Jentsch T J, Schill B S, Schwartz P, Matthes H, Keller S K, Wiederholt M
J Biol Chem. 1985 Dec 15;260(29):15554-60.
Na movement across the plasma membranes of confluent monolayers of monkey kidney epithelial cells (BSC-1) was studied using 22Na+ uptake and efflux techniques in the presence of 10(-4) M ouabain. In the presence of 28 mM bicarbonate, uptake was inhibited by both 10(-3) M amiloride and 10(-3) M 4,4'diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In DIDS-pretreated cells, 10(-3) M amiloride led to a further reduction of 22Na+ uptake, while 10(-5) furosemide was ineffective. DIDS also inhibited sodium efflux, indicating that the DIDS-sensitive pathway mediates both influx and efflux of 22Na+. DIDS-sensitive 22Na+ uptake, as studied in the presence of both 10(-4) M ouabain and 10(-3) M amiloride, was abolished by the absence of bicarbonate, which could not be substituted by other plasma membrane-permeable buffers. In 28 mM HCO3-, DIDS-sensitive uptake of 28 mM Na+ was cis-inhibited by 124 mM Na+, but no significant inhibition by K+ or Li+ was found. DIDS-sensitive 22Na+ uptake was a saturable function of both Na+ concentration (apparent Km between 20 and 40 mM at 28 mM HCO3-) and HCO3- concentration (apparent Km between 7 and 14 mM at 151 mM Na+). Intracellular microelectrode measurements showed that net Na+ transport in the presence of HCO3- is electrogenic, i.e. that there is anion cotransport with Na+. This effect is abolished by 1 mM DIDS. It is concluded that monkey kidney epithelial cells possess a stilbene-sensitive, electrogenic sodium bicarbonate symport, which may play an important role in bicarbonate reabsorption in the mammalian kidney.
运用22Na+摄取和流出技术，在存在10(-4) M哇巴因的情况下，研究了猴肾上皮细胞（BSC-1）融合单层细胞膜上的钠运动。在存在28 mM碳酸氢盐的情况下，10(-3) M氨氯吡脒和10(-3) M 4,4'-二异硫氰基芪-2,2'-二磺酸（DIDS）均抑制钠摄取。在经DIDS预处理的细胞中，10(-3) M氨氯吡脒导致22Na+摄取进一步减少，而10(-5) 速尿无效。DIDS也抑制钠流出，表明DIDS敏感途径介导22Na+的流入和流出。在存在10(-4) M哇巴因和10(-3) M氨氯吡脒的情况下研究的DIDS敏感的22Na+摄取，因不存在碳酸氢盐而被消除，其他可透过质膜的缓冲液无法替代碳酸氢盐。在28 mM HCO3-中，124 mM Na+对28 mM Na+的DIDS敏感摄取有顺式抑制作用，但未发现K+或Li+有明显抑制作用。DIDS敏感的22Na+摄取是Na+浓度（在28 mM HCO3-时表观Km在20至40 mM之间）和HCO3-浓度（在151 mM Na+时表观Km在7至14 mM之间）的饱和函数。细胞内微电极测量表明，在存在HCO3-的情况下净钠转运是生电性的，即存在与Na+的阴离子共转运。1 mM DIDS可消除此效应。结论是猴肾上皮细胞具有一种对芪敏感的生电性碳酸氢钠同向转运体，其可能在哺乳动物肾脏的碳酸氢盐重吸收中起重要作用。
