-bridge recruitment between MyBP-C+/- and wild-type myocardium. Intact ventricular myocytes from MyBP-C+/- hearts displayed abnormal sarcomere shortening but unchanged Ca²⁺ transient kinetics. Despite a lack of left ventricular hypertrophy, MyBP-C+/- hearts exhibited elevated end-diastolic pressure and decreased peak rate of LV pressure rise, which was normalized following dobutamine infusion. Furthermore, electrocardiogram recordings in conscious MyBP-C+/- mice revealed prolonged QRS and QT intervals, which are known risk factors for cardiac arrhythmia. Collectively, our data show that reduced MyBP-C expression and phosphorylation in the sarcomere result in myofilament dysfunction, contributing to contractile dysfunction that precedes compensatory adaptations in Ca²⁺ handling, and chamber remodeling. Perturbations in mechanical and electrical activity in MyBP-C+/- mice could increase their susceptibility to cardiac dysfunction and arrhythmia.
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Affiliation(s)
- Y Cheng
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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Merkulov S, Chen X, Chandler MP, Stelzer JE. In vivo cardiac myosin binding protein C gene transfer rescues myofilament contractile dysfunction in cardiac myosin binding protein C null mice. Circ Heart Fail 2012; 5:635-44. [PMID: 22855556 DOI: 10.1161/circheartfailure.112.968941] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Decreased expression of cardiac myosin binding protein C (cMyBPC) in the heart has been implicated as a consequence of mutations in cMyBPC that lead to abnormal contractile function at the myofilament level, thereby contributing to the development of hypertrophic cardiomyopathy in humans. It has not been established whether increasing the levels of cMyBPC in the intact heart can improve myofilament and in vivo contractile function and attenuate maladaptive remodeling processes because of reduced levels of cMyBPC. METHODS AND RESULTS We performed in vivo gene transfer of cMyBPC by direct injection into the myocardium of cMyBPC-deficient (cMyBPC(-/-)) mice, and mechanical experiments were conducted on skinned myocardium isolated from cMyBPC(-/-) hearts 21 days and 20 weeks after gene transfer. Cross-bridge kinetics in skinned myocardium isolated from cMyBPC(-/-) hearts after cMyBPC gene transfer were significantly slower compared with untreated cMyBPC(-/-) myocardium and were comparable to wild-type myocardium and cMyBPC(-/-) myocardium that was reconstituted with recombinant cMyBPC in vitro. cMyBPC content in cMyBPC(-/-) skinned myocardium after in vivo cMyBPC gene transfer or in vitro cMyBPC reconstitution was similar to wild-type levels. In vivo echocardiography studies of cMyBPC(-/-) hearts after cMyBPC gene transfer revealed improved systolic and diastolic contractile function and reductions in left ventricular wall thickness. CONCLUSIONS This proof-of-concept study demonstrates that gene therapy designed to increase expression of cMyBPC in the cMyBPC-deficient myocardium can improve myofilament and in vivo contractile function, suggesting that cMyBPC gene therapy may be a viable approach for treatment of cardiomyopathies because of mutations in cMyBPC.
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Affiliation(s)
- Sergei Merkulov
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Dall'Armellina E, Jung BA, Lygate CA, Neubauer S, Markl M, Schneider JE. Improved method for quantification of regional cardiac function in mice using phase-contrast MRI. Magn Reson Med 2012; 67:541-51. [PMID: 21674616 PMCID: PMC3378699 DOI: 10.1002/mrm.23022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 04/04/2011] [Accepted: 05/05/2011] [Indexed: 11/08/2022]
Abstract
Phase-contrast magnetic resonance imaging is a technique that allows for characterization of regional cardiac function and for measuring transmural myocardial velocities in human hearts with high temporal and spatial resolution. The application of this technique (also known as tissue phase mapping) to murine hearts has been very limited so far. The aim of our study was to implement and to optimize tissue phase mapping for a comprehensive assessment of murine transmural wall motion. Baseline values for regional motion patterns in mouse hearts, based on the clinically used American Heart Association's 17-segment model, were established, and a detailed motion analysis of mouse heart for the entire cardiac cycle (including epicardial and endocardial motion patterns) is provided. Black-blood contrast was found to be essential to obtain reproducible velocity encoding. Tissue phase mapping of the mouse heart permits the detailed assessment of regional myocardial velocities. While a proof-of-principle application in a murine ischemia-reperfusion model was performed, future studies are warranted to assess its potential for the investigation of systolic and diastolic functions in genetically and surgically manipulated mouse models of human heart disease.
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Affiliation(s)
- Erica Dall'Armellina
- Department of Cardiovascular Medicine, University of OxfordOxford, United Kingdom
| | - Bernd A Jung
- Department of Radiology, Medical Physics, University Hospital FreiburgGermany
| | - Craig A Lygate
- Department of Cardiovascular Medicine, University of OxfordOxford, United Kingdom
| | - Stefan Neubauer
- Department of Cardiovascular Medicine, University of OxfordOxford, United Kingdom
| | - Michael Markl
- Department of Radiology, Medical Physics, University Hospital FreiburgGermany
| | - Jürgen E Schneider
- Department of Cardiovascular Medicine, University of OxfordOxford, United Kingdom
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Desjardins CL, Chen Y, Coulton AT, Hoit BD, Yu X, Stelzer JE. Cardiac myosin binding protein C insufficiency leads to early onset of mechanical dysfunction. Circ Cardiovasc Imaging 2011; 5:127-36. [PMID: 22157650 DOI: 10.1161/circimaging.111.965772] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Decreased expression of cardiac myosin binding protein C (cMyBPC) as a result of genetic mutations may contribute to the development of hypertrophic cardiomyopathy (HCM); however, the mechanisms that link cMyBPC expression and HCM development, especially contractile dysfunction, remain unclear. METHODS AND RESULTS We evaluated cardiac mechanical function in vitro and in vivo in young mice (8-10 weeks of age) carrying no functional cMyBPC alleles (cMyBPC(-/-)) or 1 functional cMyBPC allele (cMyBPC(±)). Skinned myocardium isolated from cMyBPC(-/-) hearts displayed significant accelerations in stretch activation cross-bridge kinetics. Cardiac MRI studies revealed severely depressed in vivo left ventricular (LV) magnitude and rates of LV wall strain and torsion compared with wild-type (WT) mice. Heterozygous cMyBPC(±) hearts expressed 23±5% less cMyBPC than WT hearts but did not display overt hypertrophy. Skinned myocardium isolated from cMyBPC(±) hearts displayed small accelerations in the rate of stretch induced cross-bridge recruitment. MRI measurements revealed reductions in LV torsion and circumferential strain, as well reduced circumferential strain rates in early systole and diastole. CONCLUSIONS Modest decreases in cMyBPC expression in the mouse heart result in early-onset subtle changes in cross-bridge kinetics and in vivo LV mechanical function, which could contribute to the development of HCM later in life.
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Affiliation(s)
- Candida L Desjardins
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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