Increased phenylalanine incorporation in regenerating skeletal muscle grafts

J. Schwartz, J. Wiesen, B. Carlson, L. Yamasaki, M. Moore, M. Womble

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3 Scopus citations

Abstract

Skeletal muscle regenerates following grafting, but little is known about protein synthesis and its regulation during regeneration. We determined the sequence of changes in protein synthesis in rat extensor digitorum longus (EDL) muscle by the measurement of phenylalanine (Phe) incorporation into muscle protein at various times after grafting. Compared with control EDL, Phe incorporation in grafts doubled in 1 day, was four- to eight-fold greater from days 2 to 10 after grafting, and then subsided. Tissue mass (wet weight) increased rapidly from days 7 to 20 in EDL grafts. The maximal increase in protein synthesis occurred 7-10 days after grafting, whether or not the nerve was left intact. Autoradiography indicated that incorporated radioactivity was associated with regenerating muscle fibers on day 10. Deficiencies of insulin, pituitary or testicular hormones, or chronic in vivo administration of insulin, growth hormone, testosterone, or tri-iodothyronine did not substantially alter the elevation in corporation of the Phe into muscle protein 10 days after grafting. The breakdown of EDL protein, measured in vitro simultaneously with protein synthesis, was increased five-fold, and overall protein degradation was elevated six-fold 10 days after grafting. These findings indicate that Phe incorporation is rapidly elevated following grafting of the EDL, and that by days 7-10 reflects synthesis in regenerating muscle fibers. The increase in protein synthesis associated with muscle regeneration at this time appears to be independent of innervation and anabolic hormones.

Original languageEnglish (US)
Pages (from-to)199-205
Number of pages7
JournalCanadian Journal of Physiology and Pharmacology
Volume64
Issue number2
DOIs
StatePublished - Jan 1 1986

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ASJC Scopus subject areas

  • Physiology
  • Pharmacology
  • Physiology (medical)

Cite this

Schwartz, J., Wiesen, J., Carlson, B., Yamasaki, L., Moore, M., & Womble, M. (1986). Increased phenylalanine incorporation in regenerating skeletal muscle grafts. Canadian Journal of Physiology and Pharmacology, 64(2), 199-205. https://doi.org/10.1139/y86-030