氨茶碱对豚鼠心脏乳头肌动作电位的影响

The effect of aminophylline on the action potential of the guinea pig papillary muscle cells

研究氨茶碱对豚鼠心脏乳头肌动作电位的影响。实验结果表明：１．８ｍｍｏｌ·Ｌ－１浓度的氨茶碱对心肌动作电位各项测试指标均无明显作用。当浓度达到３．６ｍｍｏｌ·Ｌ－１时，则ＡＰＤ、ＡＰＤ９０显著延长．复极斜率Ｋ５０、Ｋ７５明显变小，而静息电位（ＲＰ）、ＡＰＡ、Ｖｍａｘ无明显变化．该剂量药物所引起的最为明显的作用是动作电位第３期晚期复极延缓．呈现隆起现象或称长尾现象，后者在一定条件下可能导致触发发放，形成早后去极化．此现象的发生可能与氨茶碱使心肌细胞Ｋ＋电导（ＧＫ１）降低．Ｋ＋外流减少．进而促进某一种内向电流活动增强有关。

The eletrophysiological actionof aminophylline was studied by standard microelectrode technique in isolated guinea pig papillary muscle cells.In low concentration(1.8mmol·L-1),aminophylline had no significanteffect on action potential.In high concentration(3.6 mmol· L-1), aminophylline also had nosignificant effect on RP,APA,and Vmax butProlonged APD, APD90 and induced a markeddelay in the final repolarization(induction of a“tail”of a hump).This process may be relatedto the decrease of potassium conductance,sothat one inward current may increase.