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Lee Y, Cansız B, Kaliske M. Computational modelling of mechano-electric feedback and its arrhythmogenic effects in human ventricular models. Comput Methods Biomech Biomed Engin 2022; 25:1767-1783. [PMID: 35238688 DOI: 10.1080/10255842.2022.2037573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The current study aims to investigate the role of mechano-electric feedback (MEF) in healthy cardiac cycles and in cardiac arrhythmia using human ventricular models. The numerical formulation of stretch-activated channels (SACs) in terms of the fibre stretch of the myocardium is incorporated into the modified Hill model that describes the myocardium as an electro-visco-active material. Additionally, we propose models of SACs formulated in terms of the rate of stretch along fibre direction and the stretch along sheet direction. We analyze the effect of the three different models for SACs and different material properties on the regular cycles by using electrocardiogram and volume-time curves, and show that the each model of SACs has regionally different influences on the heart model. Moreover, we simulate 'commotio cordis' and 'precordial thump' and demonstrate that MEF plays a major role in the occurrence of fibrillation and defibrillation in the absence of the structural cardiac damage. Furthermore, we study the role of MEF in premature ventricular contraction when the blood pressure is disturbed.
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Affiliation(s)
- Yongjae Lee
- Institute for Structural Analysis, Technische Universität Dresden, 01062 Dresden, Germany
| | - Barış Cansız
- Institute for Structural Analysis, Technische Universität Dresden, 01062 Dresden, Germany
| | - Michael Kaliske
- Institute for Structural Analysis, Technische Universität Dresden, 01062 Dresden, Germany
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Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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Oikawa J, Fukaya H, Ako J, Nakao K, Ozaki Y, Kimura K, Noguchi T, Suwa S, Fujimoto K, Nakama Y, Morita T, Shimizu W, Saito Y, Hirohata A, Morita Y, Inoue T, Okamura A, Mano T, Miyamoto Y, Ogawa H, Ishihara M. Risk Factors of In-Hospital Lethal Arrhythmia Following Acute Myocardial Infarction in Patients Undergoing Primary Percutaneous Coronary Intervention - Insight From the J-MINUET Study. Circ Rep 2019; 2:17-23. [PMID: 33693170 PMCID: PMC7929703 DOI: 10.1253/circrep.cr-19-0081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Background:
Lethal arrhythmias including ventricular tachycardia and fibrillation (VT/VF) are common complications of acute myocardial infarction (AMI). Predictors of in-hospital VT/VF after AMI, however, have not been thoroughly investigated. In this study, we sought to elucidate the predictors of in-hospital VT/VF events after AMI in the Japanese registry of acute Myocardial INfarction diagnosed by Universal dEfiniTion (J-MINUET). Methods and Results:
In-hospital VT/VF was defined as a hemodynamically unstable VT or VF in the first week of hospitalization, on which the patients were classified as the VT/VF group. Of the patients in the J-MINUET study, 3,175 were finally enrolled in this study. A total of 114 patients had VT/VF. On multivariate logistic analysis, maximum creatine kinase >3,000 IU/L (adjusted OR, 1.67; 95% CI: 1.085–2.572; P=0.02), Killip class III or IV (adjusted OR, 8.93; 95% CI: 5.668–14.082; P<0.0001), initial Thrombolysis in Myocardial Infarction (TIMI) flow grade 0 or 1 (adjusted OR, 1.67; 95% CI: 1.035–2.709; P=0.03), and concomitant chronic kidney disease (CKD; adjusted OR, 1.80; 95% CI: 1.105–2.938; P=0.02) were identified as independent predictors for in-hospital VT/VF. Conclusions:
From the J-MINUET study, extensive myocardial damage, cardiogenic shock, lower grade initial TIMI flow on coronary angiography, and concomitant CKD were independent predictors of in-hospital VT/VF after AMI.
