Nitrofurantoin-stimulated oxidant production in pulmonary endothelial cells

Nitrofurantoin, a urinary antiseptic, is associated with significant pulmonary toxicity. Our study indicates that nitrofurantoin may produce lung injury by directly stimulating lung parenchymal cells to generate toxic oxygen species such as superoxide and hydrogen peroxide, which can overwhelm cellular antioxidant defenses and result in permanent injury to the cells. Nitrofurantoin (10(-3) mol/L) stimulates bovine pulmonary artery endothelial cells to release 3.7 +/- 0.4 mumol/L superoxide per 10(5) cells and 4.4 +/- 0.5 mumol/L hydrogen peroxide per 10(5) cells (p less than 0.001 compared with endothelial cells without nitrofurantoin). Endothelial cells treated with nitroblue tetrazolium, a yellow dye reduced by superoxide to insoluble blue formazan, can be monitored both spectrophotometrically and morphologically. Nitrofurantoin (10(-5), 10(-4), and 10(-3) mol/L) stimulated pulmonary endothelial cells to reduce nitroblue tetrazolium monitored spectrophotometrically as 0.022 +/- 0.001, 0.032 +/- 0.002, and 0.071 +/- 0.004 delta A515 per 10(5) cells per hour, respectively (p less than 0.001, comparison of cells with 10(-4) and 10(-3) mol/L nitrofurantoin vs. control cells. From the same dose-response curve, endothelial cells incubated with nitrofurantoin morphologically demonstrated formazan granules in the cytoplasm in 17% +/- 6%, 71% +/- 9%, and 92% +/- 5% of cells. Nitrofurantoin (10(-5), 10(-4), and 10(-3) mol/L) directly injures 51Cr-labeled pulmonary endothelial cells, with injury expressed as a cytotoxic index of 1 +/- 1, 20 +/- 4, and 51 +/- 3, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)