Sherman W M, Friedman J E, Gao J P, Reed M J, Elton C W, Dohm G L
Exercise Physiology Laboratory, School of Health, Physical Education, and Recreation, Ohio State University, Columbus 43210.
Med Sci Sports Exerc. 1993 Mar;25(3):341-8.
The purpose of this study was to determine the effects of chronic hyperglycemia and/or exercise training on the muscle concentration of the insulin-responsive glucose transporter protein, GLUT4, and on maximally insulin-stimulated hindlimb muscle glucose transport. Five-wk-old lean and obese Zucker rats were randomly assigned to sham-operated control (CTL) or 90% pancreatectomized (PX) groups. Obese-PX animals were further randomized into sedentary or exercise trained groups (15-wk treadmill running for 2 h.d-1, 5 d.wk-1, 15% grade, at 15-18 m.min-1). Muscle GLUT4 protein content and maximally insulin-stimulated glucose transport were determined in gastrocnemius, plantaris, and soleus muscles. At 20 wk, lean-PX displayed mild fasting hyperglycemia but normal insulin levels. Obese-PX rats had insulin levels similar to lean-CTL rats but had severe hyperglycemia. Hyperglycemia in lean-PX was associated with a 28% decrease in maximal glucose transport and a 65% decrease in muscle GLUT4 (P < 0.05) compared with lean-CTL. In obese-PX, maximal glucose transport was not affected, but muscle GLUT4 was reduced by 62% (P < 0.05) compared to obese-CTL. Exercise training obese-PX reduced hyperglycemia, increased maximal glucose transport by 45%, and increased muscle GLUT4 by > 2-fold (P < 0.05) compared with obese-CTL. Thus, hyperglycemia associated with PX may be an important factor in the reduction of muscle GLUT4 levels in lean and obese rats. The reduced GLUT4 was accompanied by reduced maximal glucose transport in lean but not obese rats. Exercise training reduced hyperglycemia, normalized glucose transport, and increased muscle GLUT4 in obese-PX.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是确定慢性高血糖和/或运动训练对胰岛素反应性葡萄糖转运蛋白GLUT4的肌肉浓度以及对最大胰岛素刺激的后肢肌肉葡萄糖转运的影响。将5周龄的瘦型和肥胖型Zucker大鼠随机分为假手术对照组（CTL）或90%胰腺切除（PX）组。肥胖- PX动物进一步随机分为久坐组或运动训练组（15周的跑步机跑步，每天2小时，每周5天，坡度15%，速度15 - 18米/分钟）。测定腓肠肌、跖肌和比目鱼肌中的肌肉GLUT4蛋白含量以及最大胰岛素刺激的葡萄糖转运。在20周时，瘦- PX表现出轻度空腹高血糖但胰岛素水平正常。肥胖- PX大鼠的胰岛素水平与瘦- CTL大鼠相似，但有严重的高血糖。与瘦- CTL相比，瘦- PX中的高血糖与最大葡萄糖转运降低28%以及肌肉GLUT4降低65%相关（P < 0.05）。在肥胖- PX中，最大葡萄糖转运未受影响，但与肥胖- CTL相比，肌肉GLUT4降低了62%（P < 0.05）。与肥胖- CTL相比，运动训练肥胖- PX降低了高血糖，使最大葡萄糖转运增加了45%，并使肌肉GLUT4增加了2倍以上（P < 0.05）。因此，与PX相关的高血糖可能是瘦型和肥胖型大鼠肌肉GLUT4水平降低的一个重要因素。GLUT4降低在瘦型大鼠中伴随着最大葡萄糖转运降低，但在肥胖型大鼠中并非如此。运动训练降低了肥胖- PX中的高血糖，使葡萄糖转运正常化，并增加了肌肉GLUT4。（摘要截断于250字）
