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Taghizadeh H. Mechanobiology of the arterial tissue from the aortic root to the diaphragm. Med Eng Phys 2021; 96:64-70. [PMID: 34565554 DOI: 10.1016/j.medengphy.2021.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 01/26/2023]
Abstract
Arterial tissue microstructure and its mechanical properties directly correlate with cardiovascular diseases such as atherosclerosis and aneurysm. Experienced hemodynamic loads are the primary factor of arterial tissue remodeling. By virtue of altering hemodynamic loads along the arterial tree, respective structure-function relations will be region-dependent. Since, there is limited experimental evidence on these structure-function homeostases, the current study, aims to report microstructural and mechanical alterations along the aorta from the aortic root up to the diaphragm, where intense hemodynamic alterations take place. The ascending, arch, and descending parts of the same cadaveric aortas were investigated by histomechanical examinations. Anatomical landmarks were labeled on the specimens, and then biaxial tensile tests were conducted on samples from each region. Furthermore, area fractions of elastin and collagen were measured on stained sections of the tissue. Also, a fragmentation index of elastin tissue is proposed for quantitative measurement of ECM integrity, which correlates with the nature of experienced hemodynamic loads. For the ascending aorta and the aortic arch, different values for mechanical properties and fragmentation index are observed even in a specific cross-section of the artery. It is primarily due to the complex loading regimes and curved geometry. Conversely, microstructural and mechanical features along the descending aorta exhibited minimal variations, and hence, smooth blood flow and pressure waves are expected in this region, which is well-documented in the literature. Both of the microstructural and mechanical features of the aorta vary along the arterial tree depending on the hemodynamic and geometric complexities they incur and may shed light on the initiation of cardiovascular diseases.
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Ait Mou Y, Lacampagne A, Irving T, Scheuermann V, Blot S, Ghaleh B, de Tombe PP, Cazorla O. Altered myofilament structure and function in dogs with Duchenne muscular dystrophy cardiomyopathy. J Mol Cell Cardiol 2017; 114:345-353. [PMID: 29275006 DOI: 10.1016/j.yjmcc.2017.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 11/28/2017] [Accepted: 12/20/2017] [Indexed: 11/16/2022]
Abstract
AIM Duchenne Muscular Dystrophy (DMD) is associated with progressive depressed left ventricular (LV) function. However, DMD effects on myofilament structure and function are poorly understood. Golden Retriever Muscular Dystrophy (GRMD) is a dog model of DMD recapitulating the human form of DMD. OBJECTIVE The objective of this study is to evaluate myofilament structure and function alterations in GRMD model with spontaneous cardiac failure. METHODS AND RESULTS We have employed synchrotron X-rays diffraction to evaluate myofilament lattice spacing at various sarcomere lengths (SL) on permeabilized LV myocardium. We found a negative correlation between SL and lattice spacing in both sub-epicardium (EPI) and sub-endocardium (ENDO) LV layers in control dog hearts. In the ENDO of GRMD hearts this correlation is steeper due to higher lattice spacing at short SL (1.9μm). Furthermore, cross-bridge cycling indexed by the kinetics of tension redevelopment (ktr) was faster in ENDO GRMD myofilaments at short SL. We measured post-translational modifications of key regulatory contractile proteins. S-glutathionylation of cardiac Myosin Binding Protein-C (cMyBP-C) was unchanged and PKA dependent phosphorylation of the cMyBP-C was significantly reduced in GRMD ENDO tissue and more modestly in EPI tissue. CONCLUSIONS We found a gradient of contractility in control dogs' myocardium that spreads across the LV wall, negatively correlated with myofilament lattice spacing. Chronic stress induced by dystrophin deficiency leads to heart failure that is tightly associated with regional structural changes indexed by increased myofilament lattice spacing, reduced phosphorylation of regulatory proteins and altered myofilament contractile properties in GRMD dogs.
