【摘要】 目的探讨PD-118057对hERG电流抑制的对抗作用及对不同情况导致的豚鼠心肌细胞动作电位时程(APD)延长的影响。方法利用膜片钳技术,在稳态转染hERG基因的HEK-293细胞上,分别在常规方波和动作电位钳制下观察PD-118057对多菲利特(Dof)和莫西沙星(Mox)抑制电流的逆转情况;采用酶法急性分离豚鼠的心室肌细胞,采用穿孔膜片钳技术记录豚鼠心肌细胞的动作电位,观察PD-118057对IKr抑制剂Dof和Mox、IKs抑制剂chromanol 293B以及低钾灌流情况下引起的APD延长的影响。结果在HEK-293细胞上,10μmol·L-1PD-118057能对抗Dof(15 nmol·L-1)、Mox(100μmol·L-1)对hERG电流的抑制,明显增加了激活电流和尾电流;以心室肌动作电位诱发出hERG电流,电流形状呈"驼峰"样波形,PD-118057能逆转Dof(10 nmol·L-1)和Mox(100μmol·L-1)引起的峰值降低,但不改变电流形状和峰值的位置。在豚鼠心室肌细胞上,10μmol·L-1PD-118057能逆转Dof(15 nmol·L-1)、Mox(100μmol·L-1)、chromanol 293B(20μmol·L-1)和低钾(2.1 mmol·L-1)灌流引起的APD延长。结论 PD-118057可有效地逆转心室肌细胞APD的延长。更多还原

【Abstract】 OBJECTIVE To investigate the effects of hERG channel activator PD- 118057 on the drug- inhibited hERG current and the prolongation of action potential duration(APD) induced by different factors. METHODS Whole- cell hERG current was recorded with the conventional patch- clamp technique in human embryonic kidney 293( HEK- 293) cells,which was stably transfected with the hERG channel. Effects of PD- 118057 on the inhibition of hERG currents by dofetilide(Dof) or moxifloxacin(Mox) were tested under regular pulse protocol and action potential protocols. Action potential recordings were performed in isolated guinea pig ventricular myocytes using the perforated patch technique. Effect of PD- 118057 on converting the pathological prolongation of APD was examined.RESULTS PD- 118057 significantly attenuated the reduction of hERG current both in the step and tail current amplitudes induced by Dof(10 nmol·L- 1) and Mox(100 μmol·L- 1). Under action potential clamp,PD-118057 partly reversed the inhibition of peak repolarizing currents by Dof and Mox and did not change the"hump"shape of hERG current. Upon application of IKrinhibitor,Dof(15nmol·L- 1) or Mox(100 μmol·L- 1),or IKsinhibitor Chromanol 293B(20 μmol·L- 1) or hypokalaemia(2.1 mmol·L- 1),APD were evidently prolonged in the different extent. The APD prolongation was reversed by co- application of 10 μmol·L- 1PD- 118057.CONCLUSION The study indicated that hERG channel activator PD- 118057 can effectively attenuate hypokalaemia or drug-induced prolongation of APD.更多还原