[The effects of three dosages of nebulized unfractionated heparin on alveolar coagulation and tissue inflammation injury in endotoxin-induced acute lung injury rat model].

Objective: To observe the effects of three dosages of nebulized unfractionated heparin (UFH) on alveolar coagulation, inflammation and lung histology in endotoxin-induced acute lung injury rat model, and investigate the appropriated dose of local UFH in managing intrapulmonary coagulopathy.

Methods: Twenty-nine male Wistar rats were divided into control (n=5) and UFH group (n=24) in table of random number, which were duplicated to be endotoxin-induced ALI rat model with lipopolysaccharide (LPS) injecting by intravenous route. The UFH group was divided into three subgroups, which were administered once with 6, 12 and 18 U/g aerosolized UFH in 10 ml at 2 hours after challenge, respectively, while the control group was simply nebulized with normal saline. All rats were sacrificed at 6 hours after intravenous administration of LPS, bronchoalveolar lavage was performed, and the fluid was collected. Enzyme-linked immune sorbent assay (ELISA) was used to measure the level of thrombin-antithrombin complex (TATc), tumor necrosis factor-α (TNF-α) in bronchoalveolar lavage fluid (BALF), and lung wet/dry (W/D) weight ratio, histology score were recorded.

Results: At 6 hours after LPS-induced lung injury, the levels of TATc and TNF-α, lung W/D weight ratio and histology score in 6 U/g and 12 U/g group were all lower than those of control group significantly (TATc: 0.959±0.681 μg/L, 1.165±0.854 μg/L vs. 2.141±0.791 μg/L, TNF-α: 4.449±5.054 ng/L, 9.096±4.099 ng/L vs. 18.184±3.869 ng/L, W/D weight ratio: 7.018±1.137, 7.367±0.349 vs. 8.472±0.614, histology score: 16.0±1.0, 16.5±1.5 vs. 19.6±0.4, P<0.05 or P<0.01). There was no significant difference in the comparisons between the subgroups of UFH in TATc level in BALF and lung histology score. For the TNF-αlevel in BALF, 18 U/g group evidently exceeded that of 6 U/g group (15.503±8.753 ng/L vs. 4.449±5.054 ng/L, P<0.01), and lung W/D weight ratio in 18 U/g group was also significantly higher comparing to 6 U/g (8.850±1.157 vs. 7.018±1.137, P<0.05) and 12 U/g group (8.850±1.157 vs. 7.367±0.349, P<0.05).

Conclusion: It was appropriate for the dose of nebulized UFH to be administered no more than 12 U/g in ALI treatment, which was enough to inhibit alveolar coagulant cascade, decrease early inflammatory response and alleviate lung tissue injury.