Figure 3.

Hydrocortisone (HC) blocks hyperoxia-induced cytosolic reactive oxygen species (ROS) in fetal pulmonary artery smooth muscle cells (FPASMCs) from lambs with persistent pulmonary hypertension of the newborn (PPHN). The redox sensor ratiometic green fluorescent protein (roGFP) was used to assess oxidant levels in the cytosol (A) and mitochondrial matrix (B). A, PPHN FPASMC were exposed to 21% O₂–5% CO₂ or 95% O₂–5% CO₂ ± 100 nM HC for 24 hours, and oxidation of the cytosolic roGFP probe was measured (n = 4). B, PPHN FPASMC were exposed to 21% O₂–5% CO₂ or 95% O₂–5% CO₂ ± 100 nM HC for 24 hours, and oxidation of the mitochondrial roGFP probe was measured (n = 7). Data are shown as mean ± SEM for percentage maximal oxidation of roGFP. Asterisk indicates P < 0.05 versus 21% untreated; number sign indicates P < 0.05 versus 95% untreated.