OXIDANT GENERATION WITH K-INDUCED DEPOLARIZATION IN THE ISOLATED-PERFUSED LUNG()

This study evaluated whether cell membrane depolarization can induce o xidant generation in the isolated perfused rat lung as has been demons trated with bovine pulmonary artery endothelial cells. Depolarization was produced by perfusing the lungs with high [K+] or with glyburide a nd was evaluated with bis-oxonol lung surface fluorometry. Lung surfac e bis-oxonol fluorescence increased above baseline (at 5.9 mM K+) by 1 8.5% with 24 mM K+, 35% with 48 mM K+, and 67% with 96 mM K+, indicati ng graded membrane depolarization, and by 75% during perfusion with 10 mu M glyburide. Oxidant generation was evaluated with hydroethidine l ung surface fluorometry, and with assay of tissue thiobarbituric acid reactive substance (TBARS), conjugated dienes, and perfusate H2O2. Dep olarization by high K+ or glyburide led to significant increases in ge neration of tissue oxidants and lipid peroxidation. Bodipy-FL-glyburid e microfluorography showed localization of glyburide binding primarily to vascular endothelial cells vascular and airway smooth muscle cells , alveolar type II cells, and to nonciliated cells of the airway epith elium. These results indicate that cellular depolarization is associat ed with oxidant generation by the lung and suggests a role for K+-chan nels in these events. (C) 1997 Elsevier Science Inc.