Histochemical and mechanical properties of diaphragm muscle in morbidly obese Zucker rats

G. A. Farkas, L. E. Gosselin, W. Z. Zhan, E. H. Schlenker, G. C. Sieck

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


The purpose of the present study was to evaluate the effects of chronic mass loading produced by obesity on the structural and functional characteristics of the diaphragm in lean and obese Zucker rats. The trapezius muscle served as an internal control. The studies were carried out on 17 lean (303 ± 24 g) and 16 obese (698 ± 79 g) Zucker rats. We observed that the diaphragms from obese animals were restructured such that the overall contribution of type I and IIa fibers was significantly increased. As a consequence of this remodeling, overall diaphragm thickness was selectively greater in obese animals. In small isolated diaphragm bundles studied in vitro, we also detected a reduction in specific force in obese animals that was not detected in the trapezius muscle. In vitro fatigue resistance, assessed by repeated stimulation, was similar in muscles of lean and obese animals. Diaphragm fiber oxidative capacity (succinate dehydrogenase activity) was also comparable in lean and obese animals. We conclude that in obesity the diaphragm undergoes modest remodeling that may be beneficial in enhancing force generation.

Original languageEnglish (US)
Pages (from-to)2250-2259
Number of pages10
JournalJournal of applied physiology
Issue number5
StatePublished - 1994


  • animal models of disease
  • chest wall loading
  • diaphragm adaptability
  • fatigability
  • muscle contractility
  • muscle plasticity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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