Central systolic blood pressure relates inversely to nitric oxide synthesis in young black adults: the African-PREDICT study.

Lower nitric oxide (NO) bioavailabilty associates with hypertension in patients and elderly populations. With hypertension known to develop earlier in black populations, we compared both plasma and urinary NO-related markers and their associations with central systolic blood pressure (cSBP) and arterial stiffness in healthy young black and white adults. We included healthy black and white men and women (n = 1110; 20-30 years) and measured cSBP and pulse wave velocity (PWV), along with both plasma and urinary arginine, homoarginine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), as well as urinary ornithine/citrulline, nitrite and nitrate. In addition, the urinary nitrate-to-nitrite ratio (UNOxR) was calculated. The black men and women had higher cSBP and higher plasma arginine and ADMA, but lower urinary nitrate and UNOxR (all p ≤ 0.003) than their white counterparts. In single and forward stepwise multiple regression analyses, we found an inverse association of cSBP (adj. R2 = 0.124; ß = -0.134; p = 0.006) and plasma homoarginine in black men. Central SBP associated inversely with UNOxR in black women only (adj. R2 = 0.171; ß = -0.130; p = 0.029). In the white women, cSBP associated positively with urinary ADMA (adj. R2 = 0.372; ß = 0.162; p = 0.015). PWV associated inversely with plasma ADMA (adj. R2 = 0.253; ß = -0.163; p = 0.024) in the white women only. The lower NO synthesis and the higher cSBP in our black cohort support the notion of a potential increased risk for future large artery stiffness and hypertension development in later life.

Three-year change in oxidative stress markers is linked to target organ damage in black and white men: the SABPA study.

Oxidative stress is implicated in hypertension, carotid wall thickening, and renal dysfunction. Oxidative stress is linked to cardiovascular pathology in the black South African individuals who have a high prevalence of hypertension and early vascular aging. However, there are limited data relating changes in oxidative stress with vascular and renal deterioration over time. We aimed to investigate whether changes in oxidative stress over 3 years are associated with target organ damage in black (N = 89) and white (N = 91) men. Carotid intima-media thickness was measured using the SonoSite Micromaxx ultrasound system, and cross-sectional wall area (CSWA) was calculated. The estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease formula. The percentage change (%∆) in oxidative stress markers was calculated and included reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR). Over 3 years, black men exhibited decreased ROS, SOD, and GR, while white men revealed decreased SOD and GPx. Black men displayed positive associations of CSWA with %∆ ROS (ß = 0.28; p = 0.017) and %∆ SOD (ß = 0.24; p = 0.047). White men displayed a negative association of CSWA with %∆ SOD (ß = -0.22; p = 0.042) and positive associations of eGFR with %∆ GPx (ß = 0.33; p = 0.001) and %∆ GR (ß = 0.39; p < 0.001). In white men, the association of CSWA with decreased SOD activity suggests oxidative-stress-related carotid remodeling, while associations of eGFR with the glutathione system suggests a postponement of microvascular deterioration. In black men, associations of oxidative stress markers with CSWA suggest that a sufficiently functioning antioxidant system may delay target organ damage.