Age effect on transcript levels and synthesis rate of muscle MHC and response to resistance exercise

Prabhakaran Balagopal, Jill Coenen Schimke, Philip Ades, Deborah Adey, K. Sreekumaran Nair

Research output: Contribution to journalArticlepeer-review

186 Scopus citations

Abstract

Experimental evidence indicates that a lower synthesis rate of muscle contractile protein myosin heavy chain (MHC) occurs in age-related muscle wasting and weakness. To determine the molecular mechanism of this lower synthesis of MHC, we measured transcript levels of isoforms of MHC (MHCI, MHCIIa, and MHCIIx) in muscle biopsy samples of 7 young (20-27 yr), 12 middle-aged (47-60 yr), and 14 older (>65 yr) people. We further determined the effect of 3 mo of resistance exercise training (exercise) vs. nonintervention (control) on transcript levels of MHC isoforms on these subjects and the fractional synthesis rate (FSR) of MHC in 39 people aged 46-79 yr. MHCI mRNA levels did not significantly change with age, but MHCIIa decreased 38% (P < 0.05) from young to middle age and further decreased 50% (P < 0.05) from middle to old age. MHCIIx decreased 84% (P < 0.05) from young to middle age and 48% from middle to old age (P < 0.05). Exercise increased FSR of MHC by 47% (P < 0.01) and mixed muscle protein by 56% (P < 0.05). Exercise training results in an increase (85%) in transcript levels of MHCI and a decrease in the transcript levels of MHCIIa and MHCIIx. In conclusion, an age-related lowering of the transcript levels of MHCIIa and MHCIIx is not reversed by exercise, whereas exercise results in a higher synthesis rate of MHC in association with an increase in MHCI isoform transcript levels.

Original languageEnglish (US)
Pages (from-to)E203-E208
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume280
Issue number2 43-2
DOIs
StatePublished - Feb 2001

Keywords

  • Aging
  • Messenger ribonucleic acid
  • Muscle
  • Myosin heavy chain
  • Protein synthesis

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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