P47 TETRAHYDROBIOPTERIN AND MARKERS OF OXIDATIVE STRESS IN A YOUNG BI-ETHNIC POPULATION: THE AFRICAN-PREDICT STUDY

Background/Objectives: Tetrahydrobiopterin (BH4) is a cofactor for nitric oxide synthase (NOS). Oxidative stress, reported in black populations (1), may lead to the oxidation of BH4, the uncoupling of eNOS, decreased NO and increased superoxide levels (2,3). We compared BH4 and markers of oxidative stress and their association, between black and white cohorts. Methods: In the African-PREDICT study, we included black (n = 300) and white (N = 297) participants (aged 20–30 years). We measured blood pressure, and determined serum levels of BH4 and markers of oxidative stress. Results: Blacks had higher blood pressure (p < 0.001). In blacks the following serum levels were lower: BH4 (p < 0.0001), total antioxidant status (TAS) (p < 0.0001), glutathione peroxidase (GPx), while reactive oxygen species (ROS) (p < 0.03) was higher. In blacks BH4 related positively with GPx in single, partial (adjusted for socio-economic status, sex, age, BMI, GGT and cotinine) and multiple regression (R2 = 0.16, β = 0.17, p = 0.02) and glutathione reductase (GR) (R2 = 0.16, β = 0.15, p = 0.05). We found a negative correlation between BH4 and GPx (R2 = 0.07, β = −0.26, p = 0.0006) in whites. Conclusions: Higher oxidative stress levels in young blacks (increased ROS, lower TAS and GPx) could explain the low concentrations of BH4, the possible uncoupling of eNOS, resulting in higher blood pressure. The uncoupling of eNOS may explain the production of ROS and peroxinitrite and may be linked to the positive correlation of BH4 with GPx and GR found in blacks, that may lead to early vascular changes.