Extracellular HCO(3)(-) dependence of electrogenic Na/HCO(3) cotransporters cloned from salamander and rat kidney.
Extracellular HCO(3)(-) dependence of electrogenic Na/HCO(3) cotransporters cloned from salamander and rat kidney.
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从sal和大鼠肾脏克隆的电源Na/Hco（3）共转运蛋白的细胞外HCO（3）（ - ）依赖性。
DOI：
10.1085/jgp.115.5.533
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发表时间：
2000-05
影响因子：
3.8
通讯作者：
Boron, WF
中科院分区：
文献类型：
--
作者：
Grichtchenko, II;Romero, MF;Boron, WF
我们研究了在非洲爪蟾卵母细胞中异源表达的产电Na/HCO 3协同转运蛋白（NBC）的两个肾克隆的细胞外[HCOabstract 3 −]依赖性。用微电极法测定了从虎纹钝口螈（Ambystoma tigrinum）肾中克隆的NBC（akNBC）和从大鼠肾中克隆的NBC（rkNBC）引起的膜电位（ΔVm）的变化。我们使用双电极电压钳来测量rkNBC引起的电流变化（ΔI）。将表达NBC的卵母细胞短暂暴露于HCOabstract 3 −/CO2（0.33-99 mM HCOabstract 3 −，pHo 7.5）中，立即引起DIDS（4，4-diisothiocyanatostilbene-2，2-disulfonic acid）敏感性和Na+依赖性超极化（或外向电流）。在ΔVm实验中，akNBC（10.6 mM）和rkNBC（10.8 mM）的HCOabstract 3 −的表观Km相似。然而，在电压钳条件下，rkNBC的HCOabstract 3-的表观Km值较小（6.5 mM）。因为有报道称SOabstract 3 =/HSO abstract 3 −刺激肾膜囊泡中的Na/HCO 3共转运（这一结果支持存在SOabstract 3 =与之相互作用的CO abstract 3 =结合位点），我们研究了SOabstract 3 =/HSO abstract 3 −对rkNBC的影响。在电压钳研究中，我们发现33 mM SOabstract 4 =和33 mM SOabstract 3 =/HSOabstract 3 −都不会显著影响HCO abstract 3 −的表观Km。我们还使用微电极监测细胞内pH值（pHi），同时将rkNBC表达卵母细胞暴露于3.3 mM HCOabstract 3 −/0.5% CO2。我们发现SO抽象3 =/HSO抽象3 −并没有显著影响从初始CO2诱导酸化中恢复的pHi的DIDS敏感组分。我们还监测了rkNBC电流，同时改变[CO2]o、pHo和[COabstract 3 =]o，固定[HCOabstract 3-]o为33 mM。Michaelis-Menten方程与表示为电流与[COabstract 3 =]o的数据拟合不佳。然而，pH滴定曲线很好地拟合了表示为电流与pH值的数据。因此，在非洲爪蟾卵母细胞中表达的rkNBC似乎不与SOabstract 3 =、HSOabstract 3 −或COabstract 3 =相互作用。
We studied the extracellular [HCOabstract 3 −] dependence of two renal clones of the electrogenic Na/HCO3 cotransporter (NBC) heterologously expressed in Xenopus oocytes. We used microelectrodes to measure the change in membrane potential (ΔVm) elicited by the NBC cloned from the kidney of the salamander Ambystoma tigrinum (akNBC) and by the NBC cloned from the kidney of rat (rkNBC). We used a two-electrode voltage clamp to measure the change in current (ΔI) elicited by rkNBC. Briefly exposing an NBC-expressing oocyte to HCOabstract 3 −/CO2 (0.33–99 mM HCOabstract 3 −, pHo 7.5) elicited an immediate, DIDS (4,4-diisothiocyanatostilbene-2,2-disulfonic acid)-sensitive and Na+-dependent hyperpolarization (or outward current). In ΔVm experiments, the apparent K m for HCOabstract 3 − of akNBC (10.6 mM) and rkNBC (10.8 mM) were similar. However, under voltage-clamp conditions, the apparent K m for HCOabstract 3 − of rkNBC was less (6.5 mM). Because it has been reported that SOabstract 3 =/HSO abstract 3 − stimulates Na/HCO3 cotransport in renal membrane vesicles (a result that supports the existence of a COabstract 3 = binding site with which SOabstract 3 = interacts), we examined the effect of SOabstract 3 =/HSO abstract 3 − on rkNBC. In voltage-clamp studies, we found that neither 33 mM SOabstract 4 = nor 33 mM SOabstract 3 =/HSOabstract 3 − substantially affects the apparent K m for HCO abstract 3 −. We also used microelectrodes to monitor intracellular pH (pHi) while exposing rkNBC-expressing oocytes to 3.3 mM HCOabstract 3 −/0.5% CO2. We found that SO abstract 3 =/HSOabstract 3 − did not significantly affect the DIDS-sensitive component of the pHi recovery from the initial CO2 -induced acidification. We also monitored the rkNBC current while simultaneously varying [CO2]o, pHo, and [COabstract 3 =]o at a fixed [HCOabstract 3 −]o of 33 mM. A Michaelis-Menten equation poorly fitted the data expressed as current versus [COabstract 3 =]o . However, a pH titration curve nicely fitted the data expressed as current versus pHo. Thus, rkNBC expressed in Xenopus oocytes does not appear to interact with SOabstract 3 =, HSOabstract 3 −, or COabstract 3 =.
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影响因子：
4.5
作者：
Heyer, M;Müller-Berger, S;Frömter, E
通讯作者：
Frömter, E
影响因子：
4.8
作者：
Burnham, CE;Amlal, H;Soleimani, M
通讯作者：
Soleimani, M
基底外侧膜H+/OH-/HCO-3在大鼠近端综合小管中转运的机理。钠耦合的电源过程。
影响因子：
3.8
作者：
Alpern, R J
通讯作者：
Alpern, R J
DOI：
10.1085/jgp.99.5.817
发表时间：
1992-05
期刊：
The Journal of general physiology
影响因子：
--
作者：
Boron WF;Knakal RC
通讯作者：
Knakal RC
影响因子：
15.9
作者：
AKIBA, T;ALPERN, RJ;WARNOCK, DG
通讯作者：
WARNOCK, DG