Document Detail

Augmentation of Hypoxic Respiration after Brief Hyperoxia in the Anesthetized Cat: Putative Function of GABA(A) Neurotransmission.
MedLine Citation:
PMID:  15067215     Owner:  NLM     Status:  MEDLINE    
In this study, we attempted to determine the role of GABA neurotransmission in augmentation of hypoxic respiration by antecedent hyperoxic breathing. The experiments were performed in anesthetized, paralyzed and vagotomized cats divided into control and bicuculline (a GABA(A) receptor blocker)-injected groups. The experimental protocol consisted of exposing the animals to successive hypoxic-hyperoxic-hypoxic conditions. Respiration was assessed using phrenic electroneurograms, from which the peak phrenic height, a surrogate of the tidal volume component, and respiratory rate were obtained, and their product, the respiratory minute output, was calculated. We found that prior hyperoxic ventilation increased the subsequent respiratory response to hypoxia by an average of 23.5%, compared with the preoxygen response. This increase was driven by volume respiration. The biphasic character of the hypoxic respiratory response, consisting of stimulatory and depressant phases, was sustained. Bicuculline abolished the augmentative effect on hypoxic respiration of prior hyperoxia, which suggests that oxygenation induces GABA(A)-mediated hyperexcitability of respiratory neurons, possibly by the liberation of reactive oxygen species. We concluded that GABA neurotransmission is pertinent to the effect of hyperoxia on hypoxic respiratory reactivity.
Mieczysław Pokorski; Magdalena Marczak; Urszula Jernajczyk
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biomedical science     Volume:  11     ISSN:  1021-7770     ISO Abbreviation:  J. Biomed. Sci.     Publication Date:    2004 May-Jun
Date Detail:
Created Date:  2004-04-06     Completed Date:  2004-12-06     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421567     Medline TA:  J Biomed Sci     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  322-30     Citation Subset:  IM    
Copyright Information:
Copyright 2004 National Science Council, ROC and S. Karger AG, Basel
Department of Respiratory Research, Medical Research Center, Polish Academy of Sciences, Warsaw, Poland.
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MeSH Terms
Anoxia / physiopathology*
Hyperoxia / physiopathology*
Receptors, GABA-A / physiology*
Synaptic Transmission / physiology*
Reg. No./Substance:
0/Receptors, GABA-A

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