SummaryWe tested the hypothesis that supplementation of nicotinamide mononucleotide (NMN), a key NAD + intermediate, increases arterial SIRT1 activity and reverses age‐associated arterial dysfunction and oxidative stress. Old control mice (OC) had impaired carotid artery endothelium‐dependent dilation (EDD) (60 ± 5% vs. 84 ± 2%), a measure of endothelial function, and nitric oxide (NO)‐mediated EDD (37 ± 4% vs. 66 ± 6%), compared with young mice (YC). This age‐associated impairment in EDD was restored in OC by the superoxide (O2−) scavenger TEMPOL (82 ± 7%). OC also had increased aortic pulse wave velocity (aPWV, 464 ± 31 cm s−1 vs. 337 ± 3 cm s−1) and elastic modulus (EM, 6407 ± 876 kPa vs. 3119 ± 471 kPa), measures of large elastic artery stiffness, compared with YC. OC had greater aortic O2− production (2.0 ± 0.1 vs. 1.0 ± 0.1 AU), nitrotyrosine abundance (a marker of oxidative stress), and collagen‐I, and reduced elastin and vascular SIRT1 activity, measured by the acetylation status of the p65 subunit of NFκB, compared with YC. Supplementation with NMN in old mice restored EDD (86 ± 2%) and NO‐mediated EDD (61 ± 5%), reduced aPWV (359 ± 14 cm s−1) and EM (3694 ± 315 kPa), normalized O2− production (0.9 ± 0.1 AU), decreased nitrotyrosine, reversed collagen‐I, increased elastin, and restored vascular SIRT1 activity. Acute NMN incubation in isolated aortas increased NAD + threefold and manganese superoxide dismutase (MnSOD) by 50%. NMN supplementation may represent a novel therapy to restore SIRT1 activity and reverse age‐related arterial dysfunction by decreasing oxidative stress.

To determine whether impaired endothelium-dependent dilation (EDD) in older adults is associated with changes in the expression of major vasoconstrictor or vasodilator proteins in the vascular endothelium, endothelial cells (EC) were obtained from the brachial artery and peripheral veins of 56 healthy men, aged 18-78 yr. Brachial artery EC endothelin-1 (ET-1) [0.99 +/- 0.10 vs. 0.57 +/- 0.10 ET-1/human umbilical vein EC (HUVEC) intensity, P = 0.01] and serine 1177 phosphorylated endothelial nitric oxide synthase (PeNOS) (0.77 +/- 0.09 vs. 0.44 +/- 0.07 PeNOS/HUVEC intensity, P < 0.05) (quantitative immunofluorescence) were greater, and EDD (peak forearm blood flow to intrabrachial acetylcholine) was lower (10.2 +/- 0.9 vs. 14.7 +/- 1.7 ml.100 ml(-1).min(-1), P < 0.05) in older (n = 18, 62 +/- 1 yr) vs. young (n = 15, 21 +/- 1 yr) healthy men. EDD was inversely related to expression of ET-1 (r = -0.39, P < 0.05). Brachial artery EC eNOS expression did not differ significantly with age, but tended to be greater in the older men (young: 0.23 +/- 0.03 vs. older: 0.33 +/- 0.07 eNOS/HUVEC intensity, P = 0.08). In the sample with venous EC collections, EDD (brachial artery flow-mediated dilation) was lower (3.50 +/- 0.44 vs. 7.68 +/- 0.43%, P < 0.001), EC ET-1 and PeNOS were greater (P< 0.05), and EC eNOS was not different in older (n = 23, 62 +/- 1 yr) vs. young (n = 27, 22 +/- 1 yr) men. EDD was inversely related to venous EC ET-1 (r = -0.37, P < 0.05). ET-1 receptor A inhibition with BQ-123 restored 60% of the age-related impairment in carotid artery dilation to acetylcholine in B6D2F1 mice (5-7 mo, n = 8; 30 mo, n = 11; P < 0.05). ET-1 expression is increased in vascular EC of healthy older men and is related to reduced EDD, whereas ET-1 receptor A signaling tonically suppresses EDD in old mice. Neither eNOS nor PeNOS is reduced with aging. Changes in ET-1 expression and bioactivity, but not eNOS, contribute to vascular endothelial dysfunction with aging.

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SummaryThe vascular endothelium may develop a proinflammatory profile with aging, but evidence is limited in humans. Expression of inflammatory proteins was determined in vascular endothelial cells (EC) obtained from peripheral veins of 24 young (23 ± 1 years, mean ± SE) and 36 older (63 ± 1) healthy men and women using quantitative immunofluorescence. The older subjects had lower vascular endothelium‐dependent dilation (forearm blood flow responses to acetylcholine, p < 0.05), and higher plasma concentrations of C‐reactive protein, interleukin‐6 (IL‐6), and oxidized low‐density lipoprotein (all p < 0.05), but not tumor necrosis factor‐α (TNF‐α). Total (O: 0.52 ± 0.04 vs. Y: 0.33 ± 0.05 NFκB/HUVEC intensity, p < 0.05) and nuclear (O: 0.59 ± 0.04 vs. Y: 0.41 ± 0.04) expression of nuclear factor κ B p65 (NFκB), a proinflammatory gene transcription factor, was greater in EC from the older subjects (p < 0.05). EC expression of the inhibitor (of nuclear translocation) of NFκB (IκBα) was lower in the older subjects (O: 0.16 ± 0.02 vs. Y: 0.24 ± 0.03, p < 0.05), whereas IκB kinase (IκK) was not different. EC expression of the proinflammatory proteins IL‐6 (O: 0.42 ± 0.06 vs. Y: 0.29 ± 0.03, p < 0.05), TNF‐α (O: 0.52 ± 0.06 vs. Y: 0.33 ± 0.05, p < 0.05) and monocyte chemoattractant protein 1 (MCP‐1) (O: 0.59 ± 0.06 vs. Y: 0.38 ± 0.02, p < 0.05) was greater in the older subjects, whereas cyclooxygenase 2 and the receptor for advanced glycation end‐products did not differ. These findings indicate that impaired function with aging in healthy adults is associated with the development of a proinflammatory phenotype in the vascular endothelium that could be caused in part by reduced IκB‐mediated inhibition of NFκB.