银杏苦内酯B对缺血豚鼠心室肌动作电位、L-型钙电流和延迟整流钾电流的作用

THE EFFECT OF GINKGOLIDE B ON ACTION POTENTIAL,L-TYPE CALCIUM CURRENT AND DELAYED RECTIFIER POTASSIUM CURRENT IN ISCHEMIC GUINEA PIG VENTRICULAR MYOCYTES

目的 :研究银杏苦内酯B对正常和缺血心室肌细胞动作电位 (actionpotential,AP) ,L 型钙电流 (L typecalciumcurrent,ICa-L)、延迟整流钾电流 (DelayedRectifierCurrennt,IK)的影响。方法 :用常规细胞内微电极方法记录豚鼠心室肌细胞动作电位 ,用全细胞膜片钳技术记录游离心室肌细胞离子流。结果 :①在生理条件下 ,银杏苦内酯B可缩短心室肌细胞动作电位时程 (actionpotentialduration ,APD) ,但对AP其他参数无影响 ,银杏苦内酯B可增大IK,呈浓度依赖性 ,但对ICa-L无显著作用 ;②在缺血条件下 ,APD50 、APD90 明显缩短 ,RP、APA减小 ,Vmax减慢 ,而银杏苦内酯B则可延缓和减轻缺血所引起上述参数的变化 ;3.在缺血条件下 ,IK 和ICa -L均受到抑制 ,但加入银杏苦内酯B后可逆转缺血所造成这两种离子流的减小。结论 :银杏苦内酯B可对抗心肌缺血所引起的心肌电生理的变化 ,提示银杏苦内酯B可预防心律失常的发生。

Aim: To study the effect of ginkgolide B from Ginkgo leave on action potential (AP),L-type calcium current(I Ca-L ) and delayed rectifier potassium current(I K) in normal and ischemic guinea pig ventricular myocytes. Methods: With the standard microelectrode technique to record action potential and whole-cell variant patch-clamp technique to record calcium and potassium current. Results: ① Under normal condition,ginkgolide B shortened APD and had no effect on RP,AP and V max . Ginkgolide B also increased I K in a concentration dependent manner and had no significant effect on I Ca-L . ② Under ischemia condition,it was observed that shortening of APD, APA,decrease V max and depolarization of RP was induced by ischemia,but ginkgolide B could attenuate above-mentioned changes. ③Under ischemia condition,I Ca-L and I K were inhibited,perfusion with ischemia solution containing ginkgolide B could reverse the decrease of I Ca-L and I K. Conclusion: Ginkgolide B had protective effect on ischemic myocardium to prevent ischemic arrhythmia.