Alteration of glucose transporter in diabetic state.

我们提出了针对HepG2型葡萄糖转运蛋白三个不同结构域的三种抗肽抗体。这些抗体分别只能识别大鼠脂肪细胞和大脑中存在的所有葡萄糖转运蛋白的3%和30%，这表明大鼠脂肪细胞和大脑中存在两种以上的葡萄糖转运蛋白。用这些抗体对链脲佐菌素诱导的糖尿病大鼠的脑膜进行Western blotting，与正常大鼠或胰岛素治疗的糖尿病大鼠相比，葡萄糖转运体的数量没有差异。此外，用[^3H]细胞松弛素B对葡萄糖转运体进行光亲和标记，显示糖尿病大鼠脑内葡萄糖转运体数量未发生改变。此外，以兔脑HepG2型葡萄糖转运体cDNA为探针进行Northern blotting时，糖尿病大鼠脑内HepG2型葡萄糖转运体mRNA的数量未见明显变化。在糖尿病大鼠心脏中也观察到类似的结果，即与正常大鼠或胰岛素治疗的糖尿病大鼠相比，葡萄糖转运蛋白和HepG2型葡萄糖转运蛋白mRNA的数量没有明显变化。这些结果与糖尿病大鼠脂肪细胞中观察到的结果有显著的对比，表明糖尿病状态下不同组织中葡萄糖转运体的数量受到不同机制的调控。

We raised three antipeptide antibodies against three different domains of HepG2 type glucose transporter. These antibodies recognized only 3 and 30 % of all the glucose transporters presnt in rat adipocyte and brain, respectively, suggesting the presence of more that two types of glucose transporter in rat adipocyte and brain. Western blotting of the brain membranes from streptozotocin-induced diabetic rats with these antibodies showed no difference in the glucose transporter amount, compared with normal rats or insulin-treated diabetic rats. In addition, photoaffinity-labeling of glucose transporter with [^3H] cytochalasin B showed no alteration of glucose transporter amount in the brain from diabetic rats. Furthermore, no significant changes in the amount of HepG2 type glucose transporter mRNA was observed in the brain from diabetic rats when Northern blotting was performed with rabbit brain HepG2 type glucose transporter cDNA as a probe. The similar results were observed in the heart from diabetic rats, i. e. no significant changes were observed in the amount of both glucose transporter protein and HepG2 type glucose transporter mRNA compared with normal rats or insulin-treated diabetic rats.These results showed a remarkable contrast to the results observed in the adipocytes from diabetic rats, indicating that different mechanisms regulate the amount of glucose transporter in different tissues in diabetic state.