TRANSPORT OF D-GLUCOSE BY BRUSH-BORDER MEMBRANES ISOLATED FROM RENAL CORTEX
TRANSPORT OF D-GLUCOSE BY BRUSH-BORDER MEMBRANES ISOLATED FROM RENAL CORTEX
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DOI：
10.1016/0005-2736(74)90286-7
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发表时间：
1974-01-01
期刊：
影响因子：
--
通讯作者：
SACKTOR, B
中科院分区：
文献类型：
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作者：
ARONSON, PS;SACKTOR, B
本文研究了离体兔肾皮质刷状缘膜对葡萄糖的转运。在浓度小于2 mM时，d-葡萄糖摄取率随糖浓度线性增加。没有发现“高亲和力”（μM）可饱和位点的证据。饱和表示在浓度ofd-葡萄糖大于5 mM。摄取的d-葡萄糖是立体特异性和选择性抑制由d-半乳糖和其他糖。根皮苷在Na+存在和不存在的情况下抑制D-葡萄糖的摄取。葡萄糖甙是一种有效的葡萄糖外排抑制剂。预加载刷状缘膜囊泡与d-葡萄糖，而不是与l-葡萄糖，加速交换扩散的d-葡萄糖。这些结果表明，d-葡萄糖的肾刷状缘的摄取代表运输到囊内空间，而不是单独结合。当囊外介质中的Na+较高且膜预先装载有无Na+介质时，d-葡萄糖摄取速率增加。用Na+预加载刷状缘膜可抑制D-葡萄糖摄取速率。这些结果与肾脏中葡萄糖转运的Na+梯度假说一致。因此，在离体肾刷状缘膜中存在Na+依赖性葡萄糖易化转运。这一发现与已知的在生理学上更完整的制剂中糖的转运是一致的，并表明膜在检查肾脏中d-葡萄糖转运机制中可作为有效的模型系统。
The transport ofd-glucose by brush border membranes isolated from the rabbit renal cortex was studied. At concentrations less than 2 mM, the rate ofd-glucose uptake increased linearly with the concentration of the sugar. No evidence was found for a “high-affinity” (μM) saturable site. Saturation was indicated at concentrations ofd-glucose greater than 5 mM. The uptake ofd-glucose was stereospecific and selectively inhibited byd-galactose and other sugars. Phlorizin inhibited the uptake ofd-glucose in the presence and absence of Na+. The glycoside was a potent inhibitor of the efflux ofd-glucose. Preloading the brush border membrane vesicles withd-glucose, but not withl-glucose, accelerated exchange diffusion ofd-glucose. These results demonstrate that the uptake ofd-glucose by renal brush borders represents transport into an intravesicular space rather than solely binding. The rate ofd-glucose uptake was increased when the Na+in the extravesicular medium was high and the membranes were preloaded with a Na+-free medium. The rate ofd-glucose uptake was inhibited by preloading the brush border membranes with Na+. These results are consistent with the Na+gradient hypothesis ford-glucose transport in the kidney. Thus, the presence of a Na+-dependent facilitated transport ofd-glucose in isolated renal brush border membranes is indicated. This finding is consistent with what is known of the transport of the sugar in more physiologically intact preparations and suggests that the membranes serve as an effective model system in examining the mechanism ofd-glucose transport in the kidney.