小鼠NIH 3T3细胞中哇巴因抗性钠钾转运系统

Ouabain-resistant Na+, K+ transport system in mouse NIH 3T3 cells.

作者信息

Atlan H, Snyder D, Panet R

出版信息

J Membr Biol. 1984;81(3):181-8. doi: 10.1007/BF01868712.

Abstract

It is shown that the ouabain-resistant (OR) furosemide-sensitive K+(Rb+) transport system performs a net efflux of K+ in growing mouse 3T3 cells. This conclusion is based on the finding that under the same assay conditions the furosemide-sensitive K+(Rb+) efflux was found to be two- to threefold higher than the ouabain-resistant furosemide-sensitive K+(Rb+) influx. The ouabain-resistant furosemide-sensitive influxes of both 22Na and 86Rb appear to be Cl- dependent, and the data are consistent with coupled unidirectional furosemide-sensitive influxes of Na+, K+ and Cl- with a ratio of 1:1:2. However, the net efflux of K+ performed by this transport system cannot be coupled to a ouabain-resistant net efflux of Na+ since the unidirectional ouabain-resistant efflux of Na+ was found to be negligible under physiological conditions. This latter conclusion was based on the fact that practically all the Na+ efflux appears to be ouabain-sensitive and sufficient to balance the Na+ influx under such steady-state conditions. Therefore, it is suggested that the ouabain-resistant furosemide-sensitive transport system in growing cells performs a facilitated diffusion of K+ and Na+, driven by their respective concentration gradients: a net K+ efflux and a net Na+ influx.

摘要

结果表明，哇巴因抗性（OR）且呋塞米敏感的K⁺（Rb⁺）转运系统在生长中的小鼠3T3细胞中执行K⁺的净外流。这一结论基于以下发现：在相同的测定条件下，呋塞米敏感的K⁺（Rb⁺）外流比哇巴因抗性的呋塞米敏感的K⁺（Rb⁺）内流高两到三倍。22Na和86Rb的哇巴因抗性的呋塞米敏感内流似乎都依赖于Cl⁻，并且数据与Na⁺、K⁺和Cl⁻的单向呋塞米敏感内流耦合一致，其比例为1:1:2。然而，该转运系统执行的K⁺净外流不能与Na⁺的哇巴因抗性净外流耦合，因为在生理条件下发现Na⁺的单向哇巴因抗性外流可忽略不计。后一结论基于以下事实：实际上所有的Na⁺外流似乎对哇巴因敏感，并且在这种稳态条件下足以平衡Na⁺内流。因此，有人提出，生长细胞中哇巴因抗性的呋塞米敏感转运系统执行由其各自浓度梯度驱动的K⁺和Na⁺易化扩散：K⁺净外流和Na⁺净内流。