Passive mechanical properties of rat abdominal wall muscles suggest an important role of the extracellular connective tissue matrix

Stephen H M Brown, John Austin Carr, Samuel R. Ward, Richard L. Lieber*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Abdominal wall muscles have a unique morphology suggesting a complex role in generating and transferring force to the spinal column. Studying passive mechanical properties of these muscles may provide insights into their ability to transfer force among structures. Biopsies from rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were harvested from male Sprague-Dawley rats, and single muscle fibers and fiber bundles (4-8 fibers ensheathed in their connective tissue matrix) were isolated and mechanically stretched in a passive state. Slack sarcomere lengths were measured and elastic moduli were calculated from stress-strain data. Titin molecular mass was also measured from single muscle fibers. No significant differences were found among the four abdominal wall muscles in terms of slack sarcomere length or elastic modulus. Interestingly, across all four muscles, slack sarcomere lengths were quite long in individual muscle fibers (>2.4μm), and demonstrated a significantly longer slack length in comparison to fiber bundles (p<0.0001). Also, the extracellular connective tissue matrix provided a stiffening effect and enhanced the resistance to lengthening at long muscle lengths. Titin molecular mass was significantly less in TrA compared to each of the other three muscles (p<0.0009), but this difference did not correspond to hypothesized differences in stiffness.

Original languageEnglish (US)
Pages (from-to)1321-1326
Number of pages6
JournalJournal of Orthopaedic Research
Volume30
Issue number8
DOIs
StatePublished - Aug 2012

Keywords

  • muscle
  • passive mechanics
  • sarcomere
  • spine
  • transversus abdominis

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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