scholarly journals Theoretical Aspects of Resting-State Cardiomyocyte Communication for Multi-Nodal Nano-Actuator Pacemakers

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2792
Author(s):  
Pengfei Lu ◽  
Mladen Veletić ◽  
Jacob Bergsland ◽  
Ilangko Balasingham
Keyword(s):  
Action Potential ◽  
Resting State ◽  
Communication Channel ◽  
Potential Model ◽  
Signal Propagation ◽  
Cardiac Cells ◽  
The Body ◽  
Cardiac Muscle Cells ◽  
Leadless Pacemaker ◽  
Communication Technique

The heart consists of billions of cardiac muscle cells—cardiomyocytes—that work in a coordinated fashion to supply oxygen and nutrients to the body. Inter-connected specialized cardiomyocytes form signaling channels through which the electrical signals are propagated throughout the heart, controlling the heart’s beat to beat function of the other cardiac cells. In this paper, we study to what extent it is possible to use ordinary cardiomyocytes as communication channels between components of a recently proposed multi-nodal leadless pacemaker, to transmit data encoded in subthreshold membrane potentials. We analyze signal propagation in the cardiac infrastructure considering noise in the communication channel by performing numerical simulations based on the Luo-Rudy computational model. The Luo-Rudy model is an action potential model but describes the potential changes with time including membrane potential and action potential stages, separated by the thresholding mechanism. Demonstrating system performance, we show that cardiomyocytes can be used to establish an artificial communication system where data are reliably transmitted between 10 s of cells. The proposed subthreshold cardiac communication lays the foundation for a new intra-cardiac communication technique.

Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

2001 ◽  
Vol 280 (2) ◽  
pp. H535-H545 ◽  
Author(s):  
Fagen Xie ◽  
Zhilin Qu ◽  
Alan Garfinkel ◽  
James N. Weiss
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Cardiac Tissue ◽  
Potential Model ◽  
Dynamic Instability ◽  
Spatial Scales ◽  
Cardiac Cells ◽  
Dynamic Factors ◽  
Cardiac Model ◽  
Wave Break

Generation of wave break is a characteristic feature of cardiac fibrillation. In this study, we investigated how dynamic factors and fixed electrophysiological heterogeneity interact to promote wave break in simulated two-dimensional cardiac tissue, by using the Luo-Rudy (LR1) ventricular action potential model. The degree of dynamic instability of the action potential model was controlled by varying the maximal amplitude of the slow inward Ca2+ current to produce spiral waves in homogeneous tissue that were either nearly stable, meandering, hypermeandering, or in breakup regimes. Fixed electrophysiological heterogeneity was modeled by randomly varying action potential duration over different spatial scales to create dispersion of refractoriness. We found that the degree of dispersion of refractoriness required to induce wave break decreased markedly as dynamic instability of the cardiac model increased. These findings suggest that reducing the dynamic instability of cardiac cells by interventions, such as decreasing the steepness of action potential duration restitution, may still have merit as an antifibrillatory strategy.

Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters

2021 ◽  
Author(s):  
Rose Ellen Dixon ◽  
Manuel F. Navedo ◽  
Marc D Binder ◽  
L. Fernando Santana
Keyword(s):  
Ion Channels ◽  
Action Potential ◽  
Transient Receptor Potential ◽  
Imaging Techniques ◽  
Ryanodine Receptors ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Cardiac Cells ◽  
Fine Tuning ◽  
Voltage Gated

Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Cav1.2 and Cav1.3 channels to obligatory dimeric assembly and gating of voltage-gated Nav1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP3Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.

scholarly journals Expression of a developmentally regulated antigen on the surface of skeletal and cardiac muscle cells.

1985 ◽  
Vol 100 (6) ◽  
pp. 1977-1987 ◽  
Author(s):  
S J Kaufman ◽  
R F Foster ◽  
K R Haye ◽  
L E Faiman
Keyword(s):  
Cell Surface ◽  
Cardiac Muscle ◽  
Surface Antigen ◽  
Cardiac Cells ◽  
Cell Surface Antigen ◽  
Myoblast Differentiation ◽  
Specific Cell ◽  
Developmentally Regulated ◽  
Cardiac Muscle Cells ◽  
Species Specific

