Differences in regional distribution of K+ current densities in rat ventricle
Differences in regional distribution of K+ current densities in rat ventricle
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DOI：
10.1016/s0024-3205(98)00287-2
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发表时间：
1998-06-26
期刊：
影响因子：
6.1
通讯作者：
Sánchez-Chapula, JA
中科院分区：
文献类型：
--
作者：
Casis, O;Iriarte, M;Sánchez-Chapula, JA
本工作的目的是研究大鼠脑室动作电位时程区域差异的离子机制。这种地区多样性与地区之间的差异有关。某些钾电流在几个物种中的分布。用酶法分散大鼠心室肌组织片段，获得单个细胞。用全细胞电压钳方法识别参与不同区域动作电位复极的K+电流。4-氨基吡啶、TEA和电压方案被用来分离下列钾电流：瞬时外向电流、I-to、延迟整流、I-k和持续电流I-ss。在本工作中，我们研究了这三种复极电流以及内向整流电流I-K_1在右室游离壁、左室心尖部心外膜下和左室底心内膜下的分布。动作电位持续时间左室长于右室，左室心内膜下长于心尖部心外膜下。主要的不同是在阶段1，这表明I-to的含义。电压钳实验证实了这一点。综上所述，这项工作表明，电流密度在动作电位较短的区域较高，而i-k、i-ss或i-k1的区域分布没有差异。
The objective of the present work is to study the ionic mechanisms for the regional differences in action potential duration in rat ventricle. This regional diversity has been related to differences in the regional. distribution of some potassium currents in several species. Single cells were obtained by enzymatic dispersion of tissue segments from rat ventricular muscle. Whole cell voltage-clamp methods were used to identify the K+ currents involved in action potential repolarisation in the different regions. 4-Aminopiridine, TEA and voltage protocols were used to isolate the following potassium currents: transient outward, I-to, delayed rectifier, I-k, and sustained current, I-ss. In the present work, we have studied the distribution of these three repolarising currents, and that of the inward rectifier, I-k1, in the free wall of the right ventricle, the subepicardium of the apex of the left ventricle and in the subendocardium of the base of the left ventricle. Action potential duration was longer in the left than in the right ventricle, and in the former it was longer in the subendocardium of the base than in the subepicardium of the apex. The main difference was in the phase 1, suggesting the implication of I-to. This was confirmed with voltage-clamp experiments. In conclusion, this work shows that It, current density is higher in the regions with the shorter action potential, whereas there are no differences in the regional distribution of I-k I-ss or I-k1.