Document Detail


Hypoxia-induced periodic breathing in newborn lambs.
MedLine Citation:
PMID:  2507506     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study was designed to elucidate the effect of hypoxia on the breathing rhythmicity and the effect of hypoxia on periodic breathing (PB) in two groups of newborn lambs (less than 2 days and 10 days of age). Lambs undergoing a hypoxic ventilatory test [0.08 inspired O2 fraction (FIo2) for 13 min] experienced no apnea or PB in hypoxia, but all developed PB during the 1-min period immediately after their abrupt return to 0.21 FIo2. This PB occurred when alternation of arterial PO2 and PCO2 in mild hypoxic and hypocapnic conditions induced an overshoot-undershoot response of the chemical drive to breathe. The magnitude of PB was found to be greater in the animals with a higher peripheral chemoreflex sensitivity to hypoxia but ceased altogether when the hypoxic-hypocapnic conditions were resolved. When these conditions were removed more quickly, that is, when the animals were returned either to 0.50 FIo2 or to 0.03 FIco2, no PB was observed. To clarify the role of hypoxia as a central depressant on the genesis of PB, we tested to determine whether additional central tissue hypoxia, using carboxyhemoglobin (30%), would worsen the episodes of PB. No effect on breathing rhythmicity was observed. These findings suggest not only that, in newborn animals and adults, the mechanisms of post-hypoxia-induced PB are identical but that the PB elicited in mild hypoxic conditions is a peripheral chemoreflex-mediated event rather than a centrally mediated one.
Authors:
E Canet; J L Carroll; M A Bureau
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  67     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1989 Sep 
Date Detail:
Created Date:  1989-11-21     Completed Date:  1989-11-21     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:  1226-33     Citation Subset:  IM    
Affiliation:
McGill University, Montreal Children's Hospital Research Institute, Quebec, Canada.
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MeSH Terms
Descriptor/Qualifier:
Age Factors
Animals
Animals, Newborn
Anoxia / physiopathology*
Carbon Dioxide
Chemoreceptor Cells / physiopathology
Disease Models, Animal
Humans
Infant, Newborn
Oxygen
Periodicity*
Respiration*
Sheep
Species Specificity
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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


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