Medetomidine stereoisomers delineate two closely related subtypes of idazoxan (imidazoline) I-receptors in the guinea pig.
A number of imidazoline, imidazole and guanidinium compounds and other drugs were compared for their ability to bind to non-adrenergic idazoxan (imidazoline) I-receptors in particulate guinea pig cerebral cortex and ileum smooth muscle fractions. Radioligand binding with [3H]idazoxan was used for the experiments. Computer modelling of the binding data gave dissociation constants for drug binding to both I-receptors and alpha 2-adrenoceptors. Most drugs showed similar affinities for I-receptors in cortex and ileum. However, medetomidine stereoisomers as well as a few other drugs clearly delineated the I-receptors in cortex and ileum as different.
Department of Pharmacology, Umeå University, Sweden.
J E
JE
Wikberg
S
S
Uhlén
V
V
Chhajlani
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004146:Dioxanes / Q000494:pharmacology; D006168:Guinea Pigs; D019329:Idazoxan; D007082:Ileum / Q000378:metabolism / Q000648:ultrastructure; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D020926:Medetomidine; D009130:Muscle, Smooth / Q000378:metabolism / Q000648:ultrastructure; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D011955:Receptors, Drug / Q000187:drug effects / Q000378:metabolism*; D013237:Stereoisomerism; D014316:Tritium
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; D011955:Receptors, Drug; C064580:idazoxan receptor; D014316:Tritium; C041255:detomidine; D020926:Medetomidine; D019329:Idazoxan