Document Detail

Motor and cardiovascular effects of selective alpha 2-adrenoceptor antagonists in the decerebrated rabbit.
MedLine Citation:
PMID:  8103464     Owner:  NLM     Status:  MEDLINE    
In the decerebrated rabbit, intrathecal administration of the alpha 2-adrenoceptor antagonists idazoxan and yohimbine increases reflex responses of gastrocnemius motoneurones to electrical stimulation of the sural nerve. The maximum effect of idazoxan is about twice that of yohimbine, suggesting that part of the effect of idazoxan may be due to an action at non-adrenergic idazoxan or imidazoline binding sites. RX811059 and RX821002 are selective alpha 2-adrenoceptor antagonists with minimal affinity for imidazoline binding sites. In the present study it was found that intrathecal administration of these compounds in doses of 5-200 micrograms increased the sural-gastrocnemius reflex to the same level as idazoxan, confirming that this reflex is subject to powerful adrenergic inhibition mediated through spinal alpha 2-adrenoceptors. RX811059 and RX821002 also increased arterial blood pressure and heart rate. A retrospective analysis of data from earlier studies showed that whereas intrathecal yohimbine had increased blood pressure, idazoxan had not. It is possible that idazoxan acts at non-adrenergic idazoxan binding sites to cancel out the hypertensive effects which are associated with alpha 2-adrenoceptor blockade.
J Harris; R W Clarke
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of pharmacology     Volume:  237     ISSN:  0014-2999     ISO Abbreviation:  Eur. J. Pharmacol.     Publication Date:  1993 Jun 
Date Detail:
Created Date:  1993-10-04     Completed Date:  1993-10-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1254354     Medline TA:  Eur J Pharmacol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  323-8     Citation Subset:  IM    
Department of Physiology and Environmental Science, University of Nottingham, Loughborough, Leicestershire, UK.
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MeSH Terms
Adrenergic alpha-Antagonists / administration & dosage,  metabolism,  pharmacology*
Blood Pressure / drug effects*
Decerebrate State
Dioxanes / administration & dosage,  metabolism,  pharmacology
Electric Stimulation
Heart Rate / drug effects*
Injections, Spinal
Motor Neurons / drug effects*,  physiology
Reflex / drug effects
Retrospective Studies
Sural Nerve / drug effects,  physiology
Yohimbine / administration & dosage,  metabolism,  pharmacology
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Dioxanes; 102575-24-6/2-methoxyidazoxan; 146-48-5/Yohimbine; 79944-58-4/Idazoxan; 96576-24-8/ethoxyidazoxan

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

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