Document Detail


Hyperbaric hyperoxia reduces exercising forearm blood flow in humans.
MedLine Citation:
PMID:  21421819     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hypoxia during exercise augments blood flow in active muscles to maintain the delivery of O(2) at normoxic levels. However, the impact of hyperoxia on skeletal muscle blood flow during exercise is not completely understood. Therefore, we tested the hypothesis that the hyperemic response to forearm exercise during hyperbaric hyperoxia would be blunted compared with exercise during normoxia. Seven subjects (6 men/1 woman; 25 ± 1 yr) performed forearm exercise (20% of maximum) under normoxic and hyperoxic conditions. Forearm blood flow (FBF; in ml/min) was measured using Doppler ultrasound. Forearm vascular conductance (FVC; in ml·min(-1)·100 mmHg(-1)) was calculated from FBF and blood pressure (in mmHg; brachial arterial catheter). Studies were performed in a hyperbaric chamber with the subjects supine at 1 atmospheres absolute (ATA) (sea level) while breathing normoxic gas [21% O(2), 1 ATA; inspired Po(2) (Pi(O(2))) ≈ 150 mmHg] and at 2.82 ATA while breathing hyperbaric normoxic (7.4% O(2), 2.82 ATA, Pi(O(2)) ≈ 150 mmHg) and hyperoxic (100% O(2), 2.82 ATA, Pi(O(2)) ≈ 2,100 mmHg) gas. Resting FBF and FVC were less during hyperbaric hyperoxia compared with hyperbaric normoxia (P < 0.05). The change in FBF and FVC (Δ from rest) during exercise under normoxia (204 ± 29 ml/min and 229 ± 37 ml·min(-1)·100 mmHg(-1), respectively) and hyperbaric normoxia (203 ± 28 ml/min and 217 ± 35 ml·min(-1)·100 mmHg(-1), respectively) did not differ (P = 0.66-0.99). However, the ΔFBF (166 ± 21 ml/min) and ΔFVC (163 ± 23 ml·min(-1)·100 mmHg(-1)) during hyperbaric hyperoxia were substantially attenuated compared with other conditions (P < 0.01). Our data suggest that exercise hyperemia in skeletal muscle is highly dependent on oxygen availability during hyperoxia.
Authors:
Darren P Casey; Michael J Joyner; Paul L Claus; Timothy B Curry
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2011-03-18
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  300     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-05-02     Completed Date:  2011-07-07     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H1892-7     Citation Subset:  IM    
Affiliation:
Dept. of Anesthesiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. casey.darren@mayo.edu.
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Pressure / physiology
Exercise / physiology*
Female
Forearm / blood supply*,  ultrasonography
Humans
Hyperbaric Oxygenation*
Hyperoxia / physiopathology*
Male
Muscle, Skeletal / blood supply,  physiopathology
Oxygen / blood
Regional Blood Flow / physiology*
Ultrasonography, Doppler
Chemical
Reg. No./Substance:
7782-44-7/Oxygen
Comments/Corrections

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