[一价铊与钾在膜转运过程中的同构现象]

[The isomorphism of univalent thallium and potassium in membrane transport processes].

作者信息

Skul'skiĭ I A

出版信息

Tsitologiia. 1991;33(11):118-29.

Abstract

Thallium ions (T1+) are able to isomorphous replacement of K+ in various minerals. The similarity between. T1+ and K+ is based upon the closeness of their crystal radii, hydration energy and mobility in aqueous solutions. Under certain conditions, the behaviour of T1+ can be substantially different from that of K+. As distinguished from K+, thallium ions tend to associate with different anions forming ion pairs and complexes. As a rule, the stability of these compounds is rather low, but in many cases the T(1+)-anion interactions appear to play an important role in discriminating between T1+ and K+ involved in transport processes. T1+/K(+)-selectivity characterizes K(+)-transport mechanisms operating in different kinds of cells membranes. In excitable membranes (muscles, nerves) the rates of passive transport of T1+ and K+ are similar. In non-excitable membranes (epithelial cells, red blood cells, mitochondrial membranes, bacteria) the T1+ passive permeability is about one or two orders of magnitude higher than that of K+. A moderate T1+/K(+)-selectivity was reported for various types of K+ active transport mechanisms.

摘要

铊离子（Tl⁺）能够在各种矿物质中同晶取代钾离子（K⁺）。Tl⁺与K⁺之间的相似性基于它们晶体半径、水合能以及在水溶液中迁移率的相近性。在某些条件下，Tl⁺的行为可能与K⁺有很大不同。与K⁺不同，铊离子倾向于与不同阴离子形成离子对和配合物。通常，这些化合物的稳定性相当低，但在许多情况下，Tl⁺与阴离子的相互作用似乎在区分参与转运过程的Tl⁺和K⁺方面起着重要作用。Tl⁺/K⁺选择性表征了在不同类型细胞膜中起作用的K⁺转运机制。在可兴奋膜（肌肉、神经）中，Tl⁺和K⁺的被动转运速率相似。在非兴奋膜（上皮细胞、红细胞、线粒体膜、细菌）中，Tl⁺的被动通透性比K⁺高约一到两个数量级。对于各种类型的K⁺主动转运机制，报道了适度的Tl⁺/K⁺选择性。