Direct evidence of endothelial oxidative stress with aging in humans -: Relation to impaired endothelium-dependent dilation and upregulation of nuclear factor-κB

Aging is associated with impaired vascular endothelial function, as indicated in part by reduced endothelium-dependent dilation (EDD). Decreased EDD with aging is thought to be related to vascular endothelial cell oxidative stress, but direct evidence is lacking. We studied 95 healthy men: 51 young (23 +/- 1 years) and 44 older (63 +/- 1 years). EDD (brachial artery flow-mediated dilation) was approximate to 50% lower in older versus young men (3.9 +/- 0.3% versus 7.6 +/- 0.3%, P < 0.01; n = 42 older/n = 51 young). Abundance of nitrotyrosine (quantitative immunofluorescence), an oxidatively modified amino acid and marker of oxidative stress, was higher in endothelial cells (ECs) obtained from the brachial artery (1.25 +/- 0.12 versus 0.61 +/- 0.11 nitrotyrosine intensity/human umbilical vein EC [ HUVEC] intensity, P < 0.01; n = 11 older/n = 11 young) and antecubital veins (0.55 +/- 0.04 versus 0.34 +/- 0.03, P < 0.05; n = 19 older/n = 17 young) of older men. Flow-mediated dilation was inversely related to arterial EC nitrotyrosine expression (r =-0.62, P < 0.01; n = 22). In venous samples, EC expression of the oxidant enzyme NAD(P) H oxidase-p47(phox) was higher in older men (0.71 +/- 0.05 versus 0.57 +/- 0.05 NAD[ P] H oxidase-p47phox intensity/HUVEC intensity, P < 0.05; n = 19 older/n = 18 young), whereas xanthine oxidase and the antioxidant enzymes cytosolic and mitochondrial superoxide dismutase and catalase were not different between groups. Nuclear factor-kappa B p65, a component of the redox-sensitive nuclear transcription factor nuclear factor-kappa B, was elevated in both arterial (0.73 +/- 0.07 versus 0.53 +/- 0.05 NF-kappa B p65 intensity/HUVEC intensity, P < 0.05; n = 9 older/n = 12 young) and venous (0.65 +/- 0.07 versus 0.34 +/- 0.05, P < 0.01; n = 13 older/n = 15 young) EC samples of older men and correlated with nitrotyrosine expression (r = 0.51, P < 0.05 n = 16). These results provide direct support for the hypothesis that endothelial oxidative stress develops with aging in healthy men and is related to reductions in EDD. Increased expression of NAD(P) H oxidase and nuclear factor-kappa B may contribute to endothelial oxidative stress with aging in humans.