Protective effects and mechanisms of recombinant human superoxide dismutase in acute lung injury of rats following meconium aspiration / 中华儿科杂志

ABSTRACT

<p><b>OBJECTIVE</b>To evaluate the protective effects of recombinant human superoxide dismutase (rhSOD) in acute lung injury (ALI) following meconium aspiration.</p><p><b>METHODS</b>Thirty-two healthy male Sprage-Dawley rats were divided into two groups, 8 were used as control (saline group) by infusing 1 ml/kg saline through endotracheal tube; the other 24 rats were used to establish model of ALI by infusing 1 ml/kg of 20% human newborn meconium suspension through endotracheal tube, and then were randomized to 3 groups (8 each) meconium group with no administration of saline or rhSOD; meconium + saline group by infusing 1 ml/kg saline through endotracheal tube; meconium + rhSOD group by infusing 20 mg/kg rhSOD dissolved in 1 ml/kg saline through endotracheal tube. The rats were killed 24 h after treatment. The measurements included bronchoalveolar lavage fluid (BALF) cell counts, protein, BALF protein/plasma protein (pulmonary permibility index, PPI), lactic dehydrogenase (LDH), pulmonary myeloperoxidase (MPO) and superoxide dismutase (SOD) activity, malonyldialdehyde (MDA) and nitric oxide (NO) level. Lung injury score was also evaluated.</p><p><b>RESULTS</b>Compared with the saline group, the rats in the meconium group had significantly increased BALF cell counts (4.04 +/- 1.01 vs. 0.53 +/- 0.19), protein (2.54 +/- 0.74 vs. 0.67 +/- 0.26), PPI (0.50 +/- 0.18 vs. 0.12 +/- 0.05), LDH (263.50 +/- 97.84 vs. 17.38 +/- 3.58), pulmonary MPO (1.49 +/- 0.22 vs. 0.62 +/- 0.16), MDA (3.30 +/- 0.85 vs. 1.40 +/- 0.35), NO (12.77 +/- 5.00 vs. 4.89 +/- 1.32) and lung injury score (9.88 +/- 2.10 vs. 2.25 +/- 1.04), P < 0.01 for all, whereas pulmonary SOD activity had no statistically significant differences (103.28 +/- 24.53 vs. 94.49 +/- 12.93, P > 0.05). There were no statistically significant differences between meconium + saline group and meconium group (all P > 0.05). Compared with the meconium + saline group, meconium + rhSOD group had decreased BALF cell counts (3.13 +/- 0.77 vs. 4.68 +/- 1.40, P < 0.01), LDH (162.63 +/- 76.90 vs. 273.75 +/- 111.83, P < 0.05), pulmonary MPO activity (1.23 +/- 0.28 vs. 1.54 +/- 0.24, P < 0.05), MDA (2.46 +/- 0.42 vs. 3.50 +/- 0.82, P < 0.01), NO level (9.17 +/- 2.34 vs. 13.04 +/- 4.38, P < 0.05), lung injury score (8.63 +/- 1.30 vs. 10.00 +/- 1.07, P < 0.05) and increased pulmonary SOD activity (134.45 +/- 23.30 vs. 106.79 +/- 17.77, P < 0.05), but there were no statistically significant differences in BALF protein and PPI between these two groups.</p><p><b>CONCLUSION</b>Inflammation and lipid peroxidation might play important roles in the pathogenesis of ALI with meconium aspiration, a single early administration of 20 mg/kg rhSOD intratracheally can reduce lung damage in rats following meconium aspiration.</p>