[Effects of the treatment with different fluids on alveolar epithelium barrier in rats with acute lung injury].

Objective: To observe the effects of different fluids on alveolar epithelium barrier in rats with acute lung injury (ALI).

Methods: Thirty-six Sprague-Dawley (SD) rats were randomly assigned into six groups with 6 rats in each group. ALI was induced by intravenous injection of lipopolysaccharide(LPS). Rats in all treatment groups were given different fluids and sacrificed after 4 hours. Evans blue dye (EBD) was injected via the femoral vein 30 minutes before death. Tracheobronchial tree was washed with normal saline (NS) after death, and broncho-alveolar lavage fluid (BALF) was collected. Leakage of EBD from blood into BALF (alveolar epithelial permeability) and wet/dry (W/D) ratio were measured. The mRNA expression of surfactant protein-C (SP-C) was assessed by reverse transcription-polymerase chain reaction (RT-PCR). Alveolar epithelium apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling (TUNEL). Lung injury was evaluated by Smith lung injury score.

Results: (1) Lung injury scores in LPS and NS groups were significantly higher than in control group (both P < 0.05). Compared with NS group, lung injury scores were significantly lower in 5% albumin (ALB) and 6% hydroxyethyl starch 130/0.4 (HES) groups (both P < 0.05), and there was no significant difference in 4% succinylated gelatin (GEL) group (P > 0.05). No significant difference was found among the latter three groups. (2) W/D ratio in LPS and NS groups were significantly higher than that in control group (both P < 0.05). Compared with NS group, W/D ratios were lower in ALB, HES and GEL groups (all P < 0.05). But it showed no significant difference among the latter three groups. (3) Alveolar epithelial permeability in LPS and NS groups were remarkably higher than that in control group (both P < 0.05). Compared with NS group, the alveolar epithelial permeability were significantly lower in ALB, HES and GEL groups (all P < 0.05). The alveolar epithelial permeability in the latter two groups were significant lower than that in ALB group (both P < 0.05) but higher than that of control group. (4) The SP-C mRNA expression in LPS, NS, ALB and GEL groups were lower than that in control and HES groups (all P < 0.05), but there was no difference between control and HES groups (P > 0.05). (5) Apoptosis index (AI) of alveolar epithelial cell in all the treatment groups were significantly higher than that in control group (all P < 0.05). Compared with NS group, AI were noticeably lower in ALB and HES groups (both P < 0.05).

Conclusion: Compared with NS, colloid can probably improve the alveolar epithelial permeability and protect the barrier function.