Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise
Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise
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DOI：
10.1152/ajpendo.1997.273.2.e268
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发表时间：
1997-08-01
影响因子：
5.1
通讯作者：
Saris, WHM
中科院分区：
文献类型：
--
作者：
Coyle, EF;Jeukendrup, AE;Saris, WHM
我们确定了高血糖和高胰岛素血症引起的糖酵解通量增加是否直接减少了运动中的脂肪酸氧化。在恒速静脉输注微量长链脂肪酸（[1-C-13]棕榈酸酯; Oct）与中链脂肪酸（[1-C-13]辛酸酯; Oct）期间测量脂肪酸氧化速率。6名接受过耐力训练的男性以最大O-2摄取量的50%骑自行车40分钟：1）在过夜禁食（“禁食”）后，2）在运动前60分钟和10分钟摄入1.4 g/kg葡萄糖（Glc）后。Glc引起高胰岛素血症，运动前血糖为6 mM，运动期间总脂肪氧化减少34%，这是由于血浆游离脂肪酸（FFA）和肌内甘油三酯氧化减少大致相等（均P < 0.05）。与快速（即，70.0+/- 4.1对比86.0 +/- 1.9%示踪剂输注速率; P < 0.05）。然而，葡萄糖对Oct氧化没有影响，Oct氧化显然不受线粒体转运的限制。此外，葡萄糖降低血浆FFA的出现36%（P < 0.05），表明对脂肪组织和肌肉的作用协调。总之，运动过程中的底物氧化可以通过糖酵解通量的增加来调节，糖酵解通量的增加伴随着对长链脂肪酸氧化的直接抑制。这些观察结果表明，碳水化合物的可用性可以直接调节运动期间的脂肪氧化。
We determined whether increased glycolytic flux from hyperglycemia and hyperinsulinemia directly reduces fatty acid oxidation during exercise. Fatty acid oxidation rates were measured during constant-rate intravenous infusion of trace amounts of a long-chain fatty acid ([1-C-13]palmitate; Pal) vs. a medium-chain fatty acid ([1-C-13]octanoate; Oct). Six endurance-trained men cycled for 40 min at 50% of maximal O-2 uptake 1) after an overnight fast (''fasting'') and 2) after ingestion of 1.4 g/kg of glucose at 60 min and again 10 min before exercise (Glc). Glc caused hyperinsulinemia, a preexercise blood glucose of 6 mM, and a 34% reduction in total fat oxidation during exercise due to an approximately equal reduction in oxidation of plasma free fatty acids (FFA) and intramuscular triglycerides (all P < 0.05). Oxidation of Pal was significantly reduced during Glc compared with fast (i.e., 70.0 +/- 4.1 vs. 86.0 +/- 1.9% of tracer infusion rate; P < 0.05). However, Glc had no effect on Oct oxidation, which is apparently not limited by mitochondrial transport. Furthermore, Glc reduced plasma FFA appearance 36% (P < 0.05), indicating a coordination of effects on adipose tissue and muscle. In summary, substrate oxidation during exercise can be regulated by increased glycolytic flux that is accompanied by a direct inhibition of long-chain fatty acid oxidation. These observations indicate that carbohydrate availability can directly regulate fat oxidation during exercise.