Cardiac electrophysiological differences between Kunming and C57BL6/J mice

Area of Science:

• Cardiovascular Electrophysiology
• Cardiac Arrhythmogenesis
• Mouse Models of Cardiac Disease

Background:

• Cardiac electrophysiological properties are critical for normal heart function.
• Alterations in these properties can lead to life-threatening arrhythmias.
• Identifying stable animal models is crucial for studying arrhythmia mechanisms.

Purpose of the Study:

• To investigate cardiac electrophysiological differences between Kunming (KM) and C57BL6/J (C57) mice.
• To identify a stable mouse model for studying ventricular arrhythmias.
• To elucidate the underlying mechanisms of arrhythmogenesis in KM mice.

Main Methods:

• In vivo electrocardiogram (ECG) recordings to assess QT interval.
• In vitro monophasic action potential (MAP) recordings from ventricular epicardium.
• Programmed electrical stimulation (PES) to induce ventricular tachycardia.
• Whole-cell patch-clamp to measure transient outward potassium current (Ito) density.

Main Results:

• KM mice showed significantly prolonged QT intervals compared to C57 mice.
• Action potential duration (APD) was longer in KM mice, particularly under programmed electrical stimulation.
• KM mice exhibited increased susceptibility to ventricular tachycardia induced by PES and burst pacing.
• Significantly lower Ito densities were observed in ventricular myocytes of KM mice.

Conclusions:

• Kunming mice possess prolonged QT intervals and APD, rendering them vulnerable to ventricular arrhythmias.
• Reduced Ito current in ventricular myocytes is a key mechanism contributing to arrhythmias in KM mice.
• KM mice represent a valuable model for investigating the electrophysiological basis of cardiac arrhythmias.