Prevention of edema formation in the perfused lung preparation by oxygen radical scavengers.

Oxygen-derived free radicals have been implicated as mediators of pulmonary microvascular injury. In the present study we addressed the question of the role of radicals formed in the lung parenchyma in development of pulmonary edema. Rat lungs were perfused with cell-free solutions with and without addition of colloid. Edema formation was measured as dry-wet weight ratios. Edema developed following 30 min perfusion with all perfusates except nonoxygenated Dextran-Tyrode. Addition of free radical scavengers, superoxide dismutase and catalase, reduced the edema formation with the various oxygenated perfusates. We conclude that in the isolated lung perfused with oxygenated solutions oxygen-derived radicals are formed that mediate increased permeability.