缺氧习服大鼠骨骼肌葡萄糖转运体特点的研究

目的探讨缺氧习服后组织葡萄糖转运体的变化特点及葡萄糖摄取变化机制.方法将缺氧组大鼠置模拟海拔5 000 m低压舱内,30 d后取双后肢骨骼肌测定组织葡萄糖水平、葡萄糖摄取率,并分离细胞膜、细胞内质膜,用同位素标记的葡萄糖进行Scatchard分析测定葡萄糖转运体密度及其亲和力,通过免疫印迹测定葡萄糖转运体1、4的表达.对照组大鼠在平原进行,其它操作及条件与缺氧组相同.结果缺氧组大鼠骨骼肌葡萄糖含量增加、葡萄糖摄取率增强,骨骼肌细胞膜、细胞内质膜上葡萄糖转运体密度均非常显著地高于对照组.葡萄糖转运体1、4在细胞膜、细胞内质膜上的表达量较对照组显著增加.缺氧组葡萄糖转运体4 mRNA显著高于对照组,葡萄糖转运体1 mRNA水平变化不显著.结论表达增强,细胞膜与细胞内质膜上转运体密度均增加是缺氧习服后大鼠骨骼肌葡萄糖转运体的变化特点,是缺氧习服后骨骼肌葡萄糖摄取能力增强的重要原因之一.

Characterization of glucose transporters in skeletal muscle after acclimatization to hypobaric hypoxia

Objective To explore the mechanism of changes of glucose uptaking in the skeletal muscle during acclimatization to hypobaric hypoxia. Methods Wistar rats in the hypoxia group were exposed to hypobaric hypoxia chamber simulating 5 000 m high altitude for 30 d (23 h per day). Rats in the control group stayed outside of the chamber. The arterial blood and the skeletal muscle from the hind leg were collected from animals in both groups in the hypobaric hypoxic chamber. 3H D glucose was used to assay the glucose uptake rate (GUR) in the skeletal muscle. The intracellular and plasma membranes of the skeletal muscle were separated by discontinuous sugar gradient (25%, 35%). The maximal binding sites (Bmax) and Kd of glucose transporters on the membranes were analyzed by Scatchard. The expression of protein and mRNA of GLUT1 and GLUT4 in the skeletal muscle membrane were detected by Western blotting and RT PCR, respectively. Results Compared with that in the control group, the glucose level in the skeletal muscle of rats in the hypoxic group increased significantly. GUR in the skeletal muscle in rats in the hypoxic group was higher than that in the control group. Bmax of glucose transporters on the skeletal muscle cell plasma and intracellular membranes in rats in the hypoxia group increased as compared with that in rats in the control group, but no significant change of Kd of the glucose transporters was found during acclimatization to hypoxia. Expressions of GLUT1 and GLUT4 in the skeletal muscle plasma membrane in rats in the hypoxic group were higher than those in rats in the control group. The level of GLUT4 mRNA increased in hypoxia, but no significant change of GLUT1was found. Conclusion After acclimatization to hypobaric hypoxia, increased GLUT4 and GLUT1 expressions are found in the skeletal muscle plasma membranes and intracellular membranes, which may play an important role in the increase of glucose uptake.