Nitric oxide-related markers link inversely to blood pressure in black boys and men: the ASOS and African-PREDICT studies.

Abstract

Nitric oxide plays an important role in maintaining endothelial function, while increased oxidative stress may lead to nitric oxide inactivation and cardiovascular disease. If nitric oxide biosynthesis/bioavailability is already suppressed early in life, it may potentially predispose an individual to the early development of cardiovascular disease. We therefore aimed to identify differences in nitric oxide-related markers (urinary nitrate, nitrite and the nitrate-to-nitrite ratio (UNOxR)) between young black and white individuals, and whether these markers are associated with blood pressure and carotid intima media thickness. We included black and white healthy boys (n = 80; aged 6-8years) and men (n = 510; 20-30years) and measured blood pressure and carotid intima media thickness, along with urinary biochemical markers including nitrate and nitrite. The black boys and men had lower nitrate and UNOxR (all p ≤ 0.003) than their white counterparts. In single and multiple regression analyses, we found an inverse association of diastolic blood pressure in the black boys (adj. R2 = 0.27; β = -0.32; p = 0.030), and systolic blood pressure in black men (adj. R2 = 0.07; β = -0.13; p = 0.036) with nitrate. Carotid intima media thickness associated inversely with UNOxR in the black men (adj. R2 = 0.02; β = -0.14; p = 0.023), but not in the boys. Lower urinary nitrate in black boys and young men was associated negatively with blood pressure, suggesting that potentially lower nitric oxide bioavailability in young black individuals may contribute to hypertension development in later life.