The effect of inhaled nitric oxide on maximal oxygen consumption during exercise in acute hypoxia : a randomized double-blind crossover trial

In moderate hypoxia [partial pressure of inspired oxygen ([Formula: see text]) = 85-111 mmHg], the reduction in maximal oxygen consumption (V̇o2max) has been attributed to arterial desaturation, whereas in severe hypoxia ([Formula: see text] < 85 mmHg), elevated pulmonary artery pressure (PAP) is thought to impair peak cardiac output ([Formula: see text]) and therefore V̇o2max. The purpose of this study was to examine whether reducing PAP with inhaled nitric oxide (iNO, a selective pulmonary vasodilator) would increase V̇o2max in moderate and severe acute hypoxia. Twelve young, healthy participants (mean V̇o2max = 45.3 ± 12.2 mL/kg/min), with normal lung function completed the randomized double-blind crossover study over six sessions. Experimental cardiopulmonary exercise tests (CPET) were completed on separate days with participants under the following conditions: 1) acute moderate hypoxia ([Formula: see text] = 89 mmHg), 2) acute severe hypoxia ([Formula: see text] = 79 mmHg), 3) acute moderate hypoxia with 40 ppm iNO, and 4) acute severe hypoxia with 40 ppm iNO (order randomized). On separate days, rest, and exercise (60 W), echocardiography was conducted to determine right ventricular systolic pressure (RVSP/PAP) under conditions 1-4. Resting RVSP was reduced by 2.5 ± 0.8 mmHg with iNO in moderate hypoxia (P = 0.01) and 1.8 ± 0.2 mmHg in severe hypoxia (P = 0.05); however, iNO had no effect on peak [Formula: see text] or V̇o2max in either hypoxic condition. Despite reducing RVSP with iNO in hypoxia, peak [Formula: see text] and V̇o2max were unaffected, suggesting that iNO may not improve exercise tolerance in healthy participants during hypoxic exercise.NEW & NOTEWORTHY The elevation of pulmonary artery pressure (PAP) with hypoxia may impair peak cardiac output ([Formula: see text]) and therefore V̇o2max. Our novel findings show that despite reducing resting RVSP in acute moderate ([Formula: see text] = 89 mmHg) and severe hypoxia ([Formula: see text] = 79 mmHg) with inspired nitric oxide, peak [Formula: see text], and V̇o2max were unaffected.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:136

Enthalten in:

Journal of applied physiology (Bethesda, Md. : 1985) - 136(2024), 3 vom: 01. März, Seite 514-524

Sprache:

Englisch

Beteiligte Personen:

Rampuri, Zahrah H [VerfasserIn]
Collins, Sophie É [VerfasserIn]
Mickelsen, Benjamin S A [VerfasserIn]
Brotto, Andrew R [VerfasserIn]
Beaudry, Rhys I [VerfasserIn]
van Diepen, Sean [VerfasserIn]
Stickland, Michael K [VerfasserIn]

Links:

Volltext

Themen:

31C4KY9ESH
Exercise
Hypoxia
Inhaled nitric oxide
Journal Article
Nitric Oxide
Pulmonary circulation
Randomized Controlled Trial
Vasodilator Agents

Anmerkungen:

Date Completed 04.03.2024

Date Revised 04.03.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1152/japplphysiol.00767.2022

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM366649914