Document Detail

Scaling of respiratory variables and the breathing pattern in adult marsupials.
MedLine Citation:
PMID:  7604187     Owner:  NLM     Status:  MEDLINE    
Oxygen consumption (VO2) and a number of components of the breathing pattern were measured in 14 species of non-fossorial marsupials ranging in mass from 0.008 to 30 kg. All the exponents of the allometric relationships for VO2, ventilation (VE) and breathing pattern scaled as previously determined for eutherians. However, compared to eutherians, marsupials had significantly lower VO2 and the breathing pattern was deeper (+23%) and slower (-31%). While VE was not significantly below that reported for eutherians it matched VO2 such that VE/VO2 remained mass-independent and at a level similar to that observed in the other infraclasses of mammals. Thus, it would appear that the increase in metabolic rate that occurred during the evolution of mammalian homeothermy was accompanied by parallel changes in VE. It is suggested that these changes in VE were mediated by a shortening of the respiratory cycle, facilitated by the eventual abolition of the end-expiratory pause (TP), and an increase in respiratory drive (VT/TI). In response to 5% CO2 all animals in this study increased their VE by increasing both tidal volume (VT) and frequency (f), predominantly through the removal of TP. The increase in VE was less than previously reported for eutherians, suggesting a reduction in chemosensitivity in marsupials. Furthermore, the similarity in slopes for VE, VT and f between air and 5% CO2 suggests that the gain of the respiratory system is independent of species size within marsupials.
P B Frappell; R V Baudinette
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiration physiology     Volume:  100     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1995 Apr 
Date Detail:
Created Date:  1995-08-07     Completed Date:  1995-08-07     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  83-90     Citation Subset:  IM    
School of Zoology, La Trobe University, Melbourne, Vic., Australia.
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MeSH Terms
Body Weight
Hypercapnia / physiopathology
Marsupialia / physiology*
Oxygen Consumption / physiology
Respiration / physiology*
Respiratory Function Tests

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