TY - JOUR T1 - THE DEPLETION OF CARDIAC NOREPINEPHRINE BY 3,5-DIHYDROXY-4-METHOXYPHENETHYLAMINE AND RELATED COMPOUNDS JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 46 LP - 54 VL - 158 IS - 1 AU - C. R. Creveling AU - J. W. Daly AU - B. Witkop Y1 - 1967/10/01 UR - http://jpet.aspetjournals.org/content/158/1/46.abstract N2 - A comparison was made of the ability of phenolic phenethylamines and their O-methyl congeners to deplete both prelabeled cardiac H3-norepinephrine and endogenous norepinephrine stores in the mouse. O-methyl derivatives were inactive with the notable exception of 3,5-dihydroxy-4-methoxyphenethylamine, which proved to be an effective releasing agent. The ED50 of this amine, the β-hydroxylated analog and 3,4,5-trihydroxyphenethylamine was determined and compared to reserpine, l-metaraminol, 6-OH dopamine and tyramine. The effects of cocaine and bretylium on the release of norepinephrine induced by these trioxy amines were determined. The metabolism of H3-norepinephrine in the isolated perfused rat heart during release with 3,5-dihydroxy-4-methoxyphenethylamine was compared to the metabolism obtained with reserpine and tyramine perfusion. A shift toward metabolism by monoamine oxidase was observed and a marked increase in the release of free catecholamine. Evidence is presented showing that 3, 5-dihydroxy-4-methoxyphenethylamine was taken up by the heart and converted to the β-hydroxylated analog in vivo; also, this amine was shown to be a substrate for dopamine-β hydroxylase in vitro. © 1967 by The Williams & Wilkins Company ER -