Cardiovascular reactivity and oxidative stress in young and older adults: the African-PREDICT and SABPA studies.

Background: Oxidative stress and increased cardiovascular reactivity are associated with endothelial dysfunction and cardiovascular disease development. These factors along with early vascular compromise are more pronounced in black populations. We aimed to compare cardiovascular reactivity and investigate associations thereof with oxidative stress in two bi-ethnic cohorts (younger: 25.0 ± 3.19yrs; older: 44.7 ± 9.61yrs). Methods: Cardiovascular reactivity using the color-word conflict test was measured with the Finometer device. Oxidative stress markers included superoxide dismutase (SOD), γ-glutamyl transferase (γ-GT) and reactive oxygen species (ROS). Results: Black groups displayed greater cardiovascular responses to stress than white groups. In younger white participants, diastolic blood pressure (DBP) (β = 0.31; p = 0.001) and mean arterial blood pressure (MAP) (β = 0.28; p = 0.002) associated with ROS. In older black participants, DBP (β = 0.23; p = 0.009), MAP (β = 0.18; p = 0.033), stroke volume (β = -0.20; p = 0.023) and arterial compliance (β = -0.25; p = 0.005) associated with γ-GT. In older white participants, systolic blood pressure (β = -0.20; p = 0.006) and MAP (β = -0.19; p = 0.009) associated with SOD. Conclusions: In the older black group, cardiovascular reactivity associated with markers of glutathione metabolism, suggesting a possible compensatory up-regulation thereof in order to correct their heightened responses to stress. Independent of age, findings in the white groups support a regulatory role of ROS to maintain vascular tone during stress.