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Affiliation(s)
- Jun Oikawa
- Department of Cardiovascular Medicine, Kitasato University School of Medicine Sagamihara Japan
| | - Hidehira Fukaya
- Department of Cardiovascular Medicine, Kitasato University School of Medicine Sagamihara Japan
| | - Junya Ako
- Department of Cardiovascular Medicine, Kitasato University School of Medicine Sagamihara Japan
| | - Koichi Nakao
- Cardiovascular Center, Saiseikai Kumamoto Hospital Kumamoto Japan
| | - Yukio Ozaki
- Department of Cardiovascular Medicine, Fujita Health University Toyoake Japan
| | - Kazuo Kimura
- Department of Cardiology, Yokohama City University Medical Center Yokohama Japan
| | - Teruo Noguchi
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center Suita Japan
| | - Satoru Suwa
- Department of Cardiology, Juntendo University Shizuoka Hospital Izunokuni Japan
| | - Kazuteru Fujimoto
- Department of Cardiology, National Hospital Organization Kumamaoto Medical Center Kumamoto Japan
| | - Yasuharu Nakama
- Department of Cardiology, Hiroshima City Hiroshima Citizens Hospital Hiroshima Japan
| | - Takashi Morita
- Department of Cardiology, Osaka General Medical Center Osaka Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School Tokyo Japan
| | - Yoshihiko Saito
- Department of Cardiovascular Medicine, Nara Medical University Kashihara Japan
| | - Atsushi Hirohata
- Department of Cardiovascular Medicine, The Sakakibara Heart Institute of Okayama Okayama Japan
| | - Yasuhiro Morita
- Department of Cardiology, Ogaki Municipal Hospital Ogaki Japan
| | - Teruo Inoue
- Department of Cardiovascular Medicine, Dokkyo Medical University Tochigi Japan
| | - Atsunori Okamura
- Department of Cardiology, Sakurabashi Watanabe Hospital Osaka Japan
| | - Toshiaki Mano
- Cardiovascular Center, Kansai Rosai Hospital Amagasaki Japan
| | - Yoshihiro Miyamoto
- Department of Preventive Cardiology, National Cerebral and Cardiovascular Center Suita Japan
| | - Hisao Ogawa
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center Suita Japan
| | - Masaharu Ishihara
- Division of Cardiovascular and Renal Medicine, Hyogo College of Medicine Nishinomiya Japan
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Synchronized mechanical oscillations at the cell-matrix interface in the formation of tensile tissue. Proc Natl Acad Sci U S A 2018; 115:E9288-E9297. [PMID: 30237286 DOI: 10.1073/pnas.1801759115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The formation of uniaxial fibrous tissues with defined viscoelastic properties implies the existence of an orchestrated mechanical interaction between the cytoskeleton and the extracellular matrix. This study addresses the nature of this interaction. The hypothesis is that this mechanical interplay underpins the mechanical development of the tissue. In embryonic tendon tissue, an early event in the development of a mechanically robust tissue is the interaction of the pointed tips of extracellular collagen fibrils with the fibroblast plasma membrane to form stable interface structures (fibripositors). Here, we used a fibroblast-generated tissue that is structurally and mechanically matched to embryonic tendon to demonstrate homeostasis of cell-derived and external strain-derived tension over repeated cycles of strain and relaxation. A cell-derived oscillatory tension component is evident in this matrix construct. This oscillatory tension involves synchronization of individual cell forces across the construct and is induced in each strain cycle by transient relaxation and transient tensioning of the tissue. The cell-derived tension along with the oscillatory component is absent in the presence of blebbistatin, which disrupts actinomyosin force generation of the cell. The time period of this oscillation (60-90 s) is well-defined in each tissue sample and matches a primary viscoelastic relaxation time. We hypothesize that this mechanical oscillation of fibroblasts with plasma membrane anchored collagen fibrils is a key factor in mechanical sensing and feedback regulation in the formation of tensile tissues.
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Javidanpour S, Dianat M, Badavi M, Mard SA. The inhibitory effect of rosmarinic acid on overexpression of NCX1 and stretch- induced arrhythmias after acute myocardial infarction in rats. Biomed Pharmacother 2018; 102:884-893. [PMID: 29710544 DOI: 10.1016/j.biopha.2018.03.103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/10/2018] [Accepted: 03/17/2018] [Indexed: 11/19/2022] Open
Abstract
