Sodium uptake across basolateral membrane of rat distal colon. Evidence for Na-H exchange and Na-anion cotransport.
Sodium uptake across basolateral membrane of rat distal colon. Evidence for Na-H exchange and Na-anion cotransport.
复制标题
大鼠远端结肠基底外侧膜的钠摄取。
DOI：
10.1172/jci115444
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Binder,HJ
中科院分区：
文献类型：
--
作者：
Rajendran,VM;Oesterlin,M;Binder,HJ
本研究试图表征钠盐跨大鼠远端结肠基底外侧膜囊泡的转运机制。向外的质子梯度和向内的碳酸氢盐梯度均刺激 22Na 的吸收。质子梯度刺激的 22Na 摄取因额外存在的向内碳酸氢盐梯度而被激活数倍，并且碳酸氢盐梯度刺激的 22Na 摄取因施加的囊内膜正电位而显着增强。 0.1 mM 阿米洛利分别抑制质子梯度和碳酸氢盐梯度刺激的 22Na 摄取 80% 和 95%，而 1 mM 4,4'-二异硫氰酸芪-2,2'-二磺酸 (DIDS) 分别抑制质子梯度和碳酸氢盐梯度刺激的 22Na 摄取 40% 和 80%。质子梯度和碳酸氢盐梯度刺激的 22Na 吸收随着 Na 浓度的增加而饱和：质子梯度刺激的 22Na 吸收的 DIDS 不敏感组分的 Na 的表观动力学常数 (Km) 为 46.4 mM，而质子梯度和碳酸氢盐梯度刺激的 22Na 吸收的 DIDS 敏感组分的 Na 的表观动力学常数 (Km) 为 8.1 和 6.4 mM，分别。阿米洛利抑制 DIDS 不敏感的质子梯度和碳酸氢盐梯度刺激的 22Na 摄取，抑制常数 (Ki) 分别约为 35 和 1 µM。我们从这些结果得出结论，质子梯度刺激的 22Na 吸收代表了 DIDS 不敏感的 Na-H 交换和 DIDS 敏感的电生 Na-OH 共转运，并且质子梯度刺激的 22Na 吸收和碳酸氢盐梯度刺激的 22Na 吸收的 DIDS 敏感成分可能代表相同的电生 Na-阴离子共转运过程。
This study sought to characterize the mechanism of Na transport across basolateral membrane vesicles of rat distal colon. Both an outward proton gradient and an inward bicarbonate gradient stimulated 22Na uptake. Proton gradient-stimulated 22Na uptake was activated severalfold by the additional presence of an inward bicarbonate gradient, and bicarbonate gradient-stimulated 22Na uptake was significantly enhanced by an imposed intravesicular membrane positive potential. 0.1 mM amiloride inhibited both proton gradient- and bicarbonate gradient-stimulated 22Na uptake by 80 and 95%, respectively, while 1 mM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) inhibited both proton gradient- and bicarbonate gradient-stimulated 22Na uptake by 40 and 80%, respectively. Both proton gradient- and bicarbonate gradient-stimulated 22Na uptake saturated as a function of increasing Na concentration: the apparent kinetic constants (Km) for Na for the DIDS-insensitive component of proton gradient-stimulated 22Na uptake was 46.4 mM, while the DIDS-sensitive component of proton gradient- and bicarbonate gradient-stimulated 22Na uptake had Km for Na of 8.1 and 6.4 mM, respectively. Amiloride inhibited both DIDS-insensitive proton gradient- and bicarbonate gradient-stimulated 22Na uptake with an inhibitory constant (Ki) of approximately 35 and 1 microM, respectively. We conclude from these results that proton gradient-stimulated 22Na uptake represents both DIDS-insensitive Na-H exchange and DIDS-sensitive electrogenic Na-OH cotransport, and that the DIDS-sensitive component of proton gradient-stimulated 22Na uptake and bicarbonate gradient-stimulated 22Na uptake may represent the same electrogenic Na-anion cotransport process.Images