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

Background/Aims: Oxygen-derived free radicals are believed to be responsible for the hepatocellular injury leading to liver failure following ischemia-reperfusion in liver, endotoxemia and many other life-threatening illnesses. This study was designed to investigate the reactive oxygen species interaction in lipid peroxidation, the adenosine and energy charge levels of liver cells, and total glutathione content in ischemic-reperfusion injury of liver in rat. Methodology: To prevent intestinal congestion during the clamping of vascular 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 performed for different periods; blood and liver samples were taken at different intervals after the release. On the basis of the ischemia-reperfusion time, 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 measured: total hepatic glutathione content, adenosine values (ATP, ADP, AMP), energy charge, phosphatidylcholine hydroperoxide (PCOOH) concentrations in liver and plasma, and serum transaminases (AST, ALT). Decreased liver glutathione stores (an indicator of increased oxidative stress), increased serum hepatic transaminases (an indicator of hepatoceliular injury), and increased PCOOH (an indicator of cellular-membrane lipid peroxidation) were noted. Results: The ATP level and energy charge diminished significantly with the increase in duration of ischemia and reperfusion. A close correlation between the PCOOH levels in plasma and liver was observed. Extreme damage was noted 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 1 with the energy charge level, denoting the highest degree of oxidative stress sustained by the liver cells in this group. Conclusions: These results indicated that prolonged hepatic ischemia with reperfusion produced bursts of oxygen-derived free radicals which overwhelmed the defense mechanisms of the cells, with a resultant decrease in energy charge associated with an increase in membrane lipid peroxidation. These findings not only provide confirmation of previously reported hepatocellular injury by free radicals generated after reperfusion, but they also establish the use of PCOOH analysis in liver and plasma as a sensitive and specific indicator of the injury process in time. The plasma PCOOH level may be a useful indicator of free radical induced hepatic membrane lipid peroxidation 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.