Document Detail

Suppression by spinal alpha-2 agonists of motor and autonomic responses evoked by low- and high-intensity thermal stimuli.
MedLine Citation:
PMID:  1346645     Owner:  NLM     Status:  MEDLINE    
In halothane (0.9%)-anesthetized rats, the immersion of the tail in 52.5 degrees C or 60 degrees C water for 15 sec resulted in a short-latencied tail jerk and a subsequent tachycardia and elevation in blood pressure. The i.t. administration of the alpha-2 agonists, dexmedetomidine (DMET), clonidine (CLON) and ST-91, resulted in a dose-dependent increase in the somatomotor reflex latency and a reduction in the magnitude of the increase in the magnitude of the cardiovascular response, with the ordering of activity on all endpoints at all temperatures being: DMET greater than CLON greater than or equal to ST-91. Increasing the stimulus intensity from 52.5 to 60 degrees C resulted in right shifts in the dose-response curves for all agents with the magnitude of shift being: 1) greatest on the blood pressure and least on the tail flick, and 2) greatest for ST-91 and CLON and least for DMET. Thus, the dose ratio (ED50 at 60 degrees C/ED50 at 52.5 degrees C) for these three agents on the tail flick and blood pressure response was, respectively, 1.1 and 1.8 for DMET, 1.1 and 4.3 for CLON and 4.8 and 9.7 for ST-91 (mean +/- S.E.). On resting blood pressure, i.t. DMET and CLON produced a dose-dependent hypotension and bradycardia. ST-91 had no consistent dose-dependent effect.(ABSTRACT TRUNCATED AT 250 WORDS)
S Saeki; T L Yaksh
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  260     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1992 Feb 
Date Detail:
Created Date:  1992-03-17     Completed Date:  1992-03-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  795-802     Citation Subset:  IM    
Department of Anesthesiology, University of California, San Diego, La Jolla.
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MeSH Terms
Adrenergic alpha-Agonists / pharmacology*
Blood Pressure / drug effects
Clonidine / analogs & derivatives,  antagonists & inhibitors,  pharmacology
Heart Rate / drug effects
Hot Temperature*
Imidazoles / antagonists & inhibitors,  pharmacology
Prazosin / pharmacology
Rats, Inbred Strains
Reaction Time / drug effects
Receptors, Adrenergic, alpha / drug effects,  physiology*
Reflex / drug effects*
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Imidazoles; 0/Receptors, Adrenergic, alpha; 19216-56-9/Prazosin; 4205-90-7/Clonidine; 4751-48-8/ST 91; 86347-14-0/Medetomidine

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