Graves J S, Wheeler D D
Am J Physiol. 1982 Sep;243(3):C124-32. doi: 10.1152/ajpcell.1982.243.3.C124.
We have studied the effects of prolonged incubation in low [K+] medium (approximately 0.3 mM) on both K+ and amino acid transport in Chinese hamster ovary (CHO) cells. When incubated in low [K+] medium, CHO cells redressed partially the loss of intracellular K+ after 12 h. After 24 h of incubation, both the activity of Na+-K+-ATPase in crude homogenates, and the transport capacity (Vmax) for ouabain-sensitive (i.e., active) K+ influx approximately doubled. The magnitude of the ouabain-insensitive (i.e., passive) K+ influx decreased by 50%. Thus the regulatory response involves an apparent increase in Na+-K+ pump and a decrease in K+ leak. The transport capacity for the nonmetabolized amino acid, alpha-aminoisobutyric acid (alpha-AIB), also increased after 24 h in low [K+] medium. The Vmax for the Na+-dependent (i.e., active) alpha-AIB influx increased by about 150%, and the magnitude of the Na+-independent influx increased by 20-40%. These changes in alpha-AIB transport result in a twofold greater capacity to accumulate this amino acid. Thus the regulation of K+ and alpha-AIB transport systems appears to be linked and possible mechanisms of this linkage are discussed.
我们研究了在低[K⁺]培养基（约0.3 mM）中长时间孵育对中国仓鼠卵巢（CHO）细胞中K⁺和氨基酸转运的影响。当在低[K⁺]培养基中孵育时，CHO细胞在12小时后部分纠正了细胞内K⁺的损失。孵育24小时后，粗匀浆中Na⁺-K⁺-ATP酶的活性以及哇巴因敏感（即主动）K⁺内流的转运能力（Vmax）大约增加了一倍。哇巴因不敏感（即被动）K⁺内流的幅度降低了50%。因此，调节反应涉及Na⁺-K⁺泵的明显增加和K⁺泄漏的减少。在低[K⁺]培养基中孵育24小时后，非代谢氨基酸α-氨基异丁酸（α-AIB）的转运能力也增加了。Na⁺依赖性（即主动）α-AIB内流的Vmax增加了约150%，非Na⁺依赖性内流的幅度增加了20 - 40%。α-AIB转运的这些变化导致积累这种氨基酸的能力提高了两倍。因此，K⁺和α-AIB转运系统的调节似乎是相关的，并讨论了这种联系的可能机制。
