Smith T C, Adams R
J Membr Biol. 1977 Jun 24;35(1):57-74. doi: 10.1007/BF01869940.
The intracellular distribution of Na+, K+, Cl- and water has been studied in the Ehrlich ascites tumor cell. Comparison of the ion and water contents of whole cells with those of cells exposed to La3+ and mechanical stress indicated that La3+ treatment results in selective damage to the cell membrane and permits evaluation of cytoplasmic and nuclear ion concentrations. The results show that Na+ is sequestered within the nucleus, while K+ and Cl- are more highly concentrated in the cell cytoplasm. Reduction of the [Na+] of the incubation medium by replacement with K+ results in reduced cytoplasmic [Na+], increased [Cl-] and no change in [K+]. Nuclear concentrations of these ions are virtually insensitive to the cation composition of the medium. Concomitant measurements of the membrane potential were made. The potential in control cells was -13.7 mV. Reduction of [Na+] in the medium caused significant depolarization. The measured potential is describable by the Cl- equilibrium potential and can be accounted for in terms of cation distributions and permeabilities. The energetic implications of the intracellular compartmentation of ions are discussed.
已对艾氏腹水肿瘤细胞中Na⁺、K⁺、Cl⁻和水的细胞内分布进行了研究。将完整细胞的离子和水含量与暴露于La³⁺和机械应力的细胞的离子和水含量进行比较，结果表明La³⁺处理会对细胞膜造成选择性损伤，并允许评估细胞质和细胞核中的离子浓度。结果显示，Na⁺被隔离在细胞核内，而K⁺和Cl⁻在细胞质中浓度更高。用K⁺替代培养介质中的Na⁺会导致细胞质中[Na⁺]降低、[Cl⁻]升高，而[K⁺]不变。这些离子的核浓度实际上对介质的阳离子组成不敏感。同时进行了膜电位的测量。对照细胞中的电位为-13.7 mV。介质中[Na⁺]的降低导致显著的去极化。测得的电位可用Cl⁻平衡电位来描述，并且可以根据阳离子分布和通透性来解释。文中讨论了离子在细胞内分隔的能量学意义。
