The effect of extracellular potassium on the intracellular potassium ion activity and transmembrane potentials of beating canine cardiac Purkinje fibers.
The effect of extracellular potassium on the intracellular potassium ion activity and transmembrane potentials of beating canine cardiac Purkinje fibers.
复制标题
DOI：
10.1085/jgp.69.4.463
复制
发表时间：
1977-04
影响因子：
3.8
通讯作者：
Rosen, M R
中科院分区：
文献类型：
--
作者：
Miura, D S;Hoffman, B F;Rosen, M R
我们使用含有 K+ 敏感液体离子交换剂的开放尖端微电极来直接测定跳动的犬心脏浦肯野纤维中的细胞内 K+ 活性。对于灌注了 Tyrode 溶液（其中 K+ 浓度为 4.0 mM）的制剂，37°C 时细胞内 K+ 活性 (ak) 为 130.0+/-2.3 mM（平均值+/-SE）。计算出的 K+ 平衡电位 (EK) 为 -100.6+/- 0.5 mV。使用填充有 3 M KCl 的传统微电极测量最大舒张电位 (ED) 和静息跨膜电位 (EM)，分别为 -90.6+/-0.3 和 -84.4+/-0.4 mV。当 [K+]o 减少至 2.0 mM 或增加至 6.0、10.0 和 16.0 mM 时，ak 保持不变。 [K+]o=2.0时，ED为-97.3+/-0.4，Em为-86.0+/-0.7 mV；在[K+]o=16.0 时，ED 降至-53.8+/-0.4 mV，Em 降至相同值。在此 [K+]o 值范围内，EK 从 - 119.0+/-0.3 变为 -63.6+/-0.2 mV。这些 EK 值与之前通过其他技术间接估计的值一致。
We used open tip microelectrodes containing a K+-sensitive liquid ion exchanger to determine directly the intracellular K+ activity in beating canine cardiac Purkinje fibers. For preparations superfused with Tyrode's solution in which the K+ concentration was 4.0 mM, intracellular K+ activity (ak) was 130.0+/-2.3 mM (mean+/-SE) at 37 degrees C. The calculated K+ equilibrium potential (EK) was -100.6+/- 0.5 mV. Maximum diastolic potential (ED) and resting transmembrane potential (EM) were measured with conventional microelectrodes filled with 3 M KCl and were -90.6+/-0.3 and -84.4+/-0.4 mV, respectively. When [K+]o was decreased to 2.0 mM or increased to 6.0, 10.0, and 16.0 mM, ak remained the same. At [K+]o=2.0, ED was -97.3+/-0.4 and Em - 86.0+/-0.7 mV; at [K+]o=16.0, ED fell to -53.8+/-0.4 mV and Em to the same value. Over this range of values for [K+]o, EK changed from - 119.0+/-0.3 to -63.6+/-0.2 mV. These values for EK are consistent with those previously estimated indirectly by other techniques.