H36 is a species-specific, cell-surface antigen on differentiating newborn rat skeletal myoblasts and myogenic lines. This membrane antigen has been defined by a monoclonal antibody raised by the fusion of SP 2/0-Ag14 myeloma cells with spleen cells from mice immunized with myotubes derived from the myogenic E63 line. H36 antigen, isolated by immunoaffinity chromatography, is comprised of two polypeptides with apparent molecular weights of 98,000 and 117,000. Fluorescence photometry and radioimmunoassays have been used to follow quantitative and topographic changes in the H36 determinant during myogenesis. H36 is present at a basal level on replicating myoblasts; it increases on prefusion myoblasts and persists on myotubes. At or near the time of prefusion, it becomes concentrated between adjacent aligned myoblasts and localized on membrane "blebs". H36 is present on both skeletal and cardiac cells but absent from a variety of cells that include fibroblasts, neuronal cells, and smooth muscle. There are approximately 4 x 10(5) determinants per myoblast, and the Ka of the antibody is 3.8 x 10(8) liters/mol. The distributions of H36 on the top and attached surfaces of myoblasts and myotubes are distinct, which suggests localized specialization of these surfaces. H36 is an integral membrane component and upon cross-linking, it associates with the detergent-insoluble cytoskeletal framework. Inhibition of myogenesis by 5-bromodeoxyuridine or by calcium deprivation prevents the developmentally associated changes in the expression of H36. H36 is also absent or markedly reduced on the fu- and Ama102 developmentally defective mutant myoblast lines. We conclude that H36 is a muscle-specific, developmentally regulated cell-surface antigen that may have a role in myoblast differentiation and that can be used to determine the embryonic lineages of skeletal and cardiac muscle.

scholarly journals HYPOTHESES TESTING ON THE VALIDITY OF EFFECTIVE COMMUNICATION AND COMMON MOTIF OF SELAYAH KERINGKAM

2021 ◽  
Vol 4 (1) ◽  
pp. 98-117
Author(s):  
Norsyahbany Mansor ◽  
Qistina Donna Lee Abdullah
Keyword(s):  
Communication Channel ◽  
Effective Communication ◽  
The Body ◽  
Hypotheses Testing ◽  
Independent Variables ◽  
Body Of Knowledge ◽  
Common Motif ◽  
Dependent Variables ◽  
Research Questions ◽  
New Framework

This paper is to deliberate the subjects of the effective communication channel in delivering common motifs in Selayah Keringkam by assessing the local and International tourists’ preference. It is to evaluate the hypotheses Testing On validity of Effective Communication and Common Motif of Selayah Keringkam Towards the communication channel. The finding of this paper is to enhance the implications on developing a significant way to disseminate Selayah Keringkam as a heritage product in Sarawak. This paper will expose a substantial relationship between the independent variables (Common Motif of Selayah Keringkam), the dependent variables (Channels of Communication) and the mediator (Supplement of Effective Communication) as a new framework to the body of knowledge. This research involved 384 respondents with 5 relevant authorities related to answering research questions. The data collected from the fieldwork were analysed using SPSS version 24. The measures used in this article are methodically deliberated using factor analysis and correlation analysis. Lastly, the results of the regression analyses testing on hypotheses and summary of hypotheses assessments are presented.

scholarly journals Myocardial Damage by SARS-CoV-2: Emerging Mechanisms and Therapies

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1880
Author(s):  
Huyen Tran Ho ◽  
Stefan Peischard ◽  
Nathalie Strutz-Seebohm ◽  
Karin Klingel ◽  
Guiscard Seebohm
Keyword(s):  
Immune Response ◽  
Cell Death ◽  
Energy Metabolism ◽  
Programmed Cell Death ◽  
Viral Replication ◽  
Ion Homeostasis ◽  
Membrane Vesicles ◽  
Cardiac Cells ◽  
The Body ◽  
Double Membrane

Evidence is emerging that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect various organs of the body, including cardiomyocytes and cardiac endothelial cells in the heart. This review focuses on the effects of SARS-CoV-2 in the heart after direct infection that can lead to myocarditis and an outline of potential treatment options. The main points are: (1) Viral entry: SARS-CoV-2 uses specific receptors and proteases for docking and priming in cardiac cells. Thus, different receptors or protease inhibitors might be effective in SARS-CoV-2-infected cardiac cells. (2) Viral replication: SARS-CoV-2 uses RNA-dependent RNA polymerase for replication. Drugs acting against ssRNA(+) viral replication for cardiac cells can be effective. (3) Autophagy and double-membrane vesicles: SARS-CoV-2 manipulates autophagy to inhibit viral clearance and promote SARS-CoV-2 replication by creating double-membrane vesicles as replication sites. (4) Immune response: Host immune response is manipulated to evade host cell attacks against SARS-CoV-2 and increased inflammation by dysregulating immune cells. Efficiency of immunosuppressive therapy must be elucidated. (5) Programmed cell death: SARS-CoV-2 inhibits programmed cell death in early stages and induces apoptosis, necroptosis, and pyroptosis in later stages. (6) Energy metabolism: SARS-CoV-2 infection leads to disturbed energy metabolism that in turn leads to a decrease in ATP production and ROS production. (7) Viroporins: SARS-CoV-2 creates viroporins that lead to an imbalance of ion homeostasis. This causes apoptosis, altered action potential, and arrhythmia.

