STUDIES ON DISTRIBUTION OF PHENYLETHANOLAMINE N-METHYLTRANSFERASE AND EPINEPHRINE IN RAT

Abstract

Using 2 independent criteria, the enzyme phenylethanolamine N-methyltransferase (PNMT) was found to be present in the adrenals, lungs, brain stem, spleen, heart and skeletal muscle of the rat. The lungs contained more activity than the brain stem or any other extra-adrenal organ. PNMT was not detectable in the kidneys, stomach, liver and plasma. Trace amounts of epinephrine were found in brain stem, lung and heart; norepinephrine, was the predominant catecholamine in these tissues. Substantial quantities of epinephrine were found in the adrenal and plasma of decapitated animals, but the latter were essentially eliminated by adrenal demedullation. Although the adrenal is the principal tissue source of epinephrine and PNMT in the rat, small amounts of both substances are present in several body organs.