In vitro: |
Biol Pharm Bull. 2013;36(2):238-44. | Potential antiarrhythmic effect of methyl 3,4,5-trimethoxycinnamate, a bioactive substance from roots of polygalae radix: suppression of triggered activities in rabbit myocytes.[Pubmed: 23196428 ] | 3,4,5-Trimethoxycinnamic acid (TMCA), Methyl 3,4,5-trimethoxycinnamate (M-TMCA) and p-methoxycinnamic acid (PMCA) have been identified as the major bioactive components in the serum collected from rats treated with oral administration of Polygalae Radix ("YuanZhi," the roots of Polygala tenuifolia WILLD.), a traditional Chinese medicine used to relieve insomnia, anxiety and heart palpitation.
METHODS AND RESULTS:
Among three bioactive substances of Polygala metabolites, only Methyl 3,4,5-trimethoxycinnamate (15-30 µM) significantly shortened action potential duration at 50% and 90% repolarization (APD(50) and APD(90)) in cardiomyocytes in a concentration-dependent and a reversible manner. Methyl 3,4,5-trimethoxycinnamate also inhibited L-type calcium current (I(Ca,L)), but showed effect on neither transient outward potassium current (I(to)) nor steady-state potassium current (I(K,SS)). Furthermore, Methyl 3,4,5-trimethoxycinnamate abolished isoprenaline plus BayK8644-induced early afterdepolarizations (EADs) and suppressed delayed afterdepolarizations (DADs) and triggered activities (TAs). CONCLUSIONS: These findings suggest that Methyl 3,4,5-trimethoxycinnamate may protect the heart from arrhythmias via its inhibitory effect on calcium channel. |
|