The incidence of arrhythmias is the main cause of high mortality after myocardial infarction (AMI). The aim of the present study was to determine whether the rosmarinic acid (RA) could reduce the stretch-induced arrhythmias (SIAs) related to overexpression of NCX1 after AMI. Adult male Sprague-Dawley rats were randomly allocated into six groups: Sham, MI (100 mg/kg of isoproterenol (Iso), subcutaneously, on two consecutive days), RA (30 mg/kg, orally, 14 days), and RA (10, 15 and 30 mg/kg, 14 days) + I. MI induction was performed on the 13th and 14th days of the study period. Forty-eight hours after the first injection of Iso, the parameters of hypertrophy, plasma levels of malondialdehyde (MDA) and lipid profile were evaluated. Using Langendorff apparatus, the isolated hearts were transiently stretched for 5 s with three different end-diastolic volumes (ΔV1to3 = 0.05, 0.1 and 0.2 mL). Cardiac function parameters were measured for 30 s, and ventricular arrhythmias were recorded for 3 min after each stretch. Finally, the levels of cardiac troponin-I and NCX1 mRNA expression were examined. The rats of MI group showed a significant increase in hypertrophy index, MDA, triglyceride and cholesterol (P < 0.001). Additionally, a marked impairment in cardiac parameters, an increase in the rates of SIAs and NCX1 expression, and a decrease in troponin-I (P < 0.001) were observed. RA at three doses especially 15 mg/kg strongly improved almost all the mentioned factors (P < 0.001). Our results confirm that RA pretreatment could prevent hypertrophia, arrhythmia and cardiac dysfunction following AMI which is associated with inhibition of lipid peroxidation and overexpression of NCX1.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/blood
- Arrhythmias, Cardiac/complications
- Arrhythmias, Cardiac/drug therapy
- Arrhythmias, Cardiac/physiopathology
- Blood Pressure/drug effects
- Cardiomegaly/blood
- Cardiomegaly/complications
- Cardiomegaly/drug therapy
- Cardiomegaly/physiopathology
- Cholesterol, HDL/blood
- Cholesterol, LDL/blood
- Cinnamates/pharmacology
- Cinnamates/therapeutic use
- Depsides/pharmacology
- Depsides/therapeutic use
- Diastole/drug effects
- Electrocardiography
- Gene Expression Regulation/drug effects
- Heart Ventricles/drug effects
- Heart Ventricles/pathology
- Heart Ventricles/physiopathology
- Male
- Malondialdehyde/blood
- Myocardial Infarction/blood
- Myocardial Infarction/complications
- Myocardial Infarction/drug therapy
- Myocardial Infarction/physiopathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Sprague-Dawley
- Sodium-Calcium Exchanger/genetics
- Sodium-Calcium Exchanger/metabolism
- Stress, Mechanical
- Tachycardia/blood
- Tachycardia/complications
- Tachycardia/drug therapy
- Tachycardia/physiopathology
- Triglycerides/blood
- Troponin I/metabolism
- Ventricular Premature Complexes/blood
- Ventricular Premature Complexes/complications
- Ventricular Premature Complexes/physiopathology
- Rosmarinic Acid
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Affiliation(s)
- Somayeh Javidanpour
- Department of Physiology, Physiology Research Center, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mahin Dianat
- Department of Physiology, Physiology Research Center, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
| | - Mohammad Badavi
- Department of Physiology, Physiology Research Center, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Seyyed Ali Mard
- Department of Physiology, Physiology Research Center, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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Cao JX, Fu L, Gao QP, Xie RS, Qu F. Streptomycin inhibits electrophysiological changes induced by stretching of chronically infarcted rat hearts. J Zhejiang Univ Sci B 2014; 15:515-21. [PMID: 24903988 DOI: 10.1631/jzus.b1300297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE To investigate stretch-induced electrophysiological changes in chronically infarcted hearts and the effect of streptomycin (SM) on these changes in vivo. METHODS Sixty Wistar rats were divided randomly into four groups: a control group (n=15), an SM group (n=15), a myocardial infarction (MI) group (n=15), and an MI+SM group (n=15). Chronic MI was obtained by ligating the left anterior descending branch (LAD) of rat hearts for eight weeks. The in vivo blockade of stretch-activated ion channels (SACs) was achieved by intramuscular injection of SM (180 mg/(kg∙d)) for seven days after operation. The hearts were stretched for 5 s by occlusion of the aortic arch. Suction electrodes were placed on the anterior wall of left ventricle to record the monophasic action potential (MAP). The effect of stretching was examined by assessing the 90% monophasic action potential duration (MAPD90), premature ventricular beats (PVBs), and ventricular tachycardia (VT). RESULTS The MAPD90 decreased during stretching in both the control (from (50.27±5.61) ms to (46.27±4.51) ms, P<0.05) and MI groups (from (65.47±6.38) ms to (57.47±5.76 ms), P<0.01). SM inhibited the decrease in MAPD90 during inflation ((46.27±4.51) ms vs. (49.53±3.52) ms, P<0.05 in normal hearts; (57.47±5.76) ms vs. (61.87±5.33) ms, P<0.05 in MI hearts). The occurrence of PVBs and VT in the MI group increased compared with that in the control group (PVB: 7.93±1.66 vs. 1.80±0.86, P<0.01; VT: 7 vs. 1, P<0.05). SM decreased the occurrence of PVBs in both normal and MI hearts (0.93±0.59 vs. 1.80±0.86 in normal hearts, P<0.05; 5.40±1.18 vs. 7.93±1.66 in MI hearts, P<0.01). CONCLUSIONS Stretch-induced MAPD90 changes and arrhythmias were observed in chronically infarcted myocardium. The use of SM in vivo decreased the incidence of PVBs but not of VT. This suggests that SACs may be involved in mechanoelectric feedback (MEF), but that there might be other mechanisms involved in causing VT in chronic MI.
