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Hypoxic effects on sympathetic vasomotor outflow and blood pressure during exercise with inspiratory resistance.
MedLine Citation:
PMID:  23283938     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The purpose of the present study was to clarify the influence of inspiratory resistive breathing during exercise under hypoxic condition on muscle sympathetic nerve activity (MSNA) and blood pressure (BP). Six healthy males completed this study. The subjects performed a submaximal exercise test using a cycle ergometer in a semi-recumbent position under normoxic [inspired oxygen fraction (FIO(2)) = 0.21] and hypoxic (FIO(2) = 0.12-0.13) conditions. The subjects carried out two 10 min exercises at 40% peak oxygen uptake [spontaneous breathing for 5 min and voluntary breathing with inspiratory resistance for 5 min (breathing frequency: 60 breathes/min, inspiratory and expiratory times were set at 0.5 s each)]. MSNA was recorded via microneurography of the right median nerve at the elbow. A progressive increase in MSNA burst frequency (BF) during leg-cycling exercise with inspiratory resistance in normoxia and hypoxia were accompanied by an augmentation of BP. The increased MSNA BF and mean arterial BP (MBP) during exercise with inspiratory resistive breathing in hypoxia (MSNA BF, 55.7±1.4 bursts/min, MBP, 134.3±6.6 mmHg) were higher than those in normoxia (MSNA BF, 39.2±1.8 bursts/min, MBP, 123.6±4.5 mmHg). These results suggest that an enhancement of inspiratory muscle activity under hypoxic condition leads to large increases in muscle sympathetic vasomotor outflow and BP during dynamic leg exercise.
Authors:
Keisho Katayama; Shin Yamashita; Koji Ishida; Erika Iwamoto; Teruhiko Koike; Mitsuru Saito
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-2
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Nagoya University.
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