Figure 1.

CIH treatment impairs EDR, reduces NRF2 expression, and promotes superoxide anion production. (A) CIH treatment impaired EDR in mouse thoracic aortas in a time-dependent manner. (B) Some differentially expressed genes in aortas from C57BL/6 mice treated with normoxia (N), CIH (C), or Re-Nor post-CIH (R) were predicted to be associated with vessel contraction and dilation, and reactive oxygen species according to GO and KEGG analysis. (C) A Venn diagram illustrated overlap of genes with predicted functions related to angiogenesis (blue), reactive oxygen species (green), contraction and dilation (orange), and inflammation (yellow). (D) CIH-30d treatment reduced the expression of NRF2, and its downstream target, CAT, in C57BL/6 mouse aorta, whereas re-administering normoxia for 15 days after 30-day-CIH treatment restored the decreased expression of NRF2 and CAT induced by CIH. (E) CIH-30d treatment increased superoxide anion production in endothelial cells, as detected by en face fluorescence with dihydroethidium (DHE) dye (red), which was blocked by 30-min pretreatment with ROS scavengers, Tempol (100 µM), or Tiron (1 mM) and DETCA (0.1 mM) or NRF2 agonist, Oltipraz (0.5 g/kg in saline, gavage once per day for 4 days). Bar, 20 µm. Green autofluorescence (auto-flu), elastic fibers; Red DHE staining, ROS in endothelial cells. (F) 30-min pretreatment with ROS scavengers, Tempol (100 µM), Tiron (1 mM) and DETCA (0.1 mM), or 4-day treatment with NRF2 agonist, Oltipraz (0.5 g/kg), reversed CIH-induced endothelial dysfunction in thoracic aortas. Results are the mean ± SEM (n = 4). ^*P < 0.05 vs. Nor. ^#P < 0.05 vs. CIH (D and F). Two-way ANOVA (A and F) and two-tailed t test (D).