NONADRENAL EPINEPHRINE-FORMING ENZYMES IN HUMANS - CHARACTERISTICS, DISTRIBUTION, REGULATION, AND RELATIONSHIP TO EPINEPHRINE LEVELS

Animal studies indicate that nonadrenal tissues may synthesize epineph rine (E), Here we demonstrate phenylethanolamine N-methyltransferase ( PNMT) and/or nonspecific N-methyltransferase (NMT) enzymatic activity in human lung, kidney, heart, liver, spleen, and pancreas, There was a significant overall correlation (r = 0.34) between tissue PNMT and E, PNMT and NMT in human tissues differed in substrate and inhibitor spe cificity, thermal stability, and antigenicity, By these criteria, PNMT in human lung and in human bronchial epithelial cells were indistingu ishable from adrenal PNMT. PNMT and/or NMT activity were present in re d blood cells (RBCs), and cancer cell lines, Human kidney, lung, and p ancreas showed immunohistochemical staining with an antibody to adrena l PNMT, RBC PNMT activity was lower in males than females and was incr eased in hyperthyroidism and decreased in hypothyroidism, PNMT activit y in a human bronchial epithelial cell line was dramatically increased by incubation with dexamethasone, E and H-3-E levels in plasma and ur ine during an intravenous infusion of H-3-E into humans indicated ghat kidney may synthesize half of urinary E, We conclude that PNMT and NM T are widely distributed in human tissues, that they may synthesize E in vivo and are influenced by glucocorticoid and thyroid hormones.