[Early changes in serum neutrophil elastase in rats with burn, blast injury or combined burn-blast injury and its significance].

OBJECTIVE

To explore the early changes in serum neutrophil elastase (NE) in rats with burn, blast injury or combined burn-blast injury and its significance.

METHODS

A total of 176 male Sprague Dawley rats were randomly divided into four groups: control (C), burn (BU), blast injury (BL) and burn-blast combined injury (BB). Rats in C group were not injured. Animals in BU group were subjected to 25% TBSA full-thickness burn on back with 94 degrees C water for 12 seconds; Animals in BL group were inflicted with moderate blast injury with 5 g 8701 compressed dynamite stick as the explosion source 75 cm away while left chest facing the explosive source; Rats in BB group were burned immediately after the blast injury similarly as in BL group. During the first 24 h post-injury, animals in BU and BB groups received intraperitoneal injection of sodium lactate Ringer's solution at a dose of 50 ml x kg(-1) x 12 h(-1). Protein concentration in bronchoalveolar lavage fluid (BALF), water content of lung tissue and NE content in serum were determined at 0 h (C group), 3 h, 6 h, 12 h, 1 d, 2 d, 3 d, 7 d post-injury.

RESULTS

Protein concentration in BALF, water content of lung tissue and NE content in serum in SD rats of the injured groups were significantly higher than those in C group (P < 0.01 or P < 0.05), peaked within 2 d post-injury, especially at 2 d post-injury (NE content in serum: BU group, 319. 85 +/- 19.50 ng/ml; BL group, 467.43 +/- 31.64 ng/ml; BB group, 626.00 +/- 26.38 ng/ml vs. C group, 78.53 +/- 25.10 ng/ml). Overall, protein concentration in BALF, water content of lung tissue and NE content in serum in BB group were significantly higher than BU and BL groups (P < 0.01 or P < 0.05). Correlation analysis showed that within 3 d postinjury, a significant positive correlation was found between the protein concentration in BALF, water content of lung tissue and NE content in serum (r = 0.7910, 0.8078, P < 0.05) in BU group. NE content in serum and protein concentration in BALF were significantly positively correlated in BB group (r = 0.8672, P < 0.05).

CONCLUSION

NE may play an important role in early lung injury of burn or blast injury, especially in combined burn-blast injury.