Quantitative reverse transcription-polymerase chain reaction for apoptosis-related genes in lung tissues with mechanical ventilation of higher tidal volume (30 mL/kg). The levels of mRNAs for Bcl-2 (a) and Bcl-xL (b) significantly increased after mechanical ventilation in the presence of 2% hydrogen in air (VILI/H2). On the other hand, Bax (c) was significantly increased after mechanical ventilation with 2% nitrogen in air (VILI/N2) and was not increased after mechanical ventilation with 2% hydrogen in air. All values are reported as percentage of β-actin with normalization to β-actin mRNA expression. N = 6 for each group. *P < 0.05 versus sham/N2 and sham/H2; #P < 0.05 versus VILI/N2. Bcl-2, B-cell lymphoma-2; Bcl-xL, B-cell lymphoma-extra large; VILI, ventilator-induced lung injury.