QuestionSBA
QuestionChoice
Voltage-gated K+ channels are important in the repolarisation phase (Phase 3) of the cardiac action potential in atrial myocytes. During this phase, K+ channels open, allowing the efflux of potassium ions, which leads to the restoration of the resting membrane potential. In AF, where normal electrical signalling in the atria is disrupted, medications can be used to target voltage-gated K+ channels to help restore a more regular rhythm by influencing the repolarisation of atrial cells.
10028046
a
Voltage-gated K+ channels
QuestionChoice
HCN channels are involved in generating the pacemaker potential in the cells of the sinoatrial node, regulating heart rate.
10028050
e
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels
QuestionChoice
Chloride channels play a role in cardiac action potentials but are not primary targets for antiarrhythmic medications.
10028049
d
Voltage-gated Cl- channels
QuestionChoice
These channels are important in the cardiac action potential's plateau phase (Phase 2). They allow calcium ions to enter the cells, contributing to the sustained depolarization of the myocardium.
10028048
c
Voltage-gated Ca2+ channels
QuestionChoice
These channels are important in the cardiac action potential depolarisation phase (Phase 0) by allowing the influx of sodium ions.
10028047
b
Voltage-gated Na+ channels
Concept
Chapter
2693
6030
Cardiac Action Potential
Topic
159
Cardiovascular physiology
18007
A 78-year-old man presents with recurrent episodes of palpitations and dizziness.

ECG reveals an irregular rhythm with no P waves. Holter monitor confirms atrial fibrillation (AF).

He is prescribed an antiarrhythmic medication which targets the ion channel involved in the repolarisation phase of the cardiac action potential.

What ion channel plays a crucial role in the repolarisation phase of the cardiac action potential in atrial myocytes?
a