scholarly journals A possible role for atrial fibroblasts in postinfarction bradycardia

2002 ◽  
Vol 282 (3) ◽  
pp. H842-H849 ◽  
Author(s):  
Andre Kamkin ◽  
Irina Kiseleva ◽  
Kay-Dietrich Wagner ◽  
Alexander Pylaev ◽  
Kate P. Leiterer ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Membrane Potential ◽  
Contractile Activity ◽  
Cardiac Fibroblasts ◽  
Mechanical Stretch ◽  
Right Atrial ◽  
Resting Membrane Potential ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
The Right

Atrial fibroblasts are considered to modulate the contractile activity of the heart in response to mechanical stretch. In this study we examined whether atrial fibroblasts are possibly involved in bradyarrhythmia, which is a severe complication after myocardial infarction. For this purpose, transmembrane electrical potentials were recorded in cardiac fibroblasts near the sinoatrial node from sham-operated rats and from rats with myocardial infarction. Twenty days after infarction due to coronary artery ligation, the right atrial tissue weights and the sensitivity of the fibroblast membrane potential to mechanical stretch correlated positively with the infarct size. Cardiac growth was enhanced, but the stretch sensitivity and the resting membrane potential of the atrial fibroblasts declined between 8 and 30 days after infarction. The frequency of spontaneous atrial contractions was significantly reduced 8 days after myocardial infarction and recovered in parallel with the membrane potential of the fibroblasts. These findings suggest that changes in the susceptibility of atrial fibroblasts to mechanical stretch may contribute to bradyarrhythmia during postinfarct remodeling of the heart.

Abstract 430: Immature Cardiac Fibroblasts With Upregulated P53 Contributed to Fibrosis in Ikke Deficient Mouse Myocardial Infarction Model

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Yong Sook Kim ◽  
Hyang Hee Cho ◽  
Ju Hee Jun ◽  
Dong Im Cho ◽  
Meeyoung Cho ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Inflammatory Responses ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Healing Process ◽  
Wound Healing Process ◽  
Coronary Artery Ligation ◽  
Artery Ligation

Background: Inhibitor of NF-κB kinase (IKK), an upstream of nuclear factor-kappa B (NF-κB), is a critical modulator for pathophysiological inflammation. IKKε is a non-classical IKK and has been studied in infectious diseases and cancers. However, the role of IKKε in a myocardial infarction (MI) has not been addressed. Methods and Results: In this study, we used IKKε knockout (KO) mice to induce MI by coronary artery ligation. The IKKε KO group showed poor early survival rate, large cardiac fibrosis (14.7±4.8% in KO vs. 31.1±10.2% in WT, p <0.05), and low fractional shortening (13.47±1.21% in KO vs. 16.36±4.46% in WT, p <0.05) compared with WT group. Next, we investigated the inflammatory responses and found that inflammatory markers such as inducible nitric oxide synthase (iNOS) and CD80 were much higher in both cardiac macrophages and bone marrow-derived macrophages (BMDM) in the IKKε KO group than in the wild type (WT) group. To explore the responsible mediator, we performed phosphorylated protein array and found phosphorylated p38 was significantly downregulated in the IKKε knockout BMDM. Conversely, both knockdown of p38 by siRNA and inhibition of p38 by SB203580 treatment in RAW264.7 cells upregulated iNOS. More interestingly, IKKε deficient cardiac fibroblasts showed highly accumulated nuclear p53 and exhibited immature differentiation. The levels of myofibroblast markers containing α-smooth muscle actin, periostin, and transforming growth factor-β1 were lower, and functional contractility was substantially impaired in the cardiac fibroblasts isolated from IKKε KO mice. Conclusion: Our data showed excessive inflammation was associated with p38 inactivation in macrophages and pathological fibrosis was resulted from immature myofibroblast phenotype with p53 upregulation. Collectively, IKKε is involved in the control of inflammation resolution and wound healing process in the infarcted myocardium.

