Testosterone injection stimulates net protein synthesis but not tissue amino acid transport

Arny A. Ferrando, Kevin D. Tipton, David Doyle, Stuart M. Phillips, Joaquin Cortiella, Robert R. Wolfe

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Abstract

Testosterone administration (T) increases lean body mass and muscle protein synthesis. We investigated the effects of short-term T on leg muscle protein kinetics and transport of selected amino acids by use of a model based on arteriovenous sampling and muscle biopsy. Fractional synthesis (FSR) and breakdown (FBR) rates of skeletal muscle protein were also directly calculated. Seven healthy men were studied before and 5 days after intramuscular injection of 200 mg of testosterone enanthate. Protein synthesis increased twofold after injection (P < 0.05), whereas protein breakdown was unchanged. FSR and FBR calculations were in accordance, because FSR increased twofold (P < 0.05) without a concomitant change in FBR. Net balance between synthesis and breakdown became more positive with both methodologies (P < 0.05) and was not different from zero. T injection increased arteriovenous essential and nonessential nitrogen balance across the leg (P < 0.05) in the fasted state, without increasing amino acid transport. Thus T administration leads to an increased net protein synthesis and reutilization of intracellular amino acids in skeletal muscle.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume275
Issue number5 38-5
StatePublished - 1998

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Keywords

  • Amino nitrogen uptake
  • Fractional breakdown rate

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Biochemistry
  • Physiology (medical)

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