Document Detail


Sites of action of halothane on respiratory pattern and ventilatory response to CO2 in cats.
MedLine Citation:
PMID:  6814302     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To assess the major sites of action of halothane on the control of breathing, the ventilatory response to CO2 was studied in 11 cats and partitioned into tidal volume and frequency response. In these cats artificial perfusion of the ponto-medullary region was applied. In essence, this technique allows one to deliver to the brainstem blood-gas tensions and anesthetic concentrations at predetermined levels which are independent from those in the systemic circulation; thus the central and peripheral effects of halothane and CO2 can be determined separately. In cats exposed both centrally and peripherally to halothane (1.0-1.6%) tachypnea was observed which disappeared when the blood perfusing the brainstem was purged of halothane. From these results is follows that the tachypnea is exclusively due to an action of halothane on structures in the brainstem. In these cats the extrapolated Paco2 at zero ventilation was significantly lower during general halothane anesthesia than during light chloralose-urethane anesthesia (P less than 0.05). In cats lightly anesthetized with chloralose-urethane, halothane (0.5-1.5%) was either administered centrally or peripherally. In these experiments the "overall" ventilatory CO2 sensitivity of both the peripheral and central chemorereflex pathways decreased significantly (P less than 0.01). However, the ratio between these two sensitivities remained the same (P less than 0.5). The extrapolated Paco2 at zero ventilation was not affected by halothane provided its concentration was below 1% (P less than 0.7). From these results we conclude that the depressant effect of halothane on ventilation originates centrally as well as peripherally. Furthermore, from the findings that the ratio of the CO2 sensitivities and the extrapolated Paco2 at zero ventilation remained constant, the authors argue that halothane acts on the processing part of the neural respiratory drive (integrating centers) rather than on the neural activity of the peripheral and central chemoreceptors per se. The peripheral effect is mainly on the neuromechanical link between integrating centers and respiratory movements.
Authors:
A Berkenbosch; J de Goede; C N Olievier; P H Quanjer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  57     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  1982 Nov 
Date Detail:
Created Date:  1982-12-16     Completed Date:  1982-12-16     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  389-98     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Carbon Dioxide / blood,  pharmacology*
Cats
Chemoreceptor Cells / drug effects*
Chloralose / pharmacology
Depression, Chemical
Female
Halothane / pharmacology*
Male
Perfusion / methods
Respiration / drug effects*
Respiratory Center / drug effects*
Tidal Volume
Urethane / pharmacology
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 151-67-7/Halothane; 15879-93-3/Chloralose; 51-79-6/Urethane

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


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