PULMONARY DYSFUNCTION IN NEONATAL SP-B-DEFICIENT MICE

Pulmonary function was assessed in newborn wild-type and homozygous an d heterozygous surfactant protein B (SP-B)-deficient mice after birth. SP-B +/+ and SP-B+/- mice became well oxygenated and survived postnat ally. Although lung compliance was decreased slightly in the SP-B+/- m ice, lung volumes and compliances were decreased markedly in homozygou s SP-B-/- mice. They died rapidly after birth, failing to inflate thei r lungs or oxygenate. SP-B proprotein was absent in the SP-B-/- mice a nd was reduced in the SP-B+/- mice, as assessed by Western analysis. S urfactant protein A, surfactant proprotein C, surfactant protein D, an d surfactant phospholipid content in lungs from SP-B+/- and SP-B-/- mi ce were not altered. Lung saturated phosphatidylcholine and precursor incorporation into saturated phosphatidylcholine were not influenced b y SP-B genotype. Intratracheal administration of perfluorocarbon resul ted in lung expansion, oxygenation, and prolonged survival of SP-B-/- mice and in reduced lung compliance in SP-B+/+ and SP-B+/- mice. Lack of SP-B caused respiratory failure at birth, and decreased SP-B protei n was associated with reduced lung compliance. These findings demonstr ate the critical role of SP-B in perinatal adaptation to air breathing .