Autologous Cardiomyocyte Transplantation in an Ovine Myocardial Infarction Model

2002 ◽  
Vol 25 (1) ◽  
pp. 61-66 ◽  
Author(s):  
W.G. Kim ◽  
J.J. Park ◽  
D.H. Chung ◽  
C.Y. Na
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Culture Medium ◽  
Microscopic Analysis ◽  
Control Site ◽  
Coronary Artery Ligation ◽  
Ovine Model ◽  
Artery Ligation ◽  
Diagonal Branch ◽  
The Right

Background To evaluate the possibility of autologous cardiomyocyte transplantation, we transplanted cultured autologous cells into an infarct region developed by coronary artery ligation in an ovine model. Materials and Methods A chronic heart failure model with a considerable portion of myocardial infarction was created in sheep using sequential ligation of the homonymous artery and its diagonal branch. Autologous cardiomyocytes were cultured and isolated from the right ventricular infundibulum. After a predetermined interval (one animal for two months and the other for three months), the two animals were reanesthetized and a suspension of cultured autologous vetricular cells in 0.3 ml of culture medium (1.2 × 107 cells) was injected into the center of three out of the four sites in the infarcted area using a tuberculin syringe. The same amount of culture medium was injected with an identical procedure into the center of the remaining site, as control. The animals were kept alive for a further month, and then sacrificed for postmortem heart examinations. Light microscopic analysis and immunohistochemical study for myoglobin were done. Results and Conclusions On postmortem gross examination, well-demarcated thin-walled anteroseptal infarcts with chamber enlargement were clearly seen in specimens from the two animals. Microscopic analysis showed homogenous fibrosis throughout the infarcted areas. In both animals, one of the three sites of cardiomycyte injection showed an islet of cardiomyocytes in the mid-myocardium, while none were observed in the control site of either animal. A layer of cardiomyocytes was observed in subendocardial regions, as it was in the control areas. In conclusion, cardiomyocyte transplantation into the infarct regions developed by coronary artery ligation in an ovine model was achieved with only limited success. An understanding of why only 33% of cardiomyocyte-injection sites demonstrated viable cardiomyocytes, in the form of tiny cell islets, remains to be elucidated.

Abstract 116: Myelopoiesis Following Myocardial Ischemia (MI) Involves Activation of the Nlrp3 Inflammasome by Neutrophil-derived S100a8/a9

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Prabhakara R Nagareddy ◽  
Rahul Annabathula ◽  
Saojing Ye ◽  
Yuri Klyachkin ◽  
Ahmed Abdel-Latif ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Ventricular Remodeling ◽  
Cardiac Fibroblasts ◽  
Myocardial Damage ◽  
Heart Cell ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Hematopoietic Stem ◽  
Coronary Syndrome ◽  
Molecular Events

Ischemic myocardial damage triggers leukocytosis particularly the production of monocytes and neutrophils from the bone marrow and spleen (myelopoiesis). These cells infiltrate the evolving myocardial wound, degrade extracellular matrix and aid in the clearance of dead cardiac myocytes and their debris. Although this inflammatory process is a prerequisite for tissue healing, it is non-specific and often blunt. If unchecked, excessive production of monocytes and neutrophils may result in abnormal ventricular remodeling and heart failure. The myocardial cellular and molecular events that orchestrate with the BM/spleen to regulate myelopoiesis remain unclear. We report here that the number of circulating monocytes and neutrophils peak within 24 hours following coronary artery ligation (LAD) in mice. This is due to expansion and proliferation of hematopoietic stem and multi-potential progenitor cells (HSPC) in the BM as well as extra medullary hematopoiesis in the spleen. MI induced -myelopoiesis was associated with a dramatic increase in the expression of S100a8/a9 (a damage associated molecular pattern), its receptor (Tlr4), the Nlrp3 inflammasome and pro-IL1β in the heart. Cell separation studies revealed that the infiltrating neutrophils and cardiac fibroblasts are the predominant source of S100a8/a9 and the Nlrp3 inflammasome respectively in the heart. Further, deletion of s100a8/a9 not only reduced MI -induced myelopoiesis but also significantly improved the mortality and cardiac function in mice following LAD. These data supports our hypothesis that neutrophil-derived S100a8/a9 interact with Tlr4 on cardiac fibroblasts to induce the Nlrp3 inflammasome and produce IL1β, which in turn stimulates IL-1R on HSPCs to promote myelopoiesis. Pharmacological strategies aimed at inhibition of S100a8a/9 or the Nlrp3 inflammasome-mediated production of IL1β may be a promising approach to limit inflammation following acute coronary syndrome.

