Modulation of the ionic permeability of renal cortical brush-border membranes by cAMP.
Modulation of the ionic permeability of renal cortical brush-border membranes by cAMP.
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cAMP 对肾皮质刷状缘膜离子渗透性的调节。
DOI：
10.1152/ajprenal.1989.257.5.f769
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Abramson,RG
中科院分区：
文献类型：
--
作者：
Lipkowitz,MS;Abramson,RG
在大鼠肾皮质膜囊泡中检查了腺苷 3',5'-环单磷酸 (cAMP) 对氯化钾渗透性、相对离子渗透性和 Na+ 依赖性葡萄糖转运的影响。通过使用镁聚集技术，从配对对照和暴露于 cAMP 或毛喉素的匀浆中制备刷状缘膜囊泡。这些研究表明，暴露于外源性 cAMP 或增加内源性 cAMP 会显着增加相对于钾 (PCl/PK) 的 KCl 渗透性和离子氯渗透性，如荧光电位敏感探针 3,3'-二丙基硫二碳花青碘化物 [diS-C3-(5)] 和 36Cl 摄取所测定。由于 PNa/PK 没有变化，cAMP 也显着增加了 PCl/PNa。离子渗透率的这些变化与 Na+ 依赖性葡萄糖转运的显着刺激有关，而这与葡萄糖转运动力学的改变或向内定向的 Na+ 梯度的延迟消散无关。这些发现表明，cAMP 诱导的葡萄糖转运刺激是由于 PCl/PNa 增加继发的囊泡超极化所致。这些研究表明，体内细胞内 cAMP 浓度的变化可能通过改变肾近曲小管细胞的相对离子渗透性和膜电位来调节生电转运过程。
The effects of adenosine 3',5'-cyclic monophosphate (cAMP) on potassium chloride permeability, relative ionic permeabilities, and Na+-dependent glucose transport were examined in rat renal cortical membrane vesicles. Brush-border membrane vesicles were prepared from paired control and cAMP- or forskolin-exposed homogenates by use of a magnesium aggregation technique. These studies demonstrate that exposure to exogenous cAMP or increases in endogenous cAMP significantly increase KCl permeability and ionic chloride permeability relative to that of potassium (PCl/PK) as determined with the fluorescent potential-sensitive probe 3,3'-dipropylthiadicarbocyanine iodide [diS-C3-(5)] and 36Cl uptake. Because PNa/PK did not change, PCl/PNa was also significantly increased by cAMP. These changes in ionic permeabilities were associated with a significant stimulation of Na+-dependent glucose transport that was unassociated with either an alteration in the kinetics of glucose transport or delayed dissipation of the inwardly directed Na+ gradient. These findings indicate that the cAMP-induced stimulation of glucose transport resulted from hyperpolarization of the vesicles secondary to the increase in PCl/PNa. These studies suggest that in vivo variations in intracellular cAMP concentration may modulate electrogenic transport processes by altering relative ionic permeabilities and membrane potential in renal proximal tubule cells.