Effects of Cardiac Work and Leucine on Protein Turnover

  • B. Chua
  • D. L. Siehl
  • E. O. Fuller
  • H. E. Morgan

Abstract

The purpose of these experiments was to assess effects of cardiac work and leucine in hearts supplied only glucose or substrate and hormone mixtures that simulated plasma. Rates of protein degradation greatly exceeded protein synthesis in Langendorff preparations supplied glucose. This severely negative nitrogen balance was brought closer to zero by provision of more complete substrate mixtures. Cardiac work further improved the nitrogen balance by stimulating protein synthesis in hearts supplied glucose (mixture 1), glucose-insulin-glucagon-lactate-β-hydroxybutyrate (mixture 2), or palmitate-β-hydroxybutyrate-glucose (mixture 3) and inhibiting protein degradation in hearts supplied glucose. Cardiac work did not affect the rates of either protein synthesis or degradation in hearts provided insulin-lactate-glucose (mixture 4). The increase in protein synthesis was associated with increased rates of peptide chain initiation. Addition of 1 mM leucine had an additional effect to restore nitrogen balance to zero or to achieve positive balance in working hearts supplied substrate and hormone mixture 2.

Keywords

Protein Synthesis Protein Degradation Protein Turnover Nitrogen Balance Substrate Mixture 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1983

Authors and Affiliations

  • B. Chua
    • 1
  • D. L. Siehl
    • 1
  • E. O. Fuller
    • 1
  • H. E. Morgan
    • 1
  1. 1.Department of Physiology, The Milton S. Hershey Medical CenterThe Pennsylvania State UniversityHersheyUSA

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