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

<b>Background:</b> 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). <b>Methods:</b> 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). <b>Results:</b> Black groups displayed greater cardiovascular responses to stress than white groups. In younger white participants, diastolic blood pressure (DBP) (<i>β</i> = 0.31; <i>p</i> = 0.001) and mean arterial blood pressure (MAP) (<i>β</i> = 0.28; <i>p</i> = 0.002) associated with ROS. In older black participants, DBP (<i>β</i> = 0.23; <i>p</i> = 0.009), MAP (<i>β</i> = 0.18; <i>p</i> = 0.033), stroke volume (<i>β</i> = −0.20; <i>p</i> = 0.023) and arterial compliance (<i>β</i> = −0.25; <i>p</i> = 0.005) associated with γ-GT. In older white participants, systolic blood pressure (<i>β</i> = −0.20; <i>p</i> = 0.006) and MAP (<i>β</i> = −0.19; <i>p</i> = 0.009) associated with SOD. <b>Conclusions:</b> 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. <b>Trial registration:</b>ClinicalTrials.gov identifier: NCT03292094.

【背景】氧化应激与心血管反应增强均与内皮功能障碍及心血管疾病的发生发展密切相关。上述因素联合早期血管损伤在黑人人群中表现更为显著。本研究旨在比较两个双族裔队列（年轻组：25.0±3.19岁；年长组：44.7±9.61岁）的心血管反应差异，并探究其与氧化应激的关联。
【方法】采用色词冲突测试评估心血管反应，检测设备为Finometer。氧化应激标志物包括超氧化物歧化酶（superoxide dismutase, SOD）、γ-谷氨酰转移酶（γ-glutamyl transferase, γ-GT）以及活性氧（reactive oxygen species, ROS）。
【结果】黑人组对应激的心血管反应较白人组更为强烈。在年轻白人受试者中，舒张压（diastolic blood pressure, DBP）（β=0.31；P=0.001）与平均动脉压（mean arterial blood pressure, MAP）（β=0.28；P=0.002）均与活性氧水平呈正相关。在年长黑人受试者中，DBP（β=0.23；P=0.009）、MAP（β=0.18；P=0.033）与γ-谷氨酰转移酶水平呈正相关，每搏输出量（stroke volume）（β=-0.20；P=0.023）及动脉顺应性（arterial compliance）（β=-0.25；P=0.005）与γ-谷氨酰转移酶水平呈负相关。在年长白人受试者中，收缩压（systolic blood pressure）（β=-0.20；P=0.006）与MAP（β=-0.19；P=0.009）与超氧化物歧化酶水平呈负相关。
【结论】年长黑人组的心血管反应与谷胱甘肽代谢标志物相关，提示机体可能存在代偿性上调以纠正其增强的应激反应。无论年龄因素，白人组的研究结果均支持活性氧在应激过程中维持血管张力的调控作用。
【试验注册】ClinicalTrials.gov 注册号：NCT03292094。