Fig 1: DHFR deficiency augmented Ang II induced H4B and NO deficiencies, and uncoupling activity of eNOS: WT littermates and DHFR Het KO mice were infused with Ang II (0.7 mg/kg per day) for 14 days. (A) Total aortic H4B levels were measured using HPLC as we previously published. Mean±SEM, *p < 0.05, **p < 0.01, n = 3. (B) The aortic NO bioavailability was determined by ESR as we published previously. Upper: Representative ESR NO spectra. Lower: Quantitative grouped data of bioavailable NO levels. Mean±SEM, ***p < 0.001, **p < 0.01, n = 6–9. (C and D) Aortas of WT littermates and DHFR Het KO mice were harvested for Western blotting to detect expression of eNOS, GTPCH1, and β-actin. Mean±SEM, n = 5–8. (E) Aortic superoxide production in the presence or absence of L-NG- nitro-L-arginine methyl ester (L-NAME) was determined by ESR. Mean±SEM, ***p < 0.001, **p < 0.01, *p < 0.05, n = 3–4.