Meeting Abstract

P3.144  Sunday, Jan. 6  Chronic Hypoxia and Hyperoxia Modifies Morphology and VEGF Expression of the Lungs of the Developing Chicken LEWALLEN, MA*; BURGGREN, WW; Univ. of North Texas; Univ. of North Texas melissalewallen@my.unt.edu

Congruous developmental mechanisms occur in the parabronchial bird lung and the brochoalveoloar mammal lung. Vascular endothelial growth factor (VEGF) is critical to development of mammalian lungs by inducing angiogenesis and vasculogenesis. The chicken embryo (Gallus domesticus) offers an animal model of lung development not dependent upon maternal interaction and easily manipulated by ambient oxygen. This study determines effects of oxygen levels on the morphology and VEGF expression of developing chicken lungs. Eggs were chronically incubated in normoxia (21% O₂), hypoxia (15% O₂) or hyperoxia (30% O₂), until developmental days 16 or 18. Lung morphology was assessed using light microscopy, while VEGF expression was determined with ELISA. The proportion of parabronchial tissue to total lung tissue (measured as cross-sectional surface area) in the hypoxic group showed a significant increase from day 16 (61±2%) to day 18 (68±2%). Non-parabronchial tissue was significantly higher in the hypoxic group than in the hyperoxic group on day 16 (26±3% vs. 20±1%). However, by day 18, there were no significant differences between the groups. VEGF expression was significantly higher in the hypoxic group over the hyperoxic group on day 16 (736±91 vs. 492±31 pg/ml). By day 18, VEGF expression was significantly higher in the hyperoxic group over the normoxic group (673±76 vs. 381±37 pg/ml), while the hypoxic group remained elevated with a significant difference over the normoxic group (631±58 pg/ml). VEGF thus appears to facilitate the morphological changes to parabronchial lungs exposed to chronic hypoxia and hyperoxia.