To determine the activation of matrix metalloproteinase (MMPS-2 and MMPs-9) in a mice model of acute lung injury by inhalation of nitrogen dioxide, in order to provide experimental data for further investigation of its mechanisms.

ICR mice, weight 23~25g, were randomly divided into two groups: control group (n=8) and poisoned group (n=8). The mouth and nose of the mice were fixed to inhalation N₂O₄ through quantitative exposure device to establish the animal model of lung injury, and then blood was collected by the eye-excised method on 6 h. The serum was separated and stored at -70℃ preservation. ELISA method was used to detect the expression of MMP-2, MMP-9 and HYP.

Serum MMP-2, MMP-9 and HYP were 16.75±0.84 μg/L, 35.79±4.29 μg/L and 12.46±0.80 μg/L in the control group, 21.68±1.33 μg/L, 46.51±3.83 μg/L and 16.72±2.28 μg/L in the poisoned group, respectively. The difference was statistically significant between the poisoned group and the control group in MMP-2, MMP-9 and HYP levels (P<0.05 ).

Exposure of nitrogen oxides leads to impairment of pulmonary edema in short time. Detection of the MMP-2, MMP-9 and HYP levels could be helpful to study the pulmonary edema.