Alpha-blocking properties of idazoxan (170150 or RX 781094) and its stereoisomers: applications to bronchomotricity.
The alpha 1- and alpha 2-adrenolytic properties of idazoxan and its stereoisomers were studied on the bronchopulmonary system of unanaesthetized guinea-pigs by testing the effects of these compounds on the phenylephrine-acetylcholine and clonidine-acetylcholine interactions. Idazoxan and its (+) and (-) stereoisomers did not significantly modify the protection exerted by phenylephrine against acetylcholine modify the protection exerted by phenylephrine against acetylcholine (ACh)-induced bronchoconstriction. Idazoxan and its (+) and (-) stereoisomers reduced the potentiation of ACh bronchoconstriction induced by clonidine, but (+) idazoxan was more potent than (-) and (+/-) idazoxan. As (+) idazoxan appeared to be a preferential alpha 2 central adrenoceptor blocking agent, these results seem to indicate that the site of action of clonidine in bronchomotor responses is the central nervous system.
Floch
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Advenier
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D000109:Acetylcholine / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000403:Airway Resistance / Q000187:drug effects; D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology*; D004147:Dioxins / Q000494:pharmacology*; D004347:Drug Interactions; D006168:Guinea Pigs; D019329:Idazoxan; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D013237:Stereoisomerism
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D004147:Dioxins; D010656:Phenylephrine; D003000:Clonidine; D000109:Acetylcholine; D019329:Idazoxan