Document Detail

Influence of preload and afterload on genioglossus muscle length in awake goats.
MedLine Citation:
PMID:  9196109     Owner:  NLM     Status:  MEDLINE    
The genioglossus is an upper airway dilator muscle, the length of which is directly related to patency in the oropharyngeal region. We hypothesized that genioglossal length (Lgg) is dynamically influenced by the afterload exerted by negative upper airway pressure during inspiration and by the intrinsic length-tension characteristics of the muscle (preload). Seven awake goats were chronically instrumented with electrodes for EMGgg and sonomicrometry for Lgg. We examined the Lgg-EMGgg relationship during hypercapnia and inspiratory resistive loading (18 cm H2O/L/s). The goats breathed through the upper airway (TC) or airflow was diverted through a tracheostomy (TO). We found that: (1) passive inspiratory lengthening was observed with negative upper airway pressure (UAP) but not when UAP = 0 (TO breathing), (2) Lgg shortening for a given EMGgg was significantly decreased with negative inspiratory UAP, and (3) phasic Lgg shortening per unit EMGgg was greatest when Lgg was near optimal length (Lo). We conclude that genioglossal length is substantially influenced by afterload exerted by negative UAP and that genioglossal active shortening may be limited if the muscle operates at a length significantly greater or less than the optimal length.
M J Brennick; R A Parisi; S J England
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  155     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1997 Jun 
Date Detail:
Created Date:  1997-07-17     Completed Date:  1997-07-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2010-7     Citation Subset:  AIM; IM    
Center for Sleep and Respiratory Neurobiology, University of Pennsylvania Medical Center, Philadelphia, USA.
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MeSH Terms
Goats / physiology*
Muscle Contraction*
Muscles / physiology*
Respiration / physiology
Respiratory Physiological Phenomena
Grant Support

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

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