Influence of dietary nitrate supplementation on lung function and exercise gas exchange in COPD patients

Mehrdad Behnia, Courtney M. Wheatley, Alberto Avolio, Bruce D. Johnson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Background: During exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. Purpose: To determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. Methods: Subjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. Results: Exhaled nitric oxide levels rose >200% in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). Conclusion: Despite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.

Original languageEnglish (US)
Pages (from-to)53-61
Number of pages9
JournalNitric Oxide - Biology and Chemistry
Volume76
DOIs
StatePublished - Jun 1 2018
Externally publishedYes

Fingerprint

Dietary Supplements
Nitrates
Chronic Obstructive Pulmonary Disease
Gases
Exercise
Lung
Nitric Oxide
Blood
Placebos
Ribes
Pulmonary Gas Exchange
Lung Volume Measurements
Ergometry
Exercise Tolerance
Spirometry
Blood pressure
Carbon Monoxide
Blood Volume
Workload
Informed Consent

Keywords

  • Endothelial function
  • Lung diffusion
  • Nitric oxide
  • Pulmonary circulation

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Clinical Biochemistry
  • Cancer Research

Cite this

Influence of dietary nitrate supplementation on lung function and exercise gas exchange in COPD patients. / Behnia, Mehrdad; Wheatley, Courtney M.; Avolio, Alberto; Johnson, Bruce D.

In: Nitric Oxide - Biology and Chemistry, Vol. 76, 01.06.2018, p. 53-61.

Research output: Contribution to journalArticle

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abstract = "Background: During exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. Purpose: To determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. Methods: Subjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. Results: Exhaled nitric oxide levels rose >200{\%} in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). Conclusion: Despite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.",
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AU - Behnia, Mehrdad

AU - Wheatley, Courtney M.

AU - Avolio, Alberto

AU - Johnson, Bruce D.

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N2 - Background: During exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. Purpose: To determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. Methods: Subjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. Results: Exhaled nitric oxide levels rose >200% in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). Conclusion: Despite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.

AB - Background: During exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. Purpose: To determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. Methods: Subjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. Results: Exhaled nitric oxide levels rose >200% in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). Conclusion: Despite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.

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KW - Lung diffusion

KW - Nitric oxide

KW - Pulmonary circulation

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