Change in free radical-related substances in plasma following ischemia-reperfusion in rat liver

In order to clarify the relationship between free radicals and liver injury due to ischemia-reperfusion, we investigated the dynamics of radical-related substances in the blood of rats after liver ischemia-reperfusion. Subsequent to 60 min of liver ischemia, the generation of reactive oxygen species (ROS) from polymorphonuclear leukocytes (PMNs) initiated by phorbol myristate acetate (PMA) and lipid peroxidation significantly increased 2 h after reperfusion and showed peak values at 8-10 h. These values returned to the control level 32 h after reperfusion. The levels of nitric oxide metabolites (NO_x, NO₂^-+NO₃^-) increased biphasically at 10 and 32 h during the period of reperfusion, but did not return to control levels. Cu,Zn-superoxide dismutase (SOD) levels increased immediately after 5 min of reperfusion and showed a peak value after 20 min. This increase diminished gradually and returned to the control level 10 h after reperfusion. Mn-SOD increased 2 h after reperfusion, and this level was maintained for 48 h. The levels did not show increases at the end of ischemia and were nearly identical to the pre-ischemia levels. These finding obtained from the dynamics of radical-related substances are considered very meaningful for investigating mechanisms in the pathogenesis of liver injury by ischemia-reperfusion, and are clinically important in liver transplantation.