Document Detail


Peripheral chemoreflex regulation of sympathetic vasomotor tone in apnea divers.
MedLine Citation:
PMID:  19820987     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVES: Involuntary apnea episodes in obstructive sleep apnea patients result in selective potentiation of peripheral chemoreceptor regulation of sympathetic vasomotor tone. Breath-hold diving is associated with repeated "voluntary" apnea episodes and massive arterial oxygen desaturation, which could also perturb chemoreflex function. METHODS: We measured ventilation, heart rate, blood pressure, cardiac stroke volume, and muscle sympathetic nerve activity (MSNA) during isocapnic hypoxia in 11 breath-hold divers and eleven matched control subjects. The study was carried out at least 1 month after intense apnea training. RESULTS: Baseline MSNA frequency was 30 +/- 4 bursts/min in control subjects and 31 +/- 7 bursts/min in divers (ns). During hypoxia MSNA frequency and total activity increased similarly in both groups (30 and 66% in controls and 27 and 60% in divers, respectively). MSNA remained increased after termination of hypoxia and approached baseline measurements after 20 min. Hypoxia-induced stimulation of minute ventilation was similar in both groups, although in divers it was maintained by higher tidal volumes and lower breathing frequency compared with control subjects. In both groups, hypoxia-induced tachycardia drove an increase in cardiac output whereas total peripheral resistance decreased. Blood pressure remained unchanged. INTERPRETATION: We conclude that after the end of intensive training/competition periods, apnea divers show normal peripheral chemoreflex regulation of ventilation and sympathetic vasomotor tone. Although voluntary apnea may not lead to sustained changes in sympathetic nervous system regulation, we cannot exclude the possibility that repeated sympathetic activation elicited by voluntary apnea imposes a burden on the cardiovascular system.
Authors:
Toni Breskovic; Zoran Valic; Axel Lipp; Karsten Heusser; Vladimir Ivancev; Jens Tank; Gordan Dzamonja; Jens Jordan; J Kevin Shoemaker; Davor Eterovic; Zeljko Dujic
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-10-10
Journal Detail:
Title:  Clinical autonomic research : official journal of the Clinical Autonomic Research Society     Volume:  20     ISSN:  1619-1560     ISO Abbreviation:  Clin. Auton. Res.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-04-23     Completed Date:  2010-07-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9106549     Medline TA:  Clin Auton Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  57-63     Citation Subset:  IM    
Affiliation:
Department of Physiology, University of Split School of Medicine, Soltanska 2, 21000, Split, Croatia.
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MeSH Terms
Descriptor/Qualifier:
Adult
Apnea / physiopathology*
Blood Pressure / physiology
Case-Control Studies
Chemoreceptor Cells / physiology*
Diving / physiology*
Female
Heart Rate / physiology
Humans
Male
Pulmonary Ventilation / physiology
Stroke Volume / physiology
Sympathetic Nervous System / physiology*
Vasomotor System / physiology*
Comments/Corrections
Comment In:
Clin Auton Res. 2010 Apr;20(2):53-5   [PMID:  20405161 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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