Lücke H, Stange G, Murer H
Biochem J. 1979 Jul 15;182(1):223-9. doi: 10.1042/bj1820223.
Uptake of SO(4) (2-) into brush-border membrane vesicles isolated from rat kindey cortex by a Ca(2+)-precipitation method was investigated by using a rapid-filtration technique. Uptake of SO(4) (2-) by the vesicles was osmotically sensitive and represented transport into an intra-vesicular space. Transport of SO(4) (2-) by brush-border membranes was stimulated in the presence of Na(+), compared with the presence of K(+) or other univalent cations. A typical ;overshoot' phenomenon was observed in the presence of an NaCl gradient (100mm-Na(+) outside/zero mm-Na(+) inside). Radioactive-SO(4) (2-) exchange was faster in the presence of Na(+) than in the presence of K(+). Addition of gramicidin-D, an ionophore for univalent cations, decreased the Na(+)-gradient-driven SO(4) (2-) uptake. SO(4) (2-) uptake was only saturable in the presence of Na(+). Counter-transport of Na(+)-dependent SO(4) (2-) transport was shown with MoO(4) (2-) and S(2)O(3) (2-), but not with PO(4) (2-). Changing the electrical potential difference across the vesicle membrane by establishing different diffusion potentials (anion replacement; K(+) gradient+/-valinomycin) was not able to alter Na(+)-dependent SO(4) (2-) uptake. The experiments indicate the presence of an electroneutral Na(+)/SO(4) (2-)-co-transport system in brush-border membrane vesicles isolated from rat kidney cortex.
采用快速过滤技术，研究了通过Ca(2+)沉淀法从大鼠肾皮质分离的刷状缘膜囊泡对SO(4)(2-)的摄取。囊泡对SO(4)(2-)的摄取具有渗透敏感性，代表其转运至囊泡内空间。与存在K(+)或其他单价阳离子相比，在存在Na(+)的情况下，刷状缘膜对SO(4)(2-)的转运受到刺激。在存在NaCl梯度（外部100mM-Na(+)/内部零mM-Na(+)）的情况下观察到典型的“过冲”现象。放射性SO(4)(2-)交换在存在Na(+)时比在存在K(+)时更快。添加短杆菌肽-D（一种单价阳离子离子载体）可降低由Na(+)梯度驱动的SO(4)(2-)摄取。SO(4)(2-)摄取仅在存在Na(+)时可饱和。Na(+)依赖性SO(4)(2-)转运的反向转运在MoO(4)(2-)和S(2)O(3)(2-)存在时表现出来，但在PO(4)(2-)存在时未表现出来。通过建立不同的扩散电位（阴离子替代；K(+)梯度+/-缬氨霉素）改变囊泡膜两侧的电位差，无法改变Na(+)依赖性SO(4)(2-)摄取。这些实验表明，从大鼠肾皮质分离的刷状缘膜囊泡中存在一种电中性的Na(+)/SO(4)(2-)共转运系统。
