BackgroundProlonged exposure of immature lungs to hyperoxia contributes to neonatal lung injury and airway hyperreactivity. We have previously demonstrated that neonatal exposure of rat pups to ≥95% O2 impairs airway relaxation due to disruption of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling. Objective: We now hypothesize that these impaired relaxation responses are secondary to hyperoxia-induced upregulation of arginase, which competes with NO synthase for L-arginine.
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