The present study was performed to investigate the role of exogenous
surfactant on
hydrochloric acid (HCL) - induced
lung injury in rats. Six-week-old male Sprague-Dawley rats were anesthetized by
intraperitoneal injection of
pentobarbital sodium (40mg/kg) and HCL (0.1N, 2mL/kg) or
normal saline (NS, 2mL/kg) was instilled into the trachea. Thirty minutes after HCL instillation,
surfactant at a dose of 60mg (=2mL)/body or NS (2mL) was instilled into the rat lungs. Animals in another experimental group were also treated with the same dose of
surfactant supplement 2hours after the first administration. Bronchoalveolar lavage fluid (BALF) was obtained 5hours after HCL instillation. In BALF, increases in total nuclear cell counts, neutrophil counts, optical density at 412nm as an
indicator of pulmonary
hemorrhage,
neutrophil elastase activity, concentrations of
albumin and
cytokine-induced neutrophil
chemoattractant (CINC) induced by HCL instillation were significantly attenuated by
surfactant treatment. The wet-to-dry weight (W/D) ratio in the lung and partial
oxygen tension (P(O2)) were also estimated;
surfactant treatment significantly attenuated the W/D ratio and improved deteriorated P(O2) induced by HCL. Additional
surfactant supplementation did not show further beneficial effects on HCL-induced
lung injury compared with a single treatment. These results suggest that
surfactant shows an anti-inflammatory effect on
acid lung injury in rats but the beneficial effects may be dose limited.