Am. J. Respir. Crit. Care Med., Vol 154, No. 4, 10 1996, 1002-1005.
Increased surface tension of the lung and surfactant in bleomycin- induced pulmonary fibrosis in rats
T Horiuchi, M Ikegami, RM Cherniack and RJ Mason
Department of Pulmonology, Kanto Chuo Hospital, Tokyo, Japan.
The increased elastic recoil of the lung in bleomycin-induced pulmonary
fibrosis in the rat is due in part to increased surface forces. This study
was designed to determine the role of surface tension in situ and in vitro
21 d after instillation of bleomycin. Using sequentially measured
pressure-volume curves generated with air, saline, air after lavage with
Tween 20, and saline, surface tension was significantly higher in
bleomycin-treated lungs than in untreated lungs (4.7 +/- 1.1 versus 1.8 +/-
0.2 dyne/cm, p < 0.01). Surface tension was determined in vitro with a
Wilhelmy balance using bronchoalveolar lavage fluid, surfactant, and
organic solvent lipid extracts of surfactant. Bleomycin treatment resulted
in elevated minimal surface tensions: BALF (20.7 +/- 0.6 versus 13.6 +/-
3.8 dyne/cm, p < 0.02), isolated surfactant (12.0 +/- 1.3 versus 3.0 +/-
0.5 dyne/cm, p < 0.02), and the organic solvent lipid extracted
surfactant (11.0 versus 3.2 dyne/cm). These results indicate that the
physical properties of surfactant in lungs of rats treated with bleomycin
are abnormal and contribute to the increased elastic recoil in this model
of pulmonary fibrosis.
