Protection of Bauhinia championii on Ischemia/Reperfusion-Induced Cardiac Dysfunction

[Speaker] Yun-Fang Chen:1
[Co-author] Wei-Yu Chen:2,3, Chia-Hsin Lin:1, Chao-Lin Kuo:1, An-Sheng Lee:3
1:Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan, 2:Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, 3:Department of Medicine, Mackay Medical College, New Taipei City, Taiwan

BACKGROUND: Bauhinia championii (Benth.) Benth. (BC) also known as chu-hua-mu, is one of the commonly used medicinal herbs in Taiwan. The stem of this plant has been used in treatment of different pains and rheumatoid arthritis. With known nociceptive action, it may have potential to alternate the characteristics of different ion channels. Therefore, this study aims to investigate the effect of boiling water extracts of BC on cardiac arrhythmia and myocytes lose in an isolated mice heart model.
MATERIALS AND METHODS: Isolated hearts from 8-12 weeks male C57BL/6JNarl mice were performed with ischemia (30 min)/reperfusion (60 min) (I/R) by LAD ligation on Langendorff-perfused apparatus. Lead II electrocardiogram (ECG) was also continuously monitored. BC (10 mg/L) was pretreated 15 min before reperfusion. After reperfusion, hearts were removed for infarct size analysis by 2,3,5-triphenyltetrazolium chloride (TTC) assay. To further determine the underlying mechanism, ventricular myocytes of mice were enzymatically isolated and then action potential, sodium current (INa), L-type calcium current (ICa), and transient outward potassium current (Ito) were recorded using the whole-cell patch clamp technique.
RESULTS: BC not only decreased the frequency and duration of different types of ventricular arrhythmias, but also reduced infarct size induced by I/R. I/R-induced oxidation of Ca2+-calmodulin-dependent protein kinase (CaMKII) triggers myocardial necroptosis (myoglobin release), but when BC was presence, they are all decrease. By patch clamp technique in current-clamp mode, we found maximum rise slope of action potential was reduced by BC treatment. On the other hand, the current density of INa, but not ICa and Ito was significantly decreased by BC in voltage-clamp mode.
CONCULSION: The present study indicates that BC may prevent I/R-induced ventricular arrhythmias by inhibiting sodium channel. Since most of the clinical antiarrhythmic remedies have their own serious side effects, to develop a novel therapeutic agent for lethal arrhythmia is still needed. BC, in this concern, will be a new candidate for the treatment of myocardial infarction and ventricular arrhythmia.

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