To observe the effect of electromagnetic pulse(EMP) exposure on cerebral micro vascular permeability in rats.Methods The whole-body of male Sprague-Dawley rats were exposed or sham exposed to 200 pulses or 400 pulses(1 Hz) of EMP at 200 kV/m.At 0.5,1,3,6,and 12 h after EMP exposure,the permeability of cerebral micro vascular was detected by transmission electron microscopy and immunohistochemistry using lanthanum nitrate and endogenous albumin as vascular tracers,respectively.Results The lanthanum nitrate tracer was limited to the micro vascular lumen with no lanthanum nitrate or albumin tracer extravasation in control rat brain.After EMP exposure,the lanthanum nitrate ions reached the tight junction,basal lamina and pericapillary tissue.Similarly,the albumin immunopositive staining was identified in pericapillary tissue.The changes in brain micro vascular permeability were transient,the leakage of micro vascular vessels appeared at 1 h,and reached its peak at 3 h,and nearly recovered at 12 h,after EMP exposure.In addition,the leakage of micro vascular was more obvious after exposure of EMP at 400 pulses than after exposure of EMP at 200 pulses.Conclusion Exposure to 200 and 400 pulses(1 Hz) of EMP at 200 kV/m can increase cerebral micro vascular permeability in rats,which is recoverable. To observe the effect of electromagnetic pulse (EMP) exposure on cerebral microvascular permeability in rats. Methods The whole-body of male Sprague-Dawley rats were exposed or sham exposed to 200 pulses or 400 pulses (1 Hz) of EMP at 200 kV /m.At 0.5,1,3,6, and 12 h after EMP exposure, the permeability of cerebral microvascular was detected by transmission electron microscopy and immunohistochemistry using lanthanum nitrate and endogenous albumin as vascular tracers, respectively. Results The lanthanum nitrate tracer was limited to the microvascular lumen with no lanthanum nitrate or albumin tracer extravasation in control rat brain. After EMP exposure, the lanthanum nitrate ions reached the tight junction, basal lamina and pericapillary tissue. Similarly, the albumin immunopositive staining was identified in pericapillary tissue . The changes in brain microvascular permeability were transient, the leakage of microvascular vessels Have at 1 h, and reached its peak at 3 h, and nearly had recovered at 12 h, after EMP exposure. addition, the leakage of microvascular was more obvious after exposure of EMP at 400 pulses than after exposure of EMP at 200 pulses. Conflux Exposure to 200 and 400 pulses (1 Hz) of EMP at 200 kV / m can increase cerebral micro vascular permeability in rats, which is recoverable.