Objective: The preterm ventilated lung is characterized by an increased protein leak from the pulmonary vascular spaces into the air spaces, which interferes with lung function and plays a role in neonatal respiratory distress syndrome. To investigate the role of platelet-activating factor in this process, platelet-activating factor antagonists were given to preterm ventilated rabbits.
Study design: New Zealand White rabbits were delivered on day 28 of 31 days' gestation. Each rabbit pup received saline solution or one of two platelet-activating factor antagonists and were ventilated for 30 minutes with measurement of compliance, surfactant pool size, and protein leak into and out of the lung. Statistical analysis was performed with analysis of variance followed by Student-Newman-Keuls correction for multiple comparisons.
Results: There were no differences in lung compliance, surfactant pool size, or protein leak out of the air spaces among any of the groups. Treatment with the platelet-activating factor antagonists decreased the protein leak into the air spaces by greater than 50% and into the lung as a whole by 40% (p less than 0.01).
Conclusion: Platelet-activating factor plays a role in the protein leak seen in the preterm lung, which contributes to neonatal respiratory distress syndrome.