Lack of recovery of lung structure and function after the administration of beta-amino-propionitrile in the postnatal period.

We administered beta-amino-propionitrile (beta APN) intraperitoneally to rats from birth to 4 wk of age and allowed the animals to recover for a further 4 wk. Saline-injected rats of similar age and 8-wk-old noninjected rats served as comparison groups. We had previously shown that injections of beta APN during the first 4 wk of life produces animals with large lungs that have too few and too large alveoli, and that have lost elastic recoil. In this experiment, abnormalities persisted in the 4-wk recovery period so that at 8 wk of age, similar differences were noted. We have also been able to show that the loss of lung elastic recoil in beta APN-treated animals is due to an alteration in tissue forces. Intraperitoneal injection of saline alone produced animals with large lungs, and alterations in total alveoli number and size and pressure-volume characteristics. The last 3 findings were not as severe as in the betaAPN-treated animals. Damage to the lung in the early postnatal period may be irreversible, leading to structural and growth alterations in the lung, and predisposing the lung to injury in later life.