TAURINE TRANSPORT IN RAT ASTROCYTES ADAPTED TO HYPEROSMOTIC CONDITIONS
TAURINE TRANSPORT IN RAT ASTROCYTES ADAPTED TO HYPEROSMOTIC CONDITIONS
复制标题
DOI：
10.1016/0006-8993(93)90447-u
复制
发表时间：
1993-06-04
期刊：
影响因子：
2.9
通讯作者：
OLSON, JE
中科院分区：
文献类型：
--
作者：
BEETSCH, JW;OLSON, JE
[H-3]研究正常和高渗培养条件下培养的大鼠大脑皮层星形胶质细胞对牛磺酸的摄取和释放，以探讨细胞体积调节和适应渗透压改变状态的机制。在高浓度牛磺酸(1 MM)中，摄取在两种渗透条件下都是线性的，持续至少30分钟。1 mM牛磺酸的摄取速率不受高渗条件的影响。载体介导牛磺酸转运的平均+/-S.E.M.表观结合常数K(M)不受高渗条件的影响(等渗介质为22.8+/-5.1um，高渗介质为21.3+/-11.9um)。然而，高渗处理的星形胶质细胞的最大摄取速度V(Max)(平均值+/-S.E.M.)显著低于等渗处理的星形胶质细胞的V(Max)(0.299+/-0.026 nmol/mg蛋白.min)。扩散转运速率K(Diff)不受高渗条件下生长的影响(等渗条件下为0.221+/-0.033 mul/mg蛋白·min，高渗条件下为0.295+/-0.043 mul/mg蛋白·min)。牛磺酸的释放率，以细胞总含量的百分比表示，不受高渗暴露的影响。然而，在高渗条件下生长的星形胶质细胞含有的牛磺酸比对照细胞多近60%。因此，牛磺酸的绝对释放率(平均值+/-S.E.M.)显著增加(P<0.05)。
[H-3]Taurine uptake and release was characterized in astrocytes from rat cerebral cortex grown in normal and hyperosmotic culture conditions to investigate mechanisms of cell volume regulation and adaptation to states of altered osmolality. In high concentrations of taurine (1 mM), uptake was linear in both osmotic conditions for at least 30 min. The uptake rate in 1 mM taurine was not affected by exposure to hyperosmotic conditions. The mean +/- S.E.M. apparent binding constant for carrier-mediated taurine transport, K(m), was not altered by hyperosmotic conditions (22.8 +/- 5.1 muM in iso-osmotic media, 21.3 +/- 11.9 muM in hyperosmotic media). However, maximal velocity of uptake, V(max) (mean +/- S.E.M.), of taurine was significantly lower in hyperosmotically treated astrocytes (0.175 +/- 0.035 nmol/mg protein.min) compared with the V(max) of iso-osmotically treated astrocytes (0.299 +/- 0.026 nmol/mg protein.min). The diffusional transport rate, K(diff), was not affected by growth in hyperosmotic conditions (0.221 +/- 0.033 mul/mg protein.min in iso-osmotic media, 0.295 +/- 0.043 mul/mg protein.min in hyperosmotic media). Taurine release rate, expressed as a percent of the total cell content, was not affected by hyperosmotic exposure. However, astrocytes grown in hyperosmotic conditions contain nearly 60% more taurine than control cells. Thus, the absolute rate of taurine release (mean +/- S.E.M.) was significantly larger (P