(Imidazolinyl-2)-2-benzodioxane 1-4 (idazoxan) and its stereoisomers, new alpha 2-antagonists.
Since (+/-) idazoxan is well known as alpha 2-antagonist, the present report described some results on the alpha-adrenoceptor blocking properties of the stereoisomers of idazoxan. At peripheral sites, (+) idazoxan revealed to be equipotent for blocking postsynaptic alpha 1- and alpha 2-adrenoceptors of the rat. On the other hand, it revealed to be a full antagonist of the inhibitory effects of clonidine on presynaptic alpha 2-adrenoceptors of rats. However, in vitro investigations have shown (+) idazoxan to be less selective than (-) idazoxan for alpha 2-adrenoceptors. (-) Idazoxan was selective for postsynaptic alpha 2-adrenoceptors and antagonized presynaptic alpha 2-adrenoceptors of the rat. Results obtained in central investigations revealed species differences between chickens and mice. The present results led to the conclusion that (+) idazoxan was equipotent on alpha 1- and alpha 2-adrenoceptors whereas (-) idazoxan was selective for alpha 2-adrenoceptors. On the other hand, they suggested a stereoselectivity of peripheral and central alpha 2-adrenoceptors for alpha-antagonists.
Dabiré
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H
Mouille
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Schmitt
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H
D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002645:Chickens; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology*; D004147:Dioxins / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D019329:Idazoxan; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014649:Vas Deferens / Q000187:drug effects
D001381:Azepines; D004146:Dioxanes; D004147:Dioxins; D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; C015603:azepexole; D003000:Clonidine; C014282:cirazoline; D019329:Idazoxan