Adaptations of the diaphragm in emphysema

M. I. Lewis, W. Z. Zhan, Gary C Sieck

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

In adult male hamsters the influence of emphysema (EMP) on the in vitro contractile and fatigue properties and the histochemical, morphometric, and metabolic properties of muscle fibers in the costal diaphragm was determined 6 mo after the administration of either elastase or saline (controls, CTL). Isometric contractile properties were determined in vitro using supramaximal direct muscle stimulation. Optimal fiber length for force generation was significantly shorter in the EMP than in the CTL diaphragm. Maximum specific force (i.e., force per unit area) was 25% lower than CTL. Fatigue resistance was significantly improved in the EMP diaphragm compared with CTL. Diaphragm muscle fibers were classified as type I or II on the basis of histochemical staining for myofibrillar adenosinetriphosphatase after alkaline preincubation. The proportions of type I and II fibers were similar between the two groups. Cross-sectional areas of type II fibers were 30% larger in EMP than in CTL diaphragms. Succinate dehydrogenase activities of both type I and II fibers were higher in EMP than in CTL diaphragms. The number of capillaries surrounding both type I and II fibers increased with EMP, but in proportion to the hypertrophy of these fibers. Thus, capillary density (number of capillaries per fiber cross-sectional area) remained unchanged. We postulate that these contractile, morphometric, and metabolic adaptations reflect an increased activation of the diaphragm in response to the loads imposed by EMP.

Original languageEnglish (US)
Pages (from-to)934-943
Number of pages10
JournalJournal of Applied Physiology
Volume72
Issue number3
StatePublished - 1992

Fingerprint

Emphysema
Diaphragm
Muscles
Fatigue
Succinate Dehydrogenase
Pancreatic Elastase
Cricetinae
Hypertrophy
Adenosine Triphosphatases
Staining and Labeling

Keywords

  • capillary density
  • diaphragm contractility
  • elastase-induced emphysema
  • muscle fiber cross- sectional area
  • succinate dehydrogenase activity

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Lewis, M. I., Zhan, W. Z., & Sieck, G. C. (1992). Adaptations of the diaphragm in emphysema. Journal of Applied Physiology, 72(3), 934-943.

Adaptations of the diaphragm in emphysema. / Lewis, M. I.; Zhan, W. Z.; Sieck, Gary C.

In: Journal of Applied Physiology, Vol. 72, No. 3, 1992, p. 934-943.

Research output: Contribution to journalArticle

Lewis, MI, Zhan, WZ & Sieck, GC 1992, 'Adaptations of the diaphragm in emphysema', Journal of Applied Physiology, vol. 72, no. 3, pp. 934-943.
Lewis MI, Zhan WZ, Sieck GC. Adaptations of the diaphragm in emphysema. Journal of Applied Physiology. 1992;72(3):934-943.
Lewis, M. I. ; Zhan, W. Z. ; Sieck, Gary C. / Adaptations of the diaphragm in emphysema. In: Journal of Applied Physiology. 1992 ; Vol. 72, No. 3. pp. 934-943.
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