GO:0086048 membrane depolarization during bundle of His cell action potential: Cardiac Conduction Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0086048 describes the depolarization phase of the action potential specifically in bundle of His cardiac muscle cells, a critical component of the ventricular conduction system.
• This process is driven by a rapid influx of sodium ions through voltage-gated sodium channels, with contributions from calcium channels and gap junction-mediated current spread.
• The bundle of His acts as a relay station, transmitting electrical excitation from the atrioventricular node to the Purkinje fibers and ventricular myocardium.
• Dysregulation of bundle of His depolarization can lead to conduction blocks, arrhythmias, and sudden cardiac death.
• Key genes involved include SCN5A, CACNA1C, GJA1, HCN4, and KCNQ1, among others, which are targets for electrophysiological and pharmacological research.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) enable precise dissection of ion channel contributions to bundle of His depolarization.
Description
The bundle of His is a specialized cardiac conduction tissue that bridges the atrioventricular node and the Purkinje fiber network, ensuring rapid and coordinated ventricular activation. The action potential of bundle of His cells is characterized by a fast depolarization phase, which is essential for high-velocity conduction. GO:0086048, membrane depolarization during bundle of His cell action potential, refers to the process in which the membrane potential of these cells changes in the depolarizing direction from the negative resting potential towards the positive peak of the action potential. This process is fundamental for normal cardiac rhythm and has been studied through experimental and computational models. Understanding the ionic mechanisms underlying this depolarization is critical for developing therapies for conduction disorders and arrhythmias. Research has shown that the depolarization phase in bundle of His cells relies on a complex interplay of ion channels, including voltage-gated sodium and calcium channels, as well as gap junction proteins that facilitate current spread. Pharmacological studies have highlighted the sensitivity of these cells to various mediators, such as adenosine and cimetidine, which can modulate conduction. Moreover, autonomic neurotransmitters influence the automaticity and conduction properties of the atrioventricular junction, including the bundle of His. This article provides a comprehensive overview of the ontology, mechanisms, genes, and research methodologies associated with GO:0086048, aiming to support both basic and translational cardiac electrophysiology research.
membrane depolarization during bundle of His cell action potential At A Glance
| GO ID | GO:0086048 |
|---|---|
| GO term | membrane depolarization during bundle of His cell action potential |
| Ontology | biological_process |
| Synonym | membrane depolarization during bundle of His cardiac muscle cell action potential |
| Major function | Rapid depolarization of bundle of His cells to propagate electrical excitation to the ventricles |
| Related cellular component | Bundle of His cardiac muscle cell |
| Related molecular functions | Voltage-gated ion channel activity, ion transmembrane transport |
| Related biological processes | Cardiac conduction, action potential, membrane depolarization |
What Is GO:0086048?
GO:0086048 is defined as the process in which bundle of His cardiac muscle cell membrane potential changes in the depolarizing direction from the negative resting potential towards the positive membrane potential that will be the peak of the action potential. In simpler terms, it is the rapid electrical activation of bundle of His cells that triggers the upstroke of the action potential, enabling fast conduction of electrical signals through the heart's ventricular conduction system.
Why Is membrane depolarization during bundle of His cell action potential Important in Cell Biology?
GO:0086048 is essential for understanding the electrophysiological basis of cardiac conduction. The bundle of His is a critical node in the cardiac conduction system, and its proper depolarization ensures synchronous ventricular contraction. Disruptions in this process can result in life-threatening arrhythmias, conduction blocks, and heart failure. Studying this term helps researchers identify therapeutic targets and develop interventions for cardiac rhythm disorders.
• It is a key step in the cardiac action potential that ensures rapid conduction from the atria to the ventricles.
• Dysfunction of bundle of His depolarization can cause bundle branch blocks and complete heart block.
• It is a target for antiarrhythmic drugs that modulate ion channels.
• Understanding its mechanisms aids in the development of biological pacemakers.
