Figure 2

Group means±s.d. of flow-mediated dilation (FMD; expressed as a % dilation above baseline) in smoking subjects (black bars) vs. healthy nonsmoking controls (white bars) with and without administration of BH4. *(P<0.05) difference between groups within each condition (baseline or BH4 treatment); †(P<0.05) difference within a group with BH4 treatment.