ELECTRICAL RESTITUTION PROCESS IN DISPERSED CANINE CARDIAC PURKINJE AND VENTRICULAR CELLS
ELECTRICAL RESTITUTION PROCESS IN DISPERSED CANINE CARDIAC PURKINJE AND VENTRICULAR CELLS
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DOI：
10.1152/ajpheart.1987.253.5.h1018
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发表时间：
1987-11-01
影响因子：
--
通讯作者：
HEWETT, KW
中科院分区：
文献类型：
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作者：
ROBINSON, RB;BOYDEN, PA;HEWETT, KW
心脏动作电位持续时间（APD）的速率依赖性变化与限制性细胞外空间的离子积累和消耗有关。分离的心肌细胞缺乏细胞间隙，因此与完整的组织相比，在质膜外经历离子瞬变的可能性更小。此外，分离的浦肯野细胞缺乏在心室组织和细胞中发现的T小管，这也可能是离子积累和消耗的一个部位。因此，我们采用单犬心室和浦肯野细胞来研究限制空间对电恢复过程的贡献。在这两种细胞类型中，周期长度的突变不会改变静息电位，但APD以大约1分钟的时间常数改变。此外，这两种制剂在APD的电恢复过程中都表现出两种成分。快速组分在脑室细胞中的时间常数为66 +/- 17 ms，在浦肯野细胞中的时间常数为186 +/- 43 ms。较慢的组件既小又多变。这些值与完整犬心室和浦肯野组织的报告相似。因此，在这些分离的心脏细胞中测量到的APD的恢复过程并不明显依赖于限制性细胞外空间的存在与否。
Rate-dependent changes in cardiac action potential duration (APD) have been related to ion accumulation and depletion in restricted extracellular spaces. Isolated cardiac cells lack intercellular clefts and thus are less likely than intact tissue to experience ionic transients immediately outside the plasma membrane. Furthermore, isolated Purkinje cells lack the T tubules found in ventricular tissue and cells, which also can be a site of ion accumulation and depletion. We therefore employed single canine ventricular and Purkinje cells to investigate the contribution of restricted spaces to the electrical restitution process. In both cell types, abrupt changes in cycle length do not alter resting potential, but APD alters with a time constant of approximately 1 min. In addition, both preparations exhibit two components to the electrical restitution process of the APD. The rapid component has a time constant of 66 +/- 17 ms in the ventricle cells and 186 +/- 43 ms in the Purkinje cells. The slower component is both smaller and more variable. These values are similar to those reported in intact canine ventricular and Purkinje tissue. Thus the restitution process of APD, as measured in these isolated cardiac cells, is not markedly dependent on the presence or absence of restricted extracellular spaces.