@article {Pendleton623, author = {R G Pendleton and C Kaiser and G Gessner}, title = {Studies on adrenal phenylethanolamine N- methyltransferase (PNMT) with S K \& F 64139, a selective inhibitor.}, volume = {197}, number = {3}, pages = {623--632}, year = {1976}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {SK\&F 64139 is a potent, reversible inhibitor of phenylethanolamine N-methyltransferase; its IC50 concentration in our standard assay system was 1 X 10(-7) M. Kinetically, the compound is a competitive inhibitor with respect to norepinephrine but is uncompetitive when S-adenosylmethionine is the variable substrate. In contrast to a previously reported compound (SK\&F 7698), the drug is only a weak alpha receptor antagonist (KB = 6 X 10(-6) M). In both the rat and squirrel monkey, SK\&F 64139 produced dose-dependent decreases in the adrenal epinephrine content coupled with stoichiometrically equivalent increases in the norepinephrine pool(s). Further evidence for in vivo phenylethanolamine N-methyltransferase inhibitory activity was that the drug markedly inhibited the conversion of a tracer dose of 3H-norepinephrine to 3H-epinephrine in the rat adrenal gland after unit oral doses as low as 5 mg/kg.}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/197/3/623}, eprint = {https://jpet.aspetjournals.org/content/197/3/623.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }