Zelikovic I, Stejskal-Lorenz E, Lohstroh P, Budreau A, Chesney R W
Department of Pediatrics, University of Tennessee, College of Medicine, Memphis 38163.
Am J Physiol. 1989 Apr;256(4 Pt 2):F646-55. doi: 10.1152/ajprenal.1989.256.4.F646.
The anionic requirements and the stoichiometric relationships of Na+-taurine cotransport into rat renal brush-border membrane vesicles (BBMV) were evaluated. External Cl- (100 mM) or Br- (100 mM) gradients supported the full overshoot of Na+-taurine symport and yielded similar high-affinity transport systems for taurine uptake. No active uptake of taurine was evident in the presence of external (100 mM) NaF, NaI, Na gluconate, or Na p-aminohippurate (PAH). Na+:taurine stoichiometry was 2.18:1 in the presence of Cl- and 1.60:1 in the presence of Br-. When the external anion gluconate was employed, Na+-dependent taurine uptake was negligible over the whole range of Na+ concentrations examined. Cl-:taurine and Br-:taurine stoichiometries in the presence of external Na+ were 0.97:1 and 0.81:1, respectively. External furosemide (1 mM) or bumetanide (1 mM) did not change taurine accumulation and kinetic parameters. The anionic transport inhibitors 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (5 x 10(-4) M), N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (10(-3) M) and p-chloromercuribenzoate (5 x 10(-4) M) significantly decreased initial rate of taurine uptake by 48, 31, and 31%, respectively. These data suggest that Na+-taurine cotransport into rat renal BBMV is Cl- or Br- dependent and probably operates by means of 2 Na+:1 Cl- or Br-:1 taurine carrier complex. Na+-taurine symport across the rat renal brush-border membrane surface is not affected by diuretics that influence NaCl cotransport but is affected by selected anionic transport inhibitors. An intact anionic binding site may be needed for this translocation process.
评估了Na⁺-牛磺酸共转运进入大鼠肾刷状缘膜囊泡（BBMV）的阴离子需求和化学计量关系。外部Cl⁻（100 mM）或Br⁻（100 mM）梯度支持Na⁺-牛磺酸同向转运的完全过冲，并产生了类似的高亲和力牛磺酸摄取转运系统。在存在外部（100 mM）NaF、NaI、葡萄糖酸钠或对氨基马尿酸钠（PAH）的情况下，未观察到牛磺酸的主动摄取。在存在Cl⁻时，Na⁺:牛磺酸化学计量比为2.18:1，在存在Br⁻时为1.60:1。当使用外部阴离子葡萄糖酸盐时，在整个检测的Na⁺浓度范围内，Na⁺依赖性牛磺酸摄取可忽略不计。在存在外部Na⁺时，Cl⁻:牛磺酸和Br⁻:牛磺酸化学计量比分别为0.97:1和0.81:1。外部速尿（1 mM）或布美他尼（1 mM）不改变牛磺酸积累和动力学参数。阴离子转运抑制剂4,4'-二异硫氰基芪-2,2'-二磺酸（5×10⁻⁴ M）、N-(4-叠氮基-2-硝基苯基)-2-氨基乙磺酸盐（10⁻³ M）和对氯汞苯甲酸（5×10⁻⁴ M）分别使牛磺酸摄取的初始速率显著降低48%、31%和31%。这些数据表明，Na⁺-牛磺酸共转运进入大鼠肾BBMV是Cl⁻或Br⁻依赖性的，可能通过2个Na⁺:1个Cl⁻或Br⁻:1个牛磺酸载体复合物起作用。大鼠肾刷状缘膜表面的Na⁺-牛磺酸同向转运不受影响NaCl共转运的利尿剂影响，但受选定的阴离子转运抑制剂影响。这种转运过程可能需要完整的阴离子结合位点。
