2.6. Airway hyperresponsiveness (AHR)
Airway hypersensitivity was
measured by methacholine-induced airway contraction using a
plethysmograph (OCP-3000, Allmedicus, Anyang, Korea) after 24 h of final
OVA inhalation. Each mouse was put into the body record box of
whole-body plethysmograph nebulized with 10-80 mg/mL methacholine for 3
min at each increasing concentration. The airway term was measured for 3
min after inhalation with a haze for 3 min while increasing the
methacholine concentration. Enhanced pause (Penh) is an indicator of the
airway term obtained by the following formular:
Penh = (Te/Tr-1) × PEF/PIF
Where Te is expiratory time (sec), Tr is relaxation time (sec), PEF is
peak expiratory flow (mL/sec), and PIF is peak inspiratory flow
(mL/sec).