Polyethylene glycol-conjugated superoxide dismutase in unilateral lung injury due to re-expansion (re-oxygenation)

This study evaluated the effects of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD) in re-expansion pulmonary edema, a unilateral lung injury due in part to re-oxygenation of hypoxic, collapsed lung tissue. The hypothesis underlying this investigation was that extracellular superoxide contributed to the lung inflammation in this model, and that PEG-SOD could be used to test for extra-cellular superoxide involvement. The right lungs of 2-3 kg rabbits were collapsed for seven days by intrapleural air injections. Immediately prior to lung re-expansion, rabbits received intravenously 10,000 units/kg PEG-SOD (n = 6) or an equal volume of H2O2-inactivated PEG-SOD (n = 6). Inactive PEG-SOD pretreated rabbits had a marked increase in re-expanded lungs' lavage albumin concentration (right 1653 +/- 230 micrograms/ml, left 404 +/- 160 micrograms/ml; p less than .01). Active PEG-SOD did not inhibit this permeability increase (right 1744 +/- 242 micrograms/ml, left 180 +/- 53 micrograms/ml; p less than .01). However, active PEG-SOD significantly decreased both total number and percent neutrophils in alveolar lavage (right 24.8 +/- 9.4%, left 4.2 +/- 0.8%; p less than .05) compared to inactive PEG-SOD pretreated rabbits (right 52.8 +/- 5.8%, left 8.7 +/- 2.4%; p less than .01). Pretreatment with active PEG-SOD significantly increased lung tissue (20.4 +/- 1.5 units/mg DNA), blood (400 +/- 8 units/ml) and right lung lavage (30.0 +/- 3.1 units/ml) SOD activities compared to those from inactive PEG-SOD pretreated rabbits (respectively: 16.0 +/- 1.0 units/mg DNA, 335 +/- 14 units/ml and 10.8 +/- 1.3 units/ml; p less than .05 for each comparison).(ABSTRACT TRUNCATED AT 250 WORDS)