Objective      To study the expressions of MMP-1 and MMP-3 following time after gunshot injury.     Methods    Thirty healthy Wistar mice were divided into 2 group randomly: the control group and the experimental group. The whole thickness skin of right hind limb injured by gunshot was obtained

immediately after sacrifice in the control groups and at 0

1

3

6

12

18

24

48

72 h after gunshot injury in the experimental group . The amount of MMP-1 and MMP-3 mRNA was detected by Northern blot.     Results    The expressions of MMP-1 and MMP-3 in experimental group increased immediately after gunshot injury

kept rising at constant rate. However

no changes of expression was found in the control group.     Conclusion    Gunshot leads to the increased  expression of MMP-1 and MMP-3

and its regularity can help to deduce the damage time of gunshot injury.