Disruption of NO-cGMP signaling by neonatal hyperoxia impairs relaxation of lung parenchyma

Abstract

Mol Physiol 293: L1029–L1036, 2007. First published July 27, 2007; doi:10.1152/ajplung.00182.2007.—Exposure of immature lungs to hyperoxia for prolonged periods contributes to neonatal lung injury and airway hyperreactivity. We studied the role of disrupted nitric oxide-guanosine 3,5-cyclic monophosphate (NO-cGMP) signaling in impairing the relaxant responses of lung tissue from hyperoxia-exposed rat pups. Pups were exposed to 95 % O2 or room air for 7 days starting from days 1, 5, or 14. The animals were killed, lungs were removed, and 1-mm-thick lung parenchymal strips were pre-pared. Lung parenchymal strips of room air or hyperoxic pups were preconstricted using bethanechol and then graded electrical field stimulation (EFS) was applied to induce relaxation. EFS-induced relaxation of lung parenchymal strips was greater at 7 and 12 days than at 21 days in room air-exposed rat pups. Hyperoxic exposure significantly reduced relaxation at 7 and 12 days but not 21 day