Acute dietary nitrate supplementation enhances compensatory vasodilation during hypoxic exercise in older adults

Casey, Darren P.; Treichler, David P.; Ganger, Charles T.; Schneider, Aaron C.; Ueda, Kenichi

doi:10.1152/japplphysiol.00662.2014

Cited by 60 publications

(77 citation statements)

References 67 publications

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“…Consistent with this, other approaches to potentiate the NO pathway (e.g. dietary nitrate) have been effective at improving exercise hyperemia in such populations (Casey et al 2015; Ferguson et al 2013). In addition, sildenafil citrate has been shown previously to increase resting forearm blood flow in conditions with impaired endothelial function such as smoking (Kimura et al 2003; Vlachopoulos et al 2004) and cardiovascular disease (Halcox et al 2002; Hryniewicz et al 2005; Schofield et al 2003).…”

Section: Discussionmentioning

confidence: 56%

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Limberg

Malterer

Kellawan³

et al. 2016

Eur J Appl Physiol

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Purpose Previous work has shown nitric oxide (NO) contributes to ~15% of the hyperemic response to dynamic exercise in healthy humans. This NO-mediated vasodilation occurs, in part, via increases in intracellular cyclic guanosine monophosphate (cGMP), which is catabolized by phosphodiesterase. We sought to examine the effect of phosphodiesterase-5 (PDE-5) inhibition on forearm blood flow (FBF responses to dynamic handgrip exercise in healthy humans and the role of NO. We hypothesized exercise hyperemia would be augmented by sildenafil citrate (SDF, PDE-5 inhibitor). We further hypothesized any effect of SDF on exercise hyperemia would be abolished with intra-arterial infusion of the NO synthase (NOS) inhibitor L-NG-monomethyl arginine (L-NMMA). Methods FBF (Doppler ultrasound) was assessed at rest and during 5 minutes of dynamic forearm handgrip exercise at 15% of maximal voluntary contraction under control (saline) conditions and during 3 experimental protocols: 1) oral SDF (n=10), 2) intra-arterial L-NMMA (n=20), 3) SDF and L-NMMA (n=10). FBF responses to intra-arterial sodium nitroprusside (NTP, NO donor) were also assessed. Results FBF increased with exercise (p<0.01). Intra-arterial infusion of L-NMMA resulted in a reduction in exercise hyperemia (17±1 to 15±1 mL/dL/min, p<0.01). Although the hyperemic response to NTP was augmented by SDF (Area under the curve: 41±7 vs 61±11 AU, p<0.01), there was no effect of SDF on exercise hyperemia (p=0.33). Conclusions Despite improving NTP-mediated vasodilation, oral SDF failed to augment exercise hyperemia in young, healthy adults. These observations reflect a minor contribution of NO and the cGMP pathway during exercise hyperemia in healthy young humans.

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Section: Discussionmentioning

confidence: 56%

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Limberg

Malterer

Kellawan³

et al. 2016

Eur J Appl Physiol

View full text Add to dashboard Cite

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“…An alternative explanation is that dietary nitrate supplementation does not alter any of the specific variables we measured involved with hypoxic acclimatisation; heart rate, blood pressure, SpO 2 , and ventilation rate. This is supported somewhat by Casey et al (23) who found no effect of nitrate supplementation on heart rate, blood pressure, and SPO 2 during very acute (<10 minutes) normobaric hypoxic exposure.…”

Section: Accepted Manuscriptmentioning

confidence: 64%

“…The main differences relate to the participants' age, and the length of hypoxic exposure. Firstly, we studied teenagers as opposed to adults, and the effect of dietary nitrate supplementation has been shown to improve skeletal muscle blood flow and vasodilation during hypoxic exercise in older individuals but not in younger people (23) . This suggests that the effect of nitrate supplementation on hypoxic adaptation may be age-dependent.…”

Section: Main Findingsmentioning

confidence: 99%

Effects of dietary nitrate supplementation on symptoms of acute mountain sickness and basic physiological responses in a group of male adolescents during ascent to Mount Everest Base Camp

et al. 2016

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Effects of dietary nitrate supplementation on symptoms of acute mountain sickness and basic physiological responses in a group of male adolescents during ascent to Mount Everest Base Camp, Nitric Oxide (2016), doi: 10.1016/j.niox.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe purpose of this study was to investigate the effects of dietary nitrate supplementation, in the form of beetroot juice, on acute mountain sickness (AMS) symptoms and physiological responses, in a group of young males trekking to Mount Everest Base Camp (EBC). Forty healthy male students (mean age (SD): 16 (1) yrs) trekked to EBC over 11 days. Following an overnight fast, each morning participants completed the Lake Louise AMS questionnaire and underwent a series of physiological tests: resting blood pressure as well as resting and exercising heart rate, respiratory rate, and peripheral oxygen saturation. The exercise test consisted of a standardised 2-minute stepping protocol and measurements were taken in the last 10 seconds. Participants in the intervention arm of the study consumed 140 ml of concentrated beetroot juice daily, containing approximately 10 mmoles of nitrate, while those in the control arm consumed 140 ml of concentrated blackcurrant cordial with negligible nitrate content. Drinks were taken for the first seven days at high altitude (days 2 to 8), in two equal doses; one with breakfast, and one with the evening meal. Mixed modelling revealed no significant between-groups difference in the incidence of AMS (Odds Rationitrate vs. control: 1.16 (95% CI: 0.59; 2.29)). Physiological changes occurring during ascent to high altitude generally were not significantly different between the two groups (Model Coef (95% CI) -average difference nitrate vs. control: systolic blood pressure, 0.16 (-4.47; 4.79); peripheral oxygen saturation, 0.28 (-0.85; 1.41); heart rate, -0.48 (-8.47; 7.50) (Model Coef (95% CI) -relative difference nitrate vs. control: ventilatory rate, 0.95 (0.82; 1.08)). Modelling revealed that diastolic blood pressure was 3.37 mmHg (0.24; 6.49) higher for participants in the beetroot juice, however this difference was no larger than that found at baseline and no interaction effect was observed.Supplementation with dietary nitrate did not significantly change symptoms of AMS or alter key physiological variables, in a group of adolescent males during a high altitude trekking expedition.There was no evidence of harm from dietary nitrate supplementation in this context. Given the wide confidence intervals in all models, a larger sample size would be required to exclude a false negative M A N U S ...

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“…Interestingly, despite similar increases in plasma [NO 2 − ], NO 3 − supplementation significantly increased the vasodilation and blood flow response to hypoxic exercise in older participants (mean ± SD age 64 ± 2 years). The magnitude of the effect was such that age-related differences in compensatory vasodilation were abolished with NO 3 − supplementation, suggesting therapeutic utility of NO 3 − in older populations exercising in hypoxia [105] or potentially those afflicted with clinical conditions involving tissue hypoxia [106]. …”

Section: Physiological Effects Of Nitrate (No3−) Supplementation In Hmentioning

confidence: 99%

“Beet-ing” the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude

et al. 2017

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Exposure to altitude results in multiple physiological consequences. These include, but are not limited to, a reduced maximal oxygen consumption, drop in arterial oxygen saturation, and increase in muscle metabolic perturbations at a fixed sub-maximal work rate. Exercise capacity during fixed work rate or incremental exercise and time-trial performance are also impaired at altitude relative to sea level. Recently, dietary nitrate (NO3 −) supplementation has attracted considerable interest as a nutritional aid during altitude exposure. In this review, we summarise and critically evaluate the physiological and performance effects of dietary NO3 − supplementation during exposure to simulated and terrestrial altitude. Previous investigations at simulated altitude indicate that NO3 − supplementation may reduce the oxygen cost of exercise, elevate arterial and tissue oxygen saturation, improve muscle metabolic function, and enhance exercise capacity/performance. Conversely, current evidence suggests that NO3 − supplementation does not augment the training response at simulated altitude. Few studies have evaluated the effects of NO3 − at terrestrial altitude. Current evidence indicates potential improvements in endothelial function at terrestrial altitude following NO3 − supplementation. No effects of NO3 − supplementation have been observed on oxygen consumption or arterial oxygen saturation at terrestrial altitude, although further research is warranted. Limitations of the present body of literature are discussed, and directions for future research are provided.

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Acute dietary nitrate supplementation enhances compensatory vasodilation during hypoxic exercise in older adults

Cited by 60 publications

References 67 publications

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Effects of dietary nitrate supplementation on symptoms of acute mountain sickness and basic physiological responses in a group of male adolescents during ascent to Mount Everest Base Camp

“Beet-ing” the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude

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