RT Journal Article SR Electronic T1 Conformational requirements of alpha 2-adrenergic receptors. JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 259 OP 261 VO 21 IS 2 A1 Ruffolo, R R A1 Anderson, K S A1 Miller, D D YR 1982 UL http://molpharm.aspetjournals.org/content/21/2/259.abstract AB The conformationally restrained trans-extended and cis-folded isomers of 2-(3,4-dihydroxyphenyl)cyclobutylamine were used to establish the conformational requirements of presynaptic alpha 2-adrenergic receptors in the field-stimulated guinea pig ileum. The trans-extended isomer produced a concentration-dependent inhibition of the twitch response with an EC50 of 34 microM. The cis-folded analogue failed to produce a significant inhibition of the twitch response at concentrations up to 1 mM. These results suggest that the presynaptic alpha 2-adrenergic receptor prefers phenethylamines in the trans-extended conformation over the cis-folded conformation. The conformational requirements of alpha 1- and alpha 2-adrenergic receptors appear to be similar.