Regional adaptations of rabbit diaphragm muscle fibers to unilateral denervation

W. Z. Zhan, G. A. Farkas, M. A. Schroeder, L. E. Gosselin, G. C. Sieck

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

We hypothesized that adaptations of the rabbit diaphragm (Dia) after unilateral denervation (DNV) result from removal of a neural influence rather than from passive stress. Length changes of midcostal and sternal Dia regions were measured before and after DNV by using sonomicrometry. Midcostal fibers passively lengthened after DNV, whereas sternal fibers shortened. In both regions, these length changes were associated with minimal stress, as estimated from passive force-length relationships. Morphological and contractile adaptions of midcostal and sternal Dia regions were examined after i and 4 wk of DNV. In both Dia regions, type I fibers progressively hypertrophied, whereas type IIb fibers atrophied. After DNV, changes in isometric contraction were similar in both Dia regions. Twitch contraction and half-relaxation times increased, force-frequency relationships shifted leftward, and maximum tetanic force decreased. We conclude that passive length changes and mechanical stress are not the main determinants of the morphological and contractile adaptations of the Dia after unilateral DNV but that these adaptations result from DNV itself.

Original languageEnglish (US)
Pages (from-to)941-950
Number of pages10
JournalJournal of applied physiology
Volume79
Issue number3
DOIs
StatePublished - 1995

Keywords

  • cross-sectional area
  • hemidiaphragm
  • passive stretch
  • sonomicrometry

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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