钒酸钠对STZ-糖尿病大鼠心肌细胞膜GLUT4易位的影响

目的探讨钒酸钠类胰岛素作用及对实验性糖尿病大鼠心肌组织葡萄糖转运蛋白4 (glucose transpoter type 4, GLUT4)与胰岛素刺激GLUT4易位的影响.方法 40只Wistar大鼠随机分为2组,1组应用链脲佐菌素(55 mg/kg)腹腔内注射,5 d后血糖大于13.5 mmol/L定为实验性糖尿病大鼠(STZ-D大鼠),然后将STZ-D大鼠组及正常组再分为2组,加钒组隔日管饲0.4% 钒酸钠稀释液,持续4周后在麻醉情况下每组各一半大鼠在尾静脉注射5U /kg诺和正规胰岛素治疗,5 min后心脏抽取血液标本并提取心脏,应用Western blot 技术测定GLUT4蛋白表达.结果钒酸钠治疗使STZ-D大鼠血糖、甘油三酯、胰岛素降低,STZ-D大鼠心肌细胞膜GLUT4蛋白含量与正常对照组比较明显降低(53%),而钒酸钠与胰岛素合用治疗STZ-D大鼠可使心肌细胞膜GLUT4增加2.7倍.结论钒酸钠治疗STZ-糖尿病大鼠在不增加胰岛素释放的情况下具有明显改善糖脂代谢的效果,糖尿病大鼠心肌细胞膜GLUT4含量减少可能是引起心肌葡萄糖转运障碍及心功能下降的因素,钒酸钠治疗使胰岛素调节GLUT4转运易位增加致心肌组织对葡萄糖摄取利用加强可能是某些降低血糖的机制以及改善心功能原因.

Effects of sodium vanadate on GLUT4 translocation in cardiac tissue of streptozotocin-induced diabetic rats

Objective To investigate the effects of sodium vanadate treatment on insulin stimulated glucose transporter type 4 (GLUT4) in the cardiac tissue of streptozotocin (STZ) induced diabetic rats. Methods A total of 40 male Wistar rats (180-250 g ) were randomly divided into two groups. Rats in the first group were administered intraperitoneally with a single dose of STZ (55 mg/kg), and those in the second group received placebo (0.1% mmmol/L citric acid buffer plasma glucose). On day 5 following STZ injection (PG>13 5 mmol/L), rats were treated with 0.4% sodium vanadate by oral gavage. Half of the animals in each group after treatment for 4 weeks were administered intravenously with regular Novo insulin at the dose of 5 U/kg. GLUT4 expression in the cardiac tissue was detected by Western blotting. Results Plasma glucose, triglyceride, and insulin levels decreased in STZ induced diabetic rats after sodium vanadate treatment. Sarcolemmal membrane GLUT4 translocation after combined treatment of sodium vanadate and insulin increased by 2.7 fold. Conclusion Sodium vanadate treatment can improve the metabolism of glycolipids without increasing the insulin secretion in STZ induced diabetic rats. The decreased content of sarcolemmal membrane GLUT4 in diabetic rats might be the factor leading to glucose transportation disorder and cardiac dysfunction. The effects of sodium vanadate may be related to the increase in GLUT4 dislocation which induces the improvement of glucose uptake and utilization in cardiac tissue and cardiac function.