Change in substance P in a firearm wound and its significance

The present study was designed to detect the change of substance P (SP) in firearm wounds and its relationship with wound healing. Twenty two rabbits were randomly divided into two groups, one with firearm wounds created by steel balls shooting rabbits' thighs and another with stab wounds created by knife. The experimental design did not include direct injury to femora major peripheral nerve trunks or blood vessels. SP content in wound tissue of both groups was measured with radioimmunoassay (RIA). Histologic examination was performed on the wound and the saphenous and sciatic nerves away from the wound-track edges. It was found that both types of injuries caused an increase of SP content in the wound compared with normal tissue. At three to 10 days after injury, SP content was lower in firearm wounds than that in stab wounds. Pathomorphologic observation showed the indirect injuries to the saphenous and sciatic nerves in the rabbits with firearm wounds were more severe than those with stab wounds. Meanwhile, wound healing in the firearm wounds was poor compared with that in the stab wounds. The results suggest that the change in SP in firearm wounds differs from that in cold weapon wounds as a result of the presence of indirect injuries to major peripheral nerve trunks created by laceration shock wave and cavity effects, and SP in vivo may participate in wound healing as a growth factor. Therefore, the improvement of neuropeptide metabolism in firearm wound may be an important measure for accelerating wound healing.