Ambient ozone concentrations induce airway hyperresponsiveness in some rat strains

Area of Science:

• Environmental toxicology
• Respiratory medicine
• Genetics

Background:

• Ozone exposure is a known cause of airway hyperresponsiveness (AHR).
• Previous animal studies utilized high ozone concentrations, yielding inconsistent findings.
• Variability in AHR response suggests underlying genetic influences.

Purpose of the Study:

• To investigate the impact of a single, low-level ozone exposure on AHR in various inbred rat strains.
• To determine if ozone-induced AHR is associated with airway inflammation.
• To explore the role of genetic factors in differential sensitivity to ozone.

Main Methods:

• Exposure of nine inbred rat strains to 0.05 ppm ozone for 4 hours.
• Assessment of airway responsiveness to 5-hydroxytryptamine (5-HT) intravenously.
• Analysis of bronchoalveolar lavage fluid (BALF) for inflammatory cells and markers.

Main Results:

• Lewis, BDII, and Long-Evans rats exhibited AHR 90 minutes post-exposure.
• Wistar, Sprague-Dawley, Fisher 344, Brown-Norway, BDE, and DA rats did not develop AHR.
• No significant inflammatory cell influx or elevation in BALF markers was observed in any strain.
• In Long-Evans rats, AHR persisted for up to 12 hours without inflammation indicators.

Conclusions:

• Ambient ozone concentrations can induce AHR in susceptible inbred rat strains.
• Ozone-induced AHR can occur independently of airway inflammation.
• Genetic background significantly influences individual susceptibility to ozone-induced AHR.