Electrical properties of the basolateral membrane of the straight portion of the rabbit proximal renal tubule.
Electrical properties of the basolateral membrane of the straight portion of the rabbit proximal renal tubule.
复制标题
兔近端肾小管直部基底外侧膜的电特性。
DOI：
10.1113/jphysiol.1982.sp014176
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Bello-Reuss,E
中科院分区：
文献类型：
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作者：
Bello-Reuss,E
1.用细胞内3 M-CK 1微电极在兔近端小管的直线部分的分离的灌注段中测量细胞膜电位。2.在模拟体内情况的体外条件下，跨上皮电位差约为1.6 mV，管腔阳性，基底外侧膜电位为61 mV，细胞阴性。3.仅当[K+]增加和[HCO 3-]减少时，浴中等摩尔单离子取代（K+取代Na+，羟乙基磺酸盐取代Cl-，N-甲基-D-葡糖胺（NMDG+）取代Na+，Cl-取代HCO 3-）才导致基底外侧膜电位发生显著变化;在这两种情况下，基底外侧膜均去极化。Cl-和Na+与大的单价离子取代没有改变基底外侧膜电位。4.替代实验中的跨上皮电位变化表明，在细胞旁途径，PK大于PNa大于PNMDG，PCl大于羟乙基磺酸盐。5.得出的结论是，这些细胞的基底外侧膜主要是K+-传导的，并且电扩散PNa和PCl通过该技术检测不到。6.向浴中加入1 mM-Ba 2+可降低基底外侧膜电扩散PK，如去极化和增加浴[K+]产生的膜电位变化幅度降低所证明。7.降低浴[HCO 3-]产生的去极化似乎是由于电扩散PK的减少，因为它被Ba 2+阻断。没有必要假设HCO 3-或相关物质的传导途径。
1. Cell membrane potentials were measured with intracellular 3 M‐CKl microelectrodes in isolated, perfused segments of the straight portion of the rabbit proximal tubule. 2. Under in vitro conditions simulating the in vivo situation, the transepithelial potential difference was about 1.6 mV, lumen‐positive, and the basolateral membrane potential was 61 mV, cell negative. 3. Isomolar single ion substitutions in the bath (K+ for Na+, isethionate for Cl‐, N‐methyl‐D‐glucamine (NMDG+) for Na+, and Cl‐ for HCO3‐) resulted in significant basolateral membrane potential changes only when [K+] was increased and [HCO3‐] was reduced; in both cases the basolateral membrane depolarized. Cl‐ and Na+ substitutions with large monovalent ions did not change basolateral membrane potential. 4. Transepithelial potential changes in substitution experiments suggest that, at the paracellular pathway, PK greater than PNa greater than PNMDG, and PCl greater than Pisethionate. 5. It is concluded that the basolateral membrane of these cells is mainly K+‐conductive and that electrodiffusional PNa and PCl are undetectable by this technique. 6. Addition of 1 mM‐Ba2+ to the bath reduced basolateral membrane electro‐diffusional PK, as evidenced by depolarization and by a reduction of the magnitude of the change in membrane potential produced by increasing bath [K+]. 7. The depolarization produced by lowering bath [HCO3‐] appears to result from a reduction of electrodiffusional PK, since it is blocked by Ba2+. There is no need to postulate a conductive pathway for HCO3‐ or a related species.