Document Detail

Ventilation and oxygen consumption during acute hypoxia in newborn mammals: a comparative analysis.
MedLine Citation:
PMID:  2813986     Owner:  NLM     Status:  MEDLINE    
We asked whether the lack of sustained hyperventilation during acute hypoxia, often reported to occur in the infant, is a common characteristic among newborn mammalian species, and to which extent inter-species differences may be accounted for by differences in metabolic responses. Ventilation (VE) and breathing pattern have been measured by flow-plethysmography or by the barometric method in normoxia and after 10 min of 10% O2 breathing in newborn mammals of 17 species over a 3 g to 20 kg range in body size. In 14 of these species oxygen consumption (VO2) has also been measured by a manometric technique or by calculation from the changes in chamber O2 pressure. VE and VO2 changed in proportion, among species, both in normoxia and hypoxia. In hypoxia, VE was higher, similar, or even lower than in normoxia, with some relation to the degree of maturity of the species at birth. In general, the small or absent VE responses to hypoxia resulted from small or no increase in tidal volume, while breathing frequency stayed elevated. The few departures from this pattern could be explained by interspecies differences in hypoxic sensitivity, since additional experiments in kittens and puppies indicated that, with more severe hypoxia, the pattern changed from rapid and shallow to deep and slow. In all cases, irrespective of the magnitude of the VE response, the VE/VO2 (and the mean inspiratory flow/VO2) increased during hypoxia, because the drop in VE, when present, was accompanied by an even larger drop in VO2. In fact, VO2 in hypoxia decreased in most species, although to variable degrees. Body temperature either did not change or decreased slightly, possibly indicating a trend toward a decrease of the set point of thermoregulation during hypoxia. In conclusion, the analysis gave further support to the concept that, during acute hypoxia, changes in metabolic rate play a paramount role in the ventilatory response of the newborn mammal.
J P Mortola; R Rezzonico; C Lanthier
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiration physiology     Volume:  78     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1989 Oct 
Date Detail:
Created Date:  1989-12-14     Completed Date:  1989-12-14     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  31-43     Citation Subset:  IM; S    
Department of Physiology, Mc Gill University, Montreal, Quebec, Canada.
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MeSH Terms
Animals, Newborn / physiology*
Anoxia / physiopathology*
Body Temperature
Oxygen Consumption / physiology*
Pulmonary Circulation / physiology*

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