Civan M M
Fed Proc. 1980 Sep;39(11):2865-70.
In general, intracellular K+ appears to be compartmentalized. This phenomenon does not seem to characterize cytoplasm per se, but probably reflects the processes of sequestration and ion exclusion characterizing certain as yet unidentified organelles. The cell nucleus does not appear to participate significantly in these processes. Measurement of intracellular potassium activity (alpha K)c in small epithelial cells is complicated by significant technical problems. Recent experimental maneuvers designed to circumvent these problems have led to substantially higher estimates of (alpha K)c under baseline conditions. The time courses of short circuit current (SCC) and (alpha K)c in toad urinary bladder have been correlated under two experimental conditions. After removing external K+ or after adding ouabain, both parameters are depressed. However, the time courses of SCC and (alpha K)c are very different following return to baseline conditions. The data suggest: 1) that the processes of cell K+ accumulation and transepithelial Na+ transport are not linked with a fixed stoichiometry, and 2) if a reduction in cytosolic K+ activity does inhibit transepithelial Na+ transport, its role is indirect.
一般来说，细胞内的钾离子似乎是被分隔开的。这种现象本身似乎并非细胞质的特征，而可能反映了某些尚未明确的细胞器的隔离和离子排斥过程。细胞核似乎并未显著参与这些过程。在小上皮细胞中测量细胞内钾离子活性（αK）c存在重大技术难题。最近旨在规避这些问题的实验操作导致在基线条件下对（αK）c的估计值大幅提高。在两种实验条件下，蟾蜍膀胱中短路电流（SCC）和（αK）c的时间进程已被关联起来。去除外部钾离子或添加哇巴因后，这两个参数都会降低。然而，恢复到基线条件后，SCC和（αK）c的时间进程差异很大。数据表明：1）细胞钾离子积累过程和跨上皮钠离子转运过程并非以固定的化学计量关系相联系；2）如果细胞质中钾离子活性的降低确实抑制了跨上皮钠离子转运，其作用是间接的。
