粉防己碱对犬心浦氏纤维慢内向电流的作用

EFFECTS OF TETRANDRINE ON THE SLOW INWARD CURRENTS IN CANINE CARDIAC PURKINJE FIBERS

摘要: 应用双微电极电压钳技术,观察粉防己碱(Tet) 对犬心脏浦氏纤维细胞的慢内向电流I_si的影响,发现Tet对I_si的峰值有明显减弱作用。Tet的这种效应呈剂量及时间依赖性。当Tet浓度为30μmol/L和100μmol/L,给药后10min时,I_si的峰值分别由给药前的47.9±5.6 nA和38.4±21.5nA降至21±7.8nA和6.3±7.7nA,P值均小于0.01。Tet100μmol/L对由二价阳离子Sr²⁺所介导的I_si亦有明显的抑制作用。结果提示Tet是一慢通道阻滞剂。

Abstract: Effects of tetrandrine (Tet) on the slow inward currents in canine cardiac Purkinje fibers were studied by using two-microelectrode voltage clamp technique. Tet was shown to inhibit the peak value of the slow inward current (I_si PV) in dose-dependent and time-dependent manners. After pretreatment with Tet 30 and 100 μmol/L for 10 min, respectively, the I_si PV decreased from 47.90±5.6 nA and 38.4±21.5 nA to 21±7.8 nA and 6.3±7.7 nA (p<0.01). I_si PV induced by strontium instead of calcium ions was also significantly reduced after exposure to Tet 100 μmol/L. The results suggest that Tet is a slow channel blocker.