Experimental sodium phosphate and polyethylene glycol induce colonic tissue damage and oxidative stress

Background: Bowel washout solutions may damage colonic mucosa and cause shallow ulceration, which may result in diagnostic errors and complications. The effects of polyethylene glycol (PEG) and sodium phosphate on rat colon were investigated histologically and by measurement of indicators of oxidative stress. Methods: Thirty Wistar albino rats were divided into three groups and received PEG, sodium phosphate or tap water alone (control). After 8 h, histological changes in colonic mucosa mere evaluated. The tissue concentration of malonyldialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in colon homogenates was also measured. Results: Animals in the sodium phosphate and PEG groups had significantly more colonic mucosal damage than controls, the damage induced by sodium phosphate being worse than that caused by PEG. MDA levels were significantly higher in the sodium phosphate and PEG groups than in controls and were higher in the sodium phosphate group than in the PEG group, whereas differences in SOD and GSH-Px activities were significant only between control and both sodium phosphate and PEG groups. Conclusion: Sodium phosphate and PEG cause histological damage and trigger oxidative stress on colonic mucosa. The tissue damage and oxidative stress induced by sodium phosphate is more profound than that produced by PEG.