Am. J. Respir. Crit. Care Med., Vol 153, No. 6, 06 1996, 1844-1849.
Change in properties of exogenous surfactant in injured rabbit lung
T Ueda and M Ikegami
Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, California 90509, USA.
We asked if the function of surfactant could be enhanced after exposure to
injured lungs. We also asked if sensitivity to inhibition of the minimal
surface-tension-lowering properties of surfactant by plasma could be
altered. Lung injury in rabbits was induced with N-nitroso-N-
methylurethane (NMU) and 6 of 17 NMU-injured rabbits were treated with 100
mg/kg surfactant. All rabbits were ventilated for 2 h, and large aggregate
alveolar surfactant was isolated by centrifugation. In vivo function of the
large aggregate surfactant was evaluated by treatment of preterm
surfactant-deficient rabbits at 27 d gestation. Surfactant from NMU-injured
lungs increased compliance from 0.37 +/- 0.01 in control preterm rabbits to
0.71 +/- 0.05, a value significantly higher than found for the surfactant
used for treatment (0.55 +/- 0.04) (p < 0.05). The minimal surface
tensions of large aggregate surfactant and the surfactant used for
treatment (0.1 mg lipid/ml) were evaluated for inhibition by plasma
proteins. Surfactant from NMU-injured and surfactant-treated rabbits was
more resistant to inhibition (minimal surface tension, 5.7 +/- 3.9 dyne/cm
in the presence of 0.6 mg/ml plasma protein) than the surfactant used for
treatment (19.7 +/- 0.8 dyne/cm). These results indicate that after
exposure to the injured lung, the function of the surfactant used for
treatment was enhanced and made less sensitive to plasma inhibition of the
surface-tension- lowering properties of surfactant. These changes probably
result from the association of endogenous surfactant components with
exogenous surfactant.
