Figure 8.

Helenalin (Hel), an nuclear factor κ B (NFκB) inhibitor, blocks hyperoxia-induced phosphodiesterase-5 (PDE5) activity in fetal pulmonary artery smooth muscle cells (FPASMCs) from lambs with persistent pulmonary hypertension of the newborn (PPHN). PPHN FPASMC were exposed to 21% O₂–5% CO₂ or 95% O₂–5% CO₂ ± 100 nM hydrocortisone (HC) ± 1 μM helenalin for 24 hours. A, Protein extracts were subjected to PDE5 Western blot analysis, with β-actin normalization. Data are shown as means ± SEM (n = 4 for all groups). B, PDE5-specific activity was measured as the sildenafil-inhibitable fraction of total cGMP hydrolysis and normalized for milligram of protein. Data are shown as means ± SEM (n = 4–8; read in duplicates). Asterisk indicates P < 0.05 versus 21% untreated; number sign indicates P < 0.05 versus 95% untreated.