Denervation of the immature porcine lung impairs normal airway development

Reimplantation or allotransplantation of the immature porcine left lower lobe results in long-term functional dynamic airway obstruction that is associated with abnormally small distal airways. We have attributed this small airway size to bronchoconstriction resulting from chronic denervation rather than to impaired airway growth. To further investigate these findings, we transplanted mature left lower lobes from adult pigs into young piglets after left pneumonectomy. After approximately 12 weeks of somatic growth, the lobes were harvested and fixed through the airways with formalin. Cross-sectional areas of terminal, noncartilaginous airways from the lung periphery were traced on a video monitor. Five groups were examined: control innervated mature left lower lobes, innervated left lower lobes subjected to compensatory growth after left upper lobectomy at approximately 9 weeks of age, mature left lower lobe transplants, reimplanted immature left lower lobe autografts, and transplanted immature left lower lobe allografts. Unlike the immature porcine lobe, transplantation of the mature porcine lobe does not result in abnormally small airways. The small airways seen after transplantation or reimplantation of the immature porcine lobe are likely, therefore, to be due to impaired airway development and not to bronchoconstriction caused by denervation.