Abstract: Objective To determine the expression of water channel1protein in the lung of drown rat and that of after death thrown into the water.Methods Immunohistochemical method was used and the computer image analysis was conducted to detect the distribution of AQP1.Results The positive expres-sion of AQP1was seen in the capillary endotheliocyte of the interstitial and around bronchi and in the alveolar endothelial cells.The value of intergrated optical density was statistical significant.Conclusion It suggests that AQP1is one of sensitive signs to distinguish ante-mortem and postmortem immersion.

Key words: aquaporin, drown, immunohistochemistry, image analysis system