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Ventilation, Oxidative Stress and Nitric Oxide in Hypobaric vs. Normobaric Hypoxia.
MedLine Citation:
PMID:  22895381     Owner:  NLM     Status:  Publisher    
PURPOSE: Slight differences in physiological responses and nitric oxide (NO) have been reported at rest between hypobaric hypoxia (HH) and normobaric hypoxia (NH) during short exposureOur study reports nitric oxide and oxidative stress at rest and physiological responses during moderate exercise in hypobaric hypoxia (HH) vs. normobaric hypoxia (NH). METHODS: Ten subjects were randomly exposed for 24 h to HH (3000 m, FIO2 20.9 %, BP 530 ± 6 mmHg) or to NH (FIO2 14.7 %, BP 720 ±1 mmHg). PRE- and every 8 h during the hypoxic exposures, pulse oxygen saturation (SpO2), heart rate (HR) and gas exchanges were measured during a 6-min submaximal cycling exercise. At rest, partial pressure of exhaled NO [exNO], blood nitrate and nitrite [NOx], plasma levels of oxidative stress and pH were additionally measured. RESULTS: During exercise, minute ventilation was lower in HH compared to NH (-13% after 8 h, p<0.05). End-tidal CO2 pressure was lower (p<0.01) than PRE both in HH and NH but decreased less in HH than in NH (-25% vs. -37%, p<0.05).At rest, exNO and NOx decreased in HH (-46% and -36% after 24 h respectively, p<0.05) whilst stable in NH. By contrast, oxidative stress was higher in HH than in NH after 24 h (p<0.05). Plasma pH was stable in HH but increased in NH (p<0.01). When compared to PRE- normoxic values, SpO2, HR, oxygen consumption, breathing frequency and end-tidal O2 pressure showed similar changes in HH and NH. CONCLUSIONS: Lower ventilatory responses to a similar hypoxic stimulus during rest and exercise in HH vs. NH were sustained over 24 hours and associated with lower plasma pH, exaggerated oxidative stress and impaired NO bioavailability.
Raphael Faiss; Vincent Pialoux; Claudio Sartori; Camille Faes; Olivier Dériaz; Grégoire P Millet
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-14
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  -     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland 2IRR, SuvaCare Rehabilitation Clinic, 1950 Sion, Switzerland 3CRIS EA647, Campus la Doua, University of Lyon 1, 69622 Villeurbanne, France 4Department of Internal Medicine, University Hospital, 1015 Lausanne, Switzerland.
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