Characterization of organic cation transport by avian renal brush-border membrane vesicles.
Characterization of organic cation transport by avian renal brush-border membrane vesicles.
复制标题
禽肾刷状缘膜囊泡有机阳离子转运的表征。
DOI：
10.1152/ajpregu.1995.269.5.r1050
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Braun,EJ
中科院分区：
文献类型：
--
作者：
Villalobos,AR;Braun,EJ
有机阳离子由肾近端小管主动分泌。对哺乳动物和爬行动物灌流小管和离体膜的研究表明，有机阳离子（OC）通过OC/H+交换跨管腔（刷状缘）膜转运。我们的目的是确定是否有类似的机制存在于鸟类肾脏。通过快速过滤从鸡肾中分离的刷状缘膜囊泡（BBMV），在各种离子条件下测定了[14 C]四乙铵（TEA）的吸收。向外定向的质子梯度（pHin = 6.0：pHout = 7.5）刺激浓度TEA摄取。TEA/H+交换是可饱和的，具有约25的最大摄取速率和约500 μ M的TEA的米氏常数。nmol.mg TEA转运可间接地与钠转运偶联。未标记的TEA、N '-甲基烟酰胺（NMN）、胆碱、西咪替丁、甲哌非尼多、奎尼丁、奎宁和雷尼替丁显著顺式抑制[14 C]TEA的摄取。然而，有机阴离子丙磺舒和p-氨基马尿酸盐抑制摄取较差。未标记的TEA和NMN也反式刺激[14 C]TEA摄取。因此，在鸟类肾脏BBMV，有机阳离子运输的OC/H+交换机制定性类似于目前在哺乳动物。
Organic cations are actively secreted by the renal proximal tubule. Studies on perfused tubules and isolated membranes from mammals and reptiles have demonstrated that organic cations (OC) are transported across the luminal (brush-border) membrane by OC/H+ exchange. Our objective was to determine whether a similar mechanism was present in the avian kidney. Uptake of [14C]tetraethylammonium (TEA) was assayed under various ionic conditions by rapid filtration in brush-border membrane vesicles (BBMV) isolated from chicken kidney (Gallus domesticus). An outwardly directed proton gradient (pHin = 6.0: pHout = 7.5) stimulated concentrative TEA uptake. TEA/H+ exchange was saturable, having a maximal rate of uptake of approximately 25 nmol.mg protein-1.min-1 and a Michaelis constant for TEA of approximately 500 microM. TEA transport could be indirectly coupled to sodium transport. Unlabeled TEA, N'-methylnicotinamide (NMN), choline, cimetidine, mepiperphenidol, quinidine, quinine, and ranitidine markedly cis-inhibited uptake of [14C]TEA. However, the organic anions probenecid and p-aminohippurate poorly inhibited uptake. Unlabeled TEA and NMN also trans-stimulated [14C]TEA uptake. Thus, in avian renal BBMV, organic cations are transported by an OC/H+ exchange mechanism qualitatively similar to that present in mammals.