Hyperoxia-induced airway hyperresponsiveness and remodeling in immature rats

M. B. Hershenson, S. Aghili, N. Punjabi, C. Hernandez, D. W. Ray, A. Garland, S. Glagov, J. Solway

Research output: Contribution to journalArticlepeer-review

Abstract

We exposed 21-day-old rats to either normoxia or hyperoxia (>95% O2) for 8 days and assessed in vivo airway responsiveness to aerosolized and intravenous methacholine (MCh) and airway architecture. Airway responsiveness was determined using a plethysmographic method. Hyperoxia increased airway cholinergic responsiveness, as reflected in a decreased mean ED200 (concentration of MCh required to increase respiratory system resistance by 100%) for both aerosolized MCh [air exposed, 5.94 ± 2.50 vs. O2 exposed, 0.29 ± 3.34 (SD) mg/ml, P = 0.0013, unpaired t test] and intravenous MCh (air, 1.40 x 10-8 vs. O2, 2.45 x 10-10 mol/kg, P = 0.0002). Airway morphometry was studied in a separate cohort of animals. After fixation by distension with Formalin at 25 cmH2O pressure, each airway cross section was photographed, and airway circumference, epithelial area, and smooth muscle layer area were determined by means of contour tracing using a digitizing pad and microcomputer. For the small airways (circumference < 1,000 μm), hyperoxia increased both mean epithelial thickness (air, 4.88 ± 0.53; O2, 8.64 ± 0.90 μm) and mean smooth muscle layer thickness (air, 2.69 ± 0.11; O2, 4.79 ± 0.56 μm; P < 0.0001 for each). O2 had similar effects on the larger (1,000-3,000 μm) central airways (P < 0.0001 for both layers). We conclude that chronic hyperoxic exposure induces both airway hyperresponsiveness and airway wall thickening in immature rats.

Original languageEnglish (US)
Pages (from-to)L263-L269
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume262
Issue number3 6-3
DOIs
StatePublished - 1992
Externally publishedYes

Keywords

  • airway smooth muscle
  • asthma
  • bronchial epithelium
  • bronchopulmonary dysplasia
  • methacholine
  • rats

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

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