银杏苦内酯B对豚鼠模拟缺血心室肌细胞L-型钙电流及胞内游离钙的影响

Effect of ginkgolide B on L-type calcium current and cytosolic [Ca^(2+)]_i in guinea pig ischemic ventricular myocytes

应用全细胞膜片钳及激光共聚焦技术 ,研究银杏苦内酯B(ginkgolideB ,GB)对豚鼠心室肌细胞L 型钙电流及胞内游离钙的作用 ,并探讨GB心肌保护作用的机制。实验结果显示 ,在指令电压为 0mV时 ,GB对生理状态下豚鼠心室肌细胞L 型钙电流无明显作用。在模拟缺血状态下 ,L 型钙峰值电流减小 3 7 71% ,但加入 1μmol/LGB后 ,可逆转缺血引起的L 型钙电流的降低 ,与缺血对照组比较 ,有显著性差异 (P <0 0 5 )。 1μmol/LGB能使由于模拟缺血而上移的L 型钙电流 电压曲线回复正常。在生理状态下 ,0 1、1、10mol/LGB分别使心肌细胞内游离钙降低 10 5 8%(n =12 )、17 2 7% (n =12 )、16 3 5 % (n =10 ) ,与对照组相比有非常显著性差异。模拟缺血液灌流 12min时 ,细胞内游离钙浓度增加 2 0 15 % ,在模拟缺血液中分别加入 1μmol/Lnifedipine或 5mmol/LNiCl2 ,结果显示 :模拟缺血液灌流 12min ,与正常对照组相比细胞内钙分别增加 18 18% (P >0 0 5 )与 11% (P <0 0 5 )。在模拟缺血液中加入1mol/LGB灌流 12min时细胞内钙仅增加 9 60 % (n =12 ,P <0 0 0 1) ,与缺血对照组相比有显著性差异 (P <0 0 5 )。结果表明 ,GB可逆转模拟缺血造成L 型钙电流的降低 。

With whole cell variant patch clamp and laser scanning confocal microscope technique, we examined the effect of ginkgolide B (GB) from ginkgo leaves on L type calcium current and cytosolic [Ca 2+ ] i in guinea pig ischemic ventricular myocytes. The results showed that under normal conditions, at a test voltage of 0 mV, GB had no significant effect on I Ca,L ; and during ischemia, the peak Ca 2+ current reduced by 37 71%, and the I-V curve of I Ca,L was shifted upward. 1 μmol/L GB reversed the change induced by ischemia, a result being significantly different from those of the ishemia group ( P <0 05).Under control condition, 0 1,1,10 μmol/L GB decreased intracellular calcium concentration by 10 58%, 17 27% and 16 35% ( n = 12, 12, 10, P <0 01～0 001), respectively. With perfusion of ischemic solution for 12 min, intracellular calcium concentration increased by 20 15%. After a 12 min perfusion of ischemic solution containing 1 μmol/L nifedipine or 5 mmol/L NiCl 2, intracellular calcium concentration increased by 18 18% ( P >0 05 vs ischemia) and 11% ( P <0 05 vs ischemia), respectively. After 12 min of perfusion with ischemic solution containing 1 μmol/L GB, intracellular calcium concentration increased by 9 6% ( P <0 05 vs ischemia). It is shown that GB could reverse the decrease of I Ca,L and partially inhibit calcium overload during ischemia.