Abstract: Objective To investigate the expression of hypoxia-inducible factor 1-alpha(HIF1-α) in the heart,lung,liver and kidney in rats died of two typical models of asphyxia.Methods Two asphyxia models were made and tissue samples of the dead rats were collected from different groups at various postmortem duration.The expression and the changes of HIF1-α in various tissues were examined by immunohistochemistry and image analysis techniques.Results Significant expression of HIF1-α was observed in the myocardial fibers,kidney cells,liver cells and lung cells in both asphyxia models,but not in the control group.The expression of HIF1-α in various tissues in the rat died of nitrogen gas breathing was found in the nuclei at 0 hour and the expression level decreased gradually thereafter.The HIF1-α expression level and duration in various tissues of the rat died of hanging were higher and longer than that of the former group,with a peak of the expression level observed 6 hours after death,and then started to decline in all tissues except the heart where the expression still showed an increase 24 hours after death.The control groups showed a steady expression in the cytoplasm but not in the nuclei.Conclusion HIF1-α appears to be a valuable biomarker in the diagnosis of asphyxia within 24 hours after death.

Key words: hypoxia inducible factor1-α, death by only breathing in nitrogen gas, death by hanging, asphyxia, immunohistochemistry