Document Detail


Cardiovascular responses to chemoreflex activation with potassium cyanide or hypoxic hypoxia in awake rats.
MedLine Citation:
PMID:  12132643     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Although intravenous (iv) injection of potassium cyanide (KCN) activates the arterial chemoreflex, it has been questioned whether cytotoxic hypoxia reproduces a physiological stimulus such as hypoxic hypoxia (low inspired O2 tension). Thus, the goal of the present study was to compare the cardiovascular responses elicited by intravenous injection of KCN to those caused by hypoxic hypoxia in awake rats before and after bilateral ligature of carotid body arteries. We tested the hypothesis that hypoxic hypoxia activates the cardiovascular chemoreflex just as KCN does, causing an increase in arterial pressure and bradycardia. Intact adult Wistar rats received an intravenous injection of KCN (160 microg/kg) and were exposed to hypoxic hypoxia (7-5% O2 breathing) for 10-15 s at random while mean arterial pressure (MAP) and heart rate (HR) were measured. After the experiments, the animals were submitted to bilateral ligature of carotid body arteries or sham operation and the protocol was repeated on the subsequent day. Before surgery, all rats showed an abrupt rise in arterial pressure accompanied by a marked bradycardia in response to KCN or hypoxic hypoxia, with a very similar pattern. After surgery, these responses persisted only in the sham-operated group and were totally abolished in the ligature group. In conclusion, our data show that KCN is an appropriate stimulus to activate arterial chemoreflex because its cardiovascular responses are comparable to those induced by hypoxic hypoxia. Thus, the use of KCN as a tool to evaluate different aspects of the complex pattern of cardiovascular, respiratory, and behavioural responses to chemoreflex activation seems to be physiologically acceptable.
Authors:
Renata C H Barros; Leni G H Bonagamba; Roberta Okamoto-Canesin; Mauro de Oliveira; Luiz G S Branco; Benedito H Machado
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Autonomic neuroscience : basic & clinical     Volume:  97     ISSN:  1566-0702     ISO Abbreviation:  Auton Neurosci     Publication Date:  2002 May 
Date Detail:
Created Date:  2002-07-22     Completed Date:  2003-01-13     Revised Date:  2009-08-12    
Medline Journal Info:
Nlm Unique ID:  100909359     Medline TA:  Auton Neurosci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  110-5     Citation Subset:  IM    
Affiliation:
Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil.
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MeSH Terms
Descriptor/Qualifier:
Animals
Anoxia / physiopathology*
Blood Pressure / drug effects
Cardiovascular System / drug effects*
Chemoreceptor Cells / drug effects*,  physiology
Enzyme Inhibitors / pharmacology*
Heart Rate / drug effects
Male
Potassium Cyanide / pharmacology*
Rats
Rats, Wistar
Reflex / drug effects*,  physiology
Wakefulness
Chemical
Reg. No./Substance:
0/Enzyme Inhibitors; 151-50-8/Potassium Cyanide

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


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