Effects of insulin-like growth factor I on the rates of glucose transport and utilization in rat skeletal muscle in vitro

Author:

Dimitriadis G1,Parry-Billings M1,Bevan S1,Dunger D2,Piva T1,Krause U3,Wegener G3,Newsholme E A1

Affiliation:

1. Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.

2. Department of Pediatrics, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.

3. Institut für Zoologie, Johannes Gutenberg Universität, D-6500 Mainz, Germany

Abstract

1. The effects of insulin-like growth factor I (IGF-I) on the rates of glucose transport and utilization and its interaction with insulin were investigated in rat soleus muscle in vitro. IGF-I increased the rates of glucose transport, lactate formation, glycogen synthesis and the flux of glucose to hexose monophosphate, but it had no effect on the rate of glucose oxidation or glycogenolysis. 2. In the absence of insulin, low levels of IGF-I (0-30 ng/ml) increased the rate of glycolysis and the content of fructose 2,6-bisphosphate, but the content of glucose 6-phosphate remained unaltered; at higher levels of IGF-I (300-3000 ng/ml) the rate of glycolysis and the content of fructose 2,6-bisphosphate showed a further modest increase, but the content of glucose 6-phosphate doubled. Similar changes were seen when the level of insulin was increased from basal (0-0.4 ng/ml) to maximal (40 ng/ml). 3. Neither IGF-I nor insulin affected the contents of ATP, ADP, AMP, phosphocreatine or citrate. 4. Maximal concentrations of IGF-I increased the rate of lactate formation to a greater extent than did maximal concentrations of insulin. 5. In the presence of IGF-I, the rate of glucose utilization was less responsive to insulin. 6. The results suggest that, in rat skeletal muscle: (a) IGF-I increases the rates of glucose transport and utilization independently of insulin, and has a preferential effect on the rate of lactate formation; (b) the effects of IGF-I and insulin are not additive; (c) in addition to its effects on glucose transport, IGF-I increases the rate of glycogen synthesis and may stimulate glycolysis at the level of 6-phosphofructokinase; (d) changes in the content of fructose 2,6-bisphosphate may be part of the mechanism to regulate glycolytic flux in skeletal muscle in response to either IGF-I or insulin.

Publisher

Portland Press Ltd.

Subject

Cell Biology,Molecular Biology,Biochemistry

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3