Effects of long-term continuous respiratory resistive loading on rat diaphragm function and structure

D. J. Prezant, T. K. Aldrich, B. Richner, E. I. Gentry, D. E. Valentine, H. Nagashima, J. Cahill

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


The effects of long-term (24- to 28-wk) continuous respiratory resistive loading on diaphragm mass, contractility, fatigue, and fiber types were studied in male rats. Increased respiratory resistance was produced by extratracheal banding, and results were compared with sham-operated pair-fed controls. At the time the animals were killed, banded tracheal segment internal diameter was reduced by 57% of control values. Diaphragm surface area and muscle mass (normalized for body mass) increased by 19% of control values. Isometric diaphragm contractility and fatigue resistance indexes were measured using an in vitro diaphragm costal strip preparation at 37°C. Twitch and tetanic stimulations were evoked using direct stimulation. Compared with controls, baseline tensions (normalized for diaphragm cross- sectional area) were significantly decreased at low frequencies. Fatigue resistance (endurance) indexes were significantly increased at all frequencies. These findings were consistent with observed increases in number and cross-sectional area of type I (low-tension high-endurance) fibers. We conclude that the diaphragm adapts to chronic long-term resistive loads by sacrificing peak tensions for an increase in endurance capacity.

Original languageEnglish (US)
Pages (from-to)1212-1219
Number of pages8
JournalJournal of applied physiology
Issue number3
StatePublished - 1993


  • chronic obstructive airway diseases
  • diaphragm contractility
  • diaphragm fatigue
  • fiber types
  • respiratory muscle training
  • upper airway obstruction

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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