Effects of acute dietary nitrate supplementation on aortic blood pressure and aortic augmentation index in young and older adults

Purpose: Aging is associated with elevated blood pressure (peripheral and aortic; BP) and aortic augmentation index (AIx) which may contribute to aortic BR. Although inorganic nitrate consumption reduces peripheral BP in both young and older adults, the effects of nitrate consumption on aortic BP and wave reflection in young and older adults is unknown. Therefore, we sought to characterize the effects of nitrate consumption on aortic BP and AIx in young and older adults. Methods: Noninvasive aortic pressure waveforms were synthesized from high-fidelity radial pressure waveforms via applanation tonometry before and following (60, 90, 120, 150, and 180 min) consumption of a nitrate-rich beetroot juice in 26 healthy adults (young: 25 +/- 4 years, n = 14; older: 64 +/- 5 years, n = 12). Aortic BP and indices of aortic wave reflection (AIx and Alx normalized for heart rate; AIx@75bpm) were calculated from the generated aortic pressure waveform. Results: Nitrate consumption increased plasma nitrite in both groups 60-180 min following beetroot consumption (P < 0.001). Nitrate consumption reduced peripheral and aortic BP in both young and older adults (P < 0.05), with the change being similar between age groups. Conversely, indices of aortic wave reflection were reduced only in young adults following nitrate consumption (range of change from baseline over time: AIx@75bpm, -4.3 to -8.8%, P < 0.05), whereas aortic AIx remained unchanged in the older adults. Conclusions: Taken together, our results suggest that acute dietary nitrate supplementation reduces peripheral and aortic BP similarly in young and older adults despite differential effects on aortic AIx between age groups. (C) 2016 Elsevier Inc. All rights reserved.