Pathways of Ca2+ entry and cytoskeletal damage following eccentric contractions in mouse skeletal muscle

Bao Ting Zhang, Nicholas P. Whitehead, Othon L. Gervasio, Trent F. Reardon, Molly Vale, Diane Fatkin, Alexander Dietrich, Wai Ella Yeung, David G. Allen

Research output: Journal article publicationJournal articleAcademic researchpeer-review

43 Citations (Scopus)

Abstract

Muscles that are stretched during contraction (eccentric contractions) show deficits in force production and a variety of structural changes, including loss of antibody staining of cytoskeletal proteins. Extracellular Ca2+entry and activation of calpains have been proposed as mechanisms involved in these changes. The present study used isolated mouse extensor digitorum longus (EDL) muscles subjected to 10 eccentric contractions and monitored force production, immunostaining of cytoskeletal proteins, and resting stiffness. Possible pathways for Ca2+entry were tested with streptomycin (200 μM), a blocker of stretch-activated channels, and with muscles from mice deficient in the transient receptor potential canonical 1 gene (TRPC1 KO), a candidate gene for stretch-activated channels. At 30 min after the eccentric contractions, the isometric force was decreased to 75 ± 3% of initial control and this force loss was reduced by streptomycin but not in the TRPC1 KO. Desmin, titin, and dystrophin all showed patchy loss of immunostaining 30 min after the eccentric contractions, which was substantially reduced by streptomycin and in the TRPC1 KO muscles. Muscles showed a reduction of resting stiffness following eccentric contractions, and this reduction was eliminated by streptomycin and absent in the TRPC1 KO muscles. Calpain activation was determined by the appearance of a lower molecular weight autolysis product and μ-calpain was activated at 30 min, whereas the muscle-specific calpain-3 was not. To test whether the loss of stiffness was caused by titin cleavage, protein gels were used but no significant titin cleavage was detected. These results suggest that Ca2+entry following eccentric contractions is through a stretch-activated channel that is blocked by streptomycin and encoded or modulated by TRPC1.
Original languageEnglish
Pages (from-to)2077-2086
Number of pages10
JournalJournal of Applied Physiology
Volume112
Issue number12
DOIs
Publication statusPublished - 15 Jun 2012

Keywords

  • Calpains
  • Cytoskeletal proteins
  • Eccentric contractions
  • Stretch-induced damage
  • Titin

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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