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Affiliation(s)
- Younss Ait Mou
- College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar; Department of Cell and Molecular Physiology, Heath Science Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - Alain Lacampagne
- INSERM U1046, CNRS UMR 9214, Université de Montpellier, Physiologie et Médecine Expérimentale du cœur et des muscles - PHYMEDEXP, CHU Arnaud de Villeneuve, 34295 Montpellier cedex 05, France
| | - Thomas Irving
- Department of Cell and Molecular Physiology, Heath Science Division, Loyola University Chicago, Maywood, IL 60153, USA; Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Valérie Scheuermann
- INSERM U1046, CNRS UMR 9214, Université de Montpellier, Physiologie et Médecine Expérimentale du cœur et des muscles - PHYMEDEXP, CHU Arnaud de Villeneuve, 34295 Montpellier cedex 05, France
| | - Stéphane Blot
- Inserm U955-E10, IMRB, Université Paris Est, Ecole nationale vétérinaire d'Alfort, Maisons-Alfort 94700, France
| | | | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Heath Science Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - Olivier Cazorla
- INSERM U1046, CNRS UMR 9214, Université de Montpellier, Physiologie et Médecine Expérimentale du cœur et des muscles - PHYMEDEXP, CHU Arnaud de Villeneuve, 34295 Montpellier cedex 05, France..
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Gregorich ZR, Peng Y, Lane NM, Wolff JJ, Wang S, Guo W, Guner H, Doop J, Hacker TA, Ge Y. Comprehensive assessment of chamber-specific and transmural heterogeneity in myofilament protein phosphorylation by top-down mass spectrometry. J Mol Cell Cardiol 2015; 87:102-12. [PMID: 26268593 DOI: 10.1016/j.yjmcc.2015.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/04/2015] [Accepted: 08/08/2015] [Indexed: 11/28/2022]
Abstract
The heart is characterized by a remarkable degree of heterogeneity, the basis of which is a subject of active investigation. Myofilament protein post-translational modifications (PTMs) represent a critical mechanism regulating cardiac contractility, and emerging evidence shows that pathological cardiac conditions induce contractile heterogeneity that correlates with transmural variations in the modification status of myofilament proteins. Nevertheless, whether there exists basal heterogeneity in myofilament protein PTMs in the heart remains unclear. Here we have systematically assessed chamber-specific and transmural variations in myofilament protein PTMs, specifically, the phosphorylation of cardiac troponin I (cTnI), cardiac troponin T (cTnT), tropomyosin (Tpm), and myosin light chain 2 (MLC2). We show that the phosphorylation of cTnI and αTm vary in the different chambers of the heart, whereas the phosphorylation of MLC2 and cTnT does not. In contrast, no significant transmural differences were observed in the phosphorylation of any of the myofilament proteins analyzed. These results highlight the importance of appropriate tissue sampling-particularly for studies aimed at elucidating disease mechanisms and biomarker discovery-in order to minimize potential variations arising from basal heterogeneity in myofilament PTMs in the heart.
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Affiliation(s)
- Zachery R Gregorich
- Molecular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Nicole M Lane
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA; Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Sijian Wang
- Department of Biostatistics & Medical Informatics, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Statistics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Wei Guo
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Huseyin Guner
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA; Human Proteomics Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Justin Doop
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Timothy A Hacker
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ying Ge
- Molecular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA; Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA; Human Proteomics Program, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Walton RD, Martinez ME, Bishop MJ, Hocini M, Haïssaguerre M, Plank G, Bernus O, Vigmond EJ. Influence of the Purkinje-muscle junction on transmural repolarization heterogeneity. Cardiovasc Res 2014; 103:629-40. [PMID: 24997066 DOI: 10.1093/cvr/cvu165] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS To elucidate the properties of the PMJ and myocardium underlying these effects. Transmural heterogeneity of action potential duration (APD) is known to play an important role in arrhythmogenesis. Regions of non-uniformities of APD gradients often overlap considerably with the location of Purkinje-muscle junctions (PMJs). We therefore hypothesized that such junctions are novel sources of local endocardial and transmural heterogeneity of repolarization, and that remodelling due to heart failure modulates this response. METHODS AND RESULTS Spatial gradients of endocardial APD in left ventricular wedge preparations from healthy sheep (n = 5) were correlated with locations of PMJs identified through Purkinje stimulation under optical mapping. APD prolongation was dependent on proximity of the PMJ to the imaged surface, whereby shallow PMJs significantly modulated local APD when stimulating either Purkinje (P = 0.0116) or endocardium (P = 0.0123). In addition, we model a PMJ in 5 × 5× 10 mm transmural tissue wedges using healthy and novel failing human ventricular and Purkinje ionic models. Short distances of the PMJ to cut surfaces (<0.875 mm) revealed that APD maxima were localized to the PMJ in healthy myocardium, whereas APD minima were observed in failing myocardium. Amplitudes and spatial gradients of APD were prominent at functional PMJs and quiescent PMJs. Furthermore, increasing the extent of Purkinje fibre branching or decreasing tissue conductivity augmented local APD prolongation in both failing and non-failing models. CONCLUSIONS The Purkinje network has the potential to influence myocardial AP morphology and rate-dependent behaviour, and furthermore to underlie enhanced transmural APD heterogeneities and spatial gradients of APD in non-failing and failing myocardium.
