Effects of high-fat diet and exercise training on intracellular glucose metabolism in rats

被引:70
作者
Kim, CH
Youn, JH
Park, JY
Hong, SK
Park, KS
Park, SW
Suh, KI
Lee, KU
机构
[1] Univ Ulsan, Coll Med, Dept Internal Med, Seoul 138736, South Korea
[2] Soonchunhyang Univ, Coll Med, Dept Internal Med, Seoul 140743, South Korea
[3] Seoul Natl Univ, Coll Med, Seoul 110744, South Korea
[4] Hallym Univ, Coll Med, Anyang 431070, South Korea
[5] Univ So Calif, Sch Med, Dept Physiol & Biophys, Los Angeles, CA 90089 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM | 2000年 / 278卷 / 06期
关键词
glucose metabolic fluxes; glucose; 6-phosphate; glucose transporter; hexokinase; glycogen synthase;
D O I
10.1152/ajpendo.2000.278.6.E977
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
We examined the effects of high-fat diet (HFD) and exercise training on insulin-stimulated whole body glucose fluxes and several key steps of glucose metabolism in skeletal muscle. Rats were maintained for 3 wk on either low-fat (LFD) or high-fat diet with or without exercise training (swimming for 3 h per day). After the 3-wk diet/exercise treatments, animals underwent hyperinsulinemic euglycemic clamp experiments for measurements of insulin-stimulated whole body glucose fluxes. In addition, muscle samples were taken at the end of the clamps for measurements of glucose 6-phosphate (G-6-P) and GLUT-4 protein contents, hexokinase, and glycogen synthase (GS) activities. Insulin-stimulated glucose uptake was decreased by HFD and increased by exercise training (P < 0.01 for both). The opposite effects of HFD and exercise training on insulin-stimulated glucose uptake were associated with similar increases in muscle G-6-P levels (P < 0.05 for both). However, the increase in G-6-P level was accompanied by decreased GS activity without changes in GLUT-4 protein content and hexokinase activities in the HFD group. In contrast, the increase in G-6-P level in the exercise-trained group was accompanied by increased GLUT-4 protein content and hexokinase II (cytosolic) and GS activities. These results suggest that HFD and exercise training affect insulin sensitivity by acting predominantly on different steps of intracellular glucose metabolism. High-fat feeding appears to induce insulin resistance by affecting predominantly steps distal to G-6-P (e.g., glycolysis and glycogen synthesis). Exercise training affected multiple steps of glucose metabolism both proximal and distal to G-6-P. However, increased muscle G-6-P levels in the face of increased glucose metabolic fluxes suggest that the effect of exercise training is quantitatively more prominent on the steps proximal to G-6-P (i.e., glucose transport and phosphorylation).
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收藏
页码:E977 / E984
页数:8
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