Increased expression of fibroblast growth factors in a rabbit skeletal muscle model of exercise conditioning.

Journal Article

Increased tonic contractile activity from exercise or electrical stimulation induces a variety of changes in skeletal muscle, including vascular growth, myoblast proliferation, and fast to slow fiber type conversion. Little is known about the cellular control of such changes, but pleiotropic biochemical modulators such as fibroblast growth factors (FGFs) may be involved in this response and thus may be regulated in response to such stimuli. We examined the regulation of FGF expression in an in vivo model of exercise conditioning previously shown to exhibit vascular growth and fast to slow fiber conversion. FGFs were extracted by heparin-affinity chromatography from extensor digitorum longus muscles of adult rabbits subjected to chronic motor nerve stimulation at 10 Hz. Growth factor activity (expressed in growth factor units [GFUs]) of muscle stimulated for 3 and 21 d was assayed by [3H]thymidine incorporation in 3T3 fibroblasts and compared with that present in the contralateral unstimulated muscle. A small increase in heparin-binding mitogenic activity was observed as early as 3 d of stimulation, and by 21 d mitogenic activity increased significantly when normalized to either wet weight (stimulated, 287 +/- 61 GFU/g; unstimulated, 145 +/- 39 GFU/g) or to protein (stimulated, 5.3 +/- 1.1 GFU/mg; unstimulated, 2.2 +/- 0.6 GFU/mg) (+/- SE, P less than 0.05). Western analysis demonstrated increased amounts of peptides with immunological identity to acidic and basic FGFs in stimulated muscle. The increase in FGF content observed in this study is synchronous with neovascularization, myoblast proliferation, and fast to slow fiber type conversion previously shown in this model. These results demonstrate that increased expression of FGFs is associated with motor nerve stimulation and increased tonic contractile activity of skeletal muscle, and suggests that these proteins may play a regulatory role in the cellular changes that occur during exercise conditioning.

Full Text

Duke Authors

Cited Authors

  • Morrow, NG; Kraus, WE; Moore, JW; Williams, RS; Swain, JL

Published Date

  • June 1, 1990

Published In

Volume / Issue

  • 85 / 6

Start / End Page

  • 1816 - 1820

PubMed ID

  • 2347914

International Standard Serial Number (ISSN)

  • 0021-9738

Digital Object Identifier (DOI)

  • 10.1172/JCI114640

Language

  • eng

Conference Location

  • United States