Effect of Polyethylene Glycol Conjugated Superoxide Dismutase on Hepatic Ischemia/Reperfusion Injury in Rats

Superroxide anion radical (02-) has been suggested as a causative factor of ischemia/reperfusion injury to the liver. Superxide dismutase (SOD)is a specific scavenger for 02, but its elimination half life in the blood is about five min. Polyethylene glycol conjugated SOD (PEG-SOD) has a chracteristics of long half life (14hr) in the circulating blood and low immunogenicity. In the present study, we compared the effect of PEG-SOD to conventional SOD in protecting the ischemia/reperfusion injury to the liver. In rats with an occluded inflow against 70% of the liver for 30min followed by 30min reperfusion, elevations of serum aspartate aminotransferase and alanine aminotransferase,and lipid peroxide concentrations in the liver were not significantly inhibited by intravenous administration of PEG-SOD, compared to those treated with conventional SOD. These results indicate that sustained presence of radical scavenger activity in the circulating blood has no more beneficial effects on hepatic ischemia/reperfusion injury than its temporary presence when reperfusion begins