在存在和不存在选定代谢抑制剂的情况下，钠离子和钾离子对小鼠腹水肿瘤细胞摄取甘氨酸的影响。

The effects of sodium ions and potassium ions on glycine uptake by mouse ascites-tumour cells in the presence and absence of selected metabolic inhibitors.

作者信息

Eddy A A, Mulcahy M F, Thomson P J

出版信息

Biochem J. 1967 Jun;103(3):863-76. doi: 10.1042/bj1030863.

DOI:10.1042/bj1030863

PMID:6072273

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1270492/

Abstract

The initial rate, v, of glycine uptake by ascites-tumour cells respiring their endogenous nutrient reserves was studied as a function of the respective extracellular concentrations of glycine, Na(+) and K(+). With the extracellular concentration of Na(+)+K(+) constant at 158m-equiv./l. and that of glycine either 4 or 12mm, v tended to zero as the extracellular concentration of Na(+) approached zero. Glycine appeared to enter the cells as a ternary complex with a carrier and Na(+). K(+) competed with Na(+) for one of the carrier sites, whereas glycine was bound at a second site. The values of the five relevant binding constants showed that the two sites interacted. 2. The glycine uptake rate at various extracellular concentrations of glycine and Na(+) was scarcely affected by starving the cells for 30min. in the presence of 2mm-sodium cyanide provided that cellular Na(+) and K(+) contents were kept at the normal values. When the cells took up Na(+), however, v decreased approximately threefold. 3. When their Na(+) content was relatively small and the extracellular concentration of Na(+) was large, the starved cells accumulated glycine in the presence of cyanide for about 15min. Glycine then tended to leave the cells. An average of about 5mumoles of glycine/ml. of cell water was taken up from a 1mm solution, representing about 20% of the accumulation observed during respiration. Studies with fluoride, 2,4-dinitrophenol and other metabolic inhibitors supported the view that ATP and similar compounds were not implicated. The relation between the transient accumulation of glycine that occurred in these circumstances and the normal mode of active transport was not established.

摘要

研究了腹水肿瘤细胞利用其内源性营养储备进行呼吸时甘氨酸摄取的初始速率v，它是甘氨酸、Na⁺和K⁺各自细胞外浓度的函数。当细胞外Na⁺ + K⁺浓度恒定在158毫当量/升，甘氨酸浓度为4或12毫摩尔时，随着细胞外Na⁺浓度接近零，v趋于零。甘氨酸似乎以与载体和Na⁺形成的三元复合物形式进入细胞。K⁺与Na⁺竞争载体的一个位点，而甘氨酸结合在另一个位点。五个相关结合常数的值表明这两个位点相互作用。2. 在2毫摩尔氰化钠存在下将细胞饥饿30分钟，只要细胞内Na⁺和K⁺含量保持在正常水平，不同细胞外甘氨酸和Na⁺浓度下的甘氨酸摄取速率几乎不受影响。然而，当细胞摄取Na⁺时，v大约降低三倍。3. 当细胞内Na⁺含量相对较低且细胞外Na⁺浓度较高时，饥饿的细胞在氰化物存在下积累甘氨酸约15分钟。然后甘氨酸倾向于离开细胞。从1毫摩尔溶液中平均每毫升细胞水摄取约5微摩尔甘氨酸，约占呼吸过程中积累量的20%。用氟化物、2,4 -二硝基苯酚和其他代谢抑制剂进行的研究支持了ATP和类似化合物未参与其中的观点。在这些情况下发生的甘氨酸瞬时积累与正常主动运输模式之间的关系尚未确定。