Figure 2

Participation of nitric oxide in ACh-induced vasodilation. Concentration-response curves show acetylcholine (ACh)-induced endothelium-dependent relaxation in aortic rings under the blockade of nitric oxide synthase with L-NAME in wild-type (WT) mice (A), untreated apoE^−/− mice (B) and sildenafil-treated apoE^−/− mice (C). Bar graph (D) shows the difference in the area under the curve (AUC) of the response of aortic rings to ACh with and without L-NAME. A decreased difference in the AUC indicates an impaired response to ACh. Values are the means ± SEM. **p < 0.01 vs. without L-NAME (A, B and C: two-way ANOVA); **p < 0.01 vs. WT and ^##p < 0.01 vs. untreated apoE^−/− (D: one-way ANOVA).