缺氧和收缩状态下不同肌纤维类型骨骼肌葡萄糖转运速率与肌糖原含量的关系

Relationship between Glucose Transport Rate and Glycogen Content in Different Skeletal Muscle Fiber Types under Hypoxia or/and Contraction

目的:观察大鼠不同类型骨骼肌肌纤维在缺氧、收缩以及两者联合刺激下,其葡萄糖跨膜转运速率(GTR)与肌糖原含量的关系。方法:取不同肌纤维占优势的3种大鼠骨骼肌(比目鱼肌、趾长伸肌和肱骨内上髁肌),离体条件下进行不同的刺激处理(基础对照、缺氧、收缩、缺氧+收缩),测定GTR和肌糖原含量并分析它们之间的关系。结果:骨骼肌肌纤维类型不同,其GTR对缺氧、收缩、缺氧+收缩刺激的反应有所不同,其肌糖原的基础量、不同刺激后的残留量及消耗量也不尽相同。3种肌纤维类型骨骼肌的GTR均与肌糖原的残留量呈负相关倾向,而与消耗量呈正相关倾向。氧化型(Ⅱa型和Ⅰ型)肌纤维(趾长伸肌和比目鱼肌)比酵解型(Ⅱb型)肌纤维(肱骨内上髁肌)在肌糖原消耗量较少的情况下可引起GTR较高的增加。这一结果从肌纤维类型的角度揭示了有氧运动(可更多地动员氧化型肌纤维)在预防和改善胰岛素抵抗中能够发挥重要作用的机理。

Objective To investigate the relationship between glucose transport rate （GTR） and glycogen content in different skeletal muscle fiber types stimulated by hypoxia, or contraction or their combination in rats. Methods Muscles （soleus, flexor digitorum brevis, and epitrochlearis） with differently dominant fiber types in rats were isolated and treated by stimulation of hypoxia or contraction or hypoxia plus contraction as well as basal condition in vitro. The GTR and glycogen content in muscles were determined and their relationship was analyzed. Results With different muscle fiber types, the responses of GTR to hypoxia, contraction and hypoxia plus contraction were different, and the basal, residual and consumed glycogen contents were different, too, by the stimuli. GTR showed tendency of inverse correlation with the residual glycogen content but of positive correlation with the consumed glycogen content in all three muscle fiber types. By a less consumption of muscle glycogen, a higher GTR could be induced in the oxidative muscle fibers of type Ⅱa and Ⅰ （flexor digitorum brevis and soleus） than that in the glycolytic fibers of type Ⅱb （epitrochlearis） under the stimulation. This result revealed from the fiber type point of view why the aerobic exercise which can mobilize more oxidative muscle fibers to contract plays a very important role in prevention or improvement of insulin resistance.