Research Highlights

• Subject Category:
  • Clinical medicine

Published online: 11 June 2008 | doi:10.1038/nchina.2008.133

Atrial fibrillation: Back in the rhythm

Felix Cheung

Introduction

© (2008) Guowei Qin

Atrial fibrillation — the most common form of cardiac arrhythmia (heart rhythm disorder) — increases the risk of stroke and heart failure. The medical condition affects 5% of the population over the age of 65 and nearly 10% of the population over the age of 80. Class III antiarrhythmic agents are effective in suppressing atrial fibrillation, but can induce life-threatening arrhythmias that involve the heart's ventricles. Guirong Li at the University of Hong Kong, Guowei Qin at the Chinese Academy of Science in Shanghai and co-workers¹ have found that a natural compound extracted from Xuelianhua — a herb commonly referred to in traditional Chinese medicine as 'the snow lotus of Tianshan' — is a promising antiarrhythmic agent that affects electrical parameters in atria, rather than in ventricles.

Antiarrhythmic agents suppress arrhythmia by blocking specific protein molecules (ion channels) in the surface membrane of cardiac cells (myocytes), thereby prolonging the duration of electrical impulse (action potential). The researchers isolated four compounds from Xuelianhua and found one of the compounds, namely acacetin, blocked two major potassium channels in human atrial myocytes. One of these potassium channels — the ultrarapid delayed rectifier channel — has been previously shown to be functionally present in the atrium but not in the ventricle of the human heart.

The researchers fed acacetin to mice and found no animal deaths occurred within the two-week observation period. They then tested the acacetin in anesthetized dogs and found that the compound is effective in preventing atrial fibrillation. The findings suggest that acacetin could be an orally effective, atrium-selective, antiarrhythmic agent.

The authors of this work are from:
Department of Medicine and Department of Physiology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China; Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China; Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Cardiothoracic Unit, Grantham Hospital, University of Hong Kong, Hong Kong, China; Department of Pharmacology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.

Reference

1. Li, G. R. et al. Acacetin, a natural flavone, selectively inhibits human atrial repolarization potassium currents and prevents atrial fibrillation in dogs. Circulation 117, 2449–2457 (2008). | Article | PubMed | ChemPort |