Uniaxial cyclic stretch increases glucose uptake into C2C12 myotubes through a signaling pathway independent of insulin-like growth factor I.

M. Iwata, S. Suzuki, K. Hayakawa, T. Inoue, K. Naruse

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

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 Ca (2+)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.

Original languageEnglish
Pages (from-to)16-22
Number of pages7
JournalHormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et métabolisme
Volume41
Issue number1
DOIs
Publication statusPublished - Jan 2009

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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