Measuring Airway Hyperresponsiveness in Mice

AHR was measured by the Flexivent instrument (Scireq Inc., Montreal, Quebec, Canada) 24 hours after the final drug delivery was accomplished. Briefly, mice were anesthetized with pentobarbital (10 mg/kg, i.p.). A longitudinal midline incision was made to the neck to expose the trachea, and the trachea was cannulated and connected to the Flexivent system to ventilate at 160 breaths/min, 200 μl tidal. After the baseline of respiratory mechanics was recorded, mice were challenged with increasing doses of aerosolized methacholine (6, 12, 24, and 48 μg/g). Total respiratory resistance (Rrs) was recorded to assess the airway hyperresponsiveness.