Coupled transport of p-aminohippurate by rat kidney basolateral membrane vesicles.
Coupled transport of p-aminohippurate by rat kidney basolateral membrane vesicles.
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大鼠肾基底外侧膜囊泡对氨基马尿酸的耦合转运。
DOI：
10.1152/ajprenal.1988.255.4.f597
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
J. B. Pritchard
中科院分区：
文献类型：
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作者：
J. B. Pritchard
从大鼠肾皮质分离的基底膜(BLM)囊泡对P-氨基马酸(PAH)转运的刺激很小(向外大于向内)。然而，当加入微摩尔浓度的戊二酸或α-酮戊二酸时，OUT大于Na+梯度，PAH摄取速度加快20倍以上，并产生5倍以上的超调。其他阴离子，如富马酸，在这些条件下刺激PAH摄取非常温和(约2倍)，这种刺激可被短路完全阻止，即K+(In=Out)和呋喃霉素。戊二酸刺激的摄取被4-acetamido-4‘-isothiocyanostilbene-2，2’-disulfonic酸(SITS)和丙磺舒抑制，而施加内负膜电位则略有刺激。此外，即使在没有Na+梯度的情况下，负载戊二酸的囊泡也表现出显著的多环芳烃摄取加速(5倍)和适度超调(2.5倍)。这些结果表明，BLM PAH的摄取与Na+梯度的间接偶联是通过戊二酸的循环积累(依赖于Na+)，然后从囊泡中排出来换取PAH。这种偶联系统在根尖膜中不存在。因此，PAH的净分泌转运可能需要在BLM摄取依赖于Na+的戊二酸驱动的PAH，然后PAH沿着其电化学梯度退出到管腔，可能是为了交换其他阴离子，例如Cl-、HCO3-或OH-。
p-Aminohippuric acid (PAH) transport by basolateral membrane (BLM) vesicles isolated from rat renal cortex was stimulated very little by a Na+ gradient (out greater than in). However, when micromolar concentrations of glutaric acid or alpha-ketoglutaric acid were added in the presence of a out greater than in Na+ gradient, PAH uptake was accelerated greater than 20-fold and an overshoot of greater than fivefold was produced. Other anions, e.g., fumarate, stimulated PAH uptake very modestly under these conditions (approximately 2-fold), and that stimulation was totally prevented by short circuiting, i.e., with K+ (in = out) and valinomycin. Glutarate-stimulated uptake was inhibited by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and probenecid and was slightly stimulated by the imposition of an inside-negative membrane potential. Furthermore, even in the absence of a Na+ gradient, glutarate-loaded vesicles exhibited a marked acceleration of PAH uptake (5-fold) and a modest overshoot (2.5-fold). These results suggest an indirect coupling of BLM PAH uptake to the Na+ gradient by a cyclic accumulation (Na+-dependent) of glutarate followed by its efflux from the vesicle in exchange for PAH. This coupled system was absent in apical membranes. Thus net secretory transport of PAH may entail Na+-dependent, glutarate-driven PAH uptake at the BLM, followed by the exit of PAH into the lumen down its electrochemical gradient, probably in exchange for other anions, e.g., Cl-, HCO3-, or OH-.