Lipid peroxidation is not a major factor involved in the edema formation in perfused lungs

Perfusion of isolated rat lungs was previously found to induce edema formation, which was considered to be mediated by oxygen-free radicals as scavengers reduced the edema. In the present study we elaborated upon these findings by measuring products found by O2-radical generation. We measured reduced and oxidized glutathione as well as conjugated dienes as an estimate of lipid peroxidation. Amount of water was also measured. Perfusion with oxygenated dextran/Tyrode solution increased edema as compared to nonoxygenated dextran/Tyrode and to nonperfused control lungs. Induction of oxygen radical formation by addition of xanthine and xanthine oxidase to the nonoxygenated dextran/Tyrode perfusate significantly increased the amount of edema as measured by the percentage of water in the lung to 87.0% as compared to the control value of 78.2%. Addition of the radical scavenger superoxide dismutase and catalase to this perfusate prevented edema accumulation. Levels of conjugated dienes as well as those of reduced and oxidized glutathione in lung tissue were measured before the start of perfusion and after 5 and 30 min of perfusion. No significant changes were seen in any of these parameters, indicating that lipid peroxidation may not be a major factor contributing to the edema formation during perfusion of isolated lungs.