Hyperoxia prevents hypoxia-induced bronchial hyperreactivity via a cyclooxygenase-independent mechanism

J. D'Brot, T. Ahmed

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

We tested the hypothesis that prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity, possibly via a cyclooxygenase-dependent mechanism. In 15 sheep, specific lung resistance (sRL) was measured before and after 30 min of exposure to either air or a hypoxic gas mixture (13% O2). The sheep then inhaled 50 breaths of aerosolized 5% histamine solution (n = 9) or 10 breaths of 2.5% carbachol solution (n = 9), and measurements of sRL were repeated. On subsequent days the above protocols were repeated after a 30-min exposure to hyperoxia (O2 ≥ 95%), without or after pretreatment with indomethacin (2 mg/kg). After airsham exposure, carbachol and histamine increased mean sRL to 370 ± 40 (SE) and 309 ± 65% of baseline, respectively. Exposure to the hypoxic gas mixture had no effect on baseline sRL but enhanced the airway responsiveness to carbachol and histamine; mean sRL increased to 740 ± 104 and 544 ± 76% of baseline, respectively (P < 0.05). Prior 30-min exposure to hyperoxia prevented the hypoxia-induced enhancement of bronchial reactivity to carbachol (sRL = 416 ± 66% of baseline) and histamine (sRL = 292 ± 41% of baseline) without affecting the airway responsiveness to these agents after air. Pretreatment with indomethacin did not reverse the protective effects of hyperoxia or the hypoxia-induced enhancement of bronchial reactivity. We conclude that 1) prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity and 2) neither the protective effects of hyperoxia nor the hypoxia-induced enhancement of bronchial reactivity is mediated via a cyclooxygenase-dependent mechanism.

Original languageEnglish (US)
Pages (from-to)740-747
Number of pages8
JournalJournal of applied physiology
Volume70
Issue number2
DOIs
StatePublished - Jan 1 1991

Keywords

  • cyclooxygenase metabolites
  • indomethacin

ASJC Scopus subject areas

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

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