Cardiac adaptations to endurance training in rats with a chronic myocardial infarction

1989 ◽  
Vol 66 (2) ◽  
pp. 712-719 ◽  
Author(s):  
T. I. Musch ◽  
R. L. Moore ◽  
P. G. Smaldone ◽  
M. Riedy ◽  
R. Zelis
Keyword(s):  
Myocardial Infarction ◽  
Endurance Training ◽  
Left Ventricular ◽  
Treadmill Running ◽  
Coronary Artery Ligation ◽  
Maximal Heart Rate ◽  
Chronic Myocardial Infarction ◽  
Artery Ligation ◽  
Training Paradigm ◽  
Myosin Isozyme

The hemodynamic response to maximal exercise was determined in sedentary and trained rats with a chronic myocardial infarction (MI) produced by coronary artery ligation and in rats that underwent sham operations (SHAM). Infarct size in the MI groups of rats comprised 28–29% of the total left ventricle and resulted in both metabolic and hemodynamic changes that suggested that these animals had moderate compensated heart failure. The training regimen used in the present study produced significant increases in maximal O2 uptake (VO2max) when expressed in absolute terms (ml/min) or when normalized for body weight (ml.min-1.kg-1) and consisted of treadmill running at work loads that were equivalent to 70–80% of the animal's VO2max for a period of 60 min/day, 5 days/wk over an 8- to 10-wk interval. This training paradigm produced two major cardiocirculatory adaptations in the MI rat that had not been elicited previously when using a training paradigm of a lower intensity. First, the decrement in the maximal heart rate response to exercise (known as “chronotropic incompetence”) found in the sedentary MI rat was completely reversed by endurance training. Second, the downregulation of cardiac myosin isozyme composition from the fast ATPase V1 isoform toward the slower ATPase (V2 and V3) isoforms in the MI rat was partially reversed by endurance training. These cardiac adaptations occurred without a significant increase in left ventricular pump function as an increase in maximal cardiac output (Qmax) and maximal stroke volume (SVmax) did not occur in the trained MI rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Myocardial Infarction with Sequential Ligation of the Left Anterior Descending Artery and Its Diagonal Branch in Dogs and Sheep

2003 ◽  
Vol 26 (4) ◽  
pp. 351-357 ◽  
Author(s):  
W.G. Kim ◽  
Y.C. Shin ◽  
S.W. Hwang ◽  
C. Lee ◽  
C.Y. Na
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Pulmonary Artery ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Suitable Model ◽  
Artery Ligation ◽  
Diagonal Branch ◽  
Left Anterior Descending Artery ◽  
Arterial Blood

We report a comparison of the effects of myocardial infarction in dogs and sheep using sequential ligation of the left anterior descending artery (LAD) and its diagonal branch (DA), with hemodynamic, ultrasonographic and pathological evaluations. Five animals were used in each group. After surgical preparation, the LAD was ligated at a point approximately 40% of the distance from the apex to the base of the heart, and after one hour, the DA was ligated at the same level. Hemodynamic and ultrasonographic measurements were performed preligation, 30 minutes after LAD ligation, and 1 hour after DA ligation. As a control, two animals in each group were used for the simultaneous ligation of the LAD and the DA. Two months after the coronary ligation, the animals were evaluated as previously, and killed for postmortem examination of their hearts. All seven animals in the dog group survived the experimental procedures, while in the sheep group only animals with sequential ligation of the LAD and DA survived. Statistically significant decreases in systemic arterial blood pressure and cardiac output, and an increase in the pulmonary artery capillary wedge pressure (PACWP) were observed one hour after sequential ligation of the LAD and its DA in the sheep, while only systemic arterial pressures decreased in the dog. Ultrasonographic analyses demonstrated variable degrees of anteroseptal dyskinesia and akinesia in all sheep, but in no dogs. Data two months after coronary artery ligation showed significant increases in central venous pressure, pulmonary artery pressure, and PACWP in the sheep, but not in the dog. Left ventricular end-diastolic dimension and left ventricular end-systolic dimension in ultrasonographic studies were also increased only in the sheep. Pathologically, the well-demarcated thin-walled transmural anteroseptal infarcts with chamber enlargement were clearly seen in all specimens of sheep, and only-mild-to-moderate chamber enlargements with endocardial fibrosis were observed in the dog hearts. In conclusion, this study confirms that the dog is not a suitable model for myocardial infarction with failure by coronary artery ligation despite negligent operative mortality, when compared directly with an ovine model.

