AIM TO study the role of mitochondrial dysfunction inhydrogen peroxide-induced apoptosis of intestinal epithelialcells.METHODS:Hydrogen peroxide-induced apoptosis of humanintestinal epithelial cell line SW-480 was established.Cellapoptosis was determined by Annexin-V and PI double-stained flow cytometry and DNA gel electrophoresis.Morphological changes were examined with light and electronmicroscopy.For other observations,mitochondrial function,cytochrome c release,mitochondrial translocation andmembrane potential were determined simultaneously.RESULTS:Percentage of apoptotic cells induced with 400μmol/L hydrogen peroxide increased significantly at 1 h or 3h after stimulation and recovered rapidly.Meanwhilepercentage of apoptotic cells induced with 4 mmol/Lhydrogen peroxide increased with time.In accordance withthese changes,we observed decreased mitochondrialfunction in 400 μmol/L H_2O_2-stimualted cells at 1 h or 3 hand in 4 mmol/L H_2O_2-stimualted cells at times examined.Correspondingly,swelling cristae and vacuole-likemitochondria were noted.Release of cytochrome c,decreased mitochondrial membrane potential andmitochondrial translocation were also found to be the earlysigns of apoptosis.CONCLUSION:Dysfunctional mitochondria play a role inthe apoptosis of SW-480 cell line induced by hydrogenperoxide. AIM TO study the role of mitochondrial dysfunction in hydrogen peroxide-induced apoptosis of intestinal epithelial cells. METHODS: Hydrogen peroxide-induced apoptosis of human intestinal epithelial cell line SW-480 was established. Cellpopulation was determined by Annexin-V and PI double-stained flow cytometry and DNA gel electrophoresis. Morphological changes were examined with light and electron microscopy. For other observations, mitochondrial function, cytochrome c release, mitochondrial translocation and membrane potential were determined successfully .RESULTS: Percentage of apoptotic cells induced with 400 μmol / L hydrogen peroxide increased significantly at 1 h or 3h after stimulation and recovered rapidly. Normal and apoptotic cells induced with 4 mmol / L hydrogen peroxide increased with time in accordance with the changes, we observed decreased mitochondrial function in 400 μmol / L H 2 O 2-stimulated cells at 1 h or 3 hand in 4 mmol / L H 2 O 2-stimulated cells at times examined. Correspo releasing of cytochrome c, decreased mitochondrial membrane potential and mitochondrial translocation were also found to be the early signs of apoptosis. CONCLUSION: Dysfunctional mitochondria play a role in the apoptosis of SW-480 cell line induced by hydrogenperoxide .