关附甲素对豚鼠心室肌细胞延迟整流钾电流的抑制作用

用全细胞膜片钳制技术研究关附甲素对豚鼠心室肌细胞延迟整流钾电流的作用。结果表明,关附甲素100μmol·L^-1对延迟整流钾电流有明显的抑制作用。去极化2200和3850ms时,I_k分别由293±90和290±90pA减小至227±59和231±66pA,这种抑制作用与去极化持续时间无关。关附甲素对内向整流钾电流无影响。提示关附甲素延长心肌复极化时间似与抑制延迟整流钾电流的作用有关。

INHIBITION OF GUAN-FU BASE A ON DELAYED RECTIFIER CURRENT(Ik) IN GUINEA PIG VENTRICULAR MYOCYTES

Guan-fu base A (GFA) is a terpenoid alkaloid isolated from the tuber of Aconitum coreanum, which has been shown to prolong cardiac repolarization in vivo and in vitro . In the present study, the effects of GFA on the delayed rectifier current(I_k) were investigated using the whole cell patch clamp technique in isolated guinea pig ventricular myocytes. In the presence of CdCl₂ 100 μmol·L^-1 , I_k was observed upon depolarizing pulses to +50 mV from a holding potential -40 mV for variable duration (550, 1100, 1650, 2200, 2750, 3300, 3850 ms). The magnitude of I_k after a 2200 ms pulse was 293±90 pA prior to drug and 227±59 pA in the presence of GFA 100 μmol·L^-1 . In a 3850 ms pulse, the magnitude of I_k decreased from 290±90 to 231±66 pA after exposure to GFA. The inhibitory effects of GFA on I_k was not dependent on the duration of depolarization. The inward rectifier current (I_k1) was not affected by GFA 100 μmol·L^-1 . It is concluded that GFA has inhibitory effects on I_k, which may contribute to its prolongation of cardiac repolarization.