Sodium-bicarbonate cotransporter NBCn1/Slc4a7 inhibits NH4Cl-mediated inward current in Xenopus oocytes.
Sodium-bicarbonate cotransporter NBCn1/Slc4a7 inhibits NH4Cl-mediated inward current in Xenopus oocytes.
复制标题
DOI：
10.1113/expphysiol.2011.057844
复制
发表时间：
2011-08
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;Choi I
电中性 Na/HCO3 协同转运蛋白 NBCn1 (SLC4A7) 有助于细胞内 pH 值维持和跨上皮 HCO3− 运动。在这项研究中，我们在非洲爪蟾卵母细胞中表达NBCn1，并通过分析NH4Cl介导的膜电位、电流和细胞内pH的变化来检查NBCn1对卵母细胞NH4+转运的影响。在 HCO3−/CO2 存在的情况下，应用 NH4Cl (20 mM) 会产生卵母细胞的细胞内酸化。表达 NBCn1 的卵母细胞的酸化速度比注射水的对照卵母细胞更快。然而，在表达 NBCn1 的卵母细胞中，NH4Cl 介导的膜去极化较小。在不含 HCO3−/CO2 的溶液中，NH4Cl 在表达 NBCn1 的卵母细胞中产生较小的内向电流（20 mM NH4Cl 抑制 56%；在 -60 mV 下测量），同时对细胞内酸化的影响最小。当 BaCl2 取代 KCl 时，NBCn1 对电流的抑制不受影响。电流-电压关系显示 NH4Cl 介导的电流和电压之间呈正且接近线性的关系，而 NBCn1 显着降低了这种关系。由于之前表征的 NBCn1 的通道样活性，表达 NBCn1 的卵母细胞中产生了大的基础电流（在 NH4Cl 暴露之前）。通过去除 Na+ 来抑制这种通道样活性，消除了 NBCn1 对 NH4Cl 介导的电流的抑制作用。注射 NBCn1 cRNA 后 72-120 小时内电流逐渐减少，在此期间通道样活性很高。这些结果表明，NBCn1 通过其 Na/HCO3 共转运活性刺激 NH4+ 转运，同时通过其通道样活性降低 NH4+ 电导。
The electroneutral Na/HCO3 cotransporter NBCn1 (SLC4A7) contributes to intracellular pH maintenance and transepithelial HCO3− movement. In this study, we expressed NBCn1 in Xenopus oocytes and examined the effect of NBCn1 on oocyte NH4+ transport by analyzing changes in membrane potential, current, and intracellular pH mediated by NH4Cl. In the presence of HCO3−/CO2, applying NH4Cl (20 mM) produced intracellular acidification of oocytes. The acidification was faster in oocytes expressing NBCn1 than in control oocytes injected with water. However, NH4Cl-mediated membrane depolarization was smaller in oocytes expressing NBCn1. In HCO3−/CO2-free solution, NH4Cl produced a smaller inward current in NBCn1-expressing oocytes (56% inhibition by 20 mM NH4Cl; measured at −60 mV), while minimally affecting intracellular acidification. The inhibition of the current by NBCn1 was unaffected when BaCl2 replaced KCl. Current-voltage relationships showed a positive and nearly linear relationship between NH4Cl-mediated current and voltage, which was markedly reduced by NBCn1. Large basal currents (before NH4Cl exposure) were produced in NBCn1-expressing oocytes due to the previously characterized channel-like activity of NBCn1. Inhibiting this channel-like activity by Na+ removal abolished NBCn1’s inhibitory effect on NH4Cl-mediated currents. The currents were progressively reduced over 72–120 h after NBCn1 cRNA injection, during which the channel-like activity was high. These results indicate that NBCn1 by its Na/HCO3 cotransport activity stimulates NH4+ transport, while reducing NH4+ conductance by its channel-like activity.
登录
查看更多内容
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：
10.1111/j.1365-201x.2004.01324.x
发表时间：
2004-08-01
期刊：
ACTA PHYSIOLOGICA SCANDINAVICA
影响因子：
--
作者：
Aalkjær, C;Frische, S;Praetorius, J
通讯作者：
Praetorius, J
影响因子：
2.4
作者：
KINNE, R;KINNESAFFRAN, E;SCHOLERMANN, B
通讯作者：
SCHOLERMANN, B
影响因子：
4.5
作者：
Boldt, M;Burckhardt, G;Burckhardt, BC
通讯作者：
Burckhardt, BC