title: Effects of ring substitution on the pre- and postjunctional alpha-adrenergic activity of aryliminoimidazolidines.
abstract: The pre- and postjunctional alpha-adrenergic agonist potency of a series of aryliminoimidazolidines was determined in the isolated rabbit ear artery. This series included clonidine, an antihypertensive agent thought to act by stimulating brainstem alpha-receptors and known to be a preferentially prejunctional alpha-adrenergic agonist. Although all of the compounds acted preferentially on the prejunctional alpha-adrenoceptor, ring substitution had a dramatic effect on both potency and the degree of selectivity. 2-(3,4-Dihydroxyphenylimino) imidazolidine was both the most potent and most selective prejunctional alpha-agonist in this series.
mesh_terms: D000316:Adrenergic alpha-Agonists; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation; D003000:Clonidine / Q000494:pharmacology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011817:Rabbits; D013329:Structure-Activity Relationship; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D007093:Imidazoles; D003000:Clonidine