Correlation between plasma and hepatic phosphatidylcholine hydroperoxide, energy charge, and total glutathione content in ischemia reperfusion injuryof rat liver

Background/Aims: Oxygen-derived free radicals are believed to be responsibl e for the hepatocellular injury leading to liver failure following ischemia -reperfusion in liver, endotoxemia and many other life-threatening illnesse s. This study was designed to investigate the reactive oxygen species inter action in lipid peroxidation, the adenosine and energy charge levels of liv er cells, and total glutathione content in ischemic-reperfusion injury of l iver in rat. Methodology: To prevent intestinal congestion during the clamping of vascul ar structures, subcutaneous transposition of the spleen was done beforehand . Four to six weeks later, after the development of natural portal-systemic shunts, occlusion of the portal vein, hepatic artery and bile duct was per formed for different periods; blood and liver samples were taken at differe nt intervals after the release. On the basis of the ischemia-reperfusion ti me, the rats were divided into the following 9 groups: 30/0, 30/30, 30/60, 60/0, 60/30, 60/60, 90/0, 90/30, and 90/60. The following parameters were m easured: total hepatic glutathione content, adenosine values (ATP, ADP, AMP ), energy charge, phosphatidylcholine hydroperoxide (PCOOH) concentrations in liver and plasma, and serum trans-aminases (AST, ALT). Decreased liver g lutathione stores (an indicator of increased oxidative stress), increased s erum hepatic transaminases (an indicator of hepatocellular injury), and inc reased PCOOH (an indicator of cellular-membrane lipid peroxidation) were no ted. Results: The ATP level and energy charge diminished significantly with the increase in duration of ischemia and reperfusion. A close correlation betwe en the PCOOH levels in plasma and liver was observed. Extreme damage was no ted in the 90-minute ischemia with 60-minute reperfusion group. The hepatic total glutathione level was reduced to the lowest level in the 90/60 group and it correlated with the energy charge level, denoting the highest degre e of oxidative stress sustained by the liver cells in this group. Conclusions: These results indicated that prolonged hepatic ischemia with r eperfusion produced bursts of oxygen-derived free radicals which overwhelme d the defense mechanisms of the cells, with a resultant decrease in energy charge associated with an increase in membrane lipid peroxidation. These fi ndings not only provide confirmation of previously reported hepatocellular injury by free radicals generated after reperfusion, but they also; establi sh the use of PCOOH analysis in liver and plasma as a sensitive and specifi c indicator of the injury process in time. The plasma PCOOH level may be a useful indicator of free radical induced hepatic membrane lipid peroxidatio n during ischemia-reperfusion, and might be employed in clinical studies of the therapeutic effects of drugs in various liver diseases, as well as for determining the prognosis after different kinds of hepatic operations.