Chen Biyi, Cai Jingxia, Song Long-Sheng, Wang Xiaoqing, Chen Zhihe
Section of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
Life Sci. 2005 Jan 21;76(10):1111-21. doi: 10.1016/j.lfs.2004.08.014.
Ginkgo biloba extract (GBE), a valuable natural product for cerebral and cardiovascular diseases, is mainly composed of two classes of constituents: terpene lactones (e.g., ginkgolide A and B, bilobalide) and flavone glycosides (e.g., quercetin and kaempferol). Its electrophysiological action in heart is yet unclear. In the present study, using whole-cell patch clamp technique, we investigated electrophysiological effects of GBE on cation channel currents in ventricular myocytes isolated from rat hearts. We found that GBE 0.01-0.1% inhibited significantly the sodium current (I(Na)), L-type calcium current (I(Ca)) and transient outward potassium current (IK(to)) in a concentration-dependent manner. Surprisingly, its main ingredients, ginkgolide A (GB A), ginkgolide B (GB B) and bilobalide (GB BA) at 0.1 mM did not exhibit any significant effect on these cation channel currents. These results suggested that GBE is a potent non-selective cation channel modulator in cardiaomyocytes. Other constituents (rather than GB A, GB B and GB BA) might be responsible for the observed inhibitory effects of GBE on cation channels.
银杏叶提取物（GBE）是一种对脑和心血管疾病有重要价值的天然产物，主要由两类成分组成：萜类内酯（如银杏内酯A和B、白果内酯）和黄酮苷（如槲皮素和山奈酚）。其对心脏的电生理作用尚不清楚。在本研究中，我们使用全细胞膜片钳技术，研究了GBE对从大鼠心脏分离的心室肌细胞中阳离子通道电流的电生理效应。我们发现，0.01 - 0.1%的GBE以浓度依赖性方式显著抑制钠电流（I(Na)）、L型钙电流（I(Ca)）和瞬时外向钾电流（IK(to)）。令人惊讶的是，其主要成分，0.1 mM的银杏内酯A（GB A）、银杏内酯B（GB B）和白果内酯（GB BA）对这些阳离子通道电流没有表现出任何显著影响。这些结果表明，GBE是心肌细胞中一种有效的非选择性阳离子通道调节剂。其他成分（而非GB A、GB B和GB BA）可能是GBE对阳离子通道观察到的抑制作用的原因。
