Preliminary experiment: Evans blue dye (EBD) extravasation as an estimate of lung protein permeability for different tidal volumes, with and without 100% oxygen inhalation. LV6, rats ventilated under room air with a tidal volume of 6 ml/kg; HV20, HV30, HV35, HV40, rats ventilated under room air with tidal volumes of 20, 30, 35, and 40 ml/kg, respectively; HV35O2 and HV40O2, rats ventilated with tidal volumes of 35 and 40 ml/kg under 100% oxygen inhalation, respectively. Bars indicate mean ± SE. *P < 0.05 versus the LV6 group. n = number of rats treated with mechanical ventilation.