HeLa细胞中膜转运与碱金属阳离子含量之间的相互关系。

Interrelation between membrane transport and the contents of alkali metal cations in HeLa cells.

作者信息

Ikehara T, Sakai T, Miyamoto H, Kaniike K

出版信息

Jpn J Physiol. 1982;32(1):13-24. doi: 10.2170/jjphysiol.32.13.

DOI:10.2170/jjphysiol.32.13

Abstract

The relation of membrane transport of alkali cations to their external concentrations or to their cellular contents was studied in HeLa cells. Chilling the cells at 0 degrees C reversed cell Na+ and K+ to a mirror image of the normal pattern. Upon rewarming to 37 degrees C the ouabain-sensitive Rb+ uptake became 2-fold faster than the control. A kinetic analysis revealed that the stimulation was due to an increase in the maximal rate of Rb+ uptake, Jmax. The increase in apparent Km was relatively small. The analysis also showed that the ouabain-sensitive cation transport system seemed to have two binding sites for Rb+. The stimulation of Rb+ uptake was related to an increase in cell Na+, and an addition of ouabain abolished such a relation. Net Na+ flux which was in the direction from inside the cells to the medium at hypernormal cell Na+ was iiincreased when cell Na+ ncreased. In contrast, net Na+ flux which was in the opposite direction in the presence of ovabain was reduced and became almost 0 at cell Na+ of 900 nmol/mg of protein. The Na+/Rb+ coupling ratio in the ouabain-sensitive cation transport was apparently less than 1 at nearly physiological cell Na+, but it approached 1.5 when cell Na+ was sufficiently high. The sum of cell K+ plus Rb+ varied inversely with cell Na+, and this relation was unaffected upon treatment with ouabain. When Rb+ uptake declined below 80% of the control, cell K+ plus Rb+ was reduced, however, 40% of the sum of cell cations was still preserved even after complete inhibition of the cation pumps by ouabain treatment of 2 hr. Interrelations of these results are discussed.

摘要

在HeLa细胞中研究了碱金属阳离子的膜转运与其细胞外浓度或细胞内含量之间的关系。将细胞在0℃冷冻会使细胞内的Na⁺和K⁺逆转至正常模式的镜像状态。当重新升温至37℃时，哇巴因敏感的Rb⁺摄取速度比对照组快2倍。动力学分析表明，这种刺激是由于Rb⁺摄取的最大速率Jmax增加所致。表观Km的增加相对较小。分析还表明，哇巴因敏感的阳离子转运系统似乎有两个Rb⁺结合位点。Rb⁺摄取的刺激与细胞内Na⁺的增加有关，添加哇巴因会消除这种关系。当细胞内Na⁺高于正常水平时，从细胞内向培养基方向的净Na⁺通量会随着细胞内Na⁺的增加而增加。相反，在存在哇巴因时方向相反的净Na⁺通量会减少，当细胞内Na⁺达到900 nmol/mg蛋白质时几乎变为0。在接近生理水平的细胞内Na⁺时，哇巴因敏感的阳离子转运中的Na⁺/Rb⁺偶联比明显小于1，但当细胞内Na⁺足够高时接近1.5。细胞内K⁺与Rb⁺之和与细胞内Na⁺呈反比变化，并且这种关系在用哇巴因处理后不受影响。然而，当Rb⁺摄取下降至低于对照组的80%时，细胞内K⁺与Rb⁺之和会减少，不过，即使在用哇巴因处理2小时完全抑制阳离子泵后，细胞阳离子总和的40%仍然保留。讨论了这些结果之间的相互关系。