AIMTo investigate the influences of inflammatory mediator on permeability of the blood-brain barrier(BBB) at high altitude environmental exposure as well as relationship and water content in brain.

METHODSWistar rats were exposed to different altitude gradients, then brain tissue homogenate was prepared, and the activities of tumor necrosis factor-alpha (TNFalpha) and endothelin (ET) in brain tissue homogenate were measured by radioimmunoassay methods. The activities of nitric oxide (NO) in brain tissue homogenate were measured by chemical methods. The evans blue (EB) content in brain tissue was determined by colorimetry and the wet weight/dry weight ratio (W/D) was used to express the water content in brain.

RESULTSWith altitude going up, the activities of TNFalpha, NO and ET in the brain of rats rose, and they also rose gradually with time prolonging under high altitude hypoxia exposure. Their most obvious rise was seen during 9 days after ascending 5 000 m high altitude regions. At the same time, the EB and water content in the brain of mice showed the same change trends. Therefore, the inflammatory mediator activity and EB content as well as water content in brain showed an evidently linear relationship.

CONCLUSIONThe inflammatory mediator plays an important role in the change of permeability of BBB. It's a critical inducing factor in the change of permeability of BBB under high altitude exposure.