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Affiliation(s)
- Jun-xian Cao
- Department of Cardiology, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, China; Department of Chinese Medicine, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, China
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The importance of non-uniformities in mechano-electric coupling for ventricular arrhythmias. J Interv Card Electrophysiol 2013; 39:25-35. [DOI: 10.1007/s10840-013-9852-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 10/16/2013] [Indexed: 12/31/2022]
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The Lambeth Conventions (II): Guidelines for the study of animal and human ventricular and supraventricular arrhythmias. Pharmacol Ther 2013; 139:213-48. [DOI: 10.1016/j.pharmthera.2013.04.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 12/17/2022]
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The effects of κ-opioid receptor on stretch-induced electrophysiological changes in infarcted rat hearts. Am J Med Sci 2013; 345:129-35. [PMID: 22735633 DOI: 10.1097/maj.0b013e31824ceba7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Kappa-opioid receptors (κ-OR) and mechanoelectric feedback seem to have common pathways that influence electrophysiological changes resulting from acute myocardial infarction (MI). This study aims to determine the effects of the κ-OR on stretch-induced electrophysiological changes after acute MI. METHODS Male Sprague-Dawley rats were randomly divided into 4 groups: sham operated, MI, U-50488H (a selective κ-OR agonist) -treated MI (MI+U-50488H) and nor-BNI (a selective κ-OR antagonist) -treated MI (MI+nor-BNI). After Langendorff perfusion to maintain stabilization, a transient stretch (5 seconds) was delivered early in diastole. Electrophysiological changes were recorded for 1 minute before and after stretch. Similarly, the 20%, 50% and 90% monophasic action potential duration (MAPD20, MAPD50 and MAPD90, respectively) and stretch-induced arrhythmias were recorded. RESULTS MAPD90 significantly increased in all 4 groups. MAPD90 in the MI and MI+nor-BNI groups increased significantly before stretch (P < 0.05) and after stretch (P < 0.01) but was reversed in the MI+U-50488H group (P > 0.05). MAPD90 in the MI group was increased compared with that of the MI+U-50488H group but decreased compared with that of the MI+ nor-BNI group after stretch (P < 0.01). The arrhythmia score in the MI and MI+nor-BNI groups was higher than that of the sham-operated group (P < 0.01), and the arrhythmia score in the MI+nor-BNI group was higher than that in MI group after stretch (P < 0.01). The arrhythmia score of the MI+U-50488H group was lower than that of MI group after stretch (P < 0.01). CONCLUSIONS The κ-OR could influence the stretch-induced electrophysiological changes and play an antiarrhythmic role in stretch-induced arrhythmias after acute MI.
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Increased mechanically-induced ectopy in the hypertrophied heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:331-9. [DOI: 10.1016/j.pbiomolbio.2012.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 07/11/2012] [Indexed: 02/04/2023]
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Wall ST, Guccione JM, Ratcliffe MB, Sundnes JS. Electromechanical feedback with reduced cellular connectivity alters electrical activity in an infarct injured left ventricle: a finite element model study. Am J Physiol Heart Circ Physiol 2011; 302:H206-14. [PMID: 22058157 DOI: 10.1152/ajpheart.00272.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Myocardial infarction (MI) significantly alters the structure and function of the heart. As abnormal strain may drive heart failure and the generation of arrhythmias, we used computational methods to simulate a left ventricle with an MI over the course of a heartbeat to investigate strains and their potential implications to electrophysiology. We created a fully coupled finite element model of myocardial electromechanics consisting of a cellular physiological model, a bidomain electrical diffusion solver, and a nonlinear mechanics solver. A geometric mesh built from magnetic resonance imaging (MRI) measurements of an ovine left ventricle suffering from a surgically induced anteroapical infarct was used in the model, cycled through the cardiac loop of inflation, isovolumic contraction, ejection, and isovolumic relaxation. Stretch-activated currents were added as a mechanism of mechanoelectric feedback. Elevated fiber and cross fiber strains were observed in the area immediately adjacent to the aneurysm throughout the cardiac cycle, with a more dramatic increase in cross fiber strain than fiber strain. Stretch-activated channels decreased action potential (AP) dispersion in the remote myocardium while increasing it in the border zone. Decreases in electrical connectivity dramatically increased the changes in AP dispersion. The role of cross fiber strain in MI-injured hearts should be investigated more closely, since results indicate that these are more highly elevated than fiber strain in the border of the infarct. Decreases in connectivity may play an important role in the development of altered electrophysiology in the high-stretch regions of the heart.
