Basolateral sodium-coupled acid-base transport mechanisms of the rabbit proximal tubule.
Basolateral sodium-coupled acid-base transport mechanisms of the rabbit proximal tubule.
复制标题
DOI：
10.1152/ajprenal.1989.257.5.f790
复制
发表时间：
1989-11
期刊：
影响因子：
--
通讯作者：
J. Geibel;G. Giebisch;W. Boron
中科院分区：
文献类型：
--
作者：
J. Geibel;G. Giebisch;W. Boron
我们研究了Na+-耦合酸碱转运在基底外侧膜的单一，隔离，灌注兔近端小管通过监测细胞内pH值（pHi）的时间过程。后者使用显微荧光分光光度计装置在440和490 nm处交替激发pH敏感性荧光染料2 '，7'-双-2-羧乙基-5（和-6）-羧基荧光素（BCECF），同时在530 nm处测量荧光发射。所有实验均在名义上不存在HCO-3的情况下进行，分别检查浅表和髓质肾单位的S1、S2和S3段。我们发现从管腔和浴中去除Na+（即，基底侧溶液）导致浅表S1段（SS 1）的pHi从7.24降至6.75，SS 2从7.14降至6.67，SS 3从7.09降至6.69。同样，在髓质肾单位（J）中，双侧Na+去除导致JS 1中的pHi从7.25降至6.76，JS 2中从7.16降至6.71，JS 3中从7.10降至6.75。在所有六种近端小管亚型中，将Na+返回到浴中导致pHi恢复（即，增加）。4，4 '-二异硫氰基二苯乙烯-2，2'-二磺酸（DIDS，50 μ M），一种HCO-3转运系统的抑制剂，在所有三种浅表亚型和JS 3中阻断了这种Na+依赖性pHi恢复，但在JS 1或JS 2中没有影响。另一方面，50 μ M乙基异丙基阿米洛利（EIPA），一种Na-H交换抑制剂，阻断了JS 1和JS 2中Na+依赖性pHi恢复，但对JS 3或任何浅表亚型没有影响。（250字处删节）
We studied Na+-coupled acid-base transport at the basolateral membrane of single, isolated, perfused rabbit proximal tubules by monitoring the time course of intracellular pH (pHi). The latter was determined using a microspectrofluorometric apparatus to alternatively excite the pH-sensitive fluorescent dye 2',7'-bis-2-carboxyethyl-5(and -6)-carboxyfluorescein (BCECF) at 440 and 490 nm, while the fluorescence emission, was measured at 530 nm. All experiments were conducted in the nominal absence of HCO-3 S1, S2, and S3 segments from both superficial and juxtamedullary nephrons were examined individually. We found that removing Na+ from both the lumen and bath (i.e., basolateral solution) caused pHi to fall from 7.24 to 6.75 in the superficial S1 segment (SS1), from 7.14 to 6.67 in the SS2, and from 7.09 to 6.69 in the SS3. Similarly, in juxtamedullary nephrons (J), bilateral Na+ removal caused pHi to fall from 7.25 to 6.76 in the JS1, from 7.16 to 6.71 in the JS2, and from 7.10 to 6.75 in the JS3. In all six proximal tubule subtypes, returning Na+ to the bath caused pHi to recover (i.e., increase). 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 50 microM), an inhibitor of HCO-3 transport systems, blocked this Na+-dependent pHi recovery in all three superficial subtypes and the JS3 but had no effect in either the JS1 or JS2. On the other hand, 50 microM ethylisopropyl amiloride (EIPA), an inhibitor of Na-H exchange, blocked the Na+-dependent pHi recovery in the JS1 and JS2 but had no effect in the JS3 or any of the superficial subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)