Objective :To establish a simple

reproducible brain edema model induced by endotoxin in infant rats and explore the role of intracellular free calcium and calmodulin (CaM). in the development of brain edema. Methods: A total of 45 infant rats were divided randomly into endotoxin treated( n = 36) and control( n = 9) group. The animals were intraperitoneally injected with 10mg/kg of endotoxin or saline respectively. The brain tissue intracelluar free [Ca2 + ] as well as the expression of CaM was detected by fluorescence and protein hybridizaton methods respectively. The tissue water content

Evans Blue content and pathology under electronic microscope were also observed. Results:Brain water and EB content were remarkably increased in endotoxin treated animals compared with those in the control

in which the intracellular free [Ca2+ ] was also significantly increased and the expression of CaM up - regulated. Electron microscopic studies revealed that the blood - brain barrier(BBB)was disrupted with neuronal degeneration

neurogliocyte swelling and necrosis. Conculsion :These results suggest that LPS increases the intracellular free [Ca2+ ]

and activates the CaM - dependent function via Ca2+ /CaM pathway

which might relate to the increased BBB permeability and brain edema formation.