Abstract

3,4-Dihydroxyphenethylamine (dopamine) was shown to exhibit two properties when administered in vivo. It both released norepinephrine from sympathetic tissue and stimulated its synthesis. These findings explain how dopamine can cause norepinephrine release, with its consequent pharmacologic response, without effecting a net change in tissue norepinephrine levels. It may be necessary to revise our ideas concerning the mechanism of the pharmacologic effects of both dopamine and dopa to take into account the dual action of dopamine.