Figure 4
Paraffin lung sections stained with monoclonal anti-ED-1 antibody (panels A-C) or polyclonal anti-MPO antibody (panels D-F) of room-air (RA, panels A and D) and O 2 -exposed controls (panels B and E), and age-matched pups treated with sildenafil (100 mg/kg/day) under hyperoxia (panels C and F) at 10 days of age. Pictures were taken at a 200× magnification. Quantification of ED-1-positive monocytes and macrophages (panel G), MPO-positive neutrophilic granulocytes (panel H) and total protein concentration in bronchoalveolar lavage fluid (BALF; panel I) in room air-exposed littermates (white bars), O2-exposed control pups (black bars) and 100 mg/kg/day sildenafil-treated O2-exposed pups (Sil100, gray bars) for 10 days. Values are expressed as mean ± SEM in at least 6 different rat pups per group. Note the presence of large numbers of leukocytes, including macrophages and neutrophils in thickened septa and in the enlarged alveolar lumen in panels B and E in hyperoxia-exposed controls, and low numbers of pulmonary inflammatory cells after sildenafil treatment (panels C and F). a = alveolus. *p < 0.05 and ***p < 0.001 versus age-matched O2-exposed controls. Δ p < 0.05 and versus room air-exposed controls.