Non-phagocytic NAD(P)H oxidases have been impliinduced stimulation of NAD(P)H oxidase activity in nonphagocytic cell types could represent a mechanism by which oxidant-mediated injury is amplified in vivo and identify these NAD(P)H oxidase enzymes as therapeutic targets for the amelioration of the biological effects of chronic oxidant stress.
EXPERIMENTAL PROCEDURESCell Culture-SMC were prepared from 250 to 300-g male HarlanSprague Dawley rats as previously described (10, 11). Aortic adventitial fibroblasts were prepared from C57 BL/6 and from gp91 phox knock-out mice (Jackson Lab, Bar Harbor, ME) as described (12, 13). The cells were grown in minimum essential media supplemented with 10% fetal bovine serum and penicillin (100 IU/ml) and streptomycin (100 g/ml) in a humidified atmosphere containing 5% CO 2 at 37°C. Stocks were subcultured at subconfluence by trypsinization. All experiments were performed on cells between passages 8 and 20 grown to 70% to 95% confluence in 24-well plates, 35-or 60-mm dishes, or 4-well chamber slides.Superoxide Measurement by Enhanced Chemiluminescence-Lucigenin luminescence measurements were carried out using 5 M lucigenin, a concentration which is unlikely to induce redox cycling (14). Cells were grown to subconfluence in 35-mm dishes and growth arrested in serum-free medium for 24 h. After exposure to H 2 O 2 at the indicated concentrations and times, cells were washed twice with PBS, and 5 M lucigenin was added. Immediately afterward, NADPH (0.1 mM) was added, and after dark adaptation, luminescence was measured every 15 s for 5 min in a luminometer (Zylux Corp). Changes in luminescence were expressed as relative luminescent units per 10 5 cells per minute. No changes in luminescence were observed in the absence of NADPH, and addition of H 2 O 2 to lucigenin in PBS in the absence of cells did not increase chemiluminescence. Some experiments were also performed with coelenterazine (5 M), a structurally distinct luminescent probe which reportedly is not capable of redox cycling via autoxidation (15). Data were analyzed by ANOVA followed by Bonferroni t testing.Intracellular O 2 . Determination by Confocal Microscopy-SMC grown on chamber slides were treated as indicated under "Results" and in the figure legends, washed, and incubated with dihydroethidium (HE, 5