AMMONIUM TRANSPORT IN MEDULLARY THICK ASCENDING LIMB OF RABBIT KIDNEY - INVOLVEMENT OF THE NA(+)-COTRANSPORTER,K(+)-COTRANSPORTER,CL(-)-COTRANSPORTER
AMMONIUM TRANSPORT IN MEDULLARY THICK ASCENDING LIMB OF RABBIT KIDNEY - INVOLVEMENT OF THE NA(+)-COTRANSPORTER,K(+)-COTRANSPORTER,CL(-)-COTRANSPORTER
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DOI：
10.1007/bf01869723
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发表时间：
1986-01-01
影响因子：
2.4
通讯作者：
SCHOLERMANN, B
中科院分区：
文献类型：
--
作者：
KINNE, R;KINNESAFFRAN, E;SCHOLERMANN, B
为了探讨铵离子在Henle’s loop （TALH）厚升肢中的重吸收是否通过Na+、K+、Cl——共转运体进行，本实验以兔肾外髓TALH细胞为材料制备了质膜囊泡，并考察了。**GRAPHIC**的作用。研究了它们的输运性质。结果发现，在78 mmol/l NaCl梯度存在下，5 mmol/l。抑制布美他尼对铷通量86%；5 mmol/l K+也有类似的下降。布美他尼对铷吸收的抑制作用**GRAPHIC**。具有竞争性，表观Ki值为1.9 mmol/l。在83 mmol/l KCl梯度下测定的布美他尼敏感钠摄取不受5 mmol/l KCl梯度的抑制。然而，100 mmol/l的NH4Cl梯度能够刺激布美他尼敏感的钠摄取，其程度与KCl梯度相同。这些数据表明……被Na+，K+，Cl——共输运系统的K+位点所接受，并且转运体可以在a .**GRAPHIC**中起作用。模式。由于转运体的亲和力为。**GRAPHIC**。存在于体内TALH管腔内的浓度范围，由此得出结论：**GRAPHIC**。联合运输可以促进**图形**。管状节段的重吸收。
In order to investigate the question whether ammonium reabsorption in the thick ascending limb of Henle''s loop (TALH) proceeds via the Na+,K+,Cl--cotransporter, plasma membrane vesicles were prepared from TALH cells isolated from rabbit kidney outer medulla and the effect of .**GRAPHIC**. on their transport properties was investigated. It was found that, in the presence of a 78-mmol/liter NaCl gradient, 5 mmol/liter .**GRAPHIC**. inhibited bumetanide-sensitive rubidium flux by 86%; a similar decrease was observed for 5 mmol/liter, K+. Inhibition of bumetanide-sensitive rubidium uptake by .**GRAPHIC**. was competitive and an apparent Ki of 1.9 mmol/liter was found. Bumetanide-sensitive sodium uptake measured in the presence of a 83 mmol/liter KCl gradient was not inhibited by 5 mmol/liter .**GRAPHIC**. A 100-mmol/liter NH4Cl gradient was, however, capable of stimulating bumetanide-sensitive sodium utpake to the same extent as a KCl gradient. These data suggest that .**GRAPHIC**. is accepted by the K+ site of the Na+,K+,Cl--cotransport system and that the transporter can function in a .**GRAPHIC**. mode. Since the affinity of the transporter for .**GRAPHIC**. lies in the concentration range found in the TALH lumen in vivo, it is concluded that .**GRAPHIC**. cotransport can contribute to the .**GRAPHIC**. reabsorption in this tubular segment.