Abstract
As one important constituent extracted from a traditional Chinese medicine, Uncaria rhynchophylla Miq Jacks, isorhynchophylline has been used to treat hypertension, epilepsy, headache,
and other illnesses. Whether isorhynchophylline protects hearts against cardiac arrhythmias
is still incompletely investigated. This study was therefore aimed to examine the
preventive effects of isorhynchophylline on heart arrhythmias in guinea pigs and rats
and then explore their electrophysiological mechanisms. In vivo, ouabain and calcium chloride were used to establish experimental arrhythmic models
in guinea pigs and rats. In vitro, the whole-cell patch-lamp technique was used to study the effect of isorhynchophylline
on action potential duration and calcium channels in acutely isolated guinea pig and
rat cardiomyocytes. The dose of ouabain required to induce cardiac arrhythmias was
much larger in guinea pigs administered with isorhynchophylline. Additionally, the
onset time of cardiac arrhythmias induced by calcium chloride was prolonged, and the
duration was shortened in rats pretreated with isorhynchophylline. The further study
showed that isorhynchophylline could significantly decrease action potential duration
and inhibit calcium currents in isolated guinea pig and rat cardiomyocytes in a dose-dependent
manner. In summary, isorhynchophylline played a remarkably preventive role in cardiac
arrhythmias through the inhibition of calcium currents in rats and guinea pigs.
Key words
Uncaria rhynchophylla
- Rubiaceae - isorhynchophylline - arrhythmias - calcium channel
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Prof. Shusen Yang, PhD
Department of Cardiology
The First Affiliated Hospital of Harbin Medical University
Youzheng Street 23#
Harbin 150001
PR China
Phone: +86 4 51 86 65 04 82
Fax: +86 4 51 86 65 04 82
Email: Ganrt@126.com
