Atrial fibrillation in KCNE1-null mice

Area of Science:

• Cardiology
• Molecular Biology
• Electrophysiology

Background:

• Atrial fibrillation (AF) is a common cardiac arrhythmia with poorly understood molecular underpinnings.
• Mutations in KCNQ1, a component of cardiac potassium channels, are linked to familial AF, but in vivo mechanisms are unclear.

Purpose of the Study:

• To investigate the in vivo role of KCNE1 in cardiac electrophysiology and atrial fibrillation.
• To elucidate the molecular mechanisms by which KCNE1 deficiency affects atrial action potentials and arrhythmia susceptibility.

Main Methods:

• Generation and analysis of KCNE1 knockout (KCNE1-/-) mice.
• Electrophysiological recordings of atrial and ventricular action potentials.
• Patch-clamp studies on atrial myocytes and heterologous expression systems (CHO cells) to assess ion channel function.

Main Results:

• KCNE1-/- mice exhibited spontaneous atrial fibrillation episodes without changes in atrial size or structure.
• Atrial action potentials were unexpectedly shortened in KCNE1-/- mice, contrary to human ventricular findings.
• Increased K+ currents, including those sensitive to chromanol 293B, were observed in KCNE1-/- atrial cells.
• Rapid pacing revealed that KCNE1 modulates KCNQ1 channel kinetics, preventing current accumulation at high heart rates.

Conclusions:

• KCNE1 deficiency in mice leads to increased atrial outward K+ currents and shortened atrial action potentials.
• These electrophysiological changes enhance susceptibility to atrial fibrillation, highlighting KCNE1's critical role in maintaining cardiac rhythm.
• The findings provide novel molecular insights into the pathogenesis of atrial fibrillation.