Ayre K J, Phinney S D, Tang A B, Stern J S
Department of Biomedical Science, University of Wollongong, New South Wales 2522, Australia.
J Appl Physiol (1985). 1998 Nov;85(5):1898-902. doi: 10.1152/jappl.1998.85.5.1898.
Compared with the lean (Fa/-) genotype, obese (fa/fa) Zucker rats have a relative deficiency of muscle phospholipid arachidonate, and skeletal muscle arachidonate in humans is positively correlated with insulin sensitivity. To assess the hypothesis that the positive effects of exercise training on insulin sensitivity are mediated by increased muscle arachidonate, we randomized 20 lean and 20 obese weanling male Zucker rats to sedentary or treadmill exercise groups. After 9 wk, fasting serum, three skeletal muscles (white gastrocnemius, soleus, and extensor digitorum longus), and heart were obtained. Fasting insulin was halved by exercise training in the obese rat. In white gastrocnemius and extensor digitorum longus (fast-twitch muscles), but not in soleus (a slow-twitch muscle) or heart, phospholipid arachidonate was lower in obese than in lean rats (P < 0.001). In all muscles, exercise in the obese rats reduced arachidonate (P < 0.03, by ANOVA contrast). We conclude that improved insulin sensitivity with exercise in the obese genotype is not mediated by increased muscle arachidonate and that reduced muscle arachidonate in obese Zucker rats is unique to fast-twitch muscles.
与瘦型（Fa/-）基因型相比，肥胖型（fa/fa）的 Zucker 大鼠肌肉磷脂花生四烯酸相对缺乏，而人类骨骼肌中的花生四烯酸与胰岛素敏感性呈正相关。为了评估运动训练对胰岛素敏感性的积极作用是由肌肉花生四烯酸增加介导的这一假设，我们将 20 只瘦型和 20 只肥胖型断乳雄性 Zucker 大鼠随机分为久坐组或跑步机运动组。9 周后，采集空腹血清、三块骨骼肌（白色腓肠肌、比目鱼肌和趾长伸肌）以及心脏样本。运动训练使肥胖大鼠的空腹胰岛素减半。在白色腓肠肌和趾长伸肌（快肌）中，而非比目鱼肌（慢肌）或心脏中，肥胖大鼠的磷脂花生四烯酸低于瘦型大鼠（P < 0.001）。在所有肌肉中，肥胖大鼠的运动均降低了花生四烯酸水平（通过方差分析对比，P < 0.03）。我们得出结论，肥胖基因型大鼠运动后胰岛素敏感性的改善并非由肌肉花生四烯酸增加介导，且肥胖 Zucker 大鼠肌肉花生四烯酸的降低是快肌所特有的。
