FIG. 6.

MitoTEMPO, a mitochondrially targeted antioxidant, blocks hyperoxia-induced PDE5 activity and restores cGMP responsiveness to exogenous NO. FPASMC were exposed to 21% O₂/5% CO₂ or 95% O₂/5% CO₂ for 30 min±MitoTEMPO (25 nM) or vehicle (DMSO), followed by recovery for 30 min in 21% O₂/5% CO₂. (A) PDE5-specific cGMP hydrolytic activity in the absence or presence of MitoTEMPO is measured using a commercially available colorimetric assay (n=7, read in duplicate). Data are shown as mean±SEM pmol cGMP hydrolyzed/mg protein/min. (B) FPASMC±MitoTEMPO (MT)±DETANONOate (100 μM, NO) were assayed for cGMP by EIA, and cGMP was normalized to total protein. Data are shown as mean±SEM (n=5, read in duplicate). *p<0.05 vs. untreated FPASMC in 21% O₂/5% CO₂; ^#p<0.05 vs. untreated FPASMC in 95% O₂/5% CO₂; ⁺p<0.05 vs. NO-treated PASMC in 21% O₂/5% CO₂, ^&p<0.05 vs. NO-treated PASMC in 95% O₂/5% CO₂.