• It is relevant to inherited arrhythmia syndromes such as Brugada syndrome and long QT syndrome.
• It provides insight into the effects of autonomic neurotransmitters on cardiac conduction.
• It is influenced by pharmacological agents like adenosine and cimetidine.
• It is a focus of computational modeling to simulate cardiac excitation.
• It helps explain the vulnerability to ischemia-induced arrhythmias.
• It is critical for the safety pharmacology of cardiovascular drugs.
What Happens During membrane depolarization during bundle of His cell action potential?
Resting State and Threshold
In simple terms: Before depolarization, bundle of His cells are at a negative resting potential, ready to fire.
Bundle of His cells maintain a negative resting membrane potential, primarily set by potassium conductance. When an electrical impulse arrives from the atrioventricular node, it spreads through gap junctions, causing a slight depolarization. If this depolarization reaches threshold, voltage-gated sodium channels open, initiating the action potential upstroke.
Sodium Influx and Rapid Depolarization
In simple terms: Sodium ions rush into the cell, making the inside more positive very quickly.
The upstroke of the bundle of His action potential is driven by a rapid influx of sodium ions through voltage-gated sodium channels (Nav1.5, encoded by SCN5A). This influx causes the membrane potential to rise swiftly towards positive values. The high density of sodium channels in bundle of His cells ensures fast conduction velocity.
Calcium Current Contribution
In simple terms: Calcium ions also enter, helping to sustain the depolarization.
In addition to sodium current, L-type calcium channels (Cav1.2, encoded by CACNA1C) contribute to the later phase of depolarization and the plateau. In bundle of His cells, calcium current helps maintain the action potential duration and supports excitation-contraction coupling in the surrounding myocardium.
Gap Junction-Mediated Current Spread
In simple terms: Electrical signals pass directly from cell to cell through specialized channels.
Depolarization in one bundle of His cell rapidly spreads to neighboring cells via gap junctions composed of connexins (e.g., Cx40, Cx43). This cell-to-cell coupling ensures synchronized depolarization of the entire bundle, which is essential for efficient conduction to the Purkinje fibers.
Modulation by Autonomic and Pharmacological Agents
In simple terms: Nerves and drugs can change how easily these cells depolarize.
The depolarization process is modulated by autonomic neurotransmitters. Parasympathetic and sympathetic mediators can alter the automaticity and conduction properties of atrioventricular junctional cells, including the bundle of His. Additionally, pharmacological agents such as adenosine and cimetidine have been shown to affect cardiac electrophysiology, potentially influencing bundle of His depolarization.
Key Genes Involved in GO:0086048 membrane depolarization during bundle of His cell action potential
The following genes encode ion channels, gap junction proteins, and regulatory molecules that are critical for membrane depolarization during bundle of His cell action potential.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SCN5A | Voltage-gated sodium channel alpha subunit (Nav1.5) | Mediates rapid sodium influx during depolarization; mutations linked to Brugada syndrome and conduction disease |
| CACNA1C | Voltage-gated calcium channel alpha-1C subunit (Cav1.2) | Contributes to calcium current during action potential plateau; target for calcium channel blockers |
| GJA1 | Connexin 43 | Forms gap junctions for electrical coupling between bundle of His cells |
| GJA5 | Connexin 40 | Gap junction protein highly expressed in the conduction system; important for fast conduction |
| HCN4 | Hyperpolarization-activated cyclic nucleotide-gated channel 4 | Contributes to pacemaker current (If) in conduction tissues; involved in automaticity |
| KCNQ1 | Potassium voltage-gated channel subfamily Q member 1 (Kv7.1) | Mediates repolarization; mutations cause long QT syndrome |
