Document Detail

Role of glutamate in the nucleus isthmi on the hypoxia- and hypercarbia-induced hyperventilation of toads.
MedLine Citation:
PMID:  12706065     Owner:  NLM     Status:  MEDLINE    
The nucleus isthmi (NI) is a mesencephalic structure of the amphibian brain that has been reported to participate in CO(2) chemoreception and in the ventilatory response to hypoxia. In the present study, we assessed the role of glutamatergic transmission inside the NI on the hypoxic and hypercarbic drive to breathing. We compared the respiratory responses to 7 and 5% inspired O(2) and 3% inspired CO(2) after microinjecting 10 nmol/100 nl of kynurenic acid (an antagonist of L-glutamate receptors) into the NI of toads (Bufo paracnemis). Kynurenic acid had no effect under resting conditions. Both hypoxia and hypercarbia elicited an increase in ventilation in all groups, with hypoxia acting on tidal volume (V(T)) and hypercarbia on frequency (f). The microinjection of kynurenic acid into the NI caused an increased ventilatory response to hypoxia and hypercarbia due to a higher V(T). We conclude that glutamatergic transmission in the NI has an inhibitory effect when the respiratory drive is high, acting on V(T).
Luciane H Gargaglioni; Luiz G S Branco
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  135     ISSN:  1569-9048     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-04-22     Completed Date:  2003-07-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  47-58     Citation Subset:  IM    
Department of Morphology, Estomatology and Physiology, Faculdade de Odontologia de Ribeirão Preto, Dental School of Ribeirão Preto, University of São Paulo, 14040-904, SP, Ribeirão Preto, Brazil.
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MeSH Terms
Anoxia / complications,  physiopathology*
Bufonidae / physiology*
Carbon Dioxide
Excitatory Amino Acid Antagonists / administration & dosage,  pharmacology
Glutamic Acid / metabolism*
Hypercapnia / complications,  physiopathology*
Hyperventilation / etiology,  metabolism*
Injections, Intraventricular
Kynurenic Acid / administration & dosage,  pharmacology
Mesencephalon / drug effects,  metabolism
Pulmonary Ventilation / drug effects*,  physiology
Reg. No./Substance:
0/Excitatory Amino Acid Antagonists; 124-38-9/Carbon Dioxide; 492-27-3/Kynurenic Acid; 56-86-0/Glutamic Acid

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