Document Detail


Mechanism of cardiovascular effects of clonidine in conscious and anesthetized rabbits.
MedLine Citation:
PMID:  195037     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The actions of intravenous clonidine [2-(2,6 dichlorophenylamino)-2-imidazoline hydrochloride] on blood pressure and heart rate were examined in conscious rabbits. Complete transection of thecervical spinal cord increased the intensity and duration of the hypertensive effect of 30 microgram/kg of clonidine and completely abolished the fall in blood pressure. Heart rate slowing by clonidine was reduced. Result were similar 1 hour, 24 hours and 7 days after cord transection. Bilateral aortic sinus nerve section (baroreceptor deafferentation) increased both the hypertensive and hypotensive action of clonidine but reduced the bradycardia. When cervical cord transection was combined with batensive action, were abolished. We conclude that whereas the hypertensive action results from a direct effect on peripheral adrenoceptors, the fall in blood pressure is related to a reduction in sympathetic tone mediated at the level of the brain stem or more rostrally. The heart rate slowing results from both a reduction in sympathetic tone and also an enhanced vagal outflow. The increase in vagal tone seems to be dependent on the intergrity of baroreceptor afferent pathways.
Authors:
K K Tangri; M Petty; L M Wing; J L Reid
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  202     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1977 Jul 
Date Detail:
Created Date:  1977-08-25     Completed Date:  1977-08-25     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  69-75     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Aorta / innervation
Blood Pressure / drug effects
Carotid Sinus / innervation
Clonidine / pharmacology*
Cordotomy
Denervation
Heart Rate / drug effects
Hemodynamics / drug effects*
Male
Norepinephrine / metabolism
Phenylephrine / pharmacology
Pressoreceptors / physiology
Rabbits
Receptors, Adrenergic, alpha / drug effects
Spinal Cord / metabolism,  physiology
Time Factors
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, alpha; 4205-90-7/Clonidine; 51-41-2/Norepinephrine; 59-42-7/Phenylephrine

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


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