Document Detail


In vivo contractile properties of fatigued diaphragm.
MedLine Citation:
PMID:  3654406     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of fatigue on diaphragmatic contractility in vivo are unknown. In this study we used sonomicrometry to examine the velocity of shortening and lengthening and the amount of shortening in the fresh and fatigued canine hemidiaphragm (8 dogs) including the force generated. Fatigue was produced by epiphrenic stimulation of the left phrenic nerve; the right hemidiaphragm acted as the control. We found that 1) hemidiaphragmatic fatigue caused an increase in frequency with reduced tidal volume; 2) fatigue resulted in a near complete cessation of tidal shortening during spontaneous breathing; 3) there was an initial decrease in central activation (electromyogram) to the fatigued hemidiaphragm, an indication of central fatigue; 4) force-frequency curves showed a considerable and prolonged loss of the amount of shortening, velocity, and force generated by the fatigued hemidiaphragm during supramaximal stimulation, an indication of peripheral fatigue; and 5) during spontaneous breathing in the fatigued hemidiaphragm, tidal shortening remained reduced for up to 3 h, whereas in the right right hemidiaphragm tidal shortening and electromyographic activity did not change. We conclude that fatigue of a hemidiaphragm alters the spontaneous breathing pattern and produces profound modifications in its contractile properties without altering contralateral hemidiaphragmatic performance.
Authors:
J Road; R Vahi; P del Rio; A Grassino
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  63     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1987 Aug 
Date Detail:
Created Date:  1987-11-09     Completed Date:  1987-11-09     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  471-8     Citation Subset:  IM    
Affiliation:
Meakins-Christie Laboratories, McGill University, Quebec, Canada.
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MeSH Terms
Descriptor/Qualifier:
Animals
Diaphragm / physiology*
Dogs
Electric Stimulation
Electromyography
Muscle Contraction*
Phrenic Nerve / physiology
Respiration

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


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