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Hyperoxia increases phosphodiesterase 5 expression and activity in ovine fetal pulmonary artery smooth muscle cells.

ABSTRACT: In the pulmonary vasculature, cGMP concentrations are regulated in part by a cGMP-dependent phosphodiesterase (PDE), PDE5. Infants with persistent pulmonary hypertension of the newborn (PPHN) are often mechanically ventilated with high oxygen concentrations. The effects of hyperoxia on the developing pulmonary vasculature and PDE5 are largely unknown. Here, we demonstrate that exposure of fetal pulmonary artery smooth muscle cells (FPASMCs) to high levels of oxygen for 24 hours leads to decreased responsiveness to exogenous NO, as determined by a decreased intracellular cGMP response, increased PDE5 mRNA and protein expression, as well as increased PDE5 cGMP hydrolytic activity. We demonstrate that inhibition of PDE5 activity with sildenafil partially rescues cGMP responsiveness to exogenous NO. In FPASMCs, hyperoxia leads to increased oxidative stress without increasing cell death. Treatment of normoxic FPASMCs with H2O2 is sufficient to induce PDE5 expression and activity, suggesting that reactive oxygen species mediate the effects of hyperoxia in FPASMCs. In support of this mechanism, a chemical antioxidant, N-acetyl-cysteine, is sufficient to block the hyperoxia-mediated increase in PDE5 expression and activity and rescue cGMP responsiveness to exogenous NO. Finally, ventilation of healthy neonatal sheep with 100% O2 for 24 hours leads to increased PDE5 protein expression in the resistance pulmonary arteries and increased PDE5 activity in whole lung extracts. These data suggest that PDE5 expression and activity play a critical role in modulating neonatal pulmonary vascular tone in response to common clinical treatments for PPHN, such as oxygen and inhaled NO.

SUBMITTER: Farrow KN

PROVIDER: S-EPMC2268610 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature

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Hyperoxia increases phosphodiesterase 5 expression and activity in ovine fetal pulmonary artery smooth muscle cells.

Farrow Kathryn N KN Groh Beezly S BS Schumacker Paul T PT Lakshminrusimha Satyan S Czech Lyubov L Gugino Sylvia F SF Russell James A JA Steinhorn Robin H RH

Circulation research 20071108 2

In the pulmonary vasculature, cGMP concentrations are regulated in part by a cGMP-dependent phosphodiesterase (PDE), PDE5. Infants with persistent pulmonary hypertension of the newborn (PPHN) are often mechanically ventilated with high oxygen concentrations. The effects of hyperoxia on the developing pulmonary vasculature and PDE5 are largely unknown. Here, we demonstrate that exposure of fetal pulmonary artery smooth muscle cells (FPASMCs) to high levels of oxygen for 24 hours leads to decrease ...[more]

PMID: 17991881

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Dataset Information

Hyperoxia increases phosphodiesterase 5 expression and activity in ovine fetal pulmonary artery smooth muscle cells.

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Hyperoxia increases phosphodiesterase 5 expression and activity in ovine fetal pulmonary artery smooth muscle cells.

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