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Affiliation(s)
- Samuel T Wall
- Center for Biomedical Computing, Simula Research Laboratory, Oslo, Norway.
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Pong T, Adams WJ, Bray MA, Feinberg AW, Sheehy SP, Werdich AA, Parker KK. Hierarchical architecture influences calcium dynamics in engineered cardiac muscle. Exp Biol Med (Maywood) 2011; 236:366-73. [PMID: 21330361 DOI: 10.1258/ebm.2010.010239] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Changes in myocyte cell shape and tissue structure are concurrent with changes in electromechanical function in both the developing and diseased heart. While the anisotropic architecture of cardiac tissue is known to influence the propagation of the action potential, the influence of tissue architecture and its potential role in regulating excitation-contraction coupling (ECC) are less well defined. We hypothesized that changes in the shape and the orientation of cardiac myocytes induced by spatial arrangement of the extracellular matrix (ECM) affects ECC. To test this hypothesis, we isolated and cultured neonatal rat ventricular cardiac myocytes on various micropatterns of fibronectin where they self-organized into tissues with varying degrees of anisotropy. We then measured the morphological features of these engineered myocardial tissues across several hierarchical dimensions by measuring cellular aspect ratio, myocyte area, nuclear density and the degree of cytoskeletal F-actin alignment. We found that when compared with isotropic tissues, anisotropic tissues have increased cellular aspect ratios, increased nuclear densities, decreased myocyte cell areas and smaller variances in actin alignment. To understand how tissue architecture influences cardiac function, we studied the role of anisotropy on intracellular calcium ([Ca(2+)](i)) dynamics by characterizing the [Ca(2+)](i)-frequency relationship of electrically paced tissues. When compared with isotropic tissues, anisotropic tissues displayed significant differences in [Ca(2+)](i) transients, decreased diastolic baseline [Ca(2+)](i) levels and greater [Ca(2+)](i) influx per cardiac cycle. These results suggest that ECM cues influence tissue structure at cellular and subcellular levels and regulate ECC.
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Affiliation(s)
- Terrence Pong
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Cao J, Fu L, Sun D, Xie R, Zhou J, Qu F. Taxol inhibits stretch-induced electrophysiological alterations in isolated rat hearts with acute myocardial infarction. SCIENCE CHINA-LIFE SCIENCES 2010; 53:1009-14. [DOI: 10.1007/s11427-010-4039-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Accepted: 04/08/2010] [Indexed: 10/19/2022]
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Jie X, Gurev V, Trayanova N. Mechanisms of mechanically induced spontaneous arrhythmias in acute regional ischemia. Circ Res 2009; 106:185-92. [PMID: 19893011 DOI: 10.1161/circresaha.109.210864] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
RATIONALE Although ventricular premature beats (VPBs) during acute regional ischemia have been linked to mechanical stretch of ischemic tissue, whether and how ischemia-induced mechanical dysfunction can induce VPBs and facilitate their degradation into reentrant arrhythmias has not been yet addressed. OBJECTIVE This study used a novel multiscale electromechanical model of the rabbit ventricles to investigate the origin of and the substrate for spontaneous arrhythmias arising from ischemia-induced electrophysiological and mechanical changes. METHODS AND RESULTS Two stages of ischemia were simulated. Dynamic mechanoelectrical feedback was modeled as spatially and temporally nonuniform membrane currents through mechanosensitive channels, the conductances of which depended on local strain rate. Our results reveal that both strains and strain rates were significantly larger in the central ischemic zone than in the border zone. However, in both ischemia stages, a VPB originated from the ischemic border in the left ventricular apical endocardium because of mechanically induced suprathreshold depolarizations. It then traveled fully intramurally until emerging from the ischemic border on the anterior epicardium. Reentry was formed only in the advanced ischemia stage as the result of a widened temporal excitable gap. Mechanically induced delayed afterdepolarization-like events contributed to the formation of reentry by further decreasing the already reduced-by-hyperkalemia local excitability, causing extended conduction block lines and slowed conduction in the ischemic region. CONCLUSIONS Mechanically induced membrane depolarizations in the ischemic region are the mechanism by which mechanical activity contributes to both the origin of and substrate for spontaneous arrhythmias under the conditions of acute regional ischemia.
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Affiliation(s)
- Xiao Jie
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21218, USA
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