Fig. 4.

eNOS dimer stability under conditions of oxidative stress. COS-7 cells were transiently transfected with either WT- or C94R/C99R-eNOS. After 48 h, cells were exposed or not to increasing concentrations of H₂O₂ (0–400 µM, 30 min). Western blot analysis using LT-PAGE, was then used to determine the effect on the eNOS dimer: monomer ratio. H₂O₂ dose dependently decreased the dimer level in WT-eNOS expressing cells (A). However, the C94R/C99R mutant was resistant to dimer disruption even at 400 µM H₂O₂ (B). Basal levels of NO_x were similar in WT- or C94R/C99R-eNOS expressing cells. H₂O₂ exposure (300 µM) significantly reduced NO_x levels in WT eNOS expressing cells but not in the cells expressing the C94R/C99R eNOS mutant (C). Data are mean±SEM, N=3, ^⁎p<0.05 vs. untreated; ^† vs. WT eNOS +H₂O₂.