Sodium-bicarbonate cotransporter NBCn1 in the kidney medullary thick ascending limb cell line is upregulated under acidic conditions and enhances ammonium transport.
Sodium-bicarbonate cotransporter NBCn1 in the kidney medullary thick ascending limb cell line is upregulated under acidic conditions and enhances ammonium transport.
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DOI：
10.1113/expphysiol.2010.053967
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发表时间：
2010-09
影响因子：
2.7
通讯作者：
Choi I
中科院分区：
文献类型：
--
作者：
Lee S;Lee HJ;Yang HS;Thornell IM;Bevensee MO;Choi I
在这项研究中，我们研究了碳酸氢盐转运蛋白对髓质厚升肢细胞系ST-1中铵/氨摄取的影响。用1 mM哇巴因和0.2 mM布美他尼处理细胞以使载体介导的NH 4+转运最小化，并测定14 C-甲基铵/甲基氨（MA）的细胞内蓄积。在溶液中，细胞在正常pH值下短暂积累14 C-MA超过7分钟，并达到一个平台。然而，在溶液中，细胞显着积累14 C-MA在实验期间的30分钟。这种积累减少了碳酸氢盐转运阻滞剂4，4 '-二异硫氰酸芪-2，2'-二磺酸盐（DIDS; 0.5 mM）。用葡萄糖酸盐代替Cl-减少了积累，但在DIDS存在下减少更大。将细胞在pH 6.8（用NaHCO 3在5%CO2中调节）下孵育24小时，使平均稳态细胞内pH降至6.96，显著低于对照组的7.28。DIDS降低了对照组中14 C-MA的蓄积，但在酸孵育后无影响。免疫印迹显示，NBCn 1的上调后，酸性孵育，在NH 4Cl含介质。存在Cl/HCO 3交换器AE 2，但其表达不受酸性孵育的影响。在非洲爪蟾卵母细胞中表达，NBCn 1增加载体介导的14 C-MA运输，这是废除取代Na+。双电极电压钳的卵母细胞表现出可忽略不计的电流后NH 4Cl的应用。这些结果表明，DIDS敏感的挤出通常支配MTAL细胞中的NH 4 +/NH3摄取。我们建议，在酸性条件下，DIDS敏感的挤压失活，而NBCn 1上调刺激NH 4+运输。
In this study, we examined the effect of bicarbonate transporters on ammonium/ammonia uptake in the medullary thick ascending limb cell line ST-1. Cells were treated with 1 mM ouabain and 0.2 mM bumetanide to minimize carrier-mediated NH4+ transport, and the intracellular accumulation of 14C-methylammonium/methylammonia (MA) was determined. In solution, cells at normal pH briefly accumulated 14C-MA over 7 min and reached a plateau. In solution, however, cells markedly accumulated 14C-MA over the experiment period of 30 min. This accumulation was reduced by the bicarbonate transporter blocker 4,4’-diisothiocyanatostilbene-2,2’-disulfonate (DIDS; 0.5 mM). Replacing Cl– with gluconate reduced the accumulation but the reduction was more substantial in the presence of DIDS. Incubating cells at pH 6.8 (adjusted with NaHCO3 in 5% CO2) for 24 h lowered the mean steady-state intracellular pH to 6.96, significantly lower than 7.28 for controls. DIDS reduced 14C-MA accumulation in controls but had no effect after acidic incubation. Immunoblot showed that NBCn1 was upregulated after acidic incubation and in NH4Cl-containing media. The Cl/HCO3 exchanger AE2 was present but its expression remained unaffected by acidic incubation. Expressed in Xenopus oocytes, NBCn1 increased carrier-mediated 14C-MA transport, which was abolished by replacing Na+. Two-electrode voltage clamp of oocytes exhibited negligible current after NH4Cl application. These results suggest that DIDS-sensitive extrusion normally governs NH4+/NH3 uptake in the MTAL cells. We propose that, under acidic conditions, DIDS-sensitive extrusion is inactivated while NBCn1 is upregulated to stimulate NH4+ transport.
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影响因子：
4.5
作者：
Gamba, Gerardo;Friedman, Peter A.
通讯作者：
Friedman, Peter A.
DOI：
10.1111/j.1460-9568.2008.06611.x
发表时间：
2009-02
期刊：
The European journal of neuroscience
影响因子：
--
作者：
Cooper DS;Yang HS;He P;Kim E;Rajbhandari I;Yun CC;Choi I
通讯作者：
Choi I
影响因子：
4.8
作者：
Chang, Min-Hwang;DiPiero, Jennifer;Romero, Michael F.
通讯作者：
Romero, Michael F.
影响因子：
64.8
作者：
Choi, I;Aalkjaer, C;Boron, WF
通讯作者：
Boron, WF
DOI：
10.1152/ajprenal.00220.2000
发表时间：
2002-04-01
影响因子：
4.2
作者：
Bourgeois, S;Massé, S;Houillier, P
通讯作者：
Houillier, P