Sulfate transport in human lung fibroblasts (IMR-90): effect of pH and anions.
Sulfate transport in human lung fibroblasts (IMR-90): effect of pH and anions.
复制标题
人肺成纤维细胞 (IMR-90) 中的硫酸盐转运：pH 值和阴离子的影响。
DOI：
10.1152/ajpcell.1989.256.3.c486
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Meezan,E
中科院分区：
文献类型：
--
作者：
Elgavish,A;Meezan,E
我们先前报道了在人肺成纤维细胞（IMR-90）中存在载体介导的硫酸盐转运系统（A. Elgavish，J. B.史密斯，D. J. Pillion和E.米赞J.细胞。125：243-250，1985）。在肺成纤维细胞中进行的动力学研究表明，Cl-以竞争性方式抑制SO 4（2-）摄取。结合细胞外高Cl-刺激SO 4（2-）外排的事实，这些结果表明肺成纤维细胞通过SO 4（2-）-Cl-交换机制摄取SO 4（2-）。细胞外HCO 3-以竞争性方式抑制硫酸盐内流（pH 7.5），但对硫酸盐外排无明显影响。因此，SO 4（2-）和HCO 3-可能具有结合到共同的胞外阴离子结合位点的能力，但它们似乎不会彼此交换。降低细胞外pH对硫酸盐吸收的初始速率具有刺激作用。细胞外pH效应的pK约为pH 7.0，表明在生理条件下遇到的周围环境水平的细胞外pH的微小变化将显著影响硫酸盐流入细胞。动力学研究表明，降低细胞外pH值增加硫酸盐流入的初始速率，通过增加的亲和力的载体硫酸盐的两倍。降低细胞内pH抑制硫酸盐流入细胞的初始速率。这种细胞内pH效应的pK也在pH 7.0左右，表明生理水平的细胞内质子对于阴离子交换剂的正常活性是必需的。（250字处删节）
We previously reported the presence of a carrier-mediated sulfate transport system in human lung fibroblasts (IMR-90) (A. Elgavish, J. B. Smith, D. J. Pillion, and E. Meezan. J. Cell. Physiol. 125: 243-250, 1985). Kinetic studies carried out in the lung fibroblasts show that Cl- inhibits SO4(2-) uptake in a competitive manner. Taken together with the fact that high extracellular Cl- stimulates SO4(2-) efflux, these results suggest that SO4(2-) uptake into lung fibroblasts occurs via a SO4(2-)-Cl- exchange mechanism. Extracellular HCO3- inhibits sulfate influx in a competitive manner (pH 7.5) but has no marked effect on sulfate efflux. SO4(2-) and HCO3- may therefore have the ability to bind to a common extracellular anion binding site, but they do not appear to exchange for one another. Lowering extracellular pH has a stimulatory effect on the initial rate of sulfate uptake. The pK of the extracellular pH effect is around pH 7.0, indicating that small changes in the extracellular pH around the ambient levels encountered under physiological conditions will markedly affect sulfate influx into the cell. Kinetic studies suggest that lowering extracellular pH increases the initial rate of sulfate influx by increasing the affinity of the carrier for sulfate twofold. Lowering intracellular pH inhibits the initial rate of sulfate influx into the cell. The pK of this intracellular pH effect is also around pH 7.0, indicating that physiological levels of intracellular protons are necessary for the normal activity of the anion exchanger.(ABSTRACT TRUNCATED AT 250 WORDS)