Document Detail

Phrenic afferents and ventilatory control at increased end-expiratory lung volumes in cats.
MedLine Citation:
PMID:  2496092     Owner:  NLM     Status:  MEDLINE    
The role of phrenic afferents in controlling inspiratory duration (TI) at elevated end-expiratory lung volume (EEV) has been studied in pentobarbital-anesthetized, spontaneously breathing cats with intact vagi. Responses to increases in EEV, induced by imposition of an expiratory threshold load (ETL) of 10 cmH2O, were monitored before and after section of cervical dorsal roots C3-C7. The immediate (first-breath) effect of application of ETL was a prolongation of both TI and expiratory duration (TE). After 10 min of breathing against the ETL, average TI returned to control values but TE remained prolonged. Abolishing feedback from the diaphragm did not affect these responses. When steady-state responses to ETL were compared with those elicited by inhalation of 5-6% CO2 in O2, changes in EEV had, on average, no independent effect on respiratory drive (rate of rise of integrated phrenic activity), although phrenic activity increased greatly in some cats despite little or no change in arterial partial pressure of CO2. These data indicate that diaphragmatic receptors do not contribute to either the immediate (first-breath) or steady-state responses of phrenic motoneurons to increases in EEV in intact cats.
S Iscoe
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  66     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1989 Mar 
Date Detail:
Created Date:  1989-06-02     Completed Date:  1989-06-02     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:  1297-303     Citation Subset:  IM    
Department of Physiology, Queen's University, Kingston, Ontario, Canada.
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MeSH Terms
Afferent Pathways / physiology*
Carbon Dioxide / pharmacology
Electric Stimulation
Ganglia, Spinal / physiology
Lung / drug effects,  innervation*,  physiology
Lung Volume Measurements
Phrenic Nerve / physiology*
Reference Values
Trachea / physiology
Reg. No./Substance:
124-38-9/Carbon Dioxide

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