Aim: Obstructive sleep apnea, manifested by intermittent hypoxia (IH) and excess production of reactive oxygen species (ROS) in the airways, is associated with hyperreactive airway diseases.Sensitization of lung vagal C fibers (LVCFs) contributes to the airway hypersensitivity.In the present study, we examined whether 24 consecutive hours of IH exposure enhances the LVCF sensitivity and, if so, by what mechanisms.