Fig. 4. Effect of ventilation and hydrogen sulfide (H2S) treatment on apoptosis in the lung. As controls, mice were subjected to spontaneously breathe air (A ) or 80 ppm H2S (C ), or were ventilated (vent) with 12 ml/kg for 6 h with either synthetic air (B ) or synthetic air + 80 ppm H2S (D ). The sections from the left lung lobes were terminal deoxynucleotide transferase-mediated dUTP-biotin nick-end labeling stained. Arrows indicate apoptotic cells. Representative pictures are shown for each experimental group (magnification ×400). (E ) Quantitative analysis of eight representative photos per lung, calculated in millimeter square. Graphs represent means ± SEM, n = 6/group. Analysis of variance (Student-Newman-Keuls post hoc test), *P < 0.05 versus control; # P < 0.05 versus H2S control; §P < 0.05 versus H2S-ventilated group.