INFLUX AND EFFLUX OF 3-O-METHYL-D-GLUCOSE BY CULTURED HUMAN-FIBROBLASTS
INFLUX AND EFFLUX OF 3-O-METHYL-D-GLUCOSE BY CULTURED HUMAN-FIBROBLASTS
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DOI：
10.1152/ajpcell.1988.254.5.c628
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发表时间：
1988-05-01
影响因子：
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通讯作者：
ELSAS, LJ
中科院分区：
文献类型：
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作者：
LONGO, N;GRIFFIN, LD;ELSAS, LJ
我们通过培养的人成纤维细胞测量了3-O-甲基-D-葡萄糖（OMG）通量的初始速率。D-葡萄糖（300 mM）和细胞松弛素B（5 μ M）抑制约80%的OMG（1 mM）内流。OMG迅速进入人成纤维细胞，并且流入在20秒内呈线性。OMG流入和流出大致相等。细胞松弛素B抑制OMG（1 mM）的流入和流出20秒内的曝光。细胞松弛素B分别在0.51和0.75 μ M时最大限度地抑制OMG流入和流出。在零反式条件下，OMG流入和流出的动力学相似。然而，当OMG存在于膜的反侧时，OMG内流而不是OMG外流被刺激。反式刺激OMG流入增加了这个运输过程的最大速度，而不影响其Km。这些结果表明：1）OMG的内流和外流通过同一种转运蛋白发生; 2）培养的人成纤维细胞的葡萄糖转运蛋白在底物存在于膜的反侧时呈现功能不对称性。
We measured the initial rates of 3-O-methyl-D-glucose (OMG) fluxes by cultured human fibroblasts. D-Glucose (300 mM) and cytochalasin B (5 .mu.M) inhibited approximately 80% of OMG (1 mM) influx. OMG rapidly entered human fibroblasts, and influx was linear up to 20 s. OMG influx and efflux were about equal. Cytochalasin B inhibited OMG (1 mM) influx and efflux within 20 s of exposure. Cytochalasin B half maximally inhibited OMG influx and efflux at 0.51 and 0.75 .mu.M, respectively. In zero trans conditions, the kinetics of OMG influx and efflux were similar. However, when OMG was present on the trans side of the membrane, OMG influx but not OMG efflux was stimulated. Trans stimulation of OMG influx increased the maximal velocity of this transport process, without affecting its Km. These results suggest that 1) OMG influx and efflux occur through the same transporter, and 2) the glucose transporter of cultured human fibroblasts presents a functional asymmetry when substrate is present of the trans side of the membrane.