银杏叶提取物对模拟缺血条件下兔心室肌细胞动作电位及ATP敏感性钾通道的影响

Effect of Ginkgo Bioba Extract on Action Potential and ATP Sensitive Channels in Ischemic Rabbit's Ventricular Myocytes

研究银杏叶提取物 (EGb)对模拟缺血条件下兔心室肌细胞三磷酸腺苷敏感性钾通道电流 (IKATP)及跨膜动作电位时程 (APD)的影响 ,以探讨其抗缺血性心律失常作用的电生理机制。采用酶解法分离获取兔心室肌细胞 ,将其分为正常对照、持续缺血、缺血预处理以及含EGb液 (15 ,30 ,6 0 ,12 0 μg/L)灌流 4组。用全细胞膜片钳技术 ,记录不同条件下的IKATP和跨膜动作电位。结果 :①与持续缺血组比较 ,缺血预处理以及EGb(12 0 μg/L)可使单个心室肌细胞APD50 、APD90 明显缩短 (n =5 ,P <0 .0 5 )。EGb处理组与缺血预处理组相比较 ,对APD的影响无显著差异 ;②与持续缺血组比较 ,缺血预处理和EGb(12 0 μg/L)均可以使IKATP由 112 4± 15 3pA增至 344 0± 2 0 5和 2 95 9± 12 9pA(n =5 ,P <0 .0 5 ) ,使得IKATPI V曲线抬高 ;③增大的电流均可被Glibenclimide阻断。结论 :EGb可开放细胞膜ATP敏感性钾通道、缩短APD ,产生类似心肌缺血预适应的病理生理过程。

To investigate the effects of ginkgo biloba extract(EGb)on adenosine triphosphate-sensitive(ATP) potassium channel (K ATP) and action potential (AP) in ischemic isolated rabbit ventricular myocytes,Single rabbit's ventricular myocytes were isolated with enzyme.Groups were divided into①normal Tyrode solution perfusion;②sustained simulated ischemic solution perfusion;③ischemic precondition(IP):3 cycles of IP (5 min ischema + 5 min reperfusiuon);④EGb:with administration of EGb(15,30,60,120 μg/L),then ischemic perfusion. The whole-cell patch clamp recording technique was used to observed the changes of ATP sensitive potassium current and AP under all conditions respectively. Results:①Compared to sustained ischemia group,APD was not changed significantly at lower concentration of EGb(15,30,60 μg/L),but APD 50,APD 90 was shortened significantly following administration of EGb(120 μg/L)and classical IP. It is similar between IP group and EGb group;②Compared to sustained ischemia group,IP group and EGb(120μg/L)both can significantly increase the K ATP currents from 1 124±153pA to 3440±205,2 959±129pA(n=5,P<0.05);③These effects can be blocked by Glibenclimide.Conclusions:EGb preconditioning could activate K ATP channel and shorten APD.