Factors Influencing Dopamine β-Hydroxylase Activity and Epinephrine Levels in Guinea Pig Adrenal Gland

Abstract

An assay method was developed to permit measurement of dopamine β-hydroxylase [EC 1.14.2.1] activity in a pair of adrenal glands from a single guinea pig or rabbit. By using this method, the changes of dopamine βhydroxylase activity after various experimental procedures and during development were measured. It was found that in guinea pig adrenals dopamine β-hydroxylase and epinephrine are essentially absent at birth but reach adult values within 5 days after birth. The enzyme activity is relatively unaffected by hormones, rescrpine and even severe ascorbic acid deficiency. Only two experimental procedures were found to lower dopamine β-hydroxylase activity, administration of thyroxine or benzyloxyamines. The latter are potent inhibitors of the enzyme.