Atypical fast SERCA1a protein expression in slow myofibers and differential S-nitrosylation prevented by exercise during long term bed rest

Histochem Cell Biol. 2009 Oct;132(4):383-94. doi: 10.1007/s00418-009-0624-y. Epub 2009 Jul 31.

Abstract

We monitored changes in SERCA isoform specific expression and S-nitrosylation in myofibers of lower limb soleus (SOL) and vastus lateralis (VL) muscle biopsies before and after 60 days of voluntary long term bed rest (BR) without (BR-CTRL group, n = 8) and with exercise countermeasure (BR-EX group, n = 8). Before BR, a typical myofiber type-specific distribution of fast and slow SERCA1/2a isoforms was seen. After BR, a subpopulation (approx. 15%) of slow myofibers in BR-CTRL additionally expressed the fast SERCA1a isoform which was not seen in BR-EX. After BR, SERCA1a S-nitrosylation patterns analyzed by the biotin-switch assay decreased in disused SOL only but increased in both muscles following exercise. Differential SERCA1a S-nitrosylation and SERCA1a/2a co-expression in subsets of slow myofibers should be considered as signs of an altered cytosolic Ca(2+) homeostasis following chronic muscle disuse. Exercise preserved myofiber type-specific SERCA1a expression and S-nitrosylation in VL and SOL in a different way, suggesting muscle-specific responses to the countermeasure protocol applied during bed rest.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bed Rest / adverse effects
  • Exercise / physiology
  • Female
  • Humans
  • Lower Extremity
  • Muscle Fibers, Slow-Twitch / enzymology*
  • Muscular Disorders, Atrophic / enzymology*
  • Muscular Disorders, Atrophic / pathology
  • Muscular Disorders, Atrophic / prevention & control
  • Myofibrils / enzymology*
  • Protein Isoforms / metabolism
  • Quadriceps Muscle / enzymology
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / metabolism*

Substances

  • Protein Isoforms
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • ATP2A1 protein, human
  • ATP2A2 protein, human