Objective   To investigate the dynamic changes of cerebral blood flow in rats with brain injury caused by explosion.  Methods   A total of 160 male rats were divided randomly into enclosure group (n=48)

open-field group (n=48) and S-Nitrosoglutathione (GSNO) therapy group (n=48)

and subjected to explosion with instantaneous electric detonator. Sixteen uninjured rats served as normal control. Before and in 1

6

12

24 and 48 h after injury

cerebral blood flow of were measured by laser Doppler flowmetry (LDF)

plasma level of neuron-specific enolase (NSE) was measured by ELISA

and brain tissues were analyzed by wet-dry weight measurements and microscopy after HE staining.  Results  The CBF was significantly reduced to the lowest value in 1 h after injury in enclosure group (P0.01). The value was still lower than pre-injury in 24 h after injury (P0.01). The CBF of open field group was also reduced to the lowest value at 1 h after injury (P0.01)

but it recovered to pre-injury level at 12 h after injury. The CBF in 2 group at 1

6

12 and 24 h after injury were significantly different (P0.01). The CBF of enclosure group was significantly elevated after GSNO intervention. NSE concentration and brain water content of enclosure group were elevated to the highest value at 6 h after injury (P0.01)

and were still higher than control group at 48 h after injury (P0.05). But in open field group

the value were elevated to highest at 12 h after injury(P0.01)

and recovered to the level of control group at 48 h after injury. The value of GSNO therapy group was significantly lower than enclosure group (P0.01). The pathological changes of enclosure group showed obvious brain edema

swelling of endothelial cells

neuron shrinkage

degeneration

necrosis

significantly widened gap around neuron and so on. But the GSNO therapy group only showed neuron necrosis.  Conclusion  The reduction of cerebral blood flow sustains longer and stronger in rats in enclosed space than that in open field. Decreased cerebral blood flow may be involved in the secondary brain injury after explosive brain injury.