A Highly Sensitive Assay for Phenylethanolamine N-Methyltransferase in Human Brain

Publisher Website
Google Scholar
Abstract
A rapid, highly sensitive assay for phenylethanolamine N-methyltransferase in brain using the natural substrate, norepinephrine, is described. The method is based on the selective absorption and elution of the reaction product, epinephrine, from alumina. A small but important further lowering of blanks and increase in sensitivity is attained by removal of the radiolabeled substrate, [methyl-3H]-S-adenosylmethionine by precipitation as the reineckate prior to absorption could be measured in as little as 1 mg (wet wt) of human locus coeruleus tissue. The sensitivity is enhanced by homogenizing tissue in small volumes and removing potential inhibitors by dialysis. We report for the first time PNMT activity in specific regions of the human cerebral and cerebellar cortex.