PT - JOURNAL ARTICLE AU - R R Ruffolo, Jr AU - K S Anderson AU - D D Miller TI - Conformational requirements of alpha 2-adrenergic receptors. DP - 1982 Mar 01 TA - Molecular Pharmacology PG - 259--261 VI - 21 IP - 2 4099 - http://molpharm.aspetjournals.org/content/21/2/259.short 4100 - http://molpharm.aspetjournals.org/content/21/2/259.full SO - Mol Pharmacol1982 Mar 01; 21 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.