In addition to the primary
surfactant deficiency in newborns with
respiratory distress syndrome (RDS), in the later course of RDS substantial
protein leakage into the alveolar spaces can occur by damage to the alveolocapillary membrane.
Acute lung injury results in
surfactant dysfunction due in part to inhibition by
serum proteins. The aim of this study was to investigate the influence of SP-B on the inhibitory effects of
albumin (alb) and
fibrinogen (fib) on the surface activity of
pulmonary surfactant, using a) surface tension measurement with the pulsating bubble surfactometer in
suspensions and b) in
surfactant films applying the hypophase exchanger. After hypophase exchange a preformed film of
Survanta is very resistant to the inhibitory activity of alb or fib. The surface tensions of
suspensions are significantly higher (p <0.001) than the surface tensions of preformed
surfactant films if alb or fib were added, e.g., 42 (41 to 43) mN/m vs. 21 (19 to 22) mN/m for
Survanta with 20 mg alb/ml. After additional supplementation of
Survanta with SP-B the surface activity of
Survanta/1% SP-B films did not show inhibition by fib (2 mg/ml), (surface tension 8 (4 to 13) mN/m). These results indicate that SP-B can play an important role to protect the
pulmonary surfactant film from inactivation by
serum proteins.