Regulation of K+ and Ca2+ channels in experimental cardiac failure

1991 ◽  
Vol 261 (6) ◽  
pp. H1979-H1987 ◽  
Author(s):  
M. Gopalakrishnan ◽  
D. J. Triggle ◽  
A. Rutledge ◽  
Y. W. Kwon ◽  
J. A. Bauer ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Right Ventricle ◽  
Cardiac Failure ◽  
Radioligand Binding ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
The Right

To examine the status of ATP-sensitive K+ (K+ATP) channels and 1,4-dihydropyridine-sensitive Ca2+ (Ca2+DHP) channels during experimental cardiac failure, we have measured the radioligand binding properties of [3H]glyburide and [3H]PN 200 110, respectively, in tissue homogenates from the rat cardiac left ventricle, right ventricle, and brain 4 wk after myocardial infarction induced by left coronary artery ligation. The maximal values (Bmax) for [3H]glyburide and [3H]PN 200 110 binding were reduced by 39 and 40%, respectively, in the left ventricle, and these reductions showed a good correlation with the right ventricle-to-body weight ratio in heart-failure rats. The ligand binding affinities were not altered. In the hypertrophied right ventricle, Bmax values for both the ligands were not significantly different when data were normalized to DNA content or right ventricle weights but showed an apparent reduction when normalized to unit protein or tissue weight. Moderate reductions in channel densities were observed also in whole brain homogenates from heart failure rats. Assessment of muscarinic receptors, beta-adrenoceptors and alpha 1-adrenoceptors by [3H]quinuclidinyl benzilate, [3H]dihydroalprenolol, and [3H]prazosin showed reductions in left ventricular muscarinic and beta-adrenoceptor densities but not in alpha 1-adrenoceptor densities, consistent with earlier observations. It is suggested that these changes may in part contribute to the pathology of cardiac failure.

Abstract 12648: Deletion of 12/15 Lipoxygenase Improves Left Ventricle Function and Survival by Resolving Inflammation Post Myocardial Infarction

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Vasundhara Kain ◽  
Kevin A Ingle ◽  
Janusz Kabarowski ◽  
Sumanth D Prabhu ◽  
Ganesh V Halade
Keyword(s):  
Myocardial Infarction ◽  
Left Ventricle ◽  
Survival Rates ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Lv Remodeling ◽  
Early Expression ◽  
Cox 2

12/15 lipoxygenase (LOX) is crucial in the inflammatory process leading to diabetes and atherosclerosis. However, the role of 12/15 LOX in myocardial infarction (MI) and left ventricle (LV) remodeling is unclear. We assessed the role of 12/15 LOX in resolving inflammation in post-MI LV remodeling. 8-12 weeks old C57BL/6J wild-type (WT; n=67) and 12/15 LOX (LOX –/– ; n=78) male mice were subjected to permanent coronary artery ligation surgery and monitored through day (d)1 and d5. No MI surgery mice were maintained as d0 naïve controls. LOX -/- mice showed higher survival rate, improved fractional shortening with reduced remodeling and edema index than WT at d1 and d5 post-MI (all p<0.05). LOX -/- mice showed increased Cxcl5 expression at d1 post-MI, consistent with stimulated neutrophil recruitment in the infarct region that was decreased at d5 compared to WT. LOX -/- mice infarct had increased expression of Ccl2 and Cxcl1, that stimulated an earlier recruitment of monocytes with increased macrophages population at d5 (all p<0.05) compared to WT. The altered kinetics of immune cells post-MI indicates a rapid resolving phase, through increase in alternative macrophage phenotypes with reduced collagen density in LOX -/- mice compared to WT mice at d5 post-MI. LOX -/- mice showed a coordinated COX-1 and COX-2 response at d1 post MI, leading to an evident increase in 5-LOX and hemoxygenase-1 (HO-1) at d5 post-MI. 12/15 LOX deletion enhanced the recruitment of alternative macrophages with secretion of HO-1 to resolve inflammation. In-vitro addition of LOX metabolite 12 hydroxyeicosatetraenoic acid to LOX -/- fibroblast induced early expression of COX-2 and 5-LOX compared to WT, indicating 5LOX role in resolution of inflammation. Post-MI increased expression of TIMP-1 and decrease in MMP-9 at d1 and α-SMA at d5 in LOX -/- mice suggested controlled differentiation of fibroblast-to-myofibroblast which is key event during ventricular tissue repair and resolving phase. This change is supported by increased expression of tgf-βi, ctgf and admats-2 (all P<0.05) at d5 post MI. In conclusion, absence of 12/15 LOX improves post-MI survival rates and attenuates LV dysfunction by resolving inflammation through coordination of 5-LOX and HO-1 as key inflammation resolving enzymes.

