Fig. 5
Third-generation pulmonary artery strips from newborn (control D0), normoxic 3-day-old (control D3), and hypoxic 3-day-old piglets (PPHN D3) cultured for 72 h in aerated media without serum (synchronizing cells in contractile phenotype) with daily addition of thromboxane mimetic U46619 or diluent for 72 h. Tissues studied in Krebs physiological buffer served as a baseline control. Nuclei were stained with propidium iodide. Proportion of nuclei in each cell cycle stage (quantified by laser scanning cytometry) was calculated as percent cells in 2N and 4N DNA phases and expressed as integral fluorescence/event/cell count. Apoptosis was quantified as percent pyknotic nuclei (low area, high intensity). Mitotic nuclei in medial layer of control and PPHN arteries quantified after exposure to U46619, as Ki67-positive nuclei/ mm2 (in all panels, *p < 0.05 compared to control D3 in same treatment group; #p < 0.05 compared to PA from same animal group in media alone)