Quantitative analysis of neonatal skeletal muscle functional improvement in the mouse

David S. Gokhin, Samuel R. Ward, Shannon N. Bremner, Richard L. Lieber

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Postnatal skeletal muscle growth is classically attributed to fiber hypertrophy and myogenic differentiation, but these processes do not account for the size-independent increase of muscle mechanical performance that occurs during postnatal growth. There is also little knowledge about the precise time-course of contractile function or the underlying factors that affect it. The present study investigated morphological factors (muscle fiber size and myofibrillar packing), biochemical factors (myosin heavy chain isoform and desmln intermediate filament protein expression), and muscle architecture during postnatal development in mice. Physiological testing of the mouse tibialis anterior revealed that maximum isometric stress increased from 27±3 kPa at postnatal day 1 to 169±10 kPa by postnatal day 28, roughly a sixfold increase. Morphological measurements revealed a robust increase in the size-independent packing of myofibrillar matrix material occurring with the functional improvement, with just 48.1 ±5.5% of the cross-sectional area filled with myofibrils at postnatal day 1 whereas 92.5±0.9% was filled by day 28. Expression of four myosin heavy chain isoforms (embryonic, neonatal, HX and IIB), as well as desmin, correlated significantly with muscle mechanical function. Stepwise multiple regression showed that, of the variables measured, percentage content of neonatal myosin heavy chain was the best predictor of mechanical function during the postnatal time-course. These data provide the first specific structural basis for increases in muscle tension development during growth. Therefore, models of muscle growth must be modified to include an intrinsic quality enhancement component.

Original languageEnglish (US)
Pages (from-to)837-843
Number of pages7
JournalJournal of Experimental Biology
Volume211
Issue number6
DOIs
StatePublished - Mar 2008

Keywords

  • Desmin
  • Growth
  • Isometric stress
  • Maturation
  • Myofibril
  • Skeletal muscle

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science

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