No abstract

Dopamine (3,4-dihydroxyphenylethylamine) is considered to be the immediate metabolic precursor of norepinephrine (1), from which it differs by the absence of a P-OH group. Despite this chemical similarity, previous studies of the action of dopamine (2-9) have demonstrated that many of the circulatory and metabolic effects of this catecholamine are different from those produced by norepinephrine. Horwitz, Fox, and Goldberg (6) observed that intravenous administration of dopamine to normal subjects produced consistent increases in cardiac output and either decreased or did not change peripheral resistance. Norepinephrine, on the other hand, decreases or does not change cardiac output and increases peripheral resistance in normal subjects (10). The circulatory effects of dopamine are potentiated by monoamine oxidase inhibitors to a much greater extent than are those of norepinephrine (9). Dopamine also contrasts with norepinephrine in its failure to increase circulating free fatty acids (7,8). These differences suggest that the effects of

No abstract

No abstract