Abstract 363: In Situ Cardiac Cellular Reprogramming Using Adenoviral Vectors: Implication for Clinical Myocardial Regeneration

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Megumi Mathison ◽  
Vivek P Singh ◽  
Maria J Chiuchiolo ◽  
Deepthi Sanagasetti ◽  
Yun Mao ◽  
...  
Keyword(s):  
Cardiac Fibroblasts ◽  
Lentiviral Vectors ◽  
Adenoviral Vectors ◽  
Cellular Reprogramming ◽  
Expression Vectors ◽  
Coronary Artery Ligation ◽  
Sprague Dawley ◽  
Artery Ligation ◽  
Lentivirus Vectors

Objective: The reprogramming of cardiac fibroblasts into induced cardiomyocytes (iCMs) improves ventricular function in myocardial infarction models. Only integrating chronic expression vectors have thus far been used to administer reprogramming genes, potentially limiting clinical applicability. We hypothesized that reprogramming could be achieved using non-integrating, acute expression adenoviral vectors. Methods: Adenoviral (Ad) and lentiviral vectors encoding Gata4 (G), Mef2c (M) and Tbx5 (T) were validated in vitro . Sprague Dawley rats then underwent coronary artery ligation and Ad-mediated administration of vascular endothelial growth factor to provide infarct prevascularization. Three weeks later, Ad or lentivirus encoding G, M, or T or an equivalent dose of a null vector was administered. Outcomes were analyzed by serial echocardiography, and by terminal MRI and histology. Results: Ad and lentivirus vectors provided equivalent in vitro GMT expression by Western blotting and AdGMT induced expression of the cardiomyocyte marker cTnT in approximately 7% of cardiac fibroblasts, compared to 4% of cells infected with LentiGMT. Sections of infarcted myocardium from rats that had been treated with AdGMT or LentiGMT demonstrated higher density of cells expressing the cardiomyocyte marker MHY7 compared to AdNull treated animals (p<0.05). Echocardiography demonstrated that AdGMT significantly increased ejection fraction compared to AdNull (AdGMT: 21% ± 3%, LentiGMT: 14% ± 5%, AdNull: -0.4% ± 2%; p<0.05). Conclusions: Adenoviral vectors are at least as effective as lentiviral vectors in inducing cardiac fibroblast transdifferentiation into iCMs and improving cardiac function in post-infarct rat hearts. The utility of short-term expression Ad vectors represents an important potential tool in inducing cardiac cellular reprogramming clinically.

Abstract 48: Myelopoiesis Following Myocardial Ischemia (MI) Involves Activation of the Nlrp3 Inflammasome by Neutrophil-Derived S100a8/a9

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Prabhakara R Nagareddy ◽  
Rahul Annabathula ◽  
Shaojing Ye ◽  
Yuri M Klaychkin ◽  
Ahmed Abdel-Latif ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Ventricular Remodeling ◽  
Cardiac Fibroblasts ◽  
Myocardial Damage ◽  
Extramedullary Hematopoiesis ◽  
Heart Cell ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Hematopoietic Stem ◽  
Coronary Syndrome

Ischemic myocardial damage triggers leukocytosis, particularly the production of monocytes and neutrophils from the bone marrow and spleen (myelopoiesis). These cells infiltrate the evolving myocardial wound, degrade extracellular matrix, and aid in the clearance of dead cardiac myocytes and their debris. Although this inflammatory process is a prerequisite for tissue healing, it is non-specific and often blunt. If unchecked, excessive production of monocytes and neutrophils may result in abnormal ventricular remodeling and heart failure. The myocardial cellular and molecular events that orchestrate with the BM/spleen to regulate myelopoiesis remain unclear. We report here that the number of circulating monocytes and neutrophils peak within 24 hours following coronary artery ligation (LAD) in mice. This is due to expansion and proliferation of hematopoietic stem and multi-potential progenitor cells (HSPC) in the BM as well as extramedullary hematopoiesis in the spleen. MI induced-myelopoiesis was associated with a dramatic increase in the expression of S100a8/a9 (a damage associated molecular pattern), its receptor (Tlr4), the Nlrp3 inflammasome, and pro-IL1β in the heart. Cell separation studies revealed that the infiltrating neutrophils and cardiac fibroblasts are the predominant source of S100a8/a9 and the Nlrp3 inflammasome respectively in the heart. Furthermore, deletion of S100a8/a9 not only reduced MI-induced myelopoiesis but also significantly improved the mortality and cardiac function in mice following LAD. These data supports our hypothesis that neutrophil-derived S100a8/a9 interact with Tlr4 on cardiac fibroblasts to induce the Nlrp3 inflammasome and produce IL1β, which in turn stimulates IL-1R on HSPCs to promote myelopoiesis. Pharmacological strategies aimed at inhibition of S100a8a/9 or the Nlrp3 inflammasome-mediated production of IL1β may be a promising approach to limit inflammation following acute coronary syndrome.

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