Schneider, Aaron

Aging is associated with increased aortic stiffness and exaggerated stress-induced blood pressure (BP) responsiveness, both of which contribute to the risk of cardiovascular disease. Supplementation with inorganic nitrate increases nitric oxide (NO) bioavailability and is a promising potential treatment to improve vascular function. While the acute effects of dietary inorganic nitrate supplementation on various measures of vascular function and BP have been demonstrated in several studies, the effects of increasing NO bioavailability through prolonged use (i.e. weeks) is unclear. Therefore, we tested the hypothesis that 4-weeks of inorganic nitrate supplementation will effectively increase NO bioavailability (as measured by plasma nitrate and nitrite) and reduce central BP, aortic stiffness, and BP responsiveness to a cold pressor test (CPT) in older adults. Thirteen older adults (67±3 years; 7 males and 6 females) completed a randomized, double-blind, placebo-controlled, crossover trial consisting of two 4-week supplementation periods (nitrate vs. placebo) separated by a 4-week washout. Central BP and carotid-femoral pulse wave velocity (cfPWV) were measured via applanation tonometry. Peripheral BP responses were assessed using beat-by-beat BP at baseline and during CPT. Plasma [nitrate] (40±24 to 76±46 µM, P< 0.01) and [nitrite] (289±94 to 413± 28 nM, P< 0.01) increased following inorganic nitrate supplementation, but remained unchanged after placebo ([nitrate] 39±20 to 39±16 µM, P=0.97; [nitrite] 303±108 to 302±87 nM, P=0.95). Four weeks of inorganic nitrate supplementation reduced resting measures of central systolic BP (cSBP; 116±12 to 113±10 mmHg, P< 0.05) and diastolic BP (cDBP; 79±8 to 74±6 mmHg, P< 0.05), as well as cfPWV (10.2±1.3 to 9.4±1.0 m/sec, P< 0.01), whereas no changes were observed following placebo (cSBP 112±10 to 115±10 mmHg; cDBP 75±7 to 78±7 mmHg; cfPWV 10.0±1.1 to 9.8±1.0 m/sec, P >0.05 for all). Additionally, the peak change (Δ from baseline) in peripheral SBP (28±10 to 23±6 mmHg, P< 0.05) and mean arterial pressure (MAP; 17±6 to 14±3 mmHg, P< 0.05) during the CPT were reduced following nitrate with no changes observed after placebo (SBP 25±8 to 26±12 mmHg, P=0.51; MAP 14±4 to 16±8 mmHg, P=0.19). Our findings demonstrate 4-weeks of inorganic dietary nitrate supplementation has favorable effects on central BP, aortic stiffness and BP responsiveness in older adults. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Evidence suggests that increased sympathetic tone but no change of blood pressure (BP) via lower body negative pressure (LBNP) reduces indices of aortic wave reflection in young adults. The aim of this study was to examine whether aging affects central artery hemodynamics and indices of wave reflection during LBNP. In 12 young (27 ± 2 years, 5F/7M) and 10 older (70 ± 2 years 5F/5M) subjects, noninvasive aortic pressure waveforms were synthesized from high‐fidelity radial pressure waveforms via applanation tonometry before and during 10 minutes of LBNP (‐20mmHg). Aortic BP and indices of aortic wave reflection (i.e. Augmentation index; AIx) were calculated from the generated aortic pressure waveform. Aortic systolic BP decreased during LBNP in the young (110 ± 3 vs. 106 ± 3 mmHg, P<0.05), but not the older adults (139 ± 3 vs. 136 ± 3 mmHg, P=0.15). Aortic diastolic BP did not change in either group (P=0.56). Since heart rate (HR) changed in the young (P<0.05) but not in the older adults (P=0.33) during LBNP, we used the AIx normalized to a HR of 75bpm as an index of wave reflection. AIx@75bpm decreased in young adults (‐6 ± 3 vs. ‐13 ± 3%, P<0.001), whereas no change was observed in older adults (26 ± 3 vs. 25 ± 3%, P=0.39). Our data suggest that reductions in aortic systolic blood pressure and wave reflection during lower body negative pressure are attenuated in older compared to young adults. Funded by NIH HL‐105467

Aging is associated with increased peripheral chemoreceptor activity, reduced nitric oxide (NO) bioavailability, and attenuation of cardiovagal baroreflex sensitivity (BRS), collectively increasing the risk of cardiovascular disease. Evidence suggests that NO may attenuate peripheral chemoreflex sensitivity and increase BRS. Exogenous inorganic nitrate ([Formula: see text]) increases NO bioavailability via the [Formula: see text]-[Formula: see text]-NO pathway. Our hypothesis was that inorganic [Formula: see text] supplementation would attenuate peripheral chemoreflex sensitivity and enhance spontaneous cardiovagal BRS in older adults. We used a randomized, placebo-controlled crossover design in which 13 older (67 ± 3 yr old) adults ingested beetroot powder containing (BRA) or devoid of (BRP) [Formula: see text] and [Formula: see text] daily over 4 wk. Spontaneous cardiovagal BRS was assessed over 15 min of rest and was quantified using the sequence method. Chemoreflex sensitivity was assessed via ~5 min of hypoxia (10% fraction of inspired O2) and reported as the slope of the relationship between O2 saturation (%[Formula: see text]) and minute ventilation (in l/min) or heart rate (in beats/min). Ventilatory responsiveness to hypoxia was reduced after BRA (from −0.14 ± 0.04 to −0.05 ± 0.02 l·min−1·%[Formula: see text]−1, P = 0.01) versus BRP (from −0.10 ± 0.05 to −0.11 ± 0.05 l·min−1·%[Formula: see text]−1, P = 0.80), with no differences in heart rate responsiveness (BRA: from −0.47 ± 0.06 to −0.33 ± 0.04 beats·min−1·%[Formula: see text]−1, BRP: from −0.48 ± 0.07 to −0.42 ± 0.06 beats·min−1·%[Formula: see text]−1) between conditions (interaction effect, P = 0.41). Spontaneous cardiovagal BRS was unchanged after BRA and BRP (interaction effects, P = 0.69, 0.94, and 0.39 for all, up, and down sequences, respectively), despite a reduction in resting systolic and mean arterial blood pressure in the experimental (BRA) group ( P < 0.01 for both). These findings illustrate that inorganic [Formula: see text] supplementation attenuates peripheral chemoreflex sensitivity without concomitant change in spontaneous cardiovagal BRS in older adults. NEW & NOTEWORTHY Exogenous inorganic nitrate supplementation attenuates ventilatory, but not heart rate, responsiveness to abbreviated hypoxic exposure in older adults. Additionally, inorganic nitrate reduces systolic and mean arterial blood pressure without affecting spontaneous cardiovagal baroreflex sensitivity. These findings suggest that inorganic nitrate may attenuate sympathetically oriented pathologies associated with aging.