Isolated Giant Smooth Muscle Fibres in Beroe Ovata: Ionic Dependence of Action Potentials Reveals Two Distinct Types of Fibre

1988 ◽  
Vol 135 (1) ◽  
pp. 343-362 ◽  
Author(s):  
ANDRÉ BILBAUT ◽  
ROBERT W. MEECH ◽  
MARI-LUZ HERNANDEZ-NICAISE
Keyword(s):  
Smooth Muscle ◽  
Action Potential ◽  
Action Potentials ◽  
Marine Invertebrate ◽  
The Body ◽  
Fibre Types ◽  
Resting Membrane Potential ◽  
Muscle Fibres ◽  
Beroe Ovata ◽  
Radial Muscle

1. The ionic dependence of action potentials evoked in giant smooth muscle fibres isolated by enzymatic digestion from the body wall of the marine invertebrate Beroe ovata (Ctenophora) has been investigated using conventional electrophysiological techniques. 2. Differences were observed in the two fibre types studied. The resting membrane potential was −60 ± 1.35 mV (N = 25) in longitudinal muscle fibres and −66 ±1.37 mV (N=32) in radial fibres. Action potentials had a short plateau in longitudinal fibres but not in radial fibres. 3. The action potential overshoot of both fibre types was decreased in Ca2+-free artificial sea water (ASW). In Na+-deficient ASW, action potentials could not be generated in radial fibres and showed a reduced overshoot in longitudinal fibres. 4. Tetrodotoxin (10−5moll−5) added to ASW or Ca2+-free ASW did not affect the action potentials of either type of fibre. 5. Action potentials of both fibres were partially blocked by Co2+ (20–50 mmoll−1) or Cd2+ (l-2mmoll−1). Action potentials of longitudinal fibres in Na+-deficient ASW were abolished by Co2+ (20mmoll−1). In Ca2+-free ASW, the ction potential overshoots of both sets of fibres were restored following the addition of Sr2+ or Ba2+. In longitudinal fibres, Sr2+ increased the duration of the action potential plateau. In both longitudinal and radial muscle fibres, Ba2+ prolonged the action potential. 6. In longitudinal fibres exposed to tetraethylammonium chloride (TEAC1) or 4-aminopyridine (4AP), the action potential was slightly prolonged. In these fibres, TEA+ or 4AP added to Ca2+-free ASW induced only a long-lasting depolarizing plateau. In radial fibres, the action potential duration was slightly increased in the presence of TEA+; it was unaffected by 4AP. In Ca2+-free ASW, TEA+ and 4AP induced an oscillating membrane response which appeared to be dependent on the intensity of the injected current pulse. 7. It is concluded that (a) there are significant differences between the action potentials of longitudinal and radial muscle fibres but that both are dependent on Na+ and Ca2+, (b) in longitudinal fibres, a Ca2+-activated K+ conductance and a TEA+-sensitive voltage-activated K+ conductance contribute to the repolarizing phase of the action potential, the former being predominant, (c) in radial fibres, the repolarizing phase of action potentials probably involves different membrane K+ conductances among which is a TEA+-sensitive K+ conductance.

Insulin stimulation of protein synthesis in cultured skeletal and cardiac muscle cells

1982 ◽  
Vol 243 (1) ◽  
pp. C81-C86 ◽  
Author(s):  
J. Airhart ◽  
J. A. Arnold ◽  
W. S. Stirewalt ◽  
R. B. Low
Keyword(s):  
Protein Synthesis ◽  
Specific Activity ◽  
Muscle Cells ◽  
Cell Types ◽  
Cardiac Cells ◽  
Cardiac Muscle Cells ◽  
Significant Stimulation ◽  
Chick Heart ◽  
Embryonic Chick Heart ◽  
Stimulation Of

The effects of acute exposure to insulin on protein synthesis were examined in primary, differentiated cultures of embryonic chick heart and skeletal muscle cells. Synthetic rates were calculated using the specific activity of tRNA-bound leucine as precursor, a specific activity that was significantly less than that of extracellular leucine but greater than that of free, intracellular leucine at 0.2 mM external leucine. Insulin did not alter these relationships. Doses of insulin in the physiological range produced significant stimulation of protein synthesis in both cell types. Maximal responses, involving approximately 30% increases in both absolute and fractional rates, were observed at higher insulin concentrations. Significant stimulation by insulin was seen in cardiac cells after only 1 h of insulin treatment, and the effects of the hormone were observed both in the presence and absence of serum in the culture medium.

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