Influenza virus-induced airway hyperreactivity in rats

Lee, Hye Kyung

Abstract

BACKGROUND AND OBJECTIVE
Studies indicate that humans infected with influenza virus manifest a post-virus increase in airway responsiveness. Therefore, whether influenza virus would cause airway hyperreactivity was investigated. SUBJECT AND METHOD: Rats were infected with rat-adapted influenza virus via nasal instillation. On days 1, 2, 3, 5, 7 and 9 post-virus inoculation, pulmonary mechanics were measured during an intravenous challenge with acetylcholine (ACh, 100-140 mg/ml saline). Cumulative dose-response functions were obtained by doubling the rate of the infusion every 2 minutes.
RESULTS
ACh increased airway resistance and decreased dynamic compliance in a dosedependent manner. The airway responses to ACh was enhanced in most animals challenged 3 days after the inoculation. About half of the animals challenged 2 and 5 days after the virus inoculation showed hyperresponsiveness to ACh. No airway hyperresponsiveness was noted in animals on day 1 or 9 post-virus exposure. Tracheal muscle rings were isolated from infected, thus hyperresponsive animals and the contractile force to ACh and KCl was examined in vitro, where their dose-response characteristics were similar to those of muscles from controls.
CONCLUSION
The rat model for influenza virus-induced airway hyperreactivity was developed, which manifested a post-virus increase in airway responsiveness.