FIG. 1.
Thirty minutes of 95% O2/5% CO2 increases phosphodiesterase 5 (PDE5) activity but not protein expression. Protein was harvested from fetal pulmonary artery smooth muscle cells (FPASMC) exposed to either 21% O2/5% CO2 or 95% O2/5% CO2 for 30 min, followed by recovery for 30 min in 21% O2/5% CO2. (A) PDE5 protein expression analyzed by Western blot, normalized for β-actin (n=14). Data are shown as mean±SEM relative to FPASMC in 21% O2/5% CO2. A representative Western blot is shown for PDE5 and β-actin. (B) PDE5-specific cyclic GMP (cGMP) hydrolytic activity was measured using a commercially available colorimetric assay (n=21, read in duplicate). Data are shown as mean±SEM pmol cGMP hydrolyzed/mg protein/min. *p<0.05 vs. FPASMC in 21% O2/5% CO2.