Document Detail

Ventilatory restraint of sympathetic activity during chemoreflex stress.
MedLine Citation:
PMID:  20826706     Owner:  NLM     Status:  MEDLINE    
The within-breath modulation of muscle sympathetic nerve activity (MSNA) is well established, with greater activity occurring during expiration and less during inspiration. Whether ventilation per se affects the longer-term (i.e., minute-to-minute) regulation of MSNA has not been determined. We sought to define the specific role of ventilation in regulating sympathetic activation during chemoreflex activation, where both ventilation and MSNA are increased. Ten young healthy subjects performed both asphyxic rebreathing and repeated, rebreathing apneas to cause the same magnitude of chemoreflex stress in the presence or absence of ventilation. Both protocols caused increases in sympathetic burst frequency, burst amplitude, and burst incidence. However, burst frequency was increased more during repeated apneas (12 ± 6 to 25 ± 7 bursts/min) compared with rebreathing (12 ± 5 to 17 ± 7 bursts/min; P < 0.001) due to a greater burst incidence during apneas (36 ± 11 bursts/100 heart beats) vs. rebreathing (26 ± 8 bursts/100 heart beats, P < 0.001). The sympathetic gain to chemoreflex stress was also larger during repeated apneas (2.29 ± 1.29 au/% desaturation) compared with rebreathing (1.44 ± 0.53 au/% desaturation, P < 0.05). The augmented sympathetic response during apneas was associated with a larger pressor response and total peripheral resistance compared with rebreathing. These data demonstrate that ventilation per se restrains sympathetic activation during chemoreflex activation. Further, the augmented sympathetic response during apneas was associated with greater cardiovascular stress and may be relevant to the cardiovascular pathology associated with sleep-disordered breathing.
Craig D Steinback; Toni Breskovic; Maria Frances; Zeljko Dujic; J Kevin Shoemaker
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Publication Detail:
Type:  Journal Article; Multicenter Study; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2010-09-08
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  299     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-03     Completed Date:  2010-12-01     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1407-14     Citation Subset:  IM    
Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
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MeSH Terms
Apnea / metabolism,  physiopathology*
Blood Pressure
Chemoreceptor Cells / metabolism*
Heart Rate
Neural Inhibition*
Peroneal Nerve / physiopathology
Pulmonary Ventilation*
Respiratory Mechanics
Stress, Physiological*
Sympathetic Nervous System / physiopathology*
Time Factors
Vascular Resistance
Young Adult

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

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