Dolan P L, Boyd S G, Dohm G L
Department of Biochemistry, East Carolina University School of Medicine, Greenville, North Carolina 27858, USA.
Am J Physiol. 1995 Jun;268(6 Pt 1):E1154-60. doi: 10.1152/ajpendo.1995.268.6.E1154.
Insulin-stimulated glucose transport has been shown to decline during maturation in lean rats. To determine whether this maturation-induced decrease occurred in the muscle of obese rats and whether the contraction-stimulated pathway for glucose transport was similarly affected, glucose transport rates were measured in insulin- and electrically stimulated skeletal muscle during hindlimb perfusion of 10- and 29-wk-old lean and obese male Zucker rats. Glucose transporter (GLUT-4) protein was also measured. Insulin-stimulated glucose transport rates were significantly decreased (36-56%) in 29-wk compared with 10-wk-old lean rats. There was no maturation-related decrease in GLUT-4. Insulin-mediated glucose transport was unaltered by maturation in skeletal muscle of obese rats. Differential effects of maturation on lean and obese rats caused the effect of obesity on maximally insulin-stimulated glucose transport to be much greater in 10- than 29-wk-old animals. Maturation had no effect on contraction-stimulated glucose transport rates in either lean or obese animals. The combined effect of maximal insulin plus contraction was not altered with maturity in lean animals but was significantly increased in 29- compared with 10-wk-old obese rats. Absence of a change in GLUT-4 content together with uncompromised contraction-stimulated glucose transport suggests that the maturation-induced decrease in insulin-stimulated glucose transport in lean rats is due to a defect in the insulin signaling pathway.
在瘦大鼠成熟过程中，胰岛素刺激的葡萄糖转运已被证明会下降。为了确定这种成熟诱导的下降是否发生在肥胖大鼠的肌肉中，以及葡萄糖转运的收缩刺激途径是否受到类似影响，在对10周龄和29周龄的瘦和肥胖雄性 Zucker 大鼠进行后肢灌注期间，测量了胰岛素和电刺激的骨骼肌中的葡萄糖转运速率。还测量了葡萄糖转运蛋白（GLUT-4）的含量。与10周龄的瘦大鼠相比，29周龄的瘦大鼠胰岛素刺激的葡萄糖转运速率显著降低（36%-56%）。GLUT-4没有与成熟相关的下降。在肥胖大鼠的骨骼肌中，胰岛素介导的葡萄糖转运不受成熟的影响。成熟对瘦大鼠和肥胖大鼠的不同影响导致肥胖对最大胰岛素刺激的葡萄糖转运的影响在10周龄动物中比在29周龄动物中更大。成熟对瘦动物或肥胖动物的收缩刺激的葡萄糖转运速率没有影响。在瘦动物中，最大胰岛素加收缩的联合作用不会随成熟而改变，但在29周龄的肥胖大鼠中与10周龄相比显著增加。GLUT-4含量没有变化以及收缩刺激的葡萄糖转运未受损害表明，瘦大鼠中成熟诱导的胰岛素刺激的葡萄糖转运下降是由于胰岛素信号通路缺陷。