| KCNH2 | Potassium voltage-gated channel subfamily H member 2 (hERG) | Rapid delayed rectifier potassium current; drug target for arrhythmias |
| SCN1B | Sodium channel beta subunit 1 | Modulates sodium channel gating and cell surface expression |
| SCN2B | Sodium channel beta subunit 2 | Modulates sodium channel function in cardiac tissue |
| ATP1A1 | Na+/K+-ATPase alpha-1 subunit | Maintains resting potential by pumping sodium out and potassium in |
| ATP2A2 | SERCA2a calcium pump | Regulates calcium reuptake into sarcoplasmic reticulum, affecting action potential |
| RYR2 | Ryanodine receptor 2 | Calcium release channel in sarcoplasmic reticulum; influences calcium transients |
| PLN | Phospholamban | Regulates SERCA2a activity; modulates calcium handling |
| CALM1 | Calmodulin 1 | Calcium sensor that regulates ion channels and signaling |
| CACNB2 | Calcium channel beta-2 subunit | Modulates L-type calcium channel function |
| KCNJ2 | Inward rectifier potassium channel Kir2.1 | Sets resting membrane potential and contributes to repolarization |
| KCNJ12 | Inward rectifier potassium channel Kir2.2 | Contributes to background potassium current |
| ANK2 | Ankyrin-2 | Cytoskeletal adaptor that anchors ion channels and transporters in cardiac cells |
How Is membrane depolarization during bundle of His cell action potential Regulated?
The depolarization process in bundle of His cells is regulated by multiple factors, including autonomic nervous system activity, intracellular signaling pathways, and pharmacological agents. Autonomic neurotransmitters such as acetylcholine and norepinephrine can modulate ion channel activity and gap junction conductance, thereby affecting the rate and amplitude of depolarization. Adenosine, a purine nucleoside, acts on A1 receptors to inhibit adenylyl cyclase and reduce cAMP levels, leading to decreased calcium current and activation of potassium currents, which can blunt depolarization. Cimetidine, an H2 receptor antagonist, has been shown to have electrophysiological effects on rabbit myocardium, potentially influencing conduction. Additionally, ischemic conditions can alter ion channel function and gap junction coupling, contributing to arrhythmogenesis. These regulatory mechanisms ensure fine-tuning of cardiac conduction under physiological and pathological conditions.
membrane depolarization during bundle of His cell action potential and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SCN5A | Brugada syndrome, Lenegre disease | Knockout or point mutation in hiPSC-derived cardiomyocytes |
| CACNA1C | Timothy syndrome, Brugada syndrome | Knock-in of patient-specific mutations in cell lines |
| GJA1 | Oculodentodigital dysplasia, arrhythmias | Knockout in cardiac conduction cell models |
| KCNQ1 | Long QT syndrome type 1 | Overexpression or knockout in HEK293 or cardiomyocytes |
| HCN4 | Sinus node dysfunction, bradycardia | Knock-in of HCN4 mutations in hiPSCs |
Cardiac Conduction Blocks
Impaired depolarization in bundle of His cells can lead to conduction blocks, such as bundle branch block or complete heart block. Mutations in SCN5A, the gene encoding the cardiac sodium channel, are associated with progressive cardiac conduction defect (Lenegre disease) and Brugada syndrome, both of which involve slowed conduction and increased risk of arrhythmias.
Arrhythmias and Sudden Cardiac Death
Abnormalities in bundle of His depolarization can create a substrate for reentrant arrhythmias, including ventricular tachycardia and fibrillation. Ischemic heart disease can blunt the inward rectifier potassium current (IK1), leading to increased arrhythmia susceptibility. Pharmacological modulation of ion channels, such as with adenosine or cimetidine, can also provoke or suppress arrhythmias.
Inherited Arrhythmia Syndromes
Long QT syndrome and short QT syndrome can result from mutations in potassium or calcium channel genes that affect action potential duration and depolarization. These syndromes increase the risk of syncope and sudden death. The bundle of His is a critical site for the manifestation of these channelopathies.
Autonomic Dysregulation
Alterations in autonomic tone can affect bundle of His depolarization, contributing to sinus node dysfunction and atrioventricular block. Parasympathetic and sympathetic mediators directly influence the automaticity and conduction properties of the atrioventricular junction.
From membrane depolarization during bundle of His cell action potential-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of SCN5A in bundle of His depolarization? | SCN5A knockout in hiPSC-derived bundle of His-like cells |
| How do point mutations in CACNA1C affect action potential upstroke? | CRISPR point mutation knock-in in cardiomyocytes |
| Does overexpression of GJA1 enhance conduction velocity? | GJA1 overexpression in cardiac conduction cell lines |
| What is the effect of KCNQ1 mutations on repolarization? | Knock-in of KCNQ1 mutations in hiPSCs |
| Can tagged SCN5A be used to track channel localization? | Knock-in of fluorescent tag at SCN5A locus |
| What is the impact of HCN4 knockout on automaticity? | HCN4 knockout in hiPSC-derived pacemaker cells |
How to Study the membrane depolarization during bundle of His cell action potential Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Patch-clamp | Ion currents and action potentials | Characterize ion channel function in bundle of His cells |
| Optical mapping | Action potential propagation | Assess conduction velocity and arrhythmogenesis |
| Computational modeling | Simulated action potentials | Predict effects of ion channel mutations |
| Multi-electrode array | Extracellular field potentials | Drug screening on cardiac conduction |
| Immunohistochemistry | Protein localization | Detect ion channel and connexin expression |
| RNA-seq | Gene expression profiles | Identify transcripts enriched in bundle of His |
| CRISPR screening | Gene function in depolarization | Discover novel regulators of conduction |
Patch-Clamp Electrophysiology
Patch-clamp recordings allow direct measurement of ionic currents (e.g., sodium, calcium, potassium) in isolated bundle of His cells or heterologous expression systems. This technique is essential for characterizing the biophysical properties of ion channels involved in depolarization.
Optical Mapping and Voltage-Sensitive Dyes
Optical mapping using voltage-sensitive dyes enables visualization of action potential propagation in multicellular preparations, such as isolated bundle of His or engineered cardiac tissues. This method provides spatial and temporal resolution of depolarization patterns.
Computational Modeling
Mathematical models of cardiac conduction, such as the simulation analysis of atrioventricular node excitation, can integrate ion channel kinetics and gap junction conductances to predict bundle of His depolarization behavior under normal and pathological conditions.
Pharmacological Profiling
Testing the effects of drugs (e.g., adenosine, cimetidine) on bundle of His depolarization can reveal modulatory mechanisms and potential therapeutic targets. Such studies often use multi-electrode arrays or microelectrode recordings.
How CRISPR Can Be Used to Study GO:0086048 membrane depolarization during bundle of His cell action potential
Knockout
CRISPR knockout of genes such as SCN5A or GJA1 in bundle of His cell models can abolish or reduce depolarization, allowing researchers to assess the contribution of specific ion channels or gap junctions to the action potential upstroke. Knockout studies in hiPSC-derived cardiomyocytes have been used to model conduction defects.
Point Mutation
Introducing patient-specific point mutations (e.g., in SCN5A or CACNA1C) via CRISPR base editing or homology-directed repair enables the study of inherited arrhythmia syndromes at the cellular level. These models can reveal how single amino acid changes alter channel gating and depolarization kinetics.
Knock-in
Knock-in of reporter genes (e.g., fluorescent tags) or disease-associated alleles allows real-time tracking of ion channel localization and function in bundle of His cells. This approach is valuable for understanding trafficking defects and compensatory mechanisms.
Overexpression
CRISPR activation (CRISPRa) or transgenic overexpression of genes like GJA1 or HCN4 can enhance specific currents and modulate depolarization. Overexpression models are useful for gain-of-function studies and for engineering biological pacemakers.
How EDITGENE Supports membrane depolarization during bundle of His cell action potential Research
Researchers studying membrane depolarization during bundle of His cell action potential-related genes often need to determine whether a candidate gene is causally involved in the depolarization process or is merely a bystander. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic manipulation in cardiac cell models, from knockout to knock-in, facilitating mechanistic studies and drug discovery.
Contact EDITGENE today to design your custom CRISPR model for membrane depolarization during bundle of His cell action potential research.
Frequently Asked Questions About membrane depolarization during bundle of His cell action potential
What is GO:0086048?
GO:0086048 is a Gene Ontology biological process term describing the depolarization phase of the action potential in bundle of His cardiac muscle cells, from resting potential to the peak of the action potential.
What genes are involved in membrane depolarization during bundle of His cell action potential?
Key genes include SCN5A, CACNA1C, GJA1, GJA5, HCN4, KCNQ1, and KCNH2, which encode ion channels and gap junction proteins critical for the depolarization process.
Why is bundle of His depolarization important?
It ensures rapid conduction of electrical impulses from the atrioventricular node to the ventricles, which is essential for coordinated heart contraction. Dysfunction can lead to arrhythmias and heart block.
What diseases are associated with abnormal bundle of His depolarization?
Diseases include Brugada syndrome, Lenegre disease, long QT syndrome, bundle branch block, and sudden cardiac death.
How can I study bundle of His depolarization in the lab?
Researchers use patch-clamp electrophysiology, optical mapping, computational modeling, and CRISPR-based genetic models to study this process.
What is the role of SCN5A in bundle of His depolarization?
SCN5A encodes the cardiac sodium channel Nav1.5, which mediates the rapid sodium influx responsible for the upstroke of the action potential in bundle of His cells.
Can CRISPR be used to model bundle of His conduction disorders?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models in hiPSC-derived cardiomyocytes can recapitulate conduction disorders and help identify therapeutic targets.
What are the synonyms for GO:0086048?
The synonym is membrane depolarization during bundle of His cardiac muscle cell action potential.
How does adenosine affect bundle of His depolarization?
Adenosine can inhibit adenylyl cyclase, reduce calcium current, and activate potassium currents, thereby blunting depolarization and slowing conduction.
What research methods are used to measure bundle of His action potentials?
Patch-clamp, multi-electrode arrays, optical mapping with voltage-sensitive dyes, and computational simulations are commonly used.
Conclusion
GO:0086048, membrane depolarization during bundle of His cell action potential, is a fundamental process in cardiac electrophysiology that ensures rapid and coordinated ventricular activation. Understanding its molecular underpinnings, including the roles of ion channels and gap junctions, is crucial for deciphering the mechanisms of conduction disorders and arrhythmias. Advances in CRISPR-based models and electrophysiological techniques continue to shed light on this process, offering new avenues for therapeutic intervention. EDITGENE's comprehensive services support researchers in dissecting the genetic and molecular basis of bundle of His depolarization, from gene discovery to functional validation.
References
- 1. Urushibara S et al.. 1987. Simulation analysis of conduction of excitation in the atrioventricular node.. J Theor Biol 126(3):275-88 PMID: 3657234
- 2. Thireau J et al.. 2015. ACE Inhibitor Delapril Prevents Ca(2+)-Dependent Blunting of IK1 and Ventricular Arrhythmia in Ischemic Heart Disease.. Curr Mol Med 15(7):642-51 PMID: 26321755
- 3. Kosharskaia IL et al.. 1978. [Automatic activity of the pacemaker cells of the atrioventricular valves under the action of parasympathetic and sympathetic mediators].. Fiziol Zh SSSR Im I M Sechenova 64(3):285-91 PMID: 648660
- 4. West GA. 1987. Actions of adenosine on the sinus node.. Prog Clin Biol Res 230:97-108 PMID: 3588609
- 5. Zhang Y et al.. 1992. Electrophysiological effects of cimetidine on rabbit myocardium.. Zhongguo Yao Li Xue Bao 13(4):338-40 PMID: 1456055
