兔左室壁三层心肌细胞的分离及动作电位、钙和钾电流分布的异质性

Heterogeneity of action potential and ion currents in the left ventricular myocytes of the rabbit

探讨兔左室壁三层心肌单个细胞的分离方法以及电生理特征。实验以胶原酶按二步消化法分离兔心肌细胞 ,其中用剃须刀分离左室游离壁内、中、外三层心肌。采用全细胞膜片钳记录AP和离子电流。结果显示 :(1)中层细胞上的动作电位时程明显长于内膜下心肌和外膜下心肌 ,且存在显著的 1相切迹和 2相驼峰 ;(2 )中层细胞的ICa,L和Ito较内、外膜下的大 ,IK ,s相反。

Experiments were performed to investigate the heterogeneity of the action potential and ion currents in left ventricular myocytes of the rabbit. Myocytes were isolated by enzymatic method. The sub endocardial (Endo) and sub epicardium (Epi) tissues were separated from the other region (midmyocardium, M) with a razor. Single cells in each region were obtained by gentle shaking and dispersing in a chamber filled with normal Tyrode′s solution. The results showed that the action potential and the ion currents in the three layers were significantly different. M cells had a more pronounced spike and dome configuration, with a significantly larger phase 1 magnitude and plateau voltage. Action potential duration (APD) in M cells was longer than that in Epi or Endo cells. I Ca, L and I to in M cells were higher than those of Epi and Endo. On the contrary, I K,s in M cells was the minimum compared with those in the three LV walls. The differences in ion currents may well explain the heterogeneity of action potentials in M layers of the rabbit heart.