Document Detail

Slow to fast shift in inspiratory muscle fibers during heat tachypnea.
MedLine Citation:
PMID:  6844759     Owner:  NLM     Status:  MEDLINE    
The firing patterns of single diaphragm fibers and electromyographic moving average (M.A.) of diaphragm and parasternal intercostal muscles (P.I.) were studied in rabbits during control and heat tachypnea at nearly constant tidal volume (VT). During tachypnea the percentage of single diaphragm fibers with relatively high values of peak firing rate (fp) increased. Conversely, fibers with relatively low values of fp at control (likely slow) showed little or no increase of this parameter during tachypnea. These findings, similar to those previously found in P.I., suggest a slow to fast shift in diaphragm fibers during tachypnea. Inspiratory flow at half VT control increased significantly during tachypnea, while the corresponding M.A. of diaphragm did not change. Moreover, during tachypnea mean inspiratory flow increased significantly, while the mean M.A. over inspiratory time did not change either in diaphragm or in P.I. Since during tachypnea the firing rate of most fibers is greater than at control, a lack of increase of M.A. in spite of an increased mechanical power confirms a shift from slow to fast inspiratory muscle fibers under this condition.
G Citterio; S Sironi; S Piccoli; E Agostoni
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiration physiology     Volume:  51     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1983 Feb 
Date Detail:
Created Date:  1983-06-23     Completed Date:  1983-06-23     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  259-74     Citation Subset:  IM    
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MeSH Terms
Diaphragm / physiopathology*
Hot Temperature / adverse effects*
Intercostal Muscles / physiopathology*
Respiration Disorders / etiology,  physiopathology*

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

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