Alpha-and- beta-activity of O-methylated derivatives of norepinephrine and epinephrine

Metanephrine, iso-metanephrine, normetanephrine and isonormetaephrine were tested for alpha- and beta-activity on various tissues obtained from rats, guinea-pigs and cats. It was found that methylation of the hydroxyl groups of norepinephrine or epinephrine in either the 3- or 4-position markedly reduces or abolishes alpha- and beta-activity with the exception of the nictitating membrane of the cat. This receptor seems to show a tissue difference.