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Affiliation(s)
- Richard D Walton
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Marine E Martinez
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Martin J Bishop
- Biomedical Engineering Department, Division of Imaging Sciences, King's College London, London, UK
| | - Mélèze Hocini
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France CHU de Bordeaux, Hôpital du Haut lévêque, Pessac, France
| | - Michel Haïssaguerre
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France CHU de Bordeaux, Hôpital du Haut lévêque, Pessac, France
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - Olivier Bernus
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Edward J Vigmond
- L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France L'Institut de Mathématiques de Bordeaux UMR 5251, Université de Bordeaux, Bordeaux, France Department of Electrical and Computer Engineering, University of Calgary, Calgary, Canada
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Boyle PM, Massé S, Nanthakumar K, Vigmond EJ. Transmural IK(ATP) heterogeneity as a determinant of activation rate gradient during early ventricular fibrillation: mechanistic insights from rabbit ventricular models. Heart Rhythm 2013; 10:1710-7. [PMID: 23948344 DOI: 10.1016/j.hrthm.2013.08.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Activation rate (AR) gradients develop during ventricular fibrillation (VF), with the highest AR on the surface near Purkinje system (PS) terminals (endocardium in humans and rabbits and epicardium in pigs). The application of glibenclamide to block adenosine triphosphate (ATP)-sensitive potassium current (IK(ATP)) before VF induction eliminates transmural AR gradients and prevents the induction of sustained arrhythmia. It remains unclear whether the PS, which is resistant to ischemia, is also a factor in AR heterogeneity. OBJECTIVE To dissect IK(ATP) and PS contributions to AR gradients during VF by using detailed computer simulations. METHODS We constructed rabbit ventricular models with either subendocardial or subepicardial PS terminals. Physiologically relevant IK(ATP) gradients were implemented, and early VF was induced and observed. RESULTS Prominent AR gradients were observed only in models with large IK(ATP) gradients. The critical underlying factor of AR gradient maintenance was refractoriness in low-IK(ATP) regions, which blocked the propagation of action potentials from high-IK(ATP) regions. The PS played no role in transmural AR gradient maintenance, but did cause local spatial heterogeneity of AR on the surface adjacent to terminals. Simulated glibenclamide application during VF led to spontaneous arrhythmia termination within a few seconds in most cases, which builds on previous experimental findings of anti-VF properties of glibenclamide pretreatment. CONCLUSION Differential IK(ATP) across the ventricular wall is an important factor underlying AR gradients during VF; thus, higher epicardial AR in pigs is most likely due to an abundance of epicardial IK(ATP). For terminating early VF, our results suggest that IK(ATP) modulation is a stronger target than Purkinje ablation.
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Affiliation(s)
- Patrick M Boyle
- University of Calgary, Calgary, Alberta, Canada; Institute for Computational Medicine, Johns Hopkins University, Baltimore, Maryland.
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