HEXOSE TRANSPORT AND PHOSPHORYLATION BY CAPILLARIES ISOLATED FROM RAT-BRAIN
HEXOSE TRANSPORT AND PHOSPHORYLATION BY CAPILLARIES ISOLATED FROM RAT-BRAIN
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DOI：
10.1152/ajpcell.1979.236.1.c96
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发表时间：
1979-01-01
影响因子：
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通讯作者：
GOLDSTEIN, GW
中科院分区：
文献类型：
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作者：
BETZ, AL;CSEJTEY, J;GOLDSTEIN, GW
对大鼠脑毛细血管段己糖转运和磷酸化进行了研究。3-O-甲基-D-葡萄糖(3 Mg)的摄取可被细胞松弛素B、根茎黄素和根茎苷抑制，但不能被2，4-二硝基苯酚或哇巴因抑制。2-脱氧-D-葡萄糖(2DG)、D-葡萄糖、半乳糖和甘露糖抑制3 mg的摄取，而L葡萄糖、果糖和核糖不抑制3 mg的摄取。表现出3 mg的加速交换扩散。在平衡状态下，己糖的胞内浓度没有超过外界浓度，运输是平衡的，而不是累积的。2DG和D-葡萄糖的转运对代谢不是限速的。当内皮细胞在5 mM D-葡萄糖中孵育时，内皮细胞含有大量的游离葡萄糖。L-葡萄糖比其他己糖进入毛细血管的速度更慢，是糖简单扩散到细胞内的标志。糖分通过一种运输系统进入孤立的脑毛细血管，这种运输系统与体内负责葡萄糖跨血脑屏障运输的系统相似。
Hexose transport and phosphorylation were studied in capillary segments isolated from rat brain. Uptake of 3-o-methyl-D-glucose (3MG) could be inhibited by cytochalasin B, phloretin and phlorizin, but not by 2,4-dinitrophenol or ouabain. 2-Deoxy-D-glucose (2DG), D-glucose, galactose and mannose inhibited 3MG uptake, while L-glucose, fructose and ribose did not. Accelerative exchange diffusion of 3MG was demonstrated. At equilibrium, the intracellular concentration of hexose did not exceed the external concentration, and transport was equilibrative rather than accumulative. Transport of 2DG and D-glucose was not rate-limiting for metabolism. When incubated in 5 mM D-glucose, the endothelial cells contained a large pool of free glucose. L-Glucose entered capillaries more slowly than other hexoses and served as a marker for simple diffusion of sugars into the cells. Sugar uptake into isolated brain capillaries occurs by a transport system similar to the one responsible for glucose transport across the blood-brain barrier in vivo.