Holopainen I
Department of Biomedical Sciences, University of Tampere, Finland.
Neurochem Res. 1988 Sep;13(9):853-8. doi: 10.1007/BF00970753.
The effects of ions on taurine and beta-alanine uptake were studied in astrocytes during cellular differentiation in primary cultures. The uptakes were strictly Na+-dependent and also inhibited by the omission of K+ and in the presence of ouabain suggesting that their transport is fuelled mainly by these cation gradients. Two sodium ions were associated in the transport of one taurine and beta-alanine molecule across cell membranes. A reduction in Cl- concentration also markedly inhibited the uptake of both amino acids, indicating that this anion is of importance in the transport processes. The similar ion dependency profiles of taurine and beta-alanine uptake corroborate the assumption that the uptake of these amino acids in astrocytes is mediated by the same carrier. In Na+- and K+-free media both taurine and beta-alanine uptakes were reduced significantly more in 14-day-old or older than in 7-day-old cultures. No significant changes occurred in the coupling ratio between Na+ and taurine or beta-alanine as a function of spontaneous cellular differentiation or upon dBcAMP treatment. These results suggest that the uptake systems of these structurally related amino acids in astrocytes have reached a relatively high degree of functional maturity by two weeks in culture.
在原代培养的星形胶质细胞分化过程中，研究了离子对牛磺酸和β-丙氨酸摄取的影响。摄取严格依赖于Na +，并且在缺少K +以及存在哇巴因的情况下也受到抑制，这表明它们的转运主要由这些阳离子梯度提供能量。在一个牛磺酸和β-丙氨酸分子跨细胞膜的转运过程中，有两个钠离子参与。Cl -浓度的降低也显著抑制了这两种氨基酸的摄取，表明该阴离子在转运过程中很重要。牛磺酸和β-丙氨酸摄取的相似离子依赖性特征证实了这样的假设，即星形胶质细胞中这些氨基酸的摄取是由同一载体介导的。在无Na +和K +的培养基中，14天及以上的培养物中牛磺酸和β-丙氨酸的摄取量比7天的培养物中显著降低更多。作为自发细胞分化或经二丁酰环磷腺苷（dBcAMP）处理的函数，Na +与牛磺酸或β-丙氨酸之间的偶联比率没有显著变化。这些结果表明，在培养两周后，星形胶质细胞中这些结构相关氨基酸的摄取系统已达到相对较高的功能成熟度。
