Premium
Effect of circulating insulin concentration on whole body and muscle protein metabolism in mature thoroughbred mares
Author(s) -
Urschel Kristine L.,
Escobar Jeffery,
McCutcheon L. Jill,
Geor Raymond J.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.905.2
Subject(s) - medicine , endocrinology , metabolism , leucine , insulin , valine , phosphorylation , protein metabolism , ribosomal protein s6 , amino acid , chemistry , carbohydrate metabolism , horse , protein kinase b , biology , biochemistry , p70 s6 kinase 1 , paleontology
The role of insulin (INS) in carbohydrate metabolism and the development of certain metabolic diseases has been well studied in horsse; however, there has been minimal research with regards to the role that INS plays in equine protein metabolism. The objective of this study was to determine the effect of circulating INS concentration on whole‐body protein metabolism and the activation of translation initiation factors in muscle. Mature thoroughbred mares (n=8) underwent euglycemic clamp procedures at each of 4 different rates of INS infusion: 0, 1.2, 3 and 6 mU/kg/min. Blood samples were taken during the clamp and at the end of the clamp a biopsy from the gluteal muscle was taken. Western blotting was used to examine the phosphorylation of protein synthesis initiation factors Akt, rpS6 and 4E‐BP1 in the gluteal muscle, and HPLC was used to determine plasma and muscle free amino acid concentrations. INS infusion resulted in a decrease (P < 0.05) in the plasma concentration of all indispensable amino acids, with greater decreases seen with increasing rates of INS infusion. Muscle free valine, leucine and isoleucine concentrations were also lower (P < 0.05) following INS infusion, in a dose dependent manner. Akt phosphorylation was maximized at 6 mU/kg/min INS, while rpS6 and 4E‐BP1 phosphorylation was maximized at 3 mU/kg/min INS. INS infusion appeared to promote both whole‐body amino acid utilization and activation of translation initiation factors in muscle of mature horses. Future research should focus on the effects of altered INS sensitivity on equine protein metabolism. Funded by estate of the late Paul Mellon.