Qi Xiao-yan, Zhang Zhi-xiong, Xu You-qiu
Department of Physiology, Shanghai University of Traditional Chinese medicine, Shanghai 200032, China.
Acta Pharmacol Sin. 2004 Feb;25(2):203-7.
To investigate the effect of Ginkgolide B (GB) on action potential (AP), delayed rectifier potassium current (IK), and L-type calcium current (I(Ca-L)) in guinea pig ventricular myocytes.
Single ventricular myocytes were isolated by an enzymatic dissociation method. AP, IK, I(Ca-L) were recorded by whole-cell patch-clamp technique in either current or voltage clamp mode.
GB shortened APD in a concentration-dependent manner. GB 0.1, 1, and 10 micromol/L shortened APD50 by 7.9% (n=5, P>0.05), 18.4% (n=5, P<0.01), and 28.9% (n=6, P<0.01), respectively; APD90 by 12.4% (n=5, P>0.05), 17.6% (n=5, P<0.01), 26.4% (n=5, P<0.01), respectively. GB increased IK in a concentration-dependent manner. GB 0.1, 1, and 10 micromol/L increased IK by 20.1% (n=6, P<0.05), 43.1% (n=6, P<0.01), 55.6% (n=6, P<0.05); increased IK tail by 10.7% (n=6, P<0.05), 25.1% (n=6, P<0.05), and 37.7% (n=6, P<0.05), respectively at testing potential of +50 mV and shift the I-V curve of IK upward. But GB had no significant effect on I(Ca-L) at above concentrations.
GB significantly shortened APD in a concentration-dependent manner which mainly due to increase of IK.
研究银杏内酯B（GB）对豚鼠心室肌细胞动作电位（AP）、延迟整流钾电流（IK）和L型钙电流（I(Ca-L)）的影响。
采用酶解法分离单个心室肌细胞。在电流或电压钳模式下，用全细胞膜片钳技术记录AP、IK、I(Ca-L)。
GB以浓度依赖方式缩短动作电位时程（APD）。GB 0.1、1和10 μmol/L分别使APD50缩短7.9%（n=5，P>0.05）、18.4%（n=5，P<0.01）和28.9%（n=6，P<0.01）；使APD90分别缩短12.4%（n=5，P>0.05）、17.6%（n=5，P<0.01）、26.4%（n=5，P<0.01）。GB以浓度依赖方式增加IK。GB 0.1、1和10 μmol/L分别使IK增加20.1%（n=6，P<0.05）、43.1%（n=6，P<0.01）、55.6%（n=6，P<0.05）；在测试电位+50 mV时，使IK尾电流分别增加10.7%（n=6，P<0.05）、25.1%（n=6，P<0.05）和37.7%（n=6，P<0.05），并使IK的I-V曲线向上移位。但在上述浓度下，GB对I(Ca-L)无明显影响。
GB以浓度依赖方式显著缩短APD，其主要机制是增加IK。
