ISCHEMIA REPERFUSION ALTERS URIC-ACID AND ASCORBIC-ACID LEVELS IN LIVER/

Tissue damage in ischemia/reperfusion injury may be mediated by oxidat ive stress caused by reactive oxidant species. Since such reactive spe cies are difficult to measure directly, changes in antioxidant concent rations are often used as an indication of oxidative stress, In this s tudy, microdialysis membranes were inserted into the livers of anesthe tized rats to determine the effects of ischemia/reperfusion on the ext racellular concentrations of two antioxidants, uric acid and ascorbic acid, Total hepatic ischemia was induced for 30 min by clamping the po rtal triad and was followed by 60 min of reperfusion, Uric acid and as corbic acid concentrations were measured in microdialysis perfusates b y high-performance liquid chromatography with electrochemical detectio n. Initial uric acid and ascorbic acid concentrations were high after insertion of membranes into the liver and decreased rapidly within 90 min (P < 0.001; ANOVA with repeated measures), Uric acid concentration s increased over 300% after ischemia and by 600% during the first 30 m in of reperfusion (n = 8; P < 0.05). Ascorbic acid concentrations were 60% higher than controls after ischemia and 90% higher during the fir st 30 min of reperfusion (n = 8; P < 0.05), Alterations in concentrati ons of these redox-active molecules may be associated with oxidative s tress in liver extracellular fluid during ischemia/reperfusion. (C) 19 96 Academic Press, Inc.