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 dibuturyladenosine-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 plethysmographs 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 H2O.kg and 0.96 +/- 0.09 vs. 0.53 +/- 0.08, p less than 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.