Postnatal development of lung alveoli: suppression by 13% O2 and a critical period.
We studied the effect of 13% O2 on the development of the lung's gas-exchange region. Rats, acclimatized to 13% O2, remained in 13% O2 while pregnant, and were kept with their pups in 13% O2 until the pups were killed or were placed in air at age 15 days; other rats were always in air. Pups kept in 13% O2, unlike air pups, did not decrease mean chord length (Lm) or increase surface-to-volume ratio (S/V) of gas-exchange air spaces between age 2 and 14 days or by age 40 days. Rats placed in air at age 15 days did not change Lm or S/V even in air. Rats kept in 13% O2, and rats placed in air at age 15 days had fewer alveolar attachments to bronchioles than air rats. Gas-exchange air volume (VA) in 13% O2 rats was equal to or greater than in air rats; VA/kg was larger in 13% O2 than air rats. We conclude that maintenance of rats in 13% O2 during gestation and during the period alveoli are formed by septation blocks septation in a seemingly irrevocable manner. We suggest diminished septation decreases radial traction on conducting airways leading to increased VA/kg.
Massaro
G D
GD
Calvin and Flavia Oak Asthma Research and Treatment Facility, University of Miami School of Medicine 33136.
Olivier
J
J
Dzikowski
C
C
Massaro
D
D
D000375:Aging; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D005260:Female; D010100:Oxygen / Q000633:toxicity*; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000254:growth & development* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D010100:Oxygen