Acute dietary nitrate supplementation does not attenuate oxidative stress or the hemodynamic response during submaximal exercise in hypobaric hypoxia

2018 ◽  
Vol 43 (12) ◽  
pp. 1268-1274 ◽  
Author(s):  
Colin R. Carriker ◽  
Paige Rombach ◽  
Brooke M. Stevens ◽  
Roger A. Vaughan ◽  
Ann L. Gibson
Keyword(s):  
Oxidative Stress ◽  
Oxygen Consumption ◽  
Hypobaric Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Arterial Oxygen ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Plasma Nitrite

The purpose of this study was to investigate changes in oxidative stress, arterial oxygen saturation (SaO2), blood pressure (BP), and heart rate (HR) during exercise in hypobaric hypoxia following acute dietary nitrate supplementation. Nine well-trained (maximal oxygen consumption, 60.8 ± 7.8 mL·kg−1·min−1) males (age, 29 ± 7 years) visited the laboratory on 3 occasions, each separated by 1 week. Visit 1 included a maximal aerobic cycling test and five 5-min increasing-intensity exercise bouts in a normobaric environment (1600 m). A single dose of either a nitrate-depleted placebo (PL) or a nitrate-rich beverage (NR; 12.8 mmol nitrate) was consumed 2.5 h prior to exercise during visits 2 and 3 (3500 m) in a double-blind, placebo-controlled, crossover study consisting of a 5-min cycling warm-up and 4 bouts, each 5 min in duration, separated by 4-min periods of passive rest. Exercise wattages were determined during visit 1 and corresponded to 25%, 40%, 50%, 60%, and 70% of normobaric maximal oxygen consumption. Catalase and 8-isoprostane were measured before and after exercise (immediately before and 1 h postexercise, respectively). NR increased plasma nitrite (1.53 ± 0.83 μmol·L−1) compared with PL (0.88 ± 0.56 μmol·L−1) (p < 0.05). In both conditions, postexercise (3500 m) 8-isoprostane (PL, 23.49 ± 3.38 to 60.90 ± 14.95 pg·mL−1; NR, 23.23 ± 4.12 to 52.11 ± 19.76 pg·mL−1) and catalase (PL, 63.89 ± 25.69 to 128.15 ± 41.80 mmol·min−1·mL−1; NR, 78.89 ± 30.95 to 109.96 ± 35.05 mmol·min−1·mL−1) were elevated compared with baseline resting values (p < 0.05). However, both 8-isoprostane and catalase were similar in the 2 groups (PL and NR) (p = 0.217 and p = 0.080, respectively). We concluded that an acute, pre-exercise dose of dietary nitrate yielded no beneficial changes in oxidative stress, SaO2, BP, or HR in healthy, aerobically fit men exercising at 3500 m.

Low chemoresponsiveness and inadequate hyperventilation contribute to exercise-induced hypoxemia

1995 ◽  
Vol 79 (2) ◽  
pp. 575-580 ◽  
Author(s):  
C. A. Harms ◽  
J. M. Stager
Keyword(s):  
Oxygen Consumption ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Co2 Production ◽  
Arterial Oxygen ◽  
Ventilatory Parameters ◽  
Exercise Induced ◽  
End Tidal

Is inadequate hyperventilation a cause of the exercise-induced hypoxemia observed in some athletes during intense exercise? If so, is this related to low chemoresponsiveness? To test the hypothesis that exercise-induced hypoxemia, inadequate hyperventilation, and chemoresponsiveness are related, 36 nonsmoking healthy men were divided into hypoxemic (Hyp; n = 13) or normoxemic (Nor; n = 15) groups based on arterial oxygen saturation (SaO2; Hyp < or = 90%, Nor > 92%) observed during maximum O2 uptake (VO2max). Men with intermediate SaO2 values (n = 8) were only included in correlation analysis. Ventilatory parameters were collected at rest, during a treadmill maximal oxygen consumption (VO2max) test, and during a 5-min run at 90% VO2max. Chemoresponsiveness at rest was assessed via hypoxic ventilatory response (HVR) and hypercapnic ventilatory response (HCVR). VO2max was not significantly different between Nor and Hyp. SaO2 was 93.8 +/- 0.9% (Nor) and 87.7 +/- 2.0% (Hyp) at VO2max. End-tidal PO2 and the ratio of minute ventilation to oxygen consumption (VE/VO2) were lower while PETCO2 was higher for Hyp (P < or = 0.01). End-tidal PO2, end-tidal PCO2, and VE/VO2 correlated (P < or = 0.05) to SaO2 (r = 0.84, r = -0.70, r = 0.72, respectively), suggesting that differences in oxygenation were due to differences in ventilation. HVR and HCVR were significantly lower for Hyp. HVR was related to VE/VO2 (r = 0.43), and HCVR was related to the ratio of VE to CO2 production at VO2max (r = 0.61)

Effects of altering O2 delivery on VO2 of isolated, working muscle

1976 ◽  
Vol 230 (2) ◽  
pp. 327-334 ◽  
Author(s):  
DH Horstman ◽  
M Gleser ◽  
J Delehunt
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Muscle Blood Flow ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Hemoglobin Concentration ◽  
Arterial Oxygen ◽  
Vo2 Max ◽  
Before And After ◽  
O2 Delivery

Maximal oxygen consumption (VO2 max) and muscle blood flow (Q max) were measured in an isolated gracilis muscle preparation before and after alteration in perfusion pressure (BP), arterial oxygen saturation (SaO2), and hemoglobin concentration (Hb). Q varied directly with BP and inversely with Hb (viscosity) but was unaffected by changes in arterial SaO2. VO2 max varied directly with oxygen delivery under all conditions. These results indicate that VO2 max is normally limited by oxygen delivery rather than any intrinsic limiting of oxygen consumption of the muscle.

scholarly journals No Effect of Beetroot Juice Supplementation on 100-m and 200-m Swimming Performance in Moderately Trained Swimmers

2019 ◽  
Vol 14 (6) ◽  
pp. 706-710 ◽  
Author(s):  
Ozcan Esen ◽  
Ceri Nicholas ◽  
Mike Morris ◽  
Stephen J. Bailey
Keyword(s):  
Blood Pressure ◽  
Swimming Performance ◽  
Time Trial ◽  
Upper Body ◽  
Beetroot Juice ◽  
Nitrite Concentration ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Plasma Nitrite

Purpose: Dietary nitrate supplementation has been reported to improve performance in kayaking and rowing exercise, which mandate significant recruitment of the upper-body musculature. Because the effect of dietary nitrate supplementation on swimming performance is unclear, the purpose of this study was to assess the effect of dietary nitrate supplementation on 100-m and 200-m swimming freestyle time-trial (TT) performance. Methods: In a double-blind, randomized crossover design, 10 moderately trained swimmers underwent 2 separate 3-d supplementation periods, with a daily dose of either 140 mL nitrate-rich (∼800 mg/d nitrate) or nitrate-depleted (PLA) beetroot juice (BRJ). After blood sampling on day 3, the swimmers performed both 200-m and 100-m freestyle swimming TTs, with 30 min recovery between trials. Results: Plasma nitrite concentration was greater after BRJ relative to PLA consumption (432 [203] nmol/L, 111 [56] nmol/L, respectively, P = .001). Systolic blood pressure was lowered after BRJ compared with PLA supplementation (114 [10], 120 [10] mm Hg, respectively P = .001), but time to complete the 200-m (BRJ 152.6 [14.1] s, PLA 152.5 [14.1] s) and 100-m (BRJ 69.5 [7.2] s, PLA 69.4 [7.4] s) freestyle swimming TTs was not different between BRJ and PLA (P > .05). Conclusions: Although 3 d of BRJ supplementation increased plasma nitrite concentration and lowered blood pressure, it did not improve 100-m and 200-m swimming TT performance. These results do not support an ergogenic effect of nitrate supplementation in moderately trained swimmers, at least for 100-m and 200-m freestyle swimming performance.

Abstract P242: Dietary Nitrate Does not Reduce Resting Metabolic Rate or Oxidative Stress in Healthy Males

Circulation ◽  
2018 ◽  
Vol 137 (suppl_1) ◽  
Author(s):  
Haley M Fair ◽  
Caleb D Harrison ◽  
Evan J Bockover ◽  
Brycen J Ratcliffe ◽  
Sierra Crowe ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Dietary Nitrate ◽  
Young Males ◽  
Nitrate Supplementation ◽  
No Bioavailability ◽  
Plasma Nitrite ◽  
Healthy Males

Introduction: Nitric oxide (NO) is a vasodilator that increases blood flow by promoting relaxation of endothelium. Dietary nitrate supplementation increases plasma nitrite, a marker of overall NO bioavailability. Previously, acute dietary nitrate supplementation has been shown to reduce oxygen consumption and improve tolerance during submaximal exercise in healthy populations. Less is known about the effect of dietary nitrate on oxygen consumption at rest. Hypothesis: We hypothesized that dietary nitrate supplementation would reduce resting metabolic rate (RMR) and oxidative stress (8-isoprostane) at rest, via enhanced NO bioavailability via the oxygen independent Nitrate-Nitrite-Nitric Oxide pathway in healthy, young males. Methods: In a randomized, double-blind, cross-over study, ten healthy, young males (21 ± 2 years) visited the laboratory on 5 separate occasions. Participants completed informed consent paperwork and underwent protocol familiarization during visit 1. Prior to visits 2 and 4, participants fasted for 12 hours and adhered to an NIH-approved low-nitrate diet for 48 hours. During visits 2 and 4, an initial blood draw was performed to analyze baseline plasma nitrite and 8-isoprostane. Participants then completed a 30-minute resting metabolic rate (RMR) test. Two hours prior to visits 3 and 5, participants consumed either a placebo or dietary nitrate supplement (negligible and 6.2 mmol nitrate, respectively). During visits 3 and 5, participants also had blood drawn for analysis of the previously stated measurements, and completed an RMR test. Visits 2 and 3 were on consecutive days, followed by a week-long washout period between visit 3 and visit 4, while visit 4 and 5 also occurred on consecutive days. Results: Plasma nitrite significantly increased following dietary nitrate consumption compared to baseline values (27.56 ± 7.58 and 1.25 ± 1.51 arbitrary units, respectively). No difference was present between nitrate and baseline measurements for 8-isoprostane (155.75 ± 57.01 and 198.42 ± 66.44 pg/mL, respectively; p=0.55) and RMR (2086.60 ± 202.23 and 2050.00 ± 209.23 kcal/day, respectively; p=0.13). Conclusion: Dietary nitrate supplementation increases plasma nitrite, but does not change resting metabolic rate following an acute dose of dietary nitrate in healthy males. Individuals consuming dietary nitrate as an ergogenic aid during exercise may not, however, experience similar changes in their resting metabolism. The lack of change in oxidative stress may have been associated with the overall health of the cohort examined. Future research should investigate the clinical implications of dietary nitrate in populations with decreased NO bioavailability and associated endothelial disfunction (and elevated oxidative stress). In such populations, dietary nitrate may provide benefit. However, in a healthy cohort, dietary nitrate exerts minimal effects.

scholarly journals Endogenous Hydrogen Sulfide Is an Important Factor in Maintaining Arterial Oxygen Saturation

2021 ◽  
Vol 12 ◽  
Author(s):  
Yan Huang ◽  
Gang Wang ◽  
Zhan Zhou ◽  
Zhengshan Tang ◽  
Ningning Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lung Injury ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Wall Thickening ◽  
Alveolar Wall ◽  
Leukocyte Infiltration ◽  
Wild Type ◽  
Interstitial Edema ◽  
And Oxidative Stress

The gasotransmitter H2S is involved in various physiological and pathophysiological processes. The aim of this study was to investigate the physiological functions of H2S in the lungs. In the model of mouse with genetic deficiency in a H2S natural synthesis enzyme cystathionine-γ-lyase (CSE), we found that arterial oxygen saturation (SaO2) was decreased compared with wild type mice. Hypoxyprobe test showed that mild hypoxia occurred in the tissues of heart, lungs and kidneys in Cse-/- mice. H2S donor GYY4137 treatment increased SaO2 and ameliorated hypoxia state in cardiac and renal tissues. Further, we revealed that lung blood perfusion and airway responsiveness were not linked to reduced SaO2 level. Lung injury was found in Cse-/- mice as evidenced by alveolar wall thickening, diffuse interstitial edema and leukocyte infiltration in pulmonary tissues. IL-8, IL-1β, and TNF-α levels were markedly increased and oxidative stress levels were also significantly higher with increased levels of the pro-oxidative biomarker, MDA, decreased levels of the anti-oxidative biomarkers, T-AOC and GSH/GSSG, and reduced superoxide dismutase (SOD) activity in lung tissues of Cse-/- mice compared with those of wild type mice. GYY4137 treatment ameliorated lung injury and suppressed inflammatory state and oxidative stress in lung tissues of Cse-/- mice. A decrease in SaO2 was found in normal mice under hypoxia. These mice displayed lung injury as evidenced by alveolar wall thickening, interstitial edema and leukocyte infiltration. Increased levels of inflammatory cytokines and oxidative stress were also found in lung tissues of the mice with hypoxia insult. GYY4137 treatment increased SaO2 and ameliorated lung injury, inflammation and oxidative stress. Our data indicate that endogenous H2S is an important factor in maintaining normal SaO2 by preventing oxidative stress and inflammation in the lungs.

Dietary nitrate supplementation in COPD: An acute, double-blind, randomized, placebo-controlled, crossover trial☆

Nitric Oxide ◽  
2015 ◽  
Vol 44 ◽  
pp. 105-111 ◽  
Author(s):  
Conor P. Kerley ◽  
Kathleen Cahill ◽  
Kenneth Bolger ◽  
Aisling McGowan ◽  
Conor Burke ◽  
...  
Keyword(s):  
Crossover Trial ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Nitrate Supplementation

scholarly journals The Effect of Dietary Nitrate Supplementation on Physiology and Performance in Trained Cyclists

2017 ◽  
Vol 12 (5) ◽  
pp. 684-689 ◽  
Author(s):  
Joseph A. McQuillan ◽  
Deborah K. Dulson ◽  
Paul B. Laursen ◽  
Andrew E. Kilding
Keyword(s):  
Time Trial ◽  
Crossover Design ◽  
Moderate Intensity ◽  
Beetroot Juice ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Performance Time ◽  
Exercise Economy ◽  
Nitrate Supplementation ◽  
And Performance

Purpose:To determine the effect of dietary nitrate (NO3 –) supplementation on physiology and performance in well-trained cyclists after 6–8 d of NO3 – supplementation.Methods:Eight competitive male cyclists (mean ± SD age 26 ± 8 y, body mass 76.7 ± 6.9 kg, VO2peak 63 ± 4 mL · kg–1 · min–1) participated in a double-blind, placebo-controlled, crossover-design study in which participants ingested 70 mL of beetroot juice containing ~4 mmol NO3 – (NIT) or a NO3 –-depleted placebo (PLA), each for 8 d. Replicating pretreatment measures, participants undertook an incremental ramp assessment to determine VO2peak and first (VT1) and second (VT2) ventilatory thresholds on d 6 (NIT6 and PLA6), moderate-intensity cycling economy on d 7 (NIT7 and PLA7), and a 4-km time trial (TT) on d 8 (NIT8 and PLA8).Results:Relative to PLA, 6 d of NIT supplementation produced unclear effects for VO2peak (mean ± 95% confidence limit: 1.8% ± 5.5%) and VT1 (3.7% ± 12.3%) and trivial effects for both VT2 (–1.0% ± 3.0%) and exercise economy on d 7 (–1.0% ± 1.6%). However, effects for TT performance time (–0.7% ± 0.9%) and power (2.4% ± 2.5%) on d 8 were likely beneficial.Conclusions:Despite mostly unclear outcomes for standard physiological determinants of performance, 8 d of NO3 – supplementation resulted in likely beneficial improvements to 4-km TT performance in well-trained male endurance cyclists.

scholarly journals Acute beetroot juice supplementation on sympathetic nerve activity: a randomized, double-blind, placebo-controlled proof-of-concept study

2017 ◽  
Vol 313 (1) ◽  
pp. H59-H65 ◽  
Author(s):  
Karambir Notay ◽  
Anthony V. Incognito ◽  
Philip J. Millar
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Sympathetic Outflow ◽  
Beetroot Juice ◽  
Proof Of Concept ◽  
Burst Frequency ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Central Sympathetic Outflow

Acute dietary nitrate ([Formula: see text]) supplementation reduces resting blood pressure in healthy normotensives. This response has been attributed to increased nitric oxide bioavailability and peripheral vasodilation, although nitric oxide also tonically inhibits central sympathetic outflow. We hypothesized that acute dietary [Formula: see text] supplementation using beetroot (BR) juice would reduce blood pressure and muscle sympathetic nerve activity (MSNA) at rest and during exercise. Fourteen participants (7 men and 7 women, age: 25 ± 10 yr) underwent blood pressure and MSNA measurements before and after (165–180 min) ingestion of 70ml high-[Formula: see text] (~6.4 mmol [Formula: see text]) BR or [Formula: see text]-depleted BR placebo (PL; ~0.0055 mmol [Formula: see text]) in a double-blind, randomized, crossover design. Blood pressure and MSNA were also collected during 2 min of static handgrip (30% maximal voluntary contraction). The changes in resting MSNA burst frequency (−3 ± 5 vs. 3 ± 4 bursts/min, P = 0.001) and burst incidence (−4 ± 7 vs. 4 ± 5 bursts/100 heart beats, P = 0.002) were lower after BR versus PL, whereas systolic blood pressure (−1 ± 5 vs. 2 ± 5 mmHg, P = 0.30) and diastolic blood pressure (4 ± 5 vs. 5 ± 7 mmHg, P = 0.68) as well as spontaneous arterial sympathetic baroreflex sensitivity ( P = 0.95) were not different. During static handgrip, the change in MSNA burst incidence (1 ± 8 vs. 8 ± 9 bursts/100 heart beats, P = 0.04) was lower after BR versus PL, whereas MSNA burst frequency (6 ± 6 vs. 11 ± 10 bursts/min, P = 0.11) as well as systolic blood pressure (11 ± 7 vs. 12 ± 8 mmHg, P = 0.94) and diastolic blood pressure (11 ± 4 vs. 11 ± 4 mmHg, P = 0.60) were not different. Collectively, these data provide proof of principle that acute BR supplementation can decrease central sympathetic outflow at rest and during exercise. Dietary [Formula: see text] supplementation may represent a novel intervention to target exaggerated sympathetic outflow in clinical populations. NEW & NOTEWORTHY The hemodynamic benefits of dietary nitrate supplementation have been attributed to nitric oxide-mediated peripheral vasodilation. Here, we provide proof of concept that acute dietary nitrate supplementation using beetroot juice can decrease muscle sympathetic outflow at rest and during exercise in a normotensive population. These results have applications for targeting central sympathetic overactivation in disease.

scholarly journals Morphine for Postoperative Analgesia. A Comparison of Intramuscular and Subcutaneous Routes of Administration

1996 ◽  
Vol 24 (5) ◽  
pp. 574-578 ◽  
Author(s):  
I. M. Cooper
Keyword(s):  
Postoperative Analgesia ◽  
Intramuscular Injection ◽  
Arterial Oxygen Saturation ◽  
Subcutaneous Administration ◽  
Arterial Oxygen ◽  
Patient Acceptance ◽  
Subcutaneous Route ◽  
Double Blind ◽  
Routes Of Administration ◽  
Pain Scores

Intermittent parenteral bolus doses of morphine are commonly used for postoperative analgesia. Morphine is typically given by intramuscular or intravenous injection but there are theoretical advantages for the subcutaneous route of administration. Fifty-nine patients entered a prospective randomized double-blind cross-over study comparing intermittent intramuscular and subcutaneous morphine boluses. Patients received 0.15 mg/kg of morphine by subcutaneous or intramuscular injection. They were reviewed at the time of injection, after 15 minutes and each hour for four hours. The majority of patients indicated a strong preference for the subcutaneous route. There were no significant differences in pain scores, respiratory rate, arterial oxygen saturation, heart rate, mean arterial pressure, sedation or nausea scores between intramuscular and subcutaneous administration of morphine. Postoperative analgesia by subcutaneous morphine bolus injection is as effective as intramuscular injection with a similar side-effect profile but with greater patient acceptance and less risk.

Sign in / Sign up

Export Citation Format

Share Document