Abstract
To define the antagonist pharmacology of spinal antinociceptive effects of alpha 2-adrenoceptor agonists, the ability of WB4101 (2-(2,6-dimethoxyphenoxyethyl)-aminomethyl-1,4-benzodioxane) and imiloxan to antagonize the effect of spinal ST-91 (2-[2,6-diethylphenylamino]-2-imidazoline), clonidine and dexmedetomidine was examined. Antinociceptive effects of ST-91 were antagonized by WB4101 and imiloxan; clonidine only by WB4101; and, dexmedetomidine was not antagonized by either antagonist. It is hypothesized that the alpha 2 adrenoceptor subtype alpha 2A is involved in the antinociception of spinal clonidine and dexmedetomidine, and alpha 2B is involved in that of ST-91.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adrenergic alpha-Agonists / administration & dosage
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Adrenergic alpha-Agonists / pharmacology
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Adrenergic alpha-Antagonists / administration & dosage
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Adrenergic alpha-Antagonists / pharmacology*
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Animals
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Clonidine / administration & dosage
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Clonidine / analogs & derivatives
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Clonidine / pharmacology
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Dioxanes / administration & dosage
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Dioxanes / pharmacology*
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Dose-Response Relationship, Drug
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Imidazoles / administration & dosage
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Imidazoles / pharmacology*
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Injections, Spinal
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Male
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Medetomidine
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Nociceptors / drug effects
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Nociceptors / physiology*
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Rats
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Rats, Sprague-Dawley
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Receptors, Adrenergic, alpha / analysis
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Receptors, Adrenergic, alpha / physiology*
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Spinal Cord / chemistry
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Spinal Cord / drug effects
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Spinal Cord / physiology*
Substances
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Adrenergic alpha-Agonists
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Adrenergic alpha-Antagonists
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Dioxanes
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Imidazoles
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Receptors, Adrenergic, alpha
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ST 91
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(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane
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Clonidine
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Medetomidine
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Imiloxan