these data show that ( - ) -erythro-alpha-methylnorepinephrine and ( - ) -erythro-alpha-methylepinephrine compete with high affinity for alpha-2 receptors , thereby supporting the suggestion that alpha-2 receptors mediate hypotensive effects of l-alpha-methyldopa . furthermore , these metabolites of l-alpha-methyldopa competed with high potency for beta-1 receptors in forebrain and ( - ) -erythro-alpha-methylepinephrine was more potent than ( - ) -epinephrine , ( - ) -norepinephrine and ( - ) -erythro-alpha-methylnorepinephrine in competing for beta-2 receptors on human lymphocytes .
C0028351
norepinephrine
C0025805
alpha-methylnorepinephrine