Horm Metab Res 2009; 41(1): 16-22
DOI: 10.1055/s-0028-1087170
Original Basic

© Georg Thieme Verlag KG Stuttgart · New York

Uniaxial Cyclic Stretch Increases Glucose Uptake into C2C12 Myotubes through a Signaling Pathway Independent of Insulin-like Growth Factor I

M. Iwata 1 , 2 , S. Suzuki 1 , K. Hayakawa 3 , T. Inoue 1 , K. Naruse 4
  • 1Program in Physical and Occupational Therapy, Nagoya University Graduate School of Medicine, Higashi-ku, Nagoya, Japan
  • 2Current address: Department of Rehabilitation, Faculty of Health Sciences, Nihon Fukushi University, Handa, Japan
  • 3ICORP/SORST Cell Mechanosensing, Japan Science and Technology Agency, Showa-ku, Nagoya, Japan
  • 4Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
Further Information

Publication History

received 26.02.2008

accepted 04.06.2008

Publication Date:
07 October 2008 (online)


Insulin-like growth factor I (IGF-I), an autocrine/paracrine growth factor involved in myogenesis, has rapid effects on muscle metabolism. In a manner analogous to insulin and mechanical stimuli such as stretch, IGF-I stimulates glucose transport through recruitment of glucose transporters to surface membranes in skeletal muscles. It is known that IGF-I is secreted from skeletal muscle cells in response to stretch. Therefore, we examined whether IGF-I is involved in the mechanism by which mechanical stretch regulates glucose transport using cultured C2C12 myotubes. IGF-I increased 2-deoxy-D-glucose (2-DG) uptake, and this created an additive effect with mechanical stretch, suggesting that these stimuli enhance glucose transport through different mechanisms. In fact, IGF-I-stimulated 2-DG uptake was not blocked by dantrolene (an inhibitor of Ca2+release from sarcoplasmic reticulum), whereas the stretch-stimulated effect was abolished. Conversely, the IGF-I-stimulated 2-DG uptake was prevented by phosphatidylinositol 3-kinase inhibitor wortmannin, which did not prevent the stretch-stimulated 2-DG uptake. In addition, experiments using media conditioned by stretched myotubes indicated that a mechanically induced release of locally acting autocrine/paracrine growth factors was not sufficient for induction of 2-DG uptake. Thus, our results demonstrate that mechanical stretch signaling for glucose transport is independent of the mechanism through which IGF-I increases this transport.



S. Suzuki, PhD 

Program in Physical and Occupational Therapy

Nagoya University Graduate School of Medicine

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