Biological activity of 3-methoxy-catecholamines.

The methoxy analogs of epinephrine, norepinephrine, and dopamine manifest some activity on smooth muscle and blood pressure. Metanephrine is as potent as epinephrine on rabbit aortic strips. The same compounds demonstrate a lesser potency on rabbit duodenum preparation, while 3-methoxy-dopamine produces a slight contraction of the duodenum. Both metanephrine and 3-methoxy-dopamine have 15 to 25 percent of the pressor activity of the original nonmethylated catecholamines. Normetanephrine is 1/600 as active as norepinephrine on the blood pressure of the cat.