STUDIES ON THE BIOGENESIS AND METABOLISM OF NOREPINEPHRINE IN PATIENTS WITH PHEOCHROMOCYTOMA*

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Abstract
Chemical studies on 7 patients with pheochromocytoma are presented. Studies with C14 labeled precursors in vitro and in vivo corroborate present concepts of the biogenesis of norepinephrine from dihydroxyphenylalanine and dihydroxyphenylethylamine. Enzymes involved in the biogenesis and metabolism of norepinephrine were demonstrated in the tumors. The 3-methoxy analogue of norepinephrine (normetanephrine) was found in each of 4 pheochromocytomas studied. This is the 1st demonstration of this amine in human tissue. Preliminary evidence indicates that the 2 major urinary metabolites of norepinephrine in patients with this tumor are normetanephrine and 3-methoxy-4-hydroxymandelic acid. Measurements of these compounds may afford an alternate means of diagnosis. Estimations of norepinephrine turnover rate in 3 patients suggest a relatively short half-life in some pheochromocytomas as compared to animal adrenal glands. Some implications of these findings are discussed.