Nav1.5 Biophysical Properties and Gating
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Nav1.5 Biophysical Properties and Gating

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Questions and Answers

What gene encodes Nav1.5?

  • SCN1A
  • SCN10A
  • SCN5A (correct)
  • SCN2A

    • Which syndrome is associated with gain-of-function mutations in SCN5A?

  • Brugada syndrome
  • Long QT syndrome (Type 3) (correct)
  • Congenital sick sinus syndrome
  • Familial atrial fibrillation

    • What characteristic feature can occur spontaneously in Brugada syndrome?

  • Increased action potential duration
  • Characteristic ECG abnormalities (correct)
  • Sudden infant death syndrome
  • Prolonged QT interval

    • Which of the following is a known result of gain-of-function mutations in SCN5A in Type 3 Long QT syndrome?

    <p>Prolongation of action potential duration</p> Signup and view all the answers

    What recent gene was identified as being responsible for Brugada syndrome?

    <p>MAPRE2</p> Signup and view all the answers

    What effect do sodium-channel blockers have on Brugada syndrome?

    <p>They can unmask the characteristic ECG</p> Signup and view all the answers

    What technique is used for quantifying electrophysiological changes in whole tissues or hearts?

    <p>Optical mapping</p> Signup and view all the answers

    Which syndrome is NOT listed as a genetic polymorphism associated with SCN5A?

    <p>Wolf-Parkinson-White syndrome</p> Signup and view all the answers

    What is the primary function of Nav1.5 in the human heart?

    <p>Driving the sodium current (INa)</p> Signup and view all the answers

    Which statement best describes Nav1.5?

    <p>It is a voltage-gated sodium channel composed of α and β subunits.</p> Signup and view all the answers

    What clinical implications can arise from genetic polymorphisms in SCN5A?

    <p>Influence heart conditions such as Brugada syndrome</p> Signup and view all the answers

    Which experimental technique is appropriate to explore cardiac electrophysiology?

    <p>High resolution optical mapping</p> Signup and view all the answers

    What effect does the familial atrial fibrillation mutation M1875T-SCN5A have on sodium current?

    <p>It increases early sodium current.</p> Signup and view all the answers

    Which publication is associated with new Brugada syndrome risk loci?

    <p>Barc J., et al. (2022)</p> Signup and view all the answers

    What is NOT a characteristic of Nav1.5?

    <p>It forms part of the ion channels in the skeletal muscles.</p> Signup and view all the answers

    What is one of the biophysical properties of Nav1.5?

    <p>Voltage-gated activation</p> Signup and view all the answers

    What is a consequence of using anti-arrhythmic drugs with a narrow therapeutic window?

    <p>Increased risk of pro-arrhythmia</p> Signup and view all the answers

    Which polymorphism in SCN5A has been associated with increased sensitivity to propafenone?

    <p>R1193Q</p> Signup and view all the answers

    What major adverse event is associated with the use of flecainide?

    <p>Brugada syndrome</p> Signup and view all the answers

    What did the study by Echt et al. (1991) indicate about flecainide?

    <p>It increases mortality compared to placebo control</p> Signup and view all the answers

    What characteristic of SCN5A is mentioned in relation to familial atrial fibrillation?

    <p>Point mutation in C-terminus</p> Signup and view all the answers

    What potential effect does propafenone have on ECG patterns?

    <p>It can induce a Brugada syndrome ECG pattern</p> Signup and view all the answers

    In MAPRE KO hiPSC-CMs, what changes were observed?

    <p>Reduced Vmax and APDs</p> Signup and view all the answers

    Natural differences in biophysical properties of SCN5A are noted between which regions?

    <p>Left ventricular and right ventricular</p> Signup and view all the answers

    Study Notes

    • Nav1.5 is the pore-forming subunit of the voltage-gated sodium channel in the human heart.
    • Nav1.5 is encoded by the SCN5A gene.
    • Nav1.5 is responsible for generating the sodium current (INa) in the heart.
    • Nav1.5 undergoes a series of transitions (gating) to allow sodium ions to flow through the channel.
    • These transitions include activation, inactivation, and recovery from inactivation.

    Genetic Polymorphisms in SCN5A

    • Mutations in SCN5A can lead to various cardiac disorders.
    • Long QT Syndrome (LQTS) is caused by gain-of-function mutations in SCN5A, resulting in prolonged action potential duration (APD) and QT interval.
    • Brugada Syndrome (BrS) is caused by loss-of-function mutations in SCN5A.
    • Early Repolarisation Syndrome, Congenital Sick Sinus Syndrome, Familial Atrial Fibrillation, and Sudden Infant Death Syndrome are other disorders associated with SCN5A polymorphisms.

    Brugada Syndrome

    • BrS is characterized by a unique ECG pattern and an increased risk of sudden cardiac death.
    • New gene, MAPRE2, has been identified as a risk factor for BrS.
    • MAPRE2 deficiency leads to reductions in conduction velocity, action potential upstroke velocity, sodium current, and prolonged action potential duration.

    Optical Mapping for Cardiac Electrophysiology

    • Optical mapping uses fluorescent dyes to visualize and analyze electrical activity in heart cells and tissues.
    • It offers a powerful tool for studying arrhythmias and the effects of anti-arrhythmic drugs.

    Anti-Arrhythmic Drugs and SCN5A

    • Anti-arrhythmic drugs can be challenging to use due to narrow therapeutic windows and potential for pro-arrhythmia.
    • Flecainide and propafenone are anti-arrhythmic drugs that can cause adverse events, including prolonged QRS duration, BrS, and cardiogenic shock.
    • Flecainide can increase mortality compared to placebo in patients with ventricular arrhythmia.
    • Propafenone can induce a BrS-like pattern in individuals with specific SCN5A polymorphisms.
    • Certain SCN5A mutations can decrease sensitivity to flecainide, suggesting individual variability in drug responses.

    Biophysical Diversity in SCN5A

    • There are naturally occurring differences in the biophysical properties of Nav1.5 between left ventricular and right ventricular myocardium.

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    Related Documents

    Biophysical Properties of Nav1.5 PDF

    Description

    This quiz explores the biophysical properties and gating mechanisms of the Nav1.5 sodium channel in the heart. It also covers the genetic polymorphisms in the SCN5A gene and their association with various cardiac disorders such as Long QT Syndrome and Brugada Syndrome. Test your knowledge on how these elements contribute to cardiac function and dysfunction.

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