Improved Lung-Thorax Compliance in the Premature Rabbit Neonate After Treatment With Dibuturyladenosine-3′:5′-Cyclic Monophosphate

Premature rabbit neonates, delivered on day 28 of gestation, were treated with a single dose of dibuturylade-nosine-3′:5′-cyclic monophosphate (cyclic AMP), 300 mg/kg, immediately after delivery, saline-injected litter-mates serving as controls. All animals were kept in body ple-thysmographs and ventilated artificially with 100% oxygen for 1 h, with a maximal tidal volume of 10 ml/kg body weight. Lung-thorax compliance was significantly improved in animals treated with cyclic AMP, both 30 and 60 min after onset of ventilation (0.92±0.09 vs. 0.59±0.08 ml/cm H20.kg and 0.96±0.09 vs. 0.53±0.08, p>0.005), but there was no improvement in alveolar air expansion, evaluated histologically. Phosphatidylglycerol was absent in alveolar wash from all control animals, but present in 3 of the 8 pooled samples from the animals treated with cyclic AMP; this difference was not statistically significant, however.