title: Epinephrine enantiomers: affinity, efficacy and potency relationships in rat smooth muscle tissues.
abstract: The purpose of this study was to examine the relationship between affinity and efficacy for the epinephrine enantiomers in rat tissues. Potency and was measured for (-)- and (+)-epinephrine in aorta, longitudinal muscle of portal vein, spleen and vas deferens. After partial alpha-adrenoreceptor inactivation with phenoxybenzamine, dissociation constant was estimated for each enantiomer and used to estimate efficacy. Whereas potency, affinity and efficacy vary between tissues, there is a constant relationship between (-)- and (+)-enantiomer; the enantiomeric ratio is constant for both potency and affinity. Efficacy is similar for the enantiomers in each tissue. The potency difference between epinephrine enantiomers at alpha-adrenoreceptors in rat tissues is due to differences in affinity rather than efficacy.
authors.affiliation: Division of Pharmacology, Ohio State University College of Pharmacy, Columbus.
authors.forename: P J
authors.initials: PJ
authors.lastname: Rice
authors.forename: D D
authors.initials: DD
authors.lastname: Miller
authors.forename: P N
authors.initials: PN
authors.lastname: Patil
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects*; D011169:Portal Vein / Q000187:drug effects; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism; D013154:Spleen / Q000187:drug effects; D013237:Stereoisomerism; D014649:Vas Deferens / Q000187:drug effects
chemical_list: D011942:Receptors, Adrenergic, alpha; D004837:Epinephrine