Stenbit A E, Burcelin R, Katz E B, Tsao T S, Gautier N, Charron M J, Le Marchand-Brustel Y
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461-1602, USA.
J Clin Invest. 1996 Aug 1;98(3):629-34. doi: 10.1172/JCI118833.
The ability of muscles from Glut 4-null mice to take up and metabolize glucose has been studied in the isolated white EDL and red soleus muscles. In EDL muscles from male or female Glut 4-null mice, basal deoxyglucose uptake was lower than in control muscles and was not stimulated by insulin. In parallel, glycogen synthesis and content were decreased. Soleus muscles from male Glut 4-null mice took up twice more deoxyglucose in the absence of insulin than control muscles, but did not respond to insulin. In females, soleus deoxyglucose uptake measured in the absence of hormone was similar in Glut 4-null mice and in control mice. This uptake was stimulated twofold in Glut 4-null mice and threefold in control mice. Basal glycogen synthesis was increased by 4- and 2.2-fold in male and female null mice, respectively, compared to controls, and insulin had no or small (20% stimulation over basal) effect. These results indicate that while EDL muscles behaved as expected, soleus muscles were able to take up a large amount of glucose in the absence (males) or the presence of insulin (females). Whether this is due to a change in Glut 1 intrinsic activity or targeting and/or to the appearance of another glucose transporter remains to be determined.
在分离出的白色趾长伸肌（EDL）和红色比目鱼肌中，对Glut 4基因敲除小鼠的肌肉摄取和代谢葡萄糖的能力进行了研究。在雄性或雌性Glut 4基因敲除小鼠的EDL肌肉中，基础脱氧葡萄糖摄取低于对照肌肉，且不受胰岛素刺激。同时，糖原合成和含量降低。雄性Glut 4基因敲除小鼠的比目鱼肌在无胰岛素时摄取的脱氧葡萄糖比对照肌肉多两倍，但对胰岛素无反应。在雌性中，Glut 4基因敲除小鼠和对照小鼠在无激素情况下测得的比目鱼肌脱氧葡萄糖摄取相似。这种摄取在Glut 4基因敲除小鼠中增加了两倍，在对照小鼠中增加了三倍。与对照相比，雄性和雌性基因敲除小鼠的基础糖原合成分别增加了4倍和2.2倍，胰岛素对其无作用或作用很小（比基础水平刺激20%）。这些结果表明，虽然EDL肌肉表现符合预期，但比目鱼肌在无胰岛素（雄性）或有胰岛素（雌性）的情况下都能够摄取大量葡萄糖。这是否是由于Glut 1内在活性或靶向性的改变和/或另一种葡萄糖转运体的出现，仍有待确定。
