A bronchial epithelium-derived factor reduces pulmonary vascular tone in the newborn XXXX .

@entity2871 @entity44211 @entity4357 @entity2872 @entity7293 @entity842 @entity35 @entity4338
The factors accounting for the maintenance of a low pulmonary vascular resistance postnatally are not completely understood. The aim of this study was to test the hypothesis that bronchial epithelium produces a factor capable of relaxing adjacent pulmonary arterial smooth muscle. We studied fourth-generation intralobar pulmonary arteries and bronchi of 4- to 8-day-old @entity35 . Arteries were mounted on a wire myograph, alone or with the adjacent bronchus. The presence of the attached bronchus significantly reduced pulmonary artery force generation induced by the @entity2871 analog ( @entity2872 ) or @entity4338 whether the endothelium was present or absent (P < 0.01). The converse was not true in that bronchial force generation was not affected when studied with the adjacent pulmonary artery. Mechanical removal of the bronchial epithelium or addition of the @entity842 (NO) synthase (NOS) nonspecific @entity7293 or the specific neuronal NOS ( @entity44211 ) inhibitors increased arterial force generation to levels comparable to the isolated artery preparation. Wortmannin, a @entity4357 3-kinase inhibitor, significantly decreased (P < 0.01) NO release of pulmonary arteries only when the adjacent bronchus was present. We conclude that bronchial epithelium in the newborn @entity35 produces a factor capable of lowering pulmonary vascular muscle tone. This relaxant effect can be suppressed by NOS and @entity4357 3-kinase kinase inhibition, suggesting an action via NOS phosphorylation and NO release. We speculate that such a mechanism may be operative in vivo and plays an important role in control of pulmonary vascular